Re: [sdiy] cheap x**2 circuit

[jhaible at debitel.net]

>>http://home.t-online.de/home/jhaible/jh1_ring.gif
>>
>>Omit the two input opamps (if you have a low impedance source) and tie the two
>>inputs together. One CA3080 and one TL071 - is this cheap enough?
>
>Hi Jürgen!
>
>Very interesting circuit, it looks very good. I'll give it a try. 

I won't conceal a little drawback, though: it's not temperature compensated.
To make a 4QM from a OTA (2QM), there must be cancellation of two signals,
direct and thru the OTA. And OTA gain depends on temperature. But if your application is 
not critical for "carrier suppression" (that would be "fundamental suppression" in an x**2
application), it will do the job.

JH.