a little filter

You need Williams and Taylor's "Electronic Filter Design Handbook"

It is isn't cheap, but everybody here who knows what they are talking about swears by it.

High order Bessell filters do have up to about four times the time delay of a first order filter, but the ripple attenuation goes up much more rapidly with the order of the filter. There are also equi-ripple variants of the pure Bessel filter.

One can also choose the pulse width modulation pattern to minimise the lower frequency ripple components. Sigma Delta modulators have always exploited this since they were invented.

My 1996 paper spelled out a less thorough-going approach optimised for a different situation - fewer (power-dissipating) switching transitions - and not as much minimisation of the lower frequency ripple content.

Sloman A.W., Buggs P., Molloy J., and Stewart D. "long title" Measurement Science and Technology, 7 1653-64

--
Bill Sloman, Sydney

I am not sure if you are asking something.

You're right that filter order increases the delay, ceteris paribus, and it Bessel or Bessel-like helps to minimize ringing. But you seem to want a low-pass filter, which a Bessel is quite nominally (and by accident: its pu rpose is constant delay, not low-pass).

I played with something that has 1.0 ms equi-ripple delay, that could be sc aled. Other things are possible. If you want more rejection, some TX zeros obviously "do something."

Linear phase low-pass filter Equal ripple delay passband Low frequency delay = 1.000000 msec Upper passband edge frequency = 0.001000 MHz Delay ripple =18.022361 usec Passband edge frequency = 0.001000 MHz equal minima stop band with edge frequency= 0.001500 MHz multiplicity of zero at infinity = 2 number of finite transmission zero pairs = 2 overall filter degree = 6 transmission zeros real part imaginary part 0.0000000D+00 2.0999615D+03 0.0000000D+00 1.5476704D+03

1 +---R---+ 50.000000 ohm 2 | L 8.615928 mH 3 +---C---+ 3.325297 uF | .-+. 4 | L C 15.173470 mH res.frequency | `-+' 378.558212 nF 0.002100 MHz 5 +---C---+ 18.380877 uF | .-+. 6 | L C 12.409140 mH res.frequency | `-+' 852.200167 nF 0.001548 MHz 7 +---C---+ 3.091728 uF 9 +---R---+ 50.017324 ohm

It's a discussion group.

Williams calls lowpass Bessels lowpass filters, and I do too. He says (sec 7.3 of 4e) that lowpass filters, including Bessels, are not the most efficient delay lines.

I Spiced that. It's down 3 dB at 393 Hz, so I can scale its frequency response about 1000:1 and compare it to my 350K 3-pole Bessel.

Your scaled 0.1% settling time is about 3.8 us, compared to about 2.7 for the Bessel. Those added stages add delay. The big difference is of course frequency rolloff; my 3p Bessel is -60 dB at 4.8 MHz, and yours is -60 at the equivalent of 1.4 MHz.

It looks like sort of a wash. Your filter could allow me to PWM at a lower frequency before the ripple gets big, improving resolution, but the added settling time compromises the improvement. The advantage of the 3p Bessel is that it's easy to make from a few available parts; higher-order filters require multiple inductor values with, often, inconvenient ratios.

Like I said, PWM is awful. The more complex filter squeezes out maybe one more bit of analog signal resolution.

--

John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Precision electronic instrumentation

Do you have to use simple PWM?

If you encode the transmitted signal with a sigma-delta modulator the ripple frequency will be much higher for most codes. There will unfortunately be some values that will still give the same ripple as PWM.

kevin

I don't really understand delta-sigma dacs. The density of rising and falling edges will vary continuously, and it would take extreme rise/fall speed and symmetry to deliver an accurate average value. I suspect that real d-s dacs use some sort of charge dispensing tricks, rather than just lowpass filtering a rail-to-rail logic swing.

But I certainly can't process 1 ns pulses. I wonder what d-s clock rate it would take to get, say, a 10-bit equivalent ADC that settles in a couple of microseconds. It would still have the existing filtering problem, namely good rolloff (to kill the d-s noise, similar to killing the PWM carrier) but fast step response settling. Audio dacs don't have that same problem, so can use agressive filters.

The PWM facility already exists in our FPGA. If we go in and redesign things, we may as well just pump out a serial digital data stream, and use a DAC on the other end. The issue then becomes how best to encode it.

--

John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Precision electronic instrumentation

On a sunny day (Thu, 20 Feb 2014 20:51:26 -0800) it happened John Larkin wrote in :

How about a shift register with a R2R network at the other end? So end the 'byte' serially.

I have done R2R on CMOS output, it works, that vertical white thing is one:

Circuit diagram, IC9 (right) is the R2R ladder:

There is a simple filter in there too.. Should work for highter frequencies than 3.5 kHz too..

it

of

but

se

e:

None of that makes much sense to me, in this context.

It did set me thinking though. John Larkin's filter problem is that he want s a complex and hard to realise fast-settling filter, at a frequency where reactive components are far from ideal.

If he used a clocked shift register as a digital delay line with a resistor on every tap, and ran the other ends of the resistors into a summing junct ion, he's built an FIR filter, and 0.1% resistors on the E96 grid can give you a high-order filter characteristic with relatively little effort (and b oard space).

Finite-impulse response filters have very good transient behaviour.

--
Bill Sloman, Sydney

or on every tap, and ran the other ends of the resistors into a summing jun ction, he's built an FIR filter, and 0.1% resistors on the E96 grid can giv e you a high-order filter characteristic with relatively little effort (and board space).

As a frank newbie at this, the resistors seem to make sense...Are there eno ugh digital output lines on the FPGA to do it directly, by switching a resi stor network?

On a sunny day (Fri, 21 Feb 2014 03:38:43 -0800 (PST)) it happened Bill Sloman wrote in :

Well I should have read it better, I think just go serial some format and DAC (that could be R2R). FPGAs have these very high clock speed outputs, soo, and that is some sort of standard, but I never worked with that, Resistors work into the GHz very nicely. PWM sucks for high speeds and high accuracy. But he was talking about 'a few us', so any fast UART sort of thing, clock recovery with some flops or flips, done that, and then only filter below Niquist /2, shift register with buffer works too, 10 bits maybe, but why not. Trimpots :-) No difficult filters...

Yea, I think I would like to hear what it is used for, or at least what sort of speeds and accuracy are needed.

On a sunny day (Fri, 21 Feb 2014 05:22:06 -0800 (PST)) it happened snipped-for-privacy@gmail.com wrote in :

Yes, that is an R2R right there, for video, left to the TO220 LM317:

8 bits, but OK, why not ten. Dunno how many pins he has.

Putting a delta-sigma dither on a shorter-period PWM doesn't have either of those problems. (A trick I learned from Tim Wescott a few years ago and have used often since then.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

There must be some sort of hybrid codings, like d-s but with a limited number of edges.

