Qualcomm Incorporated

Bahman Ahrari

Jin-Su Ko

Michael Kohlmann

I-Hsiang Lin

Sang Oh Lee

Hee Choul Lee

A receiver for a wireless device is described. The receiver includes a low noise amplifier that includes differential inputs. The receiver also includes a mixer coupled to the low noise amplifier. The receiver further includes second-order intermodulation reduction circuitry coupled to a stage subsequent to the low noise amplifier. The second-order intermodulation reduction circuitry provides a biasing of the differential inputs.

Reducing non-linearities in a differential receiver path prior to a mixer using calibration

An RF transceiver integrated circuit has a novel segmented, low parasitic capacitance, internal loopback conductor usable for conducting IP2 self testing and/or calibration. In a first novel aspect, the transmit mixer of the transceiver is a current mode output mixer. The receive mixer is a passive mixer that has a low input impedance. In the loopback mode, the transmit mixer drives a two tone current signal to the passive mixer via the loopback conductor. In a second novel aspect, only one quadrature branch of the transmit mixer is used to generate both tones required for carrying out an IP2 test. In a third novel aspect, a first calibration test is performed using one quadrature branch of the transmit mixer at the same time that a second calibration test is performed using the other quadrature branch, thereby reducing loopback test time and power consumption.

RF transceiver IC having internal loopback conductor for IP2 self test

Techniques for reducing or eliminating DC (direct current) offset in transmitters are disclosed. An apparatus for DC offset reduction may include a converter, a digital engine, and a plurality of programmable current supplies. The converter is configured to provide digital representations of a plurality of DC currents associated, respectively, with a plurality of differential signal legs. The digital engine is configured to receive the digital representations and to produce instructions for generating compensating currents for the plurality of differential signal legs based on comparisons, respectively, between each of the digital representations and a calibration current. The programmable current supplies correspond, respectively, to the differential signal legs. The current supplies are configured to inject the compensating currents into the differential signal legs, respectively, to reduce DC offset between the differential signal legs, based upon the instructions. The instructions allow one-shot DC offset correction, instead of successive approximation for DC offset correction.

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Los Gatos, CA, United States of America

Bahman Ahrari