I'm wondering if a varactor can be used to replace a floating (non-grounded) variable capacitance. Specifically I'm thinking of using it for a phasing capacitor (the bottom variable capacitor) in a phasing crystal filter:
Normally the varactor anode is directly grounded, but I'm thinking if we ground the anode through an RF choke then we can pick off the RF (after it goes through the voltage-variable varactor capacitance) at the anode through a large-value DC blocking cap. Would that work?
EDIT: Unfortunately, thinking some more, it seems this can't work. If the RF signal passes through the varicap on its way to the following load, then it follows that the RF signal will be rectified by the diode, highly undesirable if only a floating variable capacitance is required. Or is there some trick to be able to get a varactor to float without rectification?