A group-selected and gain controllable CMOS active mixer for UWB applications

This paper presents a group-selected (GS) and gain controllable (GC) active mixer designed for ultra-wide-band (UWB) receiver. The double-balanced Gilbert-type configuration, current bleeding technique and resonating technique for tail capacitance are incorporated in the proposed mixer. A switched capacitance network (SCN) is used to control the resonant frequency of the tail capacitance for the group selection. Digitally controlled tail current source and bleeding current source are used to justify and compensate the loss of conversion gain due to the switched capacitance network while working at low frequency groups. These two techniques greatly enhance the conversion gain and noise performance in each group. Designed in a standard 0.18-μm CMOS technology, the mixer achieves a conversion gain of 17dB, a minimum noise figure of 7.31dB and an input IP3 of -6dBm over the 3.432GHz~7.656GHz frequency range for UWB groups #1~#3. It consumes a minimum 9mW from a 1.8V supply.