An integrated enhanced-locking-range injection-locked frequency divider with internal VCO

A 10.5-GHz divide-by-3 (1/3) injection-locked frequency divider (ILFD) with an internal Voltage Controlled Oscillator (VCO) that can provide extra locking range is presented. A phase tuner implemented on an asymmetric inductor is proposed to increase the locking range through even-harmonic phase tuning in addition to those achieved by other techniques. With a fixed internal injection signal power of only − 18 dBm, a 25% enhancement in the locking range from 12 to 15 MHz is achieved with the proposed phase tuning. The integrated 1/3 ILFD has a frequency tuning range of 3.3 – 4.2 GHz. It is realized in a 0.18-µm BiCMOS process, occupies 0.6 mm × 0.7 mm, and consumes 10.6 mA while the ILFD alone consumes 6.15 mA from 1.8-V supply.