Range Of Injection-locked Frequency Divider Research Articles

Injection-Locked Frequency Divider With a Resistively Distributed Resonator for Wide-Locking-Range Performance

Distributed LC resonator and resistively distributed resonator belong to the same technique used to extend the locking range of injection-locked frequency divider (ILFD). ILFD using the former resonator often has one locking range, and extension of locking range is attributed to oscillation frequency increment. This paper measures and analyzes the input sensitivity of a CMOS ILFD with a resistively distributed resonator and with the divide-by-3 and divide-by-2 functions, and the input sensitivity shows a wide single-band locking range. The fabricated 0.18-μm CMOS ILFD is made of a pair of cross-coupled n-type transistors, two direct-injection MOSFETs, and a resistively dualresonance resonator. The wide single-band locking range of the designed ILFD is owing to the overlapped locking ranges, and it is verified by the smooth tuning range without forbidden region and nonoverlapped locking ranges measured on the same chip with the unbalanced injection structure. The frequency tuning is obtained with large tank resistance, which also reduces the frequency tuning hysteresis effect.

Analysis and Design of Wide-Band Millimeter-Wave Transformer-Based VCO and ILFDs

Several transformer-based techniques are proposed to enhance the frequency tuning range of mm-wave voltage-controlled oscillators (VCOs) and the frequency locking range of injection-locked frequency dividers (ILFDs). Firstly, a switched-transformer VCO (ST-VCO) based on dual-band topology is proposed to increase the frequency tuning range. Secondly, transformer-distribution ILFDs (TD-ILFDs) are demonstrated to achieve much improved frequency locking range with compact chip area and low power consumption. Thirdly, the injection-saturation problem of ILFDs is identified, analyzed, and solved in this work. A VCO and three different TD-ILFDs are designed and fabricated in a 65 nm CMOS process. The proposed ST-VCO measures wide tuning range of 22.3% from 62.1 GHz to 78.3 GHz with phase noise of -112 dBc/Hz at 10 MHz offset while consuming 7.7 mW, corresponding to FoM and FoMT of -180.4 dBc/Hz and -187.4 dBc/Hz, respectively. The proposed 60-GHz TD-ILFDs measure locking range of 19.6 GHz (29.6%), 19.8 GHz (29.2%), and 3.8 GHz (6.1%) while consuming 1.44 mW, 1.44 mW, and 0.44 mW.

Analysis of Nonlinearities in Injection-Locked Frequency Dividers

The locking range of injection-locked frequency dividers is investigated and it is shown that the presence of nonlinearities, such as those exhibited in a current mode logic (CML) D flip-flop (DFF)-based divider, can result in a wider frequency locking range. A new approach to evaluate such nonlinearities is described. A new divider topology benefiting from the nonlinearity is presented that exhibits both higher operating frequencies and similar locking range compared to the conventional CML DFF-based topology. The chip was fabricated through a TSMC 90-nm CMOS process.

A Wide Locking Range Differential Colpitts Injection Locked Frequency Divider

This letter proposes a new wideband Colpitts injection locked frequency divider (ILFD) and describes the operation principle of the ILFD. The circuit consists of a differential CMOS LC-tank oscillator and a direct injection topology. The divide-by-two ILFD can provide wide locking range, and the measurement results show that at the supply voltage of 2.4 V, the tuning range of the free running ILFD is from 4.46 to 5.6 GHz, about 1.14 GHz, and the locking range of the ILFD is from 8.03 to 11.63 GHz, about 3.6 GHz, at the injection signal power of 0 dBm. The ILFD dissipates 19.92 mW at a supply voltage of 2.4 V and was fabricated in 1P6M 0.18 mum CMOS process. At the tuning voltage of 1.2 V, the measured phase noise of the free running ILFD is -110.8 dBc/Hz at 1 MHz offset frequency from 4.94 GHz and the phase noise of the locked ILFD is -135.4 dBc/Hz, while the input signal power is -4 dBm.