How to ensure no quiescent current through signal source in a common source amplifier
Shame about the confusing double meaning of "source" in the title. However...

The trick to ensuring no quiescent current flows through the signal source is to ensure no quiescent voltage applied across it.

The given circuit is a special case, using a MOSFET, (but also applicable to a JFET or a vacuum tube in certain biasing regions) in that the gate current can be taken to be 0. (For the other mentioned devices, this is true for gate (grid) voltages below 0).

In this case, the quiescent current flows purely through R1 and R2 : none into M1 gate, and none into signal source V1.

A simple way to accomplish this:







simulate this circuit &ndash; Schematic created using CircuitLab

Of course this only works if signal source V1 can float (neither terminal is grounded) but nothing in the question says it can't...