In one embodiment, a method includes receiving a first analog signal at a first input; receiving a second analog signal at a second input; mixing the first analog signal with a first oscillator signal having a first frequency; mixing the second analog signal with a second oscillator signal having a second frequency; converting a sum signal to a digital signal; generating a first control signal based on a first digital value of a first function and the digital signal; and generating a second control signal based on a second digital value of a second function and the digital signal.