Abstract:
A multi-mode receiver is disclosed that is reconfigurable to share a local oscillator signal in diversity mode to save power consumption. In an exemplary embodiment, an apparatus includes a primary receiver having a primary mixer configured to down-convert a primary signal and a secondary mixer configured to down-convert a secondary signal in carrier aggregation mode. The apparatus also includes a supplemental mixer that uses a shared primary local oscillator (LO) signal generated by a shared primary frequency synthesizer in diversity mode to reduce power consumption. The apparatus further includes a controller configured to disable the secondary mixer and to enable the supplemental mixer to down-convert the secondary signal when operating in the diversity mode.
Abstract:
Techniques are provided for reducing mismatch between the in-phase (I) and quadrature (Q) channels of a communications transmitter or receiver. In an exemplary embodiment, separate voltages are applied to bias the gates or bulks of the transistors in a mixer of the I channel versus a mixer of the Q channel. In another exemplary embodiment, separate voltages are applied to bias the common-mode reference voltage of a transimpedance amplifier associated with each channel. Techniques are further provided for deriving bias voltages to minimize a measured residual sideband in a received or transmitted signal, or to optimize other parameters of the received or transmitted signal. Techniques for generating separate bias voltages using a bidirectional and unidirectional current digital-to-analog converter (DAC) are also disclosed.