| 摘要 |
<p>PURPOSE:To accurately generate a tracking error signal even when a switched capacitor filter (SCF) is used a tuning circuit, by inserting a filter which eliminates a harmful component in the output signal of a balanced modulation circuit between the balance modulation circuit ad the tuning circuit using the SCF. CONSTITUTION:Assuming the frequency component of a reproducing pilot signal at a terminal 401 at fpt and that of a reference signal at a terminal 403 as fref, the frequency component of the output signal of the balanced modulation circuit 402 goes to ¦fpt+ or -fref¦. In such a case, a harmful component ¦fpt+fref¦ for the generation of the tracking error signal out of the output signal ¦fpt+ or -fref¦ of the balanced modulation circuit 402 is eliminated by a primary low-pass filter having a break point in the neighborhood of 100kHz, and only the component ¦fpt-fref¦ required for the generation of the tracking error signal is supplied to the turning circuit 102 where the SCF is used. In such a way, it is possible to generate the tracking error signal accurately.</p> |