Suppose I have 1 ns resolution (1 GHz clock) and make 1 MHz PWM. That gives me

0.1% resolution. If I want to make 0.501 volts, simple PWM is 501 highs and 499 lows. But that has a whopping 1 MHz ripple.

I can get the same output from 250 high, 250 low, 251 high, and 249 low. Only 4 edges and the ripple is now mostly 2 MHz, easier to filter. That's not precisely a dither, just a different way to code 501 highs.

Oh, we're about to test our gadget that dithers a 16-bit DAC down to microvolt resolution, discussed here previously. The DAC clock rate is 48 MHz and the dither waveform is a sine wave at 13.0078 MHz, which is 1110 cycles of sine wave painted into a 4K RAM, about 8 LSBs p-p. I figure on using a spectrum analyzer to see if it works.

--

John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Precision electronic instrumentation

Den torsdag den 20. februar 2014 23.35.22 UTC+1 skrev John Larkin:

JPG

er.JPG

.JPG

heres a hacked together example of pwm, pwm with reference count reversed a nd a simple delta sigma

Version 4 SHEET 1 6684 1540 WIRE 3024 -5344 1104 -5344 WIRE 3536 -5024 1392 -5024 WIRE 3472 -4976 1472 -4976 WIRE 3376 -4928 1552 -4928 WIRE 3184 -4864 1616 -4864 WIRE 2704 -4544 2448 -4544 WIRE 3024 -4544 3024 -5344 WIRE 3024 -4544 2864 -4544 WIRE 3728 -4544 3024 -4544 WIRE 3968 -4544 3888 -4544 WIRE 1936 -4512 1888 -4512 WIRE 2224 -4512 2000 -4512 WIRE 1936 -4496 1920 -4496 WIRE 2448 -4496 2448 -4544 WIRE 2448 -4496 2288 -4496 WIRE 2704 -4496 2640 -4496 WIRE 3728 -4496 3664 -4496 WIRE 2224 -4480 2208 -4480 WIRE 2112 -4416 2064 -4416 WIRE 2208 -4416 2208 -4480 WIRE 2208 -4416 2176 -4416 WIRE 2112 -4400 2080 -4400 WIRE 1616 -4352 1616 -4864 WIRE 1888 -4352 1888 -4512 WIRE 1888 -4352 1616 -4352 WIRE 1936 -4352 1888 -4352 WIRE 2064 -4336 2064 -4416 WIRE 2064 -4336 2000 -4336 WIRE 1920 -4320 1920 -4496 WIRE 1920 -4320 1440 -4320 WIRE 1936 -4320 1920 -4320 WIRE 2064 -4288 2064 -4336 WIRE 2112 -4288 2064 -4288 WIRE 2704 -4272 2176 -4272 WIRE 3184 -4272 3184 -4864 WIRE 3184 -4272 2864 -4272 WIRE 2080 -4256 2080 -4400 WIRE 2080 -4256 1776 -4256 WIRE 2112 -4256 2080 -4256 WIRE 2640 -4224 2640 -4496 WIRE 2704 -4224 2640 -4224 WIRE 1776 -4192 1776 -4256 WIRE 2416 -4192 1776 -4192 WIRE 1920 -4160 1872 -4160 WIRE 2208 -4160 1984 -4160 WIRE 1920 -4144 1904 -4144 WIRE 2416 -4144 2416 -4192 WIRE 2416 -4144 2272 -4144 WIRE 2208 -4128 2192 -4128 WIRE 2048 -4064 2096 -4080 WIRE 2192 -4064 2192 -4128 WIRE 2192 -4064 2160 -4080 WIRE 2064 -4048 2096 -4064 WIRE 2112 -4016 2112 -4032 WIRE 1552 -4000 1552 -4928 WIRE 1872 -4000 1872 -4160 WIRE 1872 -4000 1552 -4000 WIRE 1920 -4000 1872 -4000 WIRE 2048 -3984 2048 -4064 WIRE 2048 -3984 1984 -3984 WIRE 1904 -3968 1904 -4144 WIRE 1904 -3968 1488 -3968 WIRE 1920 -3968 1904 -3968 WIRE 2048 -3936 2048 -3984 WIRE 2096 -3936 2048 -3936 WIRE 2704 -3920 2160 -3920 WIRE 3376 -3920 3376 -4928 WIRE 3376 -3920 2864 -3920 WIRE 2064 -3904 2064 -4048 WIRE 2064 -3904 1760 -3904 WIRE 2096 -3904 2064 -3904 WIRE 2640 -3872 2640 -4224 WIRE 2704 -3872 2640 -3872 WIRE 1760 -3840 1760 -3904 WIRE 2416 -3840 1760 -3840 WIRE 1920 -3792 1872 -3792 WIRE 2208 -3792 1984 -3792 WIRE 1920 -3776 1888 -3776 WIRE 2416 -3776 2416 -3840 WIRE 2416 -3776 2272 -3776 WIRE 2208 -3760 2192 -3760 WIRE 2048 -3696 2112 -3728 WIRE 2192 -3696 2192 -3760 WIRE 2192 -3696 2176 -3728 WIRE 2064 -3680 2112 -3712 WIRE 2112 -3648 2128 -3680 WIRE 1472 -3632 1472 -4976 WIRE 1872 -3632 1872 -3792 WIRE 1872 -3632 1472 -3632 WIRE 1920 -3632 1872 -3632 WIRE 2048 -3616 2048 -3696 WIRE 2048 -3616 1984 -3616 WIRE 1888 -3600 1888 -3776 WIRE 1888 -3600 1536 -3600 WIRE 1920 -3600 1888 -3600 WIRE 2048 -3568 2048 -3616 WIRE 2096 -3568 2048 -3568 WIRE 2688 -3552 2160 -3552 WIRE 3472 -3552 3472 -4976 WIRE 3472 -3552 2848 -3552 WIRE 2064 -3536 2064 -3680 WIRE 2064 -3536 1760 -3536 WIRE 2096 -3536 2064 -3536 WIRE 2640 -3504 2640 -3872 WIRE 2688 -3504 2640 -3504 WIRE 1760 -3472 1760 -3536 WIRE 2400 -3472 1760 -3472 WIRE 1904 -3456 1856 -3456 WIRE 1904 -3440 1872 -3440 WIRE 2192 -3440 1968 -3440 WIRE 2400 -3424 2400 -3472 WIRE 2400 -3424 2256 -3424 WIRE 2192 -3408 2176 -3408 WIRE 2032 -3344 2080 -3360 WIRE 2176 -3344 2176 -3408 WIRE 2176 -3344 2144 -3360 WIRE 2048 -3328 2080 -3344 WIRE 2096 -3296 2096 -3312 WIRE 1392 -3280 1392 -5024 WIRE 1856 -3280 1856 -3456 WIRE 1856 -3280 1392 -3280 WIRE 1904 -3280 1856 -3280 WIRE 2032 -3264 2032 -3344 WIRE 2032 -3264 1968 -3264 WIRE 1872 -3248 1872 -3440 WIRE 1872 -3248 1584 -3248 WIRE 1904 -3248 1872 -3248 WIRE 2032 -3216 2032 -3264 WIRE 2080 -3216 2032 -3216 WIRE 2688 -3200 2144 -3200 WIRE 3536 -3200 3536 -5024 WIRE 3536 -3200 2848 -3200 WIRE 5584 -3200 5584 -3360 WIRE 1104 -3184 1104 -5344 WIRE 2048 -3184 2048 -3328 WIRE 2048 -3184 1104 -3184 WIRE 2080 -3184 2048 -3184 WIRE 2640 -3152 2640 -3504 WIRE 2688 -3152 2640 -3152 WIRE 5584 -3024 5584 -3120 WIRE 5696 -3024 5584 -3024 WIRE 5920 -3024 5776 -3024 WIRE 6048 -3024 5920 -3024 WIRE 6208 -3024 6128 -3024 WIRE 6272 -3024 6208 -3024 WIRE 5920 -3008 5920 -3024 WIRE 5584 -2992 5584 -3024 WIRE 2640 -2944 2640 -3152 WIRE 3664 -2944 3664 -4496 WIRE 3664 -2944 2640 -2944 WIRE 5584 -2912 