A quadrature signal generator receives a differential input signal and
generates quadrature output signals that are 90 degrees out-of-phase with
each other. The quadrature generator includes a coarse stage and a
plurality of refinement stages. The coarse stage generates quadrature
signals that may have some phase error, and the refinement stages process
the quadrature signals to reduce any phase error. The refinement stages
receive quadrature signals from the output of the coarse stage, and
processes the quadrature signals to reduce the phase errors. The coarse
stage and the refinement stages are configured using delay circuits that
can be implemented with inverter circuits, such as, for example, CMOS
inverter circuits. In the refinement stages, corresponding outputs of the
delay stages are averaged together to reduce the quadrature phase error.