Hi I have two sinus signals at 50kHz with different amplitudes and they are in phase. The device I am looking for should perform these two calculations: A----- ----------- A+B Device B----- ----------- A-B
In short: I have two analog signals A/B and I need two analog outputs A-B/A+B
is there any way to do so?
Opamps can perform arithmetic addition and arithmetic subtraction at
50khz. That answer seems too simple. There must be a more complicated solution involving Inphase and Quadrature signals and phase shifting and modulation and convolution.
Opamps can do more complicated things.
A - B How about Y = ------- A + B
What would be your approach? :)
BTW this function is quite common in the analog surround sound processors.
Vladimir Vassilevsky DSP and Mixed Signal Design Consultant
LVDT?
John
Something like this?
Martin
On a sunny day (Tue, 06 Nov 2007 15:50:30 -0000) it happened " snipped-for-privacy@googlemail.com" wrote in :
Here is a nice audio experiment that uses summing and substracting:
The obvious thing is to put a multiplier in the feedback path. The log/anti-log method is available too. If the problem is 2-quadrant, then the variable transconductance method can be used.
See the Analog Devices _Nonlinear Circuits Handbook_, pp.271-326. No doubt there must be something available on the Analog Devices website too.
On Tue, 06 Nov 2007 15:50:30 -0000 in sci.electronics.design, " snipped-for-privacy@googlemail.com" wrote,
Aren't adding and subtracting examples 1 and 2 in the op-amp app note?
On Nov 6, 7:50 am, " snipped-for-privacy@googlemail.com" wrote: \\
If you have power supplies and amplifiers, the solution is trivial (in the sense that a summing junction or inverting amplifier is a trivial item to build from op amps).
If there's no power, the best solution might be a center-tapped coupling transformer: drive B into the primary of the transformer, connect the secondary center tap to A, and the branches of the secondary will now have A+B and A-B signals.
The transformer has to be wound in 1:2 ratio or you will get a pair of signals A + kB and A -kB instead... if you wind your own transformer, a trifilar winding would be suitable.
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