A compact 21Â GHz inductorless differential quadrature ring oscillator implemented in SiGe HBT technology

A 21 GHz inductorless differential quadrature ring oscillator suitable for use in clock and data recovery circuits in optical network receivers is presented. Implemented using a commercially available 0.18 μm 120 GHz SiGe HBT technology, the circuit consists of only 22 SiGe HBTs and 4 resistors, and occupies an active area of less than 120×150 μm2. The circuit operates on a −3.0 V power supply and dissipates at most 152 mW of power. The oscillation frequency is tunable from 18.33 to 21.19 GHz while the output power varies from −13.5 to −9.0 dBm. A phase noise of −83.33 dBc/Hz at 1 MHz offset from the carrier frequency of 21.19 GHz is achieved. This results in an oscillator figure-of-merit of −148.03, which is comparable to other ring oscillators published in literature operating in similar frequency range.