Integrating A=D converter for processing bipolar input voltages - has parallel outputs of two preamplifiers linked, via resistors, to integrator input

摘要

In the integrating A/D converter, an integrator (I) input is connected to two preamplifiers (V1,V1'). The first preamplifier (V1) can be selectively coupled to earth, a positive and a negative reference voltage via three switches (55,56,57) in . parallel. The second preamplifier (V1') can be selectively connected to earth, a positive and a negative reference voltage, as well as to an analogue measuring voltage (US) via parallel switches (S1-S4). In operation from subsequent conversion steps are carried out, comprising each an integration and deintegration. During integration in the first step a positive voltage is connected to both preamplifiers. In the second step the first preamplifier is coupled to earth and the second preamplifier receives the positive voltage in the third step these connection are reversed, and in the fourth step the second preamplifier receives the measuring voltage and the first one, the positive voltage. A microprocessor provides fault-free digital values from conversion results.