Current mirror circuit with additional circuit

摘要

The circuit has several p-channel interlocking transistors including a reference transistor (1), an output transistor (2), and an additional circuit of regulating (20) and sensing (21) transistors. The sources of the outlet and reference transistors are coupled to a supply voltage (3) and both their gates are connected (9) to the drain (8) of the regulating transistor and the input current of a reference source (4). The additional transistors have respective channel widths (W1,W2) and channel lengths (L1,L2). The gate-source voltage (5) of the reference transistor, e.g. operating in saturation, is applied between the supply voltage and the regulating drain node (8). The gates of the additional transistors are connected (22) and coupled to the drain of the sensing transistor and to a bias current source (25) via a node (23). The sources of the additional transistors are respectively connected (10,11) to the drains of the reference and output transistors. The output transistor drain is also coupled to earth via a load resistor. The bias current is small and the ratio of the bias current to the reference current is equal to (w2/L2)/(W1/L1).