A 2.4-GHz Class-AB FBAR-Based Low Phase Noise Oscillator Using Dynamic Tail-Current Biasing

In this letter, a 2.4 GHz FBAR-based Colpitts oscillator is designed using a film bulk acoustic resonator (FBAR) resonator with high-quality characteristics. The dynamic tail-current biasing circuit allows the Colpitts transistors to operate in the Class-AB regime, which helps to increase the current efficiency and improve phase noise performance. The RC high-pass network is included to suppress the dc latch and low-frequency instability of the FBAR-based oscillator. The proposed oscillator core is fabricated in a 180 nm CMOS technology, and it occupies an area of $0.6\times0.53$ mm2. Measurement results show that the oscillator achieves a phase noise of −141.1 dBc/Hz@100 kHz offset with a figure-of-merit (FoM) of 226.4. The oscillator consumes a dc power of 1.82 mW under a supply voltage of 0.9 V.