This function can be achieved with 2 pnp, 3 npn and 3 resistors. The pnp emitters connect to the current sense resistor. The npn emitters have R's to ground. 1 pnp and 1 npn are diode connected. These are connected by resistor, which sets the bias current (varies with High side sense voltage). The pnp2 collector connects to npn2 collector. This net connects to npn3 base, which is the output device. npn 3 resistor connects to npn1 emitter. This is the feedback signal.