MOTM

On Thursday, December 6, 2001, at 11:20 AM, Tkacs, Ken wrote:

>
> I think you're thinking "voltage" instead of "frequency." A ring 
> modulator
> IS a four-quadrant multiplier, kind of a "through-zero" VCA, but you 
> have to
> think in terms of frequency. You get the sum of the two input 
> frequencies
> and the difference of them.

I understand that with frequency you get the sum and difference. But we 
wouldn't
call it multiplier unless somewhere multiplication was going on. If I put
DC 1.5 volts into X and DC 2.0 volts into Y, won't I get DC 3.0 volts on
the output? And if I put two negative DC voltages into X and Y, won't the
output be positive?

Okay, I just went and played around with the O-scope. Obviously my 
assumptions
were half wrong. Putting DC -1.5 and -2 into a ring modulator results in
an output of +.5. A triangle wave into both X and Y results in a waveform
resembling a upside down full rectified sin. So this means the response
is exponential? Is there such a creature as a linear response four 
quardrant
multiplier.

Tomy