A test system (and methodology) suitable for testing a resonant sensor circuit configured to drive a sensor resonator with a negative resistance. Example embodiments include a test sensor resonator setup configured to simulate a sensor resonator with a selectable loss factor Rs, and includes, in a single-ended configuration, a first oscillator signal source that generates a first oscillation signal, coupled to a first controllable resistor that provides a controlled resistance R1 that simulates a selectable sensor resonator loss factor Rs, which together generate a first oscillation voltage signal based on the controlled resistance R1. A DUT resonant sensor circuit is coupled to receive the first oscillation voltage signal at a first input, and generate a negative resistance −Ra that substantially counterbalances the resistance R1 (corresponding to sustained oscillation). A differential configuration includes first and second oscillator signal sources, coupled to first and second controllable resistors R1 and R2.