A Single-Inductor Two-Step-Mixing Injection-Locked Frequency Divider by Four with Concurrent Tail-Injection

The paper presents a novel single-inductor injection- locked frequency divider (ILFD) by four. The topology improves the ILFD by four two-step-mixing circuit by introducing an additional tail-injection path driven by a common-mode tone at the input frequency. This new path adds a further contribution to the injection current thus boosting the locking-range. When compared with the single-inductor two-step-mixing ILFD by four at the same operating conditions and CMOS process, the novel topology shows a 67% locking-range enhancement. The novel scheme is then exploited to design a 20-GHz divide-by-four prescaler in a standard 65-nm LP CMOS process. With a 0.4- V input signal amplitude, the circuit shows a 22% lock range at 4.6 mW DC power consumption, which is competitive with state-of-art ILFDs, which, however, use two or more inductors