Low drift, high current, precision constant current source circuit

Theoretical and component data show that the performance of the precision voltage reference source based on the Zener diode is better than the constant current source based on the energy band, so a high-performance precision voltage reference source is used to indirectly obtain the required precision phase current source. The circuit is shown in Figure 2.

Figure 2 High-precision low-temperature drift constant current source circuit REF102 is a 10V precision voltage reference source with an accuracy of ±0.0025V and a temperature drift of 2.5ppm/℃max, which can meet the requirements of the resistance
measurement of this system . The precision operational amplifier is used as a voltage follower, so that the GND terminal of REF102 is equal to the in-phase terminal of the amplifier, that is, R* is a high-precision, low-temperature drift precision resistor, and the current flowing through RL is a precision constant current. The entire circuit is equivalent to a constant current source circuit.