Patent ID: 8253504
Filing Date: 2012-08-28
Classification: H03H

Abstract:
1. An electronically variable oscillator circuit comprising: a piezoelectric resonator, a capacitance connected in parallel with the piezoelectric resonator, the capacitance comprising two capacitances connected in series, and an electronically variable simulated inductor connected in parallel with the piezoelectric resonator and the capacitance that comprises the two capacitances connected in series, the electronically variable simulated inductor comprising: a simulated inductor input comprising first and second input terminals, the two capacitances being connected in series between the first and second input terminals, an integrator having an integrator input connected to receive a scaled version of the voltage present at the simulated inductor input from a node between the two capacitances and being responsive to the voltage present at the simulated inductor input to provide a voltage signal that is an integrated version of the voltage signal at the integrator input; and a transconductor having controlled current terminals connected to the simulated inductor input and a control terminal connected to receive the signal output by the integrator, and being responsive to the signal output by the integrator to control the current passed by the controlled current terminals, wherein a gain around a loop that includes the integrator and the transconductor is variable in response to an electronic control signal.