A new method of frequency compensation for bipolar Wilson current mirror

This paper proposes a new method of frequency compensation for a bipolar Wilson current mirror. The mirror is, first, modified: a resistor is inserted into the collector circuit of the diode-connected transistor, and another resistor of equal value is added into the emitter circuit of the same transistor. A compensation capacitor is connected between the collector and base of the feedback transistor. It is shown that the modification produces a pole-zero pair in the current-source transfer function. The split between pole and zero is reduced when the resistor value increases. This results in a wider bandwidth of the mirror transfer function and a faster step-transient response. These improvements are paid for in a small degradation of noise performance.