Is it possible to make a ring modulator where we replace the transformers with op-amps?
The diode modulator works well when one signal source (likely 20 kHz) saturates the diodes, so that they act as switches...this signal source would be called the &quot;local oscillator&quot; in R.F. parlance. The other signal source in the modulator application (likely 1 kHz) remains linear, smaller than the forward voltage of the diodes.
The alternative uses an actual analog switch. There are lots of JFET-based, or MOSfet-based analog switches that make excellent modulators that work equivalently to the 4-diode modulator. No transformers are needed. A single-pole double-throw switch is shown in the conceptual circuit below. SPST switches plus an inverter can substitute.



simulate this circuit &ndash; Schematic created using CircuitLab
 This modulator can deliver larger output voltage than the diode version.