| 摘要 |
PURPOSE:To improve the servo characteristics to an external disturbance factor of a low frequency and to maintain the sufficient phase margin, by increasing the open loop gain against reduction of frequency of an error signal of a servo mechanism. CONSTITUTION:Input terminals I1 and I2 are connected to the reverse input terminals of operational amplifiers 1 and 2 having grounded forward phase input terminals. The output of the amplifier 1 is grounded via a series circuit of partial pressure resistors R1 and R2. The junction between R1 and R2 is connected to the forward phase input of an operational amplifier 3. While the output of the amplifier 2 is connected to the reverse input of the amplifier 3 via a resistance R3. The output of the amplifier 3 is connected to the inputs of a phase compensating circuit 4 and an LPF5 respectively. The output of a filter 5 is supplied to a multiplier circuit 8 via an absolute value amplifier 6. Thus the margin of gain increases at a low frequency band. It is possible to improve simultaneously both the vibration resistance to the tracking of a DC player as well as the durability against the injuries on the CD surface. |
