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 BW_3dB 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.