Wide-Locking-Range Multi-Phase-Outputs Regenerative Frequency Dividers Using Even-Harmonic Mixers and CML Loop Dividers

This paper presents a divide-by-4 (D4) and divide- by-8 (D8) regenerative frequency dividers (RFDs) with the quadrature and the octet outputs. The topologies of the D4 and D8 RFDs use the even-harmonic mixers and the current-mode-logic (CML) loop dividers to achieve high division ratio and wide locking ranges. The modified Gilbert cells with quadrature- and octet-phases local-oscillator switching transistors are adopted to perform 2x and 4x subharmonic mixing with good conversion efficiency. The divide-by-2 and D4 CML loop dividers are used to obtain wide frequency range and the quadrature and the octet outputs. The D4 and D8 RFDs were fabricated by using a 90-nm CMOS process. With consuming 10.8 and 17.8 mW of dc power, the measured locking ranges of the D4 and D8 dividers are 13.2-18.4 and 16.8-26 GHz, respectively. Over the whole locking range, the two dividers with the phase deviation between the quadrature and the octet signals to be less than 2.2 degrees and 4.4 degrees, respectively. The proposed circuits achieve wide locking ranges and accurate output phases, making them very attractive for application into a multi-phase generator.