Patent ID: 7586357

Claim:
A system for providing a desired substantially constant resistance comprising: A. a first transistor interconnected between a first node and a second node; B. a second transistor, the second transistor being diode connected, the first transistor and the second transistor forming a current mirror; C. a voltage divider coupled to provide a portion of a voltage associated with the first transistor to the second transistor, the voltage divider being configured parallel to the first transistor to provide a substantially constant resistance between the first node and the second node; D. a current source coupled to the second transistor, the current source being controlled to draw an amount of current through the second transistor that sets the substantially constant resistance substantially equal to the desired substantially constant resistance; and E. the voltage divider comprising two matched N-well resistors having substantially equal resistance values, such that the second transistor is coupled to an intermediate node of the voltage divider having a voltage that is one-half of a drain-source voltage associated with the first transistor.