Abstract: A circuit includes first, second, third, and fourth transistors, first, second, and third current sources, an amplifier, and a voltage-to-current converter (V2I). The second transistor is coupled between the first transistor and the third transistor. The third transistor is coupled between the second transistor and a first input of the V2I. The fourth transistor is coupled between the first transistor and a second input of the V2I. The amplifier has a first input coupled to a reference voltage terminal, and a second input coupled to the first transistor. The V2I has a third input coupled to an output of the amplifier, a fourth input coupled to the second current source, and a fifth input coupled to the third current source. The first current source is coupled between the fourth transistor and the reference terminal.