On 01/03/2020 06:10, Jan Panteltje wrote:
> On a sunny day (1 Mar 2020 00:57:14 GMT) it happened Robert Riches
>  wrote in
:
>
>> 
>> On the last statement: I can confirm that a CMOS inverter does
>> make a pretty decent analog amplifier for some purposes.  In the
>> latter 1970s, while a freshman studying EE, I used CMOS part
>> number 4449 inverters (balanced current drive) as analog gain
>> elements for an integrated stereo amplifier.  I think it was an
>> article in Popular Electronics that gave me the idea.  IIRC, the
>> article showed that unity gain was around 1 MHz with a 15V power
>> supply.  For audio purposes, the inverters worked very well.
>
> Yes it works, been there done that, but it is no HiFi etc etc,
> avoid it!
>
> In those days the LM380 was a much better choice, real power amp,
> just got a bunch from ebay a few month ago, still available
>
> The issue of using logic gates with half-way input voltage may indeed
> cause excessive power consumption.
>
Bifet is not bad but there exists today an opamp that is low enough
noise to match the very best discrete circuit that I used to design back
in the 70s .

I think unity gain on CMOS is a lot more than 1Mhz tho.

--
"When a true genius appears in the world, you may know him by this sign,
that the dunces are all in confederacy against him."

Jonathan Swift.

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