A method and apparatus are disclosed for generating a quadrature signal that may be used to modulate and/or demodulate communication signals transmitted between communication devices. A quadrature signal generator may include a control block, a mixer, and a filter. The control block may generate a reference signal and a filter control signal based on an input clock signal. The mixer may generate a mixer output signal based on the input clock signal and the reference signal. The filter, controlled by the filter control signal, may filter the mixer output signal to suppress a band of frequencies within the mixer output signal.