Tuning Range Enhancement by Negative Resistance

Abstract

A tank circuit includes a tunable resonator subcircuit having an effective parallel resistance that varies with tuning of the tunable resonator subcircuit. The tank circuit further comprises a variable negative-resistance subcircuit coupled in parallel to the tunable resonator subcircuit, where the variable negative-resistance subcircuit is configured to provide a variable negative resistance, so as to increase the effective parallel resistance of the tank circuit. A control circuit is configured to increase the negative resistance presented by the variable negative-resistance subcircuit in response to a change in the tunable resonator subcircuit that lowers the resonant frequency of the tunable resonator subcircuit.

Dependencies are inferred from the claim text.