Variable gain electro-mechanical oscillator and method for starting balanced oscillations

Abstract

A cross-coupled complementary balanced electro-mechanical oscillator and a method for generating balanced oscillations. The oscillator comprises an electro-mechanical resonator connected to an oscillator core. The oscillator core comprises capacitively cross-coupled complementary programmable inverters and a resistor network. The capacitors inhibit the inverters from latching to a non-oscillatory direct-current (DC) state. The resistor network forms a high pass filter with the capacitors to inhibit relaxation oscillations. The inverters are programmable such that their gain can be varied over time to avoid parasitic oscillations. The oscillator may be frequency-tunable. The method comprises starting balanced oscillations in the oscillator with a low gain to inhibit high-frequency parasitic oscillation modes, inhibiting latching to a DC state using a capacitance, and inhibiting relaxation oscillations using a high pass filter, and varying gain over time to improve phase noise performance. The oscillator may comprise a clock source to excite oscillations in the oscillator core at a frequency close to the resonator frequency to inhibit unwanted oscillations.