A MEMS RF phase and frequency modulator

We present a method to create an RF MEMS oscillator with continuous control of the output phase and frequency. When the weakly nonlinear oscillating system becomes synchronized with an imposed sinusoidal force of close frequency, the resonator frequency can be detuned with a DC bias on a resistive actuator to produce an easily controlled phase differential between the injected signal and the resonator feedback. We demonstrate a 26 MHz MEMS oscillator with frequency tunability of 0.3% and phase tunability of 200/spl deg/. By modulating the Joule heat dissipated in the structure, a 26 MHz carrier frequency was either frequency modulated by a 30 kHz baseband signal with a modulation depth of 15 kHz, or phase modulated by a 20 kHz baseband signal with a modulation depth of 160/spl deg/.