A design of novel transducer converting output signals of sensor modules to 4∼20mA

A novel transducer converting output signals of sensor modules to 4~20mA was designed. The interface was composed with digital controllable universal voltage-to-current converter(VIC) with a current gain amplifier. The VIC used seven analog switches and six weighted resistors for selecting universal input signals. The simulation result shows that the circuit has good output current characteristics of 4~20mA for the signal 1~5V, 0~5V, -10~+10V, -5~+5V, and 0~20mA. The nonlinearity error is less than 0.1% for the input signals.