5584 -2928 WIRE 5920 -2912 5920 -2944 WIRE 6272 -2896 6272 -2944 WIRE 1584 -2848 1584 -3248 WIRE 2368 -2848 1584 -2848 WIRE 2640 -2720 2640 -2944 WIRE 2640 -2720 1344 -2720 WIRE 2688 -2576 2640 -2576 WIRE 2976 -2576 2752 -2576 WIRE 2688 -2560 2672 -2560 WIRE 3744 -2560 3040 -2560 WIRE 4016 -2560 3904 -2560 WIRE 2976 -2544 2960 -2544 WIRE 1536 -2528 1536 -3600 WIRE 2304 -2528 1536 -2528 WIRE 3040 -2528 3024 -2528 WIRE 3664 -2512 3664 -2944 WIRE 3744 -2512 3664 -2512 WIRE 1488 -2496 1488 -3968 WIRE 2240 -2496 1488 -2496 WIRE 2864 -2480 2816 -2480 WIRE 2960 -2480 2960 -2544 WIRE 2960 -2480 2928 -2480 WIRE 5584 -2480 5584 -2640 WIRE 2864 -2464 2832 -2464 WIRE 2640 -2416 2640 -2576 WIRE 2640 -2416 1984 -2416 WIRE 2688 -2416 2640 -2416 WIRE 2816 -2400 2816 -2480 WIRE 2816 -2400 2752 -2400 WIRE 1440 -2384 1440 -4320 WIRE 2176 -2384 1440 -2384 WIRE 2672 -2384 2672 -2560 WIRE 2672 -2384 2176 -2384 WIRE 2688 -2384 2672 -2384 WIRE 2816 -2352 2816 -2400 WIRE 2864 -2352 2816 -2352 WIRE 2832 -2320 2832 -2464 WIRE 2832 -2320 2528 -2320 WIRE 2864 -2320 2832 -2320 WIRE 5584 -2304 5584 -2400 WIRE 5696 -2304 5584 -2304 WIRE 5920 -2304 5776 -2304 WIRE 6048 -2304 5920 -2304 WIRE 6208 -2304 6128 -2304 WIRE 6272 -2304 6208 -2304 WIRE 5920 -2288 5920 -2304 WIRE 5584 -2272 5584 -2304 WIRE 2528 -2256 2528 -2320 WIRE 3168 -2256 2528 -2256 WIRE 2672 -2224 2624 -2224 WIRE 2960 -2224 2736 -2224 WIRE 2672 -2208 2656 -2208 WIRE 3168 -2208 3168 -2256 WIRE 3168 -2208 3024 -2208 WIRE 2960 -2192 2944 -2192 WIRE 5584 -2192 5584 -2208 WIRE 5920 -2192 5920 -2224 WIRE 6272 -2176 6272 -2224 WIRE 2800 -2128 2848 -2144 WIRE 2944 -2128 2944 -2192 WIRE 2944 -2128 2912 -2144 WIRE 2816 -2112 2848 -2128 WIRE 2864 -2080 2864 -2096 WIRE 2624 -2064 2624 -2224 WIRE 2624 -2064 2080 -2064 WIRE 2672 -2064 2624 -2064 WIRE 2800 -2048 2800 -2128 WIRE 2800 -2048 2736 -2048 WIRE 2240 -2032 2240 -2496 WIRE 2656 -2032 2656 -2208 WIRE 2656 -2032 2240 -2032 WIRE 2672 -2032 2656 -2032 WIRE 2800 -2000 2800 -2048 WIRE 2848 -2000 2800 -2000 WIRE 2816 -1968 2816 -2112 WIRE 2816 -1968 2512 -1968 WIRE 2848 -1968 2816 -1968 WIRE 5584 -1920 5584 -2080 WIRE 1344 -1904 1344 -2720 WIRE 1344 -1904 1200 -1904 WIRE 2512 -1904 2512 -1968 WIRE 3168 -1904 2512 -1904 WIRE 2672 -1856 2624 -1856 WIRE 2960 -1856 2736 -1856 WIRE 2672 -1840 2640 -1840 WIRE 3168 -1840 3168 -1904 WIRE 3168 -1840 3024 -1840 WIRE 2960 -1824 2944 -1824 WIRE 2800 -1760 2864 -1792 WIRE 2944 -1760 2944 -1824 WIRE 2944 -1760 2928 -1792 WIRE 2816 -1744 2864 -1776 WIRE 5584 -1744 5584 -1840 WIRE 5696 -1744 5584 -1744 WIRE 5920 -1744 5776 -1744 WIRE 6048 -1744 5920 -1744 WIRE 6192 -1744 6128 -1744 WIRE 6272 -1744 6192 -1744 WIRE 5920 -1728 5920 -1744 WIRE 2864 -1712 2880 -1744 WIRE 5584 -1712 5584 -1744 WIRE 2624 -1696 2624 -1856 WIRE 2624 -1696 2112 -1696 WIRE 2672 -1696 2624 -1696 WIRE 2800 -1680 2800 -1760 WIRE 2800 -1680 2736 -1680 WIRE 2304 -1664 2304 -2528 WIRE 2640 -1664 2640 -1840 WIRE 2640 -1664 2304 -1664 WIRE 2672 -1664 2640 -1664 WIRE 2800 -1632 2800 -1680 WIRE 2848 -1632 2800 -1632 WIRE 5584 -1632 5584 -1648 WIRE 5920 -1632 5920 -1664 WIRE 6272 -1616 6272 -1664 WIRE 2816 -1600 2816 -1744 WIRE 2816 -1600 2512 -1600 WIRE 2848 -1600 2816 -1600 WIRE 2512 -1536 2512 -1600 WIRE 3152 -1536 2512 -1536 WIRE 1984 -1520 1984 -2416 WIRE 1984 -1520 -432 -1520 WIRE 2656 -1520 2608 -1520 WIRE 2656 -1504 2624 -1504 WIRE 2944 -1504 2720 -1504 WIRE 3152 -1488 3152 -1536 WIRE 3152 -1488 3008 -1488 WIRE 1920 -1472 -352 -1472 WIRE 2080 -1472 2080 -2064 WIRE 2080 -1472 1920 -1472 WIRE 2944 -1472 2928 -1472 WIRE 1872 -1424 -272 -1424 WIRE 2112 -1424 2112 -1696 WIRE 2112 -1424 1872 -1424 WIRE 2784 -1408 2832 -1424 WIRE 2928 -1408 2928 -1472 WIRE 2928 -1408 2896 -1424 WIRE 2800 -1392 2832 -1408 WIRE 1808 -1360 -208 -1360 WIRE 2608 -1360 2608 -1520 WIRE 2608 -1360 1808 -1360 WIRE 2848 -1360 2848 -1376 WIRE 2608 -1344 2608 -1360 WIRE 2656 -1344 2608 -1344 WIRE 2784 -1328 2784 -1408 WIRE 2784 -1328 2720 -1328 WIRE 2368 -1312 2368 -2848 WIRE 2624 -1312 2624 -1504 WIRE 2624 -1312 2368 -1312 WIRE 2656 -1312 2624 -1312 WIRE 2784 -1280 2784 -1328 WIRE 2832 -1280 2784 -1280 WIRE 2528 -1248 2496 -1248 WIRE 2800 -1248 2800 -1392 WIRE 2800 -1248 2608 -1248 WIRE 2832 -1248 2800 -1248 WIRE 112 -1008 64 -1008 WIRE 400 -1008 176 -1008 WIRE 112 -992 96 -992 WIRE 608 -992 464 -992 WIRE 400 -976 384 -976 WIRE 2688 -960 2640 -960 WIRE 2976 -960 2752 -960 WIRE 2688 -944 2672 -944 WIRE 3744 -944 3040 -944 WIRE 4016 -944 3904 -944 WIRE 2976 -928 2960 -928 WIRE 288 -912 240 -912 WIRE 384 -912 384 -976 WIRE 384 -912 352 -912 WIRE 3040 -912 3024 -912 WIRE 288 -896 256 -896 WIRE 3664 -896 3664 -2512 WIRE 3744 -896 3664 -896 WIRE 2864 -864 2816 -864 WIRE 2960 -864 2960 -928 WIRE 2960 -864 2928 -864 WIRE -208 -848 -208 -1360 WIRE 64 -848 64 -1008 WIRE 64 -848 -208 -848 WIRE 112 -848 64 -848 WIRE 2864 -848 2832 -848 WIRE 240 -832 240 -912 WIRE 240 -832 176 -832 WIRE 1808 -832 1808 -1360 WIRE 2640 -832 2640 -960 WIRE 2640 -832 1808 -832 WIRE 96 -816 96 -992 WIRE 96 -816 -208 -816 WIRE 112 -816 96 -816 WIRE 2640 -800 2640 -832 WIRE 2688 -800 2640 -800 WIRE 240 -784 240 -832 WIRE 288 -784 240 -784 WIRE 2816 -784 2816 -864 WIRE 2816 -784 2752 -784 WIRE 880 -768 352 -768 WIRE 1360 -768 1040 -768 WIRE 1808 -768 1808 -832 WIRE 1808 -768 1360 -768 WIRE 2176 -768 2176 -2384 WIRE 2672 -768 2672 -944 WIRE 2672 -768 2176 -768 WIRE 2688 -768 2672 -768 WIRE 256 -752 256 -896 WIRE 256 -752 -48 -752 WIRE 288 -752 256 -752 WIRE 2816 -736 2816 -784 WIRE 2864 -736 2816 -736 WIRE 880 -720 816 -720 WIRE 2832 -704 2832 -848 WIRE 2832 -704 2528 -704 WIRE 2864 -704 2832 -704 WIRE -48 -688 -48 -752 WIRE 592 -688 -48 -688 WIRE 96 -656 48 -656 WIRE 384 -656 160 -656 WIRE 96 -640 80 -640 WIRE 592 -640 592 -688 WIRE 592 -640 448 -640 WIRE 2528 -640 2528 -704 WIRE 3168 -640 2528 -640 WIRE 384 -624 368 -624 WIRE 2672 -608 2624 -608 WIRE 2960 -608 2736 -608 WIRE 2672 -592 2656 -592 WIRE 3168 -592 3168 -640 WIRE 3168 -592 3024 -592 WIRE 2960 -576 2944 -576 WIRE 224 -560 272 -576 WIRE 368 -560 368 -624 WIRE 368 -560 336 -576 WIRE 240 -544 272 -560 WIRE 288 -512 288 -528 WIRE 2800 -512 2848 -528 WIRE 2944 -512 2944 -576 WIRE 2944 -512 2912 -528 WIRE -272 -496 -272 -1424 WIRE 48 -496 48 -656 WIRE 48 -496 -272 -496 WIRE 96 -496 48 -496 WIRE 2816 -496 2848 -512 WIRE 224 -480 224 -560 WIRE 224 -480 160 -480 WIRE 1872 -480 1872 -1424 WIRE 2624 -480 2624 -608 WIRE 2624 -480 1872 -480 WIRE -208 -464 -208 -816 WIRE 80 -464 80 -640 WIRE 80 -464 -208 -464 WIRE 96 -464 80 -464 WIRE 2864 -464 2864 -480 WIRE 2624 -448 2624 -480 WIRE 2672 -448 2624 -448 WIRE 224 -432 224 -480 WIRE 272 -432 224 -432 WIRE 2800 -432 2800 -512 WIRE 2800 -432 2736 -432 WIRE 880 -416 336 -416 WIRE 1360 -416 1040 -416 WIRE 1872 -416 1872 -480 WIRE 1872 -416 1360 -416 WIRE 2240 -416 2240 -2032 WIRE 2656 -416 2656 -592 WIRE 2656 -416 2240 -416 WIRE 2672 -416 2656 -416 WIRE 240 -400 240 -544 WIRE 240 -400 -64 -400 WIRE 272 -400 240 -400 WIRE 2800 -384 2800 -432 WIRE 2848 -384 2800 -384 WIRE 816 -368 816 -720 WIRE 880 -368 816 -368 WIRE 2816 -352 2816 -496 WIRE 2816 -352 2512 -352 WIRE 2848 -352 2816 -352 WIRE -64 -336 -64 -400 WIRE 592 -336 -64 -336 WIRE 96 -288 48 -288 WIRE 384 -288 160 -288 WIRE 2512 -288 2512 -352 WIRE 3168 -288 2512 -288 WIRE 96 -272 64 -272 WIRE 592 -272 592 -336 WIRE 592 -272 448 -272 WIRE 384 -256 368 -256 WIRE 2672 -240 2624 -240 WIRE 2960 -240 2736 -240 WIRE 2672 -224 2640 -224 WIRE 3168 -224 3168 -288 WIRE 3168 -224 3024 -224 WIRE 2960 -208 2944 -208 WIRE 224 -192 288 -224 WIRE 368 -192 368 -256 WIRE 368 -192 352 -224 WIRE 240 -176 288 -208 WIRE 288 -144 304 -176 WIRE 2800 -144 2864 -176 WIRE 2944 -144 2944 -208 WIRE 2944 -144 2928 -176 WIRE -352 -128 -352 -1472 WIRE 48 -128 48 -288 WIRE 48 -128 -352 -128 WIRE 96 -128 48 -128 WIRE 2816 -128 2864 -160 WIRE 224 -112 224 -192 WIRE 224 -112 160 -112 WIRE 1920 -112 1920 -1472 WIRE 2624 -112 2624 -240 WIRE 2624 -112 1920 -112 WIRE -208 -96 -208 -464 WIRE 64 -96 64 -272 WIRE 64 -96 -208 -96 WIRE 96 -96 64 -96 WIRE 2864 -96 2880 -128 WIRE 2624 -80 2624 -112 WIRE 2672 -80 2624 -80 WIRE 224 -64 224 -112 WIRE 272 -64 224 -64 WIRE 2800 -64 2800 -144 WIRE 2800 -64 2736 -64 WIRE 864 -48 336 -48 WIRE 1360 -48 1024 -48 WIRE 1920 -48 1920 -112 WIRE 1920 -48 1360 -48 WIRE 2304 -48 2304 -1664 WIRE 2640 -48 2640 -224 WIRE 2640 -48 2304 -48 WIRE 2672 -48 2640 -48 WIRE 240 -32 240 -176 WIRE 240 -32 -64 -32 WIRE 272 -32 240 -32 WIRE 2800 -16 2800 -64 WIRE 2848 -16 2800 -16 WIRE 816 0 816 -368 WIRE 864 0 816 0 WIRE 2816 16 2816 -128 WIRE 2816 16 2512 16 WIRE 2848 16 2816 16 WIRE -64 32 -64 -32 WIRE 576 32 -64 32 WIRE 80 48 32 48 WIRE 80 64 48 64 WIRE 576 80 576 32 WIRE 576 80 432 80 WIRE 2512 80 2512 16 WIRE 3152 80 2512 80 WIRE 368 96 352 96 WIRE 2656 96 2608 96 WIRE 2656 112 2624 112 WIRE 2944 112 2720 112 WIRE 3152 128 3152 80 WIRE 3152 128 3008 128 WIRE 2944 144 2928 144 WIRE 208 160 256 144 WIRE 352 160 352 96 WIRE 352 160 320 144 WIRE 224 176 256 160 WIRE 272 208 272 192 WIRE 2784 208 2832 192 WIRE 2928 208 2928 144 WIRE 2928 208 2896 192 WIRE -432 224 -432 -1520 WIRE 32 224 32 48 WIRE 32 224 -432 224 WIRE 80 224 32 224 WIRE 2800 224 2832 208 WIRE 208 240 208 160 WIRE 208 240 144 240 WIRE -288 256 -336 256 WIRE -208 256 -208 -96 WIRE -208 256 -224 256 WIRE 48 256 48 64 WIRE 48 256 -208 256 WIRE 80 256 48 256 WIRE 1984 256 1984 -1520 WIRE 2608 256 2608 96 WIRE 2608 256 1984 256 WIRE 2848 256 2848 240 WIRE 2608 272 2608 256 WIRE 2656 272 2608 272 WIRE -288 288 -288 272 WIRE 208 288 208 240 WIRE 256 288 208 288 WIRE 2784 288 2784 208 WIRE 2784 288 2720 288 WIRE 864 304 320 304 WIRE 1360 304 1024 304 WIRE 1984 304 1984 256 WIRE 1984 304 1360 304 WIRE 2368 304 2368 -1312 WIRE 2624 304 2624 112 WIRE 2624 304 2368 304 WIRE 2656 304 2624 304 WIRE -16 320 -80 320 WIRE 224 320 224 176 WIRE 224 320 48 320 WIRE 256 320 224 320 WIRE 2784 336 2784 288 WIRE 2832 336 2784 336 WIRE 816 352 816 0 WIRE 864 352 816 352 WIRE 2528 368 2496 368 WIRE 2800 368 2800 224 WIRE 2800 368 2608 368 WIRE 2832 368 2800 368 WIRE 816 496 816 352 WIRE 1200 496 1200 -1904 WIRE 1200 496 816 496 WIRE 816 640 816 496 WIRE 2176 672 2176 -768 WIRE 2928 672 2176 672 WIRE 3232 672 3008 672 WIRE 3008 688 3008 672 WIRE 2240 800 2240 -416 WIRE 2928 800 2240 800 WIRE 3008 800 3008 768 