Analysis of Zero-locked Circuit of Operational Amplifier and Its Improvement

Working principles of existing zero-locked circuits for operational amplifiers composed of NPN BJT or N channel JFET were introduced separately and corresponding improvement methods were proposed for shortcomings of zero-locked circuit with N channel JFET，namely the diode could be replaced by a resistor for convenient maintain and N channel JFET could be replaced by P channel JFET for simplifying control circuit of computer locking zero. Finally it was pointed out that remaining voltage can be eliminated by use of relay in zero-locked circuit of operational amplifiers.