Phase-locked loop based controller for adjusting an adaptive continuous-time filter

摘要

A direct conversion radio-frequency (RF) receiver includes a controller and an adaptive continuous-time filter. The adaptive continuous-time filter receives a multiple-bit control signal generated by the controller to adjust a characteristic of the continuous-time filter. The controller generates the multiple-bit control signal in response to process variation in the semi-conductor material used to implement the controller and the adaptive continuous-time filter. A method for tuning an adaptive continuous-time filter comprises determining a RC time constant, converting the RC time constant to a digital word, comparing a select bit of the digital word to a respective bit of a predetermined reference word to generate a control bit, applying the control bit to an adjustable element to modify the RC time constant, repeating the determining, converting, comparing and applying steps until the control bits generate an output word and providing the output word to the adaptive continuous-time filter.

主权项

1. An apparatus comprising:
an adaptive continuous-time filter including a first array of elements and a control input configured to receive an output word that generates a filter response to account for effects of semiconductor process variation in the first array of elements; and a controller configured to generate a digital word responsive to a time constant, to compare a select bit of the digital word to a corresponding reference word to generate a control bit, to apply the control bit to an adjustable element to modify the time constant, and to provide the output word to the adaptive continuous-time filter.