| 摘要 |
<p>PURPOSE:To prevent the titled circuit from mislock at the turning-on of a power supply, to adjust the frequency of an input signal to an optimum value, to make said frequency precisely coincide with a prescribed intermediate frequency, and to reduce a steady deviation by forming plural parameter adjusting circuits. CONSTITUTION:An input signal Si is inputted to the 1st and 2nd filter circuits 1, 2 and outputted to a subtractor 5 through the 1st and 2nd detecting circuits 3, 4. In this case, the characteristic parameters of the circuits 1, 2 are adjusted by the 1st and 2nd parameter adjusting circuits 7, 8 so that the spectrum of an intermediate frequency signal is wide and asymmetrical spectrums are formed. When an offset voltage is applied from an offset voltage generating circuit 6, the parameters are adjusted to the optimum values so that tuning shear is not generated. Consequently, the circuit can be prevented from malfunction at the turning-on of the power supply, a leading-in range can be adjusted to an optimum value, the frequency of an input signal can be made to coincide with a prescribed intermediate frequency, and the steady deviation of the frequency can be reduced.</p> |
