Patent ID: 6313692
Filing Date: 2001-11-06
Classification: G05F

Abstract:
A current source for providing matched currents at low and variable bias voltages comprising:a first circuit for providing a reference voltage;a first transistor including a control terminal, first terminal, and second terminal receiving said reference voltage at said control terminal and said first terminal being coupled to a supply voltage;a second transistor including a control terminal, a first terminal, and a second terminal, said first terminal of said second transistor being coupled to said second terminal of said first transistor, and said second terminal of said second transistor being coupled to a ground reference;a third transistor including a control terminal, a first terminal, and a second terminal, said control terminal of said third transistor being coupled to receive said reference voltage and said first terminal of said third transistor being coupled to said supply voltage;a fourth transistor including a control terminal, a first terminal, and a second terminal, said control terminal of said fourth transistor receiving a bias voltage, said first terminal of said fourth transistor being coupled to said second terminal of said third transistor, and said second terminal of said fourth transistor being coupled to a terminal of a load circuit; anda bias circuit comprising:a fifth transistor having a control terminal, a first terminal and a second terminal, said control terminal being coupled to receive said reference voltage, said first transistor being coupled to said supply voltage;a sixth transistor having a control terminal, a first terminal and a second terminal; anda seventh transistor having a control terminal, a first terminal and a second terminal, said second terminal of said seventh transistor being coupled to said ground reference, wherein (a) said control terminal of said seventh transistor, said first terminal of said sixth transistor and said second terminal of said fifth transistor are commonly connected, and (b) said first terminal of said seventh transistor, said control terminal of said sixth transistor and said second terminal of said sixth transistor are commonly connected to provide said bias voltage.