A 4.8-mW 4-GHz CMOS Class-B-Like Down-Converter for Harmonic Mixing Rejection

Abstract

In a wideband receiver, higher frequency channels may be converted to the frequency of a desired signal by a harmonic mixing mechanism. To alleviate this issue, this paper proposes a topology, called the classBlike converter, to achieve high harmonic mixing rejection in frequency translation without any filtering. The converter is based on a linear commutation with a sinusoidal local oscillator for a small harmonic mixing, while its gain and noise performances are comparable to that of a switching-type converter. Most important, the circuitry of the proposed converter is simple and can be incorporated with other harmonic rejection techniques. The circuit is implemented with a 0.18-m 1.8-V CMOS technology and the power consumption is 4.8 mW. Measurement results indicate that the third-to ninth-order harmonic rejections are more than 45 dB in average within a 4-GHz frequency range. A polyphase prototype with the proposed converter achieves higher than 70-dB third-order harmonic rejection even under a 2 phase and 2% gain mismatch.

Wideband complementary metal–oxide–semiconductor double‐bulk harmonic‐rejection mixer

“…Although the third‐ and fifth‐HRRs of this simple HRM are less than that of the mixers with much more complex circuit implementation [12, 13], a good seventh‐ and ninth‐HRRs are obtained without extra hardware. Comparing with [14, 15], comparable third‐ and fifth‐HRRs and superior seventh‐, and ninth‐HRRs are achieved. The mixer in this work only consumes 5 mW including the buffer, whereas the mixer core consumes 1.5 mW.…”

“…The HRR performance and other performance (measured with RF input at 2 GHz and LO at 2.05 GHz) are compared with that of other HRMs in Table 1. The HRRs of this worker and of [12][13][14] are the worst case during the LO frequency range, whereas the HRRs of [15] is obtained at a fixed LO frequency. The performance of the mixer in [15] is obtained at LO = 50 mV under which the best HRR was achieved.…”

“…Class‐B‐like mixer based on a linear commutation was proposed in [14]. Although this technique has small hardware and power consumption comparing with the HRMs with poly‐phase LO, extra transistors are added and extra matching efforts have to be made in the layout.…”

“…A square‐law HRM was reported in [15], which essentially works as a multiplier to reject the harmonic mixing. Since, comparing with switching‐type mixer, a multiplier usually suffers from degraded gain and noise performance [14], the square‐law mixer worked at 2.5 V power supply to improve the gain and the noise, while it used 65 nm complementary metal–oxide–semiconductor (CMOS) technology. Moreover, the HR ratios (HRRs) and the trade‐off between gain/noise and HRRs of the square‐law mixer in [15] are sensitive to the LO amplitude since it essentially works as a multiplier.…”