Triple Capacitive Cross-Coupled Divide-by-2 Injection-Locked Frequency Divider

This letter proposes a new LC injection-locked frequency divider (ILFD). The ILFD consists of three capacitive cross-coupled sub-ILFDs operating at 1.85, 4.73 and 5.74 GHz respectively. The two sub-ILFDs are coupled by a pair of MIM capacitors. The proposed ILFD has been implemented with the TSMC 0.18 μm BiCMOS technology. The die area is 1.2×1.196 mm2. By controlling the gate voltages of the switching transistors, the ILFD has at least three different operational modes, high-band dominant mode, low-band dominant mode and middle-band dominant oscillation mode. The ILFD can operate at low power of 1.592 mW. At gate bias 0.55V, an external injected signal power Pinj of 0 dBm provides a low-band locking range from 1.9 to 5.8 GHz (101.29%) and the maximum figure of merit (FOM) is 63.63.