| 摘要 |
PROBLEM TO BE SOLVED: To provide a tuning circuit for radio equipment capable of improving productivity and maintaining excellent properties.SOLUTION: The tuning circuit comprises a ROM 14 in which a rough tuning control voltage value is written. In tuning, a rough tuning control voltage is applied to a VCF 13, white noise from a signal generator 16 is inputted in place of an input signal, an output signal is down converted and detected by a detector 20, and a peak voltage of a detection signal is detected and held by a peak hold circuit 21. Next, the rough tuning control voltage is interrupted, a comparator 22 inputs the detection signal from the detector 20 and the peak voltage from the peak hold circuit 21, adds a differential voltage to a voltage that is equal to the rough tuning control voltage, such that a fine tuning control voltage is generated, outputted to the VCF 13 and held by a hold circuit 23. In operation, an input signal is inputted to the VCF 13 in place of white noise, and the fine tuning control voltage from the hold circuit 23 is applied to the VCF 13 for operation.SELECTED DRAWING: Figure 1 |
