In constructing a modulator, isolation both at the mixer and oscillator helps in the problems such as feedthrough, self-mixing, etc. Normally cascode stage buffer is utilized in providing better isolation, in a oscillator a buffer stage proceeds at the output to provide isolation upon integration, whereas in a mixer, utilization of differential architecture and cascode stage switching, such as in a typical Gilbert cell architure combats the feedthrough and gives better isolation.

Rgds