1. A direct conversion radio-frequency (RF) receiver, comprising: a controller including a RC time constant replicator using an array of elements, a digital phase-locked loop responsive to a system clock, and an oscillator configured to generate a signal having a frequency responsive to a RC time constant; and a word generator configured to receive a multiple-bit control signal generated by the controller, the multiple-bit control signal responsive to process variation in the semiconductor material used to implement the controller and the RC time constant replicator.