A sub-100µW 2GHz differential colpitts CMOS/FBAR VCO

We present a thin film bulk acoustic wave resonator (FBAR)-based Colpitts VCO with a cross-coupled gain boosting transistor pair. The combination of the cross-coupled pair and capacitive feedback in the Colpitts oscillator increases the effective gm to reduce the start-up current requirement, increases the output swing at a low supply voltage, and reduces the phase noise. The differential Colpitts VCO was fabricated in a 0.13 μm CMOS process and oscillates at 2 GHz under a wide range of supply voltage (0.51 V-1.5 V). The minimum power consumption is 67 μW with -141 dBc/Hz phase noise at a 1 MHz offset and a -220 dB Figure-of-Merit. At nominal 0.6 V supply voltage, the VCO consumes 126 μW, achieves -149 dBc/Hz phase noise at 1 MHz offset and shows a FOM of -224 dB.