A Q-Band CMOS Image-Rejection Receiver Integrated with LO and Frequency Dividers

Abstract

This paper presents a Q-band image-rejection receiver using a 65 nm CMOS technology. For a high image-rejection ratio (IMRR), the Q-band receiver employs the Hartley architecture which consists of a Q-band low-noise amplifier, two down-conversion mixers, a 90° hybrid coupler, and two IF baluns. In addition, a Q-band fundamental voltage-controlled oscillator (VCO) and a frequency divider chain divided by 256 are integrated into the receiver for LO. A charge injection technique is employed in the mixers to reduce the DC power while maintaining a high conversion gain and linearity. The VCO adopts a cross-coupled topology to secure stable oscillation with high output power in the Q-band. The frequency divider chain is composed of an injection-locked frequency divider (ILFD) and a multi-stage current-mode logic (CML) divider to achieve a high division ratio of 256, which facilitates the LO signal locking to an external phase-locked loop. An inductive peaking is employed in the ILFD to widen the locking range. The Q-band image-rejection receiver exhibits a peak conversion gain of 16.4 dB at 43 GHz. The IMRR is no less than 35.6 dBc at the IF frequencies from 1.5 to 5 GHz.