A 16-band channelizer employing harmonic rejection mixers with enhanced image rejection

Abstract

A channelizing broadband receiver for a spectrum analysis application that employs a bank of two-stage harmonic rejection mixers (HRMs) is described. Each HRM internally synthesizes a distinct downconversion LO. In addition to minimizing LO harmonic response, the HRMs also include a quadrature phase matching technique for enhancing image rejection. The technique reduces the two-dimensional calibration for enhancing image performance, that requires amplitude and phase correction, into a one-dimensional problem, thereby significantly reducing calibration complexity. The prototype receiver downconverts an I/Q input of bandwidth 250 MHz to baseband and channelizes the signal concurrently into 16 sub-bands of bandwidth 15.625 MHz each. The design is implemented in 65nm CMOS. It achieves an image rejection of 56 dB with amplitude calibration alone, and a harmonic rejection of 56.5 dB without any calibration for a 1 MHz baseband output.