3.3-mA 2.8-GHz bufferless LC oscillator directly driving a 10-mm on-chip clock distribution line

A bufferless LC oscillator can potentially offer an attractive solution for low-power, high-speed clock distribution due to the absence of repeaters on the clock distribution line and utilization of LC resonance. However, conventional bufferless LC oscillators suffer from a fundamental tradeoff between the frequency and power consumption due to their high-frequency sensitivity. In this paper, we have introduced a low-frequency sensitivity bufferless LC oscillator that is directly connected to a 10-mm on-chip clock distribution line in the TSMC 0.18-µm 1-Poly 6-Metal CMOS technology. The core area of the LC oscillator is only 270 × 280 µm². The measurement results show that a 2.8-GHz oscillation frequency, 3.3-mA current consumption, and −112.8 dBc/Hz phase noise at 1 MHz offset can be achieved.