| 摘要 |
<p>PURPOSE:To provide a high frequency receiver for performing video synchronization detection with improved detection output linearity in high frequency television signal reception. CONSTITUTION:A capacitor 19 and a variable capacitative element 17 are serially connected between one end of a reference solid oscillation element 4 and an earth, the output of a first low-pass filter 14 is connected through a buffer amplifier 16 and a second low-pass filter 18 to the connection point and the time constant of the second low-pass filter 18 is made larger than the time constant of the first low-pass filter 14. Thus, even when a phase difference between an oscillator 11 for detection and an intermediate frequency is not pi/2 (rad), the parallel capacitance of the reference solid oscillation element 4 used for a PLL circuit 5 can be finely adjusted by the variable capacitance element 17. Thus, the oscillation frequency of the oscillator 6 can be finely adjusted, the intermediate frequency can be accurately adjusted within the oscillation frequency range of the oscillator 11 for the detection and the high frequency receiver for performing the video synchronization detection for which the detection output linearity is improved can be obtained.</p> |
