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This article designs and analyzes LC injection-locked frequency dividers (ILFDs) using dual-resonance LC resonator. The ILFD consists of two single-resonance LC-tank capacitive cross-coupled sub-ILFDs operating at 3.7 and 5.1 GHz, respectively, and the two sub-ILFDs are coupled by the electric field through a pair of metal–insulator–metal (MIM) capacitors. The die area in the Taiwan Semiconductor Manufacturing Corporation (TSMC) 0.18- $\mu \text{m}$ CMOS is $0.65\times1.023$ mm2. By controlling the gate voltages of the switching transistors, the ILFD has three different operational modes—high-band dominant mode, low-band dominant mode, and concurrent oscillation mode. Overlapped locking range is demonstrated for the first time in the designed electric-field coupling resonator ILFD. Non-overlapped locking range is found for the ILFD manifesting an effect of the dual-resonance resonator. [ABSTRACT FROM AUTHOR]

This article presents and analyzes a wide-locking range divide-by-5 injection-locked frequency divider (ILFD) manufactured in the TSMC 0.18- $\mu \text{m}$ processes. The ILFD uses the balanced injection method and uses the pure harmonic mixing approach at low injection power, and it is designed with an RLC dual-resonance resonator. The harmonic mixer relies on the self-generated second harmonic, which increases with injection power. Because of no narrowband filter as used in the linear mixer counterpart, the divide-by-5 ILFD uses a wideband design method. In addition, the ILFD enhances the divide-by-5 locking range via the overlapped dual-band locking ranges as verified by both experiment and simulation. At the drain–source bias ${V} _{\text{DD}}$ of 0.8 V and at the incident power of 0 dBm, the locking range of the divide-by-5 ILFD is 3.6 GHz, from the incident frequency 13.0–16.6 GHz with the percentage 24.3%. The core power consumption is 4.09 mW, and the die area is $1.02\times0.93$ mm2. [ABSTRACT FROM AUTHOR]

This article designs and analyzes wide locking range (LR) high even-modulus LC-tank injection-locked frequency dividers (ILFDs) with current-reused topologies. The current-reused LC ILFD uses two stacked LC sub-ILFDs sharing the same dc current. The current-reused ILFD becomes a divide-by-4 ($\div 4$) ILFD, when both sub-ILFDs are used $\div 2$ ILFDs, and it is used as a divide-by-8 ($\div 8$) ILFD when one sub-ILFD is used a $\div 4$ ILFD. Both sub-ILFDs use nMOSFETs as linear injection mixers for high conversion gain. For the $\div 8$ LC ILFD designed in the TSMC 0.18- $\mu \text{m}$ CMOS process, the circuit uses one high-frequency $\div 4$ sub-ILFD and one low-frequency $\div 2$ sub-ILFD, at the supply of 1.6 V, and at the incident power of 0 dBm, the LR is 4 GHz (38.835%), from the incident frequency 8.3 to 12.3 GHz. The $\div 8$ ILFD core power consumption is 13.98 mW, and the die size is $1.2 \times 1.2$ mm2. Both the $\div 8$ LC ILFD and the $\div 4$ sub-ILFD have nonoverlapped and overlapped LRs, which are due to a dual-resonance resonator used in the varactor-free n-core sub-ILFD. The LC dual-resonance resonator is due to parasitic capacitors in active FETs and on-chip spiral inductors and inductive elements, and it is used to get wide overlapped LR. Two $\div 4$ LC ILFDs inherent in the designed circuit are also studied. [ABSTRACT FROM AUTHOR]

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- $\mu \text{m}$ CMOS ILFD is made of a pair of cross-coupled n-type transistors, two direct-injection MOSFETs, and a resistively dual-resonance 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. [ABSTRACT FROM AUTHOR]