Patent ID: 6677802
Filing Date: 2004-01-13
Classification: H03K

Abstract:
An apparatus for biasing a body voltage of a silicon-on-insulator transistor having a gate and a body, comprising:a. an operational amplifier that senses a voltage difference between a desired gate-source threshold voltