| 摘要 |
PURPOSE:To prevent the deterioration in S/N for a minute input by changing a threshold value by the output of a circuit detecting a peak value of an analog input signal. CONSTITUTION:An analog signal inputted to an input terminal AIN is led to comparators C1-Cn receiving plural different threshold values, the binary signal being the result of comparison of the amplitude is coded into a digital signal by a coder COD and the result is outputted from output terminals D1-Dm. The analog signal is led also to a peak detection circuit PH, and the output of the circuit PH changes the output level of a threshold voltage source VR. The output is fed to a series connection circuit comprising impedance elements Z0-Zn, and a threshold voltage divided from each connection point is fed respectively to the input terminals of the comparators C1-Cn. Thus, the deterioration in S/N for a minute input is prevented by changing the threshold value in response to the input analog signal so as to change the quantization step.
|
