A 6.2 - 38-GHz Image-Reject Receiver With Hybrid LO Generation and Linear-in-dB Gain Control

This article presents a 6.2-38-GHz dual-channel receiver (RX) based on a configurable Hartley architecture, featuring sideband selection and achieving 28-49 dB calibration-free full-band image rejection ratio (IRR). The RX supports low-IF and zero-IF operation and features a 3.5-GHz bi-directional IF interface for flexible off-chip filtering. A pseudo-exponential (PE) digital control technique is introduced in the low-noise variable gain amplifier (LN-VGA) to realize linear-in-dB characteristics over a 14-dB range, while resistive compensation is employed to reduce phase variation across the wide bandwidth. Quadrature LO signals are derived from a single 19-34.5-GHz clock via a hybrid generation scheme combining a transformer-based poly-phase network (TPPN) and a divide-by-2 divider, achieving I/Q amplitude and phase mismatches within ±0.2 dB and ±0.5° across 8-34.5 GHz. To handle signal attenuation in the LO distribution chain, switchable current injection is introduced in the frequency divider to enhance input sensitivity, extending the locking range to 30 GHz. Fabricated in a 45-nm CMOS SOI technology, the RX demonstrates a BW3dB of 6.2-38 GHz, while the required LO bandwidth is 15.5 GHz. In low-IF mode, the peak conversion gain (CG) is 43 dB, and the NF is 2.4-4.9 dB. In zero-IF mode, the peak gain reaches 75 dB, with a gain control range of 81 dB with a 2-dB step.