Analysis of Circuit Structure Schematic Diagram of Double Integral a / D Converter

V-T type indirect conversion ADC.

two   circuit structure

Fig. 1 is the principle circuit of this converter, which is composed of integrator (composed of integrated operational amplifier a), zero crossing comparator (c), clock pulse control gate (g) and counter (ff0 FFN)

Figure 1 dual integral A / D converter

(1) Integrator  

      The integrator is the core part of the converter, and the switch S1 connected to its input is controlled by the timing signal QN. When QN is at different levels, the input voltage VI and the reference voltage Vref with opposite polarity will be added to the input of the integrator respectively for two integration in opposite directions, and the integration time constant τ= RC。

(2) Zero crossing comparator

     The zero crossing comparator is used to determine the time when the output voltage V0 of the integrator crosses zero. When V0 ≥ 0, the comparator output VC is low level; When V0