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A new injector topology is proposed for the design of CMOS millimeter-wave divide-by-5 injection-locked frequency dividers (ILFDs). The topology is based on a distributed-element harmonic termination by an open-stub structure connected to the floating source end of the differential injection pair. ILFDs operating at 24 and 60 GHz are demonstrated in this study. The new topology combined with an N-MOS cross-coupled oscillator core can greatly reduce the supply voltage and power consumption requirement of the divider. The simulated results indicate that, by using the distributed-element harmonic termination, the locking range can be improved by over 40 and 72% for the 24- and 60-GHz operations, respectively. The test circuits for the 24- and 60-GHz ILFDs are implemented by a 0.18-\mum and 90-nm CMOS process, respectively. The power consumption is 7.4 and 3.75 mW at a supply voltage of 0.7 and 0.6 V, with a very wide locking range of 1.9 and 4.1 GHz, for the 24- and 60-GHz ILFDs, respectively. The proposed 24- and 60-GHz divide-by-5 ILFDs have the outstanding figure-of-merit (FOM) values of 6.4 and 69.4, respectively, compared with reported works. [ABSTRACT FROM AUTHOR]

This paper presents the design of a direct-injection divide-by-3 frequency divider operating at the K-band. The divider is implemented in a 0.18-\mu\ m CMOS process. The measured free-running frequency of the divider is 7.96 GHz. By utilizing a floating-source differential injector and without a varactor tuning in the divider core, the total locking range is 3.2 GHz with a power consumption of 8.28 mW from a supply voltage of 0.9 V. The total power consumption of the buffers is 9.54 mW from a supply voltage of 1.8 V. The measured phase noise of the divider is -141.3 dBc/Hz at 1-MHz offset when the input referred signal with a phase noise of -132.8 dBc/Hz at 1-MHz offset from 24 GHz. The phase-noise difference of 8.5 dB is close to the theoretical value of 9.5 dB for division-by-3. The output power of the divider is more than -11 dBm over the whole locking range. [ABSTRACT FROM PUBLISHER]