Inverter Amplifier Circuit

The detector is biased over a 5V supply.

When there's no suffix, the longtime rule was, whole numbers are pF, fractional numbers are uF. So that's 1nF. :>)

That's the input coax cable.

A photodiode? No, you likely need a trans-resistance amplifier. But tell us, under what conditions do you see 100mV, into 50 ohms?

As for the amplifying capability of 74hc04 inverters: not as good as the more modern low-voltage 74LVC04 inverters, or better, for a linear-feedback circuit use 74vhcu04, etc., *unbuffered* parts. Tiny single-gate ICs are nice for this purpose, 74vhc1GU04, etc.

The diodes won't conduct if the input signal is smaller than say 3V p-p. But they do provide additional static protection.

Yes, that lowers its self-capacitance and makes it more linear at very high opto-currents. But into what load do you observe a 100mV signal? And is this at up to 15-20MHz?

Hello Winfield,

In the US that has always been the convention, along with some rather bizarre ones such as mmF for uF. But since AoE sells everywhere from here to Mars maybe it would be worth to actually place uF or pF behind these numbers. Much of the world uses nF and I have seen a lot of confusion about it in my consulting life. Like caps being three orders of magnitude off of what they should be because the local engineer took a US app note and misinterpreted the (missing) designator. Or had given the whole chebang to a local tech and just said "Wire this up for me, please".

This will also help if the book gets translated. Then you could just leave the schematics as they are, assuming that any EE will master enough of English to comprehend the few words that may be on the drawings.

Regards, Joerg

mF and uF were used interchangeably. mmF was never uF. mmf and pF were interchangeable. Not that anyone but me gives a rip, but I think the use of nF is a pain in the ass.

It seems to be catching on the US as well. Perhaps due to chip designers deciding "enough is enough" (with stuff like mmF, .001uF, etc.) after finding their need to routinely use values between 1 and 999 fF in their work?

I routinely use fF, pF, and nF on-chip. ** That's no typo, I used 1nF gate capacitance recently on a heavily transient-loaded regulator **

...Jim Thompson

Hello Jim,

And then the LDO chip designers are whining about not being able to place proper compensation on board. After the last debacle I am not going to use LDOs anymore until they figure that out.

Anyway, how many acres did that cap swallow up?

Regards, Joerg

M=150 (stripes), each L=2u x W=380u (thin oxide, 1.8V device)

on a HUGE RAM chip, so it's barely noticed ;-)

BTW, "compensation" whining is BS. The regulator only needed 5pF compensation... 1nF was for output energy storage (BIG transients)...

...Jim Thompson

Hello Jim,

Yes, that's like a parking spot on a Texas ranch.

Then why are many of these regulators so lousy? Is that 5pF already too much real estate for the bean counters or is it a lack of design skills?

Regards, Joerg

The 5pF WAS an extra processing step (metal-oxide-metal cap)... could not use gate capacitance for that, due to no voltage drop at the compensation point. So maybe it's a cost issue for the LDO people, my chip was MIL, or maybe it IS lack of design skills ;-)

...Jim Thompson

Hello Jim,

Avoiding a processing step is certainly understandable. But they didn't even provide a couple of pins where one could connect an external cap. Maybe that is expecting too much these days.

The real problems that mfgs don't see (usually) aren't at the circuit designers. They can select output caps where the ESR falls into a certain range. What they often can't control is the client hanging some additional stuff onto the rail that comes with more decoupling caps. Or a "smart" purchaser who hasn't read the module spec and got cajoled into buying this wonderful new ceramic cap for three cents less. What we hear a lot is "Yabbut it had lower ESR". The last LDO circuit even drowned out Rush on the local AM station after that happened. A solid 2Vpp on a heavily loaded 4.7V rail, pretty impressive.

Regards, Joerg

Analog Devices makes some LDOs that are supposed to tolerate AnyCap (tm) on the output. I've used the ADP3300 and ADP3330 and I haven't managed to make one oscillate yet but I have not been deliberately trying. Only one hint: If you do not use the noise reduction pin (NR) then don't hang a long trace off the pin, just put a pad and no track.

Chris

I read in sci.electronics.design that Jim Thompson wrote (in ) about 'Inverter Amplifier Circuit', on Wed, 5 Oct 2005:

No, we want the answer in acres. Or nano-acres.(;-)

Google: 114000 square microns in acres ->

Best regards, Spehro Pefhany

Hello Spehro,

Regards, Joerg

"Joerg" schreef in bericht news:d2d1f.1518$ snipped-for-privacy@newssvr13.news.prodigy.com...

Which you can explore on your picofahrad.

I read in sci.electronics.design that Frank Bemelman wrote (in ) about 'Inverter Amplifier Circuit', on Thu, 6 Oct 2005:

I doubt that many will appreciate that. Has the spelling reform changed it from 'Fahrrad'?

"John Woodgate" schreef in bericht news: snipped-for-privacy@jmwa.demon.co.uk...

I knew you would, and Joerg, no doubt. It sort of felt (after hitting the send button) as if I was stealing your joke ;)