电路能力测试：运算放大器音频电路

Circuit Knowledge Test-5: Audio Operation Amplifier

1. What will be the major function for this operation amplifier circuit?

    2.   What will be the amplifier gain for this whole circuit?(without frequency response consideration)

3. Explain the function of CD30, RD18, RD20 components?

4. Explain the function of CD26, CD28, RD17 components?

5. Explain the function of CD27, RD19, RD16 components?

试题解答

Circuit Knowledge Test-5: Audio Operation Amplifier

ANS-1:

Band pass filter for DVD output.

ANS-2:

Amplifier Gain: Av = RD16/RD17 = 1

ANS-3:

RD18 and RD20 set up the center bias for maximum undistorted output of ICA3.

CD30: the ripple filter for ICA3.

ANS-4:

CD26 and RD17 set up the low frequency cut-off point for band pass filter.

CD28 and RD17 set up the high frequency cut-off point for band pass filter.

CD26 also acts as dc-isolation capacitor.

ANS-5:

CD27 and RD19 act as a second low pass filter and set for cut-off point 40 KHz or more to improve S/N. To set at 40 KHz means there will be 3 db cut-off for 20 KHz. (while RD19 in series with RD17)

RD16 sets up the gain for band pass filter. (Av = RD16/RD17)