WIRE 3008 832 3008 800 WIRE 2304 928 2304 -48 WIRE 2928 928 2304 928 WIRE 3008 928 3008 912 WIRE 3008 960 3008 928 WIRE 2368 1072 2368 304 WIRE 2928 1072 2368 1072 WIRE 3008 1072 3008 1040 WIRE 3008 1184 3008 1152 WIRE 2240 1232 2240 800 WIRE 2368 1232 2368 1072 WIRE 2304 1328 2304 928 WIRE 2176 1344 2176 672 WIRE 2176 1520 2176 1424 WIRE 2240 1520 2240 1312 WIRE 2304 1520 2304 1408 WIRE 2368 1520 2368 1312 FLAG 96 112 0 FLAG 112 288 0 FLAG 272 208 0 FLAG 288 352 0 FLAG 384 128 0 FLAG 112 -240 0 FLAG 128 -64 0 FLAG 288 -144 0 FLAG 304 0 0 FLAG 400 -224 0 FLAG 112 -608 0 FLAG 128 -432 0 FLAG 288 -512 0 FLAG 304 -368 0 FLAG 400 -592 0 FLAG 128 -960 0 FLAG 144 -784 0 FLAG 304 -864 0 FLAG 320 -720 0 FLAG 416 -944 0 FLAG 960 -672 0 FLAG 960 -320 0 FLAG 944 48 0 FLAG 944 400 0 FLAG 944 256 0 FLAG 944 -96 0 FLAG 960 -464 0 FLAG 960 -816 0 FLAG -80 320 0 FLAG -16 336 0 FLAG 816 720 0 FLAG 2672 160 0 FLAG 2688 336 0 FLAG 2848 256 0 FLAG 2864 400 0 FLAG 2960 176 0 FLAG 2688 -192 0 FLAG 2704 -16 0 FLAG 2864 -96 0 FLAG 2880 48 0 FLAG 2976 -176 0 FLAG 2688 -560 0 FLAG 2704 -384 0 FLAG 2864 -464 0 FLAG 2880 -320 0 FLAG 2976 -544 0 FLAG 2704 -912 0 FLAG 2720 -736 0 FLAG 2880 -816 0 FLAG 2896 -672 0 FLAG 2992 -896 0 FLAG 2496 368 0 FLAG 2672 -1456 0 FLAG 2688 -1280 0 FLAG 2848 -1360 0 FLAG 2864 -1216 0 FLAG 2960 -1440 0 FLAG 2688 -1808 0 FLAG 2704 -1632 0 FLAG 2864 -1712 0 FLAG 2880 -1568 0 FLAG 2976 -1792 0 FLAG 2688 -2176 0 FLAG 2704 -2000 0 FLAG 2864 -2080 0 FLAG 2880 -1936 0 FLAG 2976 -2160 0 FLAG 2704 -2528 0 FLAG 2720 -2352 0 FLAG 2880 -2432 0 FLAG 2896 -2288 0 FLAG 2992 -2512 0 FLAG 2496 -1248 0 FLAG -336 256 0 FLAG -288 288 0 FLAG 2176 1520 0 FLAG 2240 1520 0 FLAG 2304 1520 0 FLAG 2368 1520 0 FLAG 1360 304 b0 FLAG 1360 -48 b1 FLAG 1360 -416 b2 FLAG 1360 -768 b3 FLAG 1920 -3392 0 FLAG 1936 -3216 0 FLAG 2096 -3296 0 FLAG 2112 -3152 0 FLAG 2208 -3376 0 FLAG 1936 -3744 0 FLAG 1952 -3568 0 FLAG 2112 -3648 0 FLAG 2128 -3504 0 FLAG 2224 -3728 0 FLAG 1936 -4112 0 FLAG 1952 -3936 0 FLAG 2112 -4016 0 FLAG 2128 -3872 0 FLAG 2224 -4096 0 FLAG 1952 -4464 0 FLAG 1968 -4288 0 FLAG 2128 -4368 0 FLAG 2144 -4224 0 FLAG 2240 -4448 0 FLAG 2784 -4176 0 FLAG 2784 -3824 0 FLAG 2768 -3456 0 FLAG 2768 -3104 0 FLAG 2768 -3248 0 FLAG 2768 -3600 0 FLAG 2784 -3968 0 FLAG 2784 -4320 0 FLAG 2784 -4448 0 FLAG 2784 -4592 0 FLAG 3968 -4544 vo3 FLAG 5584 -2912 0 FLAG 5584 -3360 vo3 FLAG 5584 -2640 vo2 FLAG 5584 -2080 vo1 FLAG 3008 1184 0 FLAG 3808 -4448 0 FLAG 3808 -4592 0 FLAG 3824 -2464 0 FLAG 3824 -2608 0 FLAG 3824 -848 0 FLAG 3824 -992 0 FLAG 4016 -944 vo1 FLAG 4016 -2560 vo2 FLAG 3728 -4448 0 FLAG 3744 -2464 0 FLAG 3744 -848 0 FLAG 5920 -2912 0 FLAG 6272 -2896 0 FLAG 5584 -2192 0 FLAG 5920 -2192 0 FLAG 6272 -2176 0 FLAG 5584 -1632 0 FLAG 5920 -1632 0 FLAG 6272 -1616 0 FLAG 6208 -3024 dsm FLAG 6208 -2304 pwmrev FLAG 6192 -1744 pwm SYMBOL Digital\\and 112 16 R0 SYMATTR InstName A1 SYMBOL Digital\\xor 128 192 R0 SYMATTR InstName A2 SYMBOL Digital\\xor 304 256 R0 SYMATTR InstName A3 SYMBOL Digital\\or 400 32 R0 SYMATTR InstName A4 SYMBOL Digital\\and 288 96 R0 SYMATTR InstName A5 SYMBOL Digital\\and 128 -336 R0 SYMATTR InstName A6 SYMBOL Digital\\xor 144 -160 R0 SYMATTR InstName A7 SYMBOL Digital\\xor 320 -96 R0 SYMATTR InstName A8 SYMBOL Digital\\or 416 -320 R0 SYMATTR InstName A9 SYMBOL Digital\\and 320 -272 R0 SYMATTR InstName A10 SYMBOL Digital\\and 128 -704 R0 SYMATTR InstName A11 SYMBOL Digital\\xor 144 -528 R0 SYMATTR InstName A12 SYMBOL Digital\\xor 320 -464 R0 SYMATTR InstName A13 SYMBOL Digital\\or 416 -688 R0 SYMATTR InstName A14 SYMBOL Digital\\and 304 -624 R0 SYMATTR InstName A15 SYMBOL Digital\\and 144 -1056 R0 SYMATTR InstName A16 SYMBOL Digital\\xor 160 -880 R0 SYMATTR InstName A17 SYMBOL Digital\\xor 336 -816 R0 SYMATTR InstName A18 SYMBOL Digital\\or 432 -1040 R0 SYMATTR InstName A19 SYMBOL Digital\\and 320 -960 R0 SYMATTR InstName A20 SYMBOL Digital\\dflop 944 256 R0 WINDOW 3 8 12 Left 2 SYMATTR Value td=1n SYMATTR InstName A21 SYMBOL Digital\\dflop 944 -96 R0 WINDOW 3 8 12 Left 2 SYMATTR Value td=1n SYMATTR InstName A22 SYMBOL Digital\\dflop 960 -464 R0 WINDOW 3 8 12 Left 2 SYMATTR Value td=1n SYMATTR InstName A23 SYMBOL Digital\\dflop 960 -816 R0 WINDOW 3 8 12 Left 2 SYMATTR Value td=1n SYMATTR InstName A24 SYMBOL Digital\\inv -16 256 R0 SYMATTR InstName A25 SYMBOL voltage 816 624 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value PULSE(0 1 1u .1n .1n 50n 100n) SYMBOL Digital\\and 2688 64 R0 SYMATTR InstName A26 SYMBOL Digital\\xor 2704 240 R0 SYMATTR InstName A27 SYMBOL Digital\\xor 2880 304 R0 SYMATTR InstName A28 SYMBOL Digital\\or 2976 80 R0 SYMATTR InstName A29 SYMBOL Digital\\and 2864 144 R0 SYMATTR InstName A30 SYMBOL Digital\\and 2704 -288 R0 SYMATTR InstName A31 SYMBOL Digital\\xor 2720 -112 R0 SYMATTR InstName A32 SYMBOL Digital\\xor 2896 -48 R0 SYMATTR InstName A33 SYMBOL Digital\\or 2992 -272 R0 SYMATTR InstName A34 SYMBOL Digital\\and 2896 -224 R0 SYMATTR InstName A35 SYMBOL Digital\\and 2704 -656 R0 SYMATTR InstName A36 SYMBOL Digital\\xor 2720 -480 R0 SYMATTR InstName A37 SYMBOL Digital\\xor 2896 -416 R0 SYMATTR InstName A38 SYMBOL