Softransceiver transmit origin offset compensation: Digital to the rescue of RF-CMOS

Multi-mode, multi-band Softransceiver core allows seamless support for the second to the fourth generation of modern wireless standards. Targeting such a transceiver core becomes a stretch goal as one implementation needs to simultaneously meet the conflicting requirements for various standards. Such a goal is achieved by designing radio-frequency and baseband circuits such that various operational parameters can be tweaked using a standard-specific configuration file. This is aided by addition of quality calibration hardware and algorithms. However, the wireless performance needs to be guaranteed across varying temperatures and voltages. This is achieved using active compensation loops, which keep the transceiver parameters at their optimum levels during operation. This work describes a practical origin offset compensation scheme employed for the transmit (Tx) path, which allows for the specification compliant performance across temperature, voltage and process over the required power control range.