Abstract: In accordance with the present invention, a circuit provides a bias voltage V1 which is substantially insensitive to variations of a power supply voltage powering the circuit. The circuit includes a detector circuit for generating a signal from the power supply voltage and the bias voltage V1, wherein the signal is substantially insensitive to variations in the power supply voltage while being responsive to the bias voltage V1. The circuit further includes a voltage generator circuit for generating the bias voltage V1 wherein the voltage generator is responsive to the signal such that the detector circuit and the voltage generator maintain the bias voltage V1 at a substantially constant value over power supply voltage variations. The detector circuit also includes a circuit for allowing bias voltage V1 to get arbitrarily close to the ground voltage but not allowing the bias voltage V1 to become positive.