Digital\\or 2992 -640 R0 SYMATTR InstName A39 SYMBOL Digital\\and 2880 -576 R0 SYMATTR InstName A40 SYMBOL Digital\\and 2720 -1008 R0 SYMATTR InstName A41 SYMBOL Digital\\xor 2736 -832 R0 SYMATTR InstName A42 SYMBOL Digital\\xor 2912 -768 R0 SYMATTR InstName A43 SYMBOL Digital\\or 3008 -992 R0 SYMATTR InstName A44 SYMBOL Digital\\and 2896 -912 R0 SYMATTR InstName A45 SYMBOL Digital\\and 2688 -1552 R0 SYMATTR InstName A47 SYMBOL Digital\\xor 2704 -1376 R0 SYMATTR InstName A49 SYMBOL Digital\\xor 2880 -1312 R0 SYMATTR InstName A50 SYMBOL Digital\\or 2976 -1536 R0 SYMATTR InstName A51 SYMBOL Digital\\and 2864 -1472 R0 SYMATTR InstName A52 SYMBOL Digital\\and 2704 -1904 R0 SYMATTR InstName A53 SYMBOL Digital\\xor 2720 -1728 R0 SYMATTR InstName A54 SYMBOL Digital\\xor 2896 -1664 R0 SYMATTR InstName A55 SYMBOL Digital\\or 2992 -1888 R0 SYMATTR InstName A56 SYMBOL Digital\\and 2896 -1840 R0 SYMATTR InstName A57 SYMBOL Digital\\and 2704 -2272 R0 SYMATTR InstName A58 SYMBOL Digital\\xor 2720 -2096 R0 SYMATTR InstName A59 SYMBOL Digital\\xor 2896 -2032 R0 SYMATTR InstName A60 SYMBOL Digital\\or 2992 -2256 R0 SYMATTR InstName A61 SYMBOL Digital\\and 2880 -2192 R0 SYMATTR InstName A62 SYMBOL Digital\\and 2720 -2624 R0 SYMATTR InstName A63 SYMBOL Digital\\xor 2736 -2448 R0 SYMATTR InstName A64 SYMBOL Digital\\xor 2912 -2384 R0 SYMATTR InstName A65 SYMBOL Digital\\or 3008 -2608 R0 SYMATTR InstName A66 SYMBOL Digital\\and 2896 -2528 R0 SYMATTR InstName A67 SYMBOL Digital\\buf1 -288 192 R0 SYMATTR InstName A46 SYMBOL voltage 2176 1328 R0 WINDOW 3 -397 59 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value PULSE(0 1 70u 1n 1n 80u 160u) SYMATTR InstName V2 SYMBOL voltage 2240 1216 R0 WINDOW 3 -445 43 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value PULSE(0 1 30u 1n 1n 40u 80u) SYMATTR InstName V3 SYMBOL voltage 2304 1312 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V4 SYMATTR Value PULSE(0 1 10u 1n 1n 20u 40u) SYMBOL voltage 2368 1216 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V5 SYMATTR Value PULSE(0 1 0 1n 1n 10u 20u) SYMBOL voltage 2624 368 R90 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V6 SYMATTR Value 0.1 SYMBOL voltage 2624 -1248 R90 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V7 SYMATTR Value 0.1 SYMBOL Digital\\and 1936 -3488 R0 SYMATTR InstName A48 SYMBOL Digital\\xor 1952 -3312 R0 SYMATTR InstName A68 SYMBOL Digital\\xor 2128 -3248 R0 SYMATTR InstName A69 SYMBOL Digital\\or 2224 -3472 R0 SYMATTR InstName A70 SYMBOL Digital\\and 2112 -3408 R0 SYMATTR InstName A71 SYMBOL Digital\\and 1952 -3840 R0 SYMATTR InstName A72 SYMBOL Digital\\xor 1968 -3664 R0 SYMATTR InstName A73 SYMBOL Digital\\xor 2144 -3600 R0 SYMATTR InstName A74 SYMBOL Digital\\or 2240 -3824 R0 SYMATTR InstName A75 SYMBOL Digital\\and 2144 -3776 R0 SYMATTR InstName A76 SYMBOL Digital\\and 1952 -4208 R0 SYMATTR InstName A77 SYMBOL Digital\\xor 1968 -4032 R0 SYMATTR InstName A78 SYMBOL Digital\\xor 2144 -3968 R0 SYMATTR InstName A79 SYMBOL Digital\\or 2240 -4192 R0 SYMATTR InstName A80 SYMBOL Digital\\and 2128 -4128 R0 SYMATTR InstName A81 SYMBOL Digital\\and 1968 -4560 R0 SYMATTR InstName A82 SYMBOL Digital\\xor 1984 -4384 R0 SYMATTR InstName A83 SYMBOL Digital\\xor 2160 -4320 R0 SYMATTR InstName A84 SYMBOL Digital\\or 2256 -4544 R0 SYMATTR InstName A85 SYMBOL Digital\\and 2144 -4464 R0 SYMATTR InstName A86 SYMBOL Digital\\dflop 2768 -3248 R0 WINDOW 3 8 12 Left 2 SYMATTR Value td=1n SYMATTR InstName A87 SYMBOL Digital\\dflop 2768 -3600 R0 WINDOW 3 8 12 Left 2 SYMATTR Value td=1n SYMATTR InstName A88 SYMBOL Digital\\dflop 2784 -3968 R0 WINDOW 3 8 12 Left 2 SYMATTR Value td=1n SYMATTR InstName A89 SYMBOL Digital\\dflop 2784 -4320 R0 WINDOW 3 8 12 Left 2 SYMATTR Value td=1n SYMATTR InstName A90 SYMBOL Digital\\dflop 2784 -4592 R0 WINDOW 3 8 12 Left 2 SYMATTR Value td=1n SYMATTR InstName A91 SYMBOL res 5568 -3216 R0 SYMATTR InstName R17 SYMATTR Value 125 SYMBOL cap 5568 -2992 R0 SYMATTR InstName C1 SYMATTR Value 1.2n SYMBOL res 3024 1056 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R20 SYMATTR Value 1k SYMBOL res 3024 912 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R21 SYMATTR Value 1k SYMBOL res 3024 784 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R22 SYMATTR Value 1k SYMBOL res 3024 656 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R23 SYMATTR Value 1k SYMBOL res 2992 944 R0 SYMATTR InstName R24 SYMATTR Value 500 SYMBOL res 2992 816 R0 SYMATTR InstName R25 SYMATTR Value 500 SYMBOL res 2992 672 R0 SYMATTR InstName R26 SYMATTR Value 500 SYMBOL res 2992 1056 R0 SYMATTR InstName R27 SYMATTR Value 1k SYMBOL Digital\\dflop 3808 -4592 R0 WINDOW 3 8 12 Left 2 SYMATTR Value td=1n SYMATTR InstName A92 SYMBOL Digital\\dflop 3824 -2608 R0 WINDOW 3 8 12 Left 2 SYMATTR Value td=1n SYMATTR InstName A93 SYMBOL Digital\\dflop 3824 -992 R0 WINDOW 3 8 12 Left 2 SYMATTR Value td=1n SYMATTR InstName A94 SYMBOL cap 5904 -3008 R0 SYMATTR InstName C4 SYMATTR Value 8n SYMBOL res 6256 -3040 R0 SYMATTR InstName R9 SYMATTR Value 50 SYMBOL ind 5792 -3040 R90 WINDOW 0 5 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName L1

