i wish there was a tiny 4pin IC with a single CMOS inverter on the market so we could have that as clipping amplifier to add to whatever circuit were designing.
Texas Instruments sells the grain-of-rice SN74LVC2GU04 dual unbuffered inverter, but I had trouble applying it as a linear amplifier: the devices were too cold-biased to pass a signal without producing severe crossover. I defeatedly replaced the chip with an adapter board that substitutes a CD4049UBE into the circuit.
In retrospect I have two theories as to what went wrong:
- The 5 V supply voltage, as supplied by a capacitance multiplier, was too high for linear amplification. Lowering the voltage should have increased the quiescent current. In the future I should try a lower-voltage zener or LED.
- TI's device is simply unsuitable as a linear device; while Nexperia's datasheet for the equivalent part lists "linear amplifier" as an application (along with the linear parameters for the device!) the Texas Instruments part documentation does not mention linear applications in the least. That particular chip could be simply unsuitable for the purpose.
I would like to see more people take a crack at using this chip; at best, it's two free gain stages, multiple-feedback filters, soft clippers, signal summers, etc. in a six-pin SOT-23 package; at worst it's just enough for a toggle switch.
Done!
I tried a lot of single gate CMOS-Inverters over 10 years ago.
This is what I noted on the datasheets of the ones I tested*:
Fairchild - NC7SZU04 : "not usable"
Texas Instr. - SN74LVC1GU04 : "not usable"
Texas Instr. - SN74AHC1GU04 : "not good"
ON Semi - MC74VHC1GU04 : "inconsistent tolerances" **
**(= variations of output-voltage Vcc/2 from device-to-device)
ST - 74V1GU04 : "similar to ON"
Fairchild - NC7SU04 : "better tolerances than ON"
Toshiba - TC7SHU04F : "good"
*tested were the SMD chips that had a pin-pitch of 0.95mm coz I had adapters for them.
The ones that come in tiny 0,65 mm pitch were not tested yet, but these look promising:
NXP - 74AHC1GU04 and especially: NXP - 74HC1GU04
https://www.mouser.de/datasheet/2/916/74HC1GU04-1541805.pdfAnd: don`t worry about the max. 6V Vcc powersupplyvoltage:
just use a resistor (1k - 100k) from the + pin to your 9V (or higher) supply;
(and maybe a second symmetric R from the - pin to ground for symmetry);
the voltage at the + pin will be reduced, but the output (and input) will
sit at half the voltage of what the + pin sees.
This will reduce the max. output-voltage, but who cares?
The "clipping"-performance stays the same, just at a little reduced scale.
The optimum ideal single CMOS-Inverter that truly is or represents a CD4049UB/6 or 4069U/6
will be subject of a post (soon) in the Members Only part of the forum,
but unfortunately that chip is obsolete ...
(and its currently available possible replacement part has not been tested by me yet ...).