On chip current source

Current source comprising a MOS transistor (T1) having a first terminal (D) connected to a high voltage input (HV), a second terminal (S) providing an output current (Iout) to a current output terminal (Q), and a gate, the current source further including a bias unit (T2) connected to the high voltage input (HV) for generating a small bias current for the gate (G), the gate (G) further being connected to an output (Q1) of a voltage comparator (A1) for comparing a sensed voltage (Vsense) caused by the output current (Iout) over a voltage sensor means (Rsense) with a reference voltage and providing at said comparator output (Q1) a regulation voltage for the gate (G) based on the difference between the sensed voltage and the reference voltage, wherein the bias unit (T2) includes a transistor (T2) having a gate electrode (g) which is coupled to one of the nodes of the voltage sensor (Rsense).