AnsweredAssumed Answered

AD630 Balanced Modulator Problem

Question asked by M.G on Apr 22, 2018
Latest reply on May 29, 2018 by George.Kadziolka

I am trying to reproduce the result shown in Fig.30 of the AD 630 data sheet, using the circuit mentioned in the datasheet itself. I have a strong DC level at the output, instead of the result shown in Fig.30. This means the output signal is modulated only at the top region (see attachment, yellow trace. Blue is carrier. Ground levels are indicated by right arrows).

AD 630 modulator o/p 


The carrier and modulation input is pure AC signals. Also, the grounds of the CRO, power supplies and function generators used, are all tied together. Still the problem is there. Varying the voltage levels of carrier and modulating signal did not yield a different outcome. Can someone suggest how we may conclude if this is a problem due to a damaged 630 (I have a replacement 630, but hesitant to use it until I am sure that my circuit is ok) or a mistake in the circuit I have?