super nice transconductance amplifiers

[CGS2510.SEP.STUDENT.UCA at CUB.UCA.EDU]

> Also, has anyone tried using 4-quadrant multipliers?  I just got some
> Analog Devices 633JN low-cost multipliers ($6.20), and they couldn't

Since when was $6.20 low cost.  You can make a very fine ring mod 
from two LM13700's and a couple dual op-amps and
$.73 + 2X $.35 + resistors < $6.20

I guess I'll have to try the 633 some time though.