Design of a PCI bus high precision and wide range programmable current generator

Corresponding to the common dilemma of programmable current generator's narrow output range and low precision, this paper is intended to present one design of a PCI bus high precision and wide programmable current generator. A 16-bit DAC is put into use to improve the precision of output voltage and V-I transition is easily realized by means of the operational amplifiers which has features such as low noise, temperature drift, distortion and high driving ability. By the precise sampling resistors and 24-bit ADC, the design samples the output current. And then based on the results, discrete increment PID close loop control is adopted in the drivers to realize self calibration of the output. Finally, validated by HP 34401A millimeter, the results shows the output ranges from -50mA to +50mA when the output error is smaller than ± 3μA, which proves that the design improves output range and precision.