Fully-integrated Capacitive Cross-Coupled Class-D Oscillator with Frequency Doubler

This letter designs a class-D oscillator with frequency doubler implemented in the TSMC standard 0.18 μm BiCMOS processes. The die area is 1x1 mm². At the supply voltage of 0.4 V below the nominal threshold voltage, the n-core oscillator outputs a frequency source at 2.80 GHz. This class-D oscillator with frequency doubler is made of a parallel LC resonator and a capacitive cross-coupled MOSFET pair with inductive gate voltage booting, which enables the class-D mode operation by switching the FETs to deep cut-off region in shorter time.