Certain aspects of the present disclosure provide methods and apparatus for generating a two-tone signal for performing linearity calibration of a radio frequency (RF) circuit. One example apparatus generally includes a tone generating circuit configured to generate a first single-tone signal from a digital clock signal and a mixer connected with the tone generating circuit and configured to mix the first single-tone signal with a second single-tone signal to provide a two-tone signal having frequencies at a sum and a difference of frequencies of the first and second single-tone signals.