The Design Of A Precision Current Miror Using A High-gain Current Amplifier
An improved high gain, precision, low sensitivity current mirror is designed around a feedback circuit. This mirror utilizes a buffered Widlar current mirror to drive the constant input reference current, two beta helpers to compensate for the loss of base current and an active load, and a feedback loop in the amplifier. This design provides a comparison node for detecting the input error signal. The output collector current is substantially equal to the input reference current when driving multiple transistor loads. The circuit has been fabricated with National's VIP10 process, which caters to the high gain bipolar technology. Measurement results obtained are a good reflection of the precision and low sensitivity to indicate a substantial agreement to the simulated results.