摘要 |
PURPOSE:To attain high speed by providing a comparison means obtaining a difference signal between an input analog signal and a reference analog signal and a D/A converter obtaining the reference analog signal for two sets each and operating them alternately thereby increasing the sampling frequency. CONSTITUTION:Two kinds of comparision means are provided: one is combination of a sample-and-hold circuit 3 and an adder 5 and the other is combination of a sample-and-hold circuit 4 and an adder 6. The sample-and-hold circuits 3, 4 sample and hold an input analog signal alternately. Each period can be twice the sampling period ts. An integration device 8 uses a selector switch 7 so as to extract and integrate alternately the output of the adders 5, 6. The output 102 of the integrator is quantized by a quantizer 9 and the output 103 of the quantizer controls the D/A converters 12, 13 via a control logic circuit 10 and two D/A convertors 12, 13 are operated alternately by a switching circuit 11. Thus, the D/A converter, adder and integration device have only to be operated within the sampling time ts and there is a margin for the operating time.
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