Patent ID: 7808309
Filing Date: 2010-10-05
Classification: G05F

Abstract:
1. A current source circuit comprising: a first transistor, having a first source/drain terminal coupled to a bias voltage, a second source/drain terminal receiving a current signal, and the second source/drain terminal coupled to the gate terminal of the first transistor; and at least one second transistor, having a first source/drain terminal directly grounded, a second source/drain terminal coupled to a voltage source to output a bias current, and a gate terminal coupled to the gate terminal of the first transistor, wherein the bias voltage is different from a voltage at the first source/drain terminal of the second transistor, and the bias current outputted by the second transistor is independent of a threshold voltage of the second transistor when the threshold voltage of the second transistor is substantially equal to a threshold voltage of the first transistor such that the bias voltage determines the bias current.