A parallel structure for CMOS four-quadrant analog multipliers and its application to a 2-GHz RF downconversion mixer

A parallel structure for a CMOS four-quadrant analog multiplier is proposed and analyzed. By applying differential input signals to a set of combiners, the multiplication function can be implemented. Based on the proposed structure, a low-voltage high-performance CMOS four-quadrant analog multiplier is designed and fabricated by 0.8 μm N-well double-poly-double-metal CMOS technology. Experimental results have shown that, under a single 1.2 V supply voltage, the circuit has 0.89% linearity error and 1.1% total harmonic distortion under the maximum-scale input 500 mV_p-p at both multiplier inputs. The -3 dB bandwidth is 2.2 MHz and the DC current is 2.3 mA. By using the proposed multiplier as a mixer-core and connecting a newly designed output buffer, a CMOS RF downconversion mixer is designed and implemented by 0.5 μm single-poly-double-metal N-well CMOS technology. The experimental results have shown that, under 3 V supply voltage and 2 dBm LO power, the mixer has -1 dB conversion gain, 2.2 GHz input bandwidth, 180 MHz output bandwidth, and 22 dB noise figure. Under the LO frequency 1.9 GHz and the total DC current 21 mA, the third-order input intercept point is +7.5 dBm and the input 1 dB compression point is -9 dBm