Recursive Receiver Down-Converters With Multiband Feedback and Gain-Reuse

Abstract

Receiver down-converter topologies are presented that provide simultaneous frequency conversion and baseband amplification within a mixer, in order to reduce power dissipation for a given dynamic range. The down-converted IF output of a mixer is reapplied to its input stage in a recursive manner, which significantly enhances the conversion gain, with current requirement determined primarily by the input transconductor of the mixer. Two down-converter topologies based on this technique are presented. One topology utilizes common-source NMOS devices as the RF input stage of the mixer, and reuses their transconductance for providing baseband gain. The second topology utilizes differential pairs as the RF input stage, and employs the transconductance of the tail current-source devices for baseband gain. The designs are implemented in a 0.13 mum CMOS technology and achieve peak conversion gains of 50 dB and 56 dB, with single side-band noise figures of 12.7 dB and 9.4 dB, and OIP3 values of 8 and 11 , respectively. They operate at a nominal supply of 1.2 V with bias current of 2.9 mA and 2.1 mA, respectively. The active die area is less than 0.1 mm for each design. Noise and linearity performance of the down-converters is analyzed, and the potential for enhancement of IIP3 through cancellation of nonlinear products is discussed.