A product modulator achieves double sideband suppressed carrier (DSB-SC) modulation by multiplying the modulating baseband signal with the carrier signal. Balanced modulators use nonlinear resistances to produce AM modulation and cancel the carrier signal, resulting in a DSB output containing the upper and lower sideband frequencies. A ring modulator works by suppressing the carrier signal when no modulation is present and multiplying the positive and negative halves of the modulating signal by 1 and -1 respectively during modulation.

1. Product ModulatorSince expression for DSB-SC is s(t)=x(t)coswctFrom this expression, we see that DSB-SC signal is basically the product of the modulating or baseband signal and the carrier signal.So, circuit to achieve the generation of DSB-SC is called a Product Modulator.

2. Modulation using nonlinear devices(Balanced Modulator)Balanced modulators are AM circuits that cancel or suppress the carrier but generate a DSB output signal that contains the upper and lower sideband frequencies.Non linear resistances are used to produce AM. If two nonlinear devices are connected in balanced mode so as to suppress the carriers of each other, then only sidebands are left.

5. Ring Modulator/ Chopper Modulator

6. Working Operation of Ring modulatorMode 1: Carrier Suppression Assume that Modulating signal is absentPositive half cycle: D1 and D2 are on.

7. Negative half cycle: D3 and D4 are on.Mode 2: In presence of modulating signal+ve half of modulating signal: x(t) is multiplied by +1