On the tracking of resonance and antiresonance of a piezoelectric resonator. II. Accurate models of the phase locked loop.

For pt.I see ibid., vol.38, no.3, p.231 (May 1991). The previous model of the phase-locked loop for the tracking of resonance and antiresonance has been extended so that the observed transient waveforms of the voltage-controlled oscillator (VCO) may be reproduced for a wide range of off-resonant initial frequencies. The use of an accurate VCO response function and accurate admittance phase angles has brought significant improvements. The remaining discrepancies have been removed nearly completely by making an integrator within the loop filter slightly imperfect.