A BiCMOS single ended multiband RF-amplifier and mixer with DC-offset and second order distortion suppression

Abstract

Direct conversion receivers are widely used for full duplex mobile radio communication systems. This paper describes a novel SAW-less single-ended RF amplifier connected to a single-ended mixer with a feedback loop that suppresses the second-order distortion from TX cross modulation of the LO-leakage as well as DCoffset at the mixer output. In Monte Carlo simulations the design achieves ?47 dBm minimum IIP 2 with 32 dB conversion voltage gain. The advantage with the proposed architecture is that it is fully single-ended. Especially in multiband integrated radios this is highly desirable since the pin-count for the LNAs is reduced by half. The PCB routing of the RF input signal is simplified. The design requires two off-chip filter capacitors of non critical value intended to be placed on the laminate inside the package.