SYMBOL res 6144 -3040 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R10 SYMATTR Value 75 SYMBOL res 5568 -2496 R0 SYMATTR InstName R11 SYMATTR Value 125 SYMBOL cap 5568 -2272 R0 SYMATTR InstName C2 SYMATTR Value 1.2n SYMBOL cap 5904 -2288 R0 SYMATTR InstName C3 SYMATTR Value 8n SYMBOL res 6256 -2320 R0 SYMATTR InstName R12 SYMATTR Value 50 SYMBOL ind 5792 -2320 R90 WINDOW 0 5 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName L2

SYMBOL res 6144 -2320 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R13 SYMATTR Value 75 SYMBOL res 5568 -1936 R0 SYMATTR InstName R14 SYMATTR Value 125 SYMBOL cap 5568 -1712 R0 SYMATTR InstName C5 SYMATTR Value 1.2n SYMBOL cap 5904 -1728 R0 SYMATTR InstName C6 SYMATTR Value 8n SYMBOL res 6256 -1760 R0 SYMATTR InstName R15 SYMATTR Value 50 SYMBOL ind 5792 -1760 R90 WINDOW 0 5 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName L3

SYMBOL res 6144 -1760 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R16 SYMATTR Value 75 TEXT -112 584 Left 2 !.tran 1024u

