How to get more bandwidth?

"John Larkin"

** Then keep on guessing - asshole.

The 90 degree outphaser design was part of my "Audio Frequency Shifter " published as a project in Electronics Australia magazine in August 1997.

The schematic posted on ABSE, originally done with Protel Schema, was scanned off a dot matrix print of the file dating from that time.

The magazine staff created their own versions of all supplied schematics intended for publication using a graphics page ( Corel Draw, IIRC) .

....... Phil

I found it now. Thanks phil, but let me to look at it correctly then I'll back here.

with

Please feel free to do so.

Heavens no! This was a simple intrusion detector, not unlike the devices used to open doors at stores. We're talking low cost here, as in a single 2N3866 oscillator and a 1N34 detector. Ability to discriminate advance targets from receding targets enabled elimination of a lot of false alarms because a target that makes no net progress, e.g. something fluttering in a breeze, is not a threat.

r with

1 kHz.

(5kHz)here is the link about the Op Amp Hilbert which I mentioned

It is like Phil circuit somewhat so?

By the way the bandwidth for 741 is not more than 7 or 8kHz.

Adam =D9=86=D9=88=D8=B4=D8=AA=D9=87 =D8=A7=D8=B3=D8=AA:

ter with

21 kHz.

The link is here:

fter with

o 21 kHz.

ut

Thanks " Don Foreman"

Today I'll send you an Email.

Why would you do that, Phil?

John, if what you see is what I see, the lines disappearing down off the bottom of the page are two channels that will be nearly in quadrature over the frequency range Phil specifies. I haven't checked the pole and zero locations of each of the 4 stages in each channel, but I've no reason to doubt that it works as Phil claims. It's a straightforward approach: cascaded all-pass sections of different center frequencies to get the bandwidth, one channel offset from the other so the difference is nearly 90 degrees over the range of interest. Both channels will have significant phase shift and delay from the input signal, but the difference between them is the matter of interest here.

In message , dated Wed, 30 Aug 2006, Adam writes

Where did you get that idea? The small-signal bandwidth is one thing, the large-signal bandwidth is another, and only matters if you need a near rail-to-rail signal output.

--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
2006 is YMMVI- Your mileage may vary immensely.

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

"Adam"

By the way the bandwidth for 741 is not more than 7 or 8kHz.

** Rubbish.

The "unity gain" bandwidth of a LM741 is just over 1MHz.

The "full output swing" ( ie +/- 14 volts) limit is 10kHz before slew limiting occurs.

You have confused the terminology.

....... Phil

"Don Foreman"

** Because the rest is NOT relevant to the OP's question and will only confuse the poor child.

Confuse the HELL out of JL too.

......... Phil

fter with

o 21 kHz.

ut

Don Foreman, your current Email Address does not work?! There was a failure when I tried to send an Email to you. I sent It to Phil because of the second part of my writing there...

fter with

o 21 kHz.

ut

Don Foreman, your current Email Address does not work?! There was a failure when I tried to send an Email to you. I sent It to Phil because of the second part of my writing there...

"Adam"

Don Foreman, your current Email Address does not work?! There was a failure when I tried to send an Email to you. I sent It to Phil because of the second part of my writing there...

** OK - looks like this "Adam" f****it is

T R O U BL E !!

...... Phil

I was wondering what was clipped off below, and what R67 was for.

John

Lots of things confuse me, but not this one. 8 opamps, 2 degree error, wu/wl=1146 is right out of the tables in chapter 7 of the Williams+Taylor filter book; all that's left is to grind out the normalizations and ponder the component tolerances.

What does confuse me is this: If you design, say a 6-pole iir lowpass straight out of the average dsp filter text, you get a nasty mess with a huge span of multiplier coefficients. But if you design a classic state-variable (integrator based) opamp filter, and simulate it digitally, it's a lot more managable, but I don't see people doing this.

I'm playing with the idea of doing a realtime ac power analyzer, with most of the math in an fpga. I'd need a nice 90 degree digital-data phase shifter, inside an fpga, that covers, say, 20 Hz to 1 KHz, to do everything from diesel to jet engine power systems. If I just call up the Xilinx fir Hilbert synthesizer for, say, 16 bit data, and clock it at some reasonable super-Nyquist rate, I'd get some huge number of shift-multiply-add stages, hundreds of them maybe, even with the clever folding and stuff they do. But you can do this with just 6 or 8 opamps using the allpass thing. Digitally simulating an rc lowpass is just

out = out + k*(in-out) k

In message , dated Thu, 31 Aug 2006, John Larkin writes

A friend of mine, who is into these digital things, found the same situation, and used my analogue solution instead. Modest specification, well met, and only four op-amps.

--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
2006 is YMMVI- Your mileage may vary immensely.

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

Did he actually use four opamps, or did he simulate the opamps digitally? Either could well be preferential to some of the common DSP techniques.

John

In message , dated Thu, 31 Aug 2006, John Larkin writes

Genuine infinite sampling rate, infinite bits, continuous-time op-amps. It's called 'analogue'. (;-)

--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
2006 is YMMVI- Your mileage may vary immensely.

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

John Woodgate a écrit :

With an infinity of LSBs totally random?

--
Thanks,
Fred.