| 摘要 |
PURPOSE:To output faithfully a signal containing a high-frequency component and to improve the reliability of a circuit by providing an LPF which is inserted selectively according to the error signal of an input signal on the output side of a quantizing means, and varying the cutoff characteristics of the LPF according to variation of the input signal. CONSTITUTION:A sampling frequency generator 4 is connected to the quantizing circuit 3 of a signal processing circuit and the input signal is quantized adaptively by the circuit 3. A step width control generator 20 is connected to the output side of this circuit 3, and the output of a shift register 21 of the generator 20 is applied to a step width generator 22 to generate an output signal with step width corresponding to the frequency or level of the input signal. Further, the contents of the register 21 are checked by AND circuits 23 and 28 and an OR circuit 29 and the result is outputted from a time constant circuit 30. The output of the generator 20 is applied to the LPF24 with variable frequency characteristics through an integrator 6 and an HPF7. The cutoff frequency of this LPF24 are varied according to the output of the circuit 30 to output the input signal containing the high-frequency component accurately. |