Well, the D-S extended PWM has exactly 2 transitions per cycle, and the cycles are, say, 32 times faster than the original PWM. You do lose a bit of linearity at the edges, where some of the time your data word is

0 or 0xFF, so there are no transitions.

That's pretty much what I mean, if you use a D-S register to count how many 250s and how many 251s.

I'd be interested to see how well it works.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

ht

ripple frequency will be much higher for most codes. There will unfortuna tely be some values that will still give the same ripple as PWM.

all

t

ust

e it

le of

ly

r)

em,

it.

mber of edges.

There is - I spelled it out in my 1996 paper (of which you have a copy).

If you make your simple PWM waveform by using a digital comparator to compa re your desired digital value with a continuously incrementing counter, you get one "high" and one "low" period in each cycle.

If you reverse the order of the higher order bits coming out of the counter before they get to the comparator, you get what you've asked for.

My application reversed the top four, so MSB went to MSB-3, MSB-1 went to M SB-2, MSB-2 went to MSB-1 and MSB-3 went to MSB.

The extreme PWM waveforms are still single negative or positive going spike s, but over most of the range you get 16 high and low periods, and a single bit increment makes just of of them narrower or wider.

es

s

Only

As discussed in my 1996 paper. Which has now been cited fifteen times (plus twice by me). At least one of the citing authors hadn't read it - or at le ast not very carefully - whence one of my self-citations. It's probably a l ittle long for John's attention span too.

10

--
Bill Sloman, Sydney

Interesting idea, but it seems like it has a bad case of low-frequency birdies over most of its code space, compared with a four-bit delta-sigma extender.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

Yeah, this is the familiar frequencyvoltage conversion that is used in auto tachometers. The problem is, you can send a ten-bit digital signal in ten blink times. You can send a ten-bit analog frequency update in 1000 blink times.

For a good conversion, it probably would suffice to start a ramp at pulse #1, and stop it (track/hold fashion) at pulse #1000. In short, do a single-slope conversion, backward. This will be easier than the filter problem, and has a similar limit on how fast the output updates.

Part-per-thousand accuracy will probably be easiest if you trim rather than find 0.1% capacitors. NP0 is nice and stable, and voltage references and precision resistors will hold a calibration pretty well. The trim can be on a resistor divider outside the integrator section.

It's more than an idea - it worked in production for a number of years, unt il Thermoelectron decided that Affinity Sensors wasn't making them enough m oney, and closed it down.

As I pointed out when I wrote the paper, and John Larkin has observed in th is thread, the non-linearity of PWM DAC does depend on the number of transi tions per cycle, so you are trading off low frequency ripple against non-li nearity.

In my application, each transition also dumped the heat from the switching transient in my MOSFETs, which were switching a current that could go up to three amps. I limited the number of transitions to the point where the swi tching dissipation was as high as the static dissipation in the devices.

--
Bill Sloman, Sydney

'Twaren't my question, though. Vanilla PWM has been working fine in lots of applications, since well before 1996, but it has the nasty quadratic frequency vs. resolution tradeoff. Of course it keeps the same number of transitions per cycle as well, namely 2.

Your method has more transitions, but since they are spaced irregularly (very irregularly indeed for some codes), ISTM that it's only a partial solution to the problem.

The delta-sigma extended PWM wasn't my idea--I got it from Tim Wescott, as I said, and it probably wasn't original with him either. (If it was, Tim, I apologize in advance.) However, it works great, and keeps the low frequency schmutz to a minimum. A second-order D-S extender would do even better, but I haven't needed one so far.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net