Abstract: A circuit and method is disclosed for self trimming in frequency acquisition and clock recovery. The circuit can be simplified as having a VCO in communication with three loops including a trimming loop, a frequency loop and a phase loop. The trimming loop includes a ramp generator for supplying a steady increase of bias current to the VCO causing the frequency of the VCO to increase. At each step, the averaged output of the frequency detector is measured by a comparator. A decision circuit included in the trimming loop registers the output of the comparator in digital format. The trimming loop continues until the decision circuit detects a long string of positives followed by a long string of negatives and at this point, the trimming loop is shut off and the frequency loop is in operation. The frequency loop drives the VCO frequency to within a small difference of the incoming data frequency. The phase loop cleans up the data and locks the phase.