Patent ID: 8339189

Claim:
A high voltage current source implemented in a low voltage process, comprising: a plurality of stacked transistors having their conduction paths coupled in series between a first and a second terminal, wherein the first terminal is an output terminal; a voltage divider having a first and a second terminal, wherein the voltage divider generates a plurality of control voltages based on a bias voltage (Vbias) coupled to the second terminal of the voltage divider, and each of the plurality of control voltages is coupled to a respective control terminal of the plurality of stacked transistors; a diode coupled in series between the first terminal of the voltage divider and the output terminal; wherein the plurality of control voltages applied to the respective control terminals of the stacked transistors are configured for the plurality of stacked transistors to withstand a voltage greater than the breakdown voltage of any transistor of the plurality of stacked transistors; and a first transistor coupled in series between the second terminal of the plurality of stacked transistors and a ground terminal, wherein the first transistor is configured to set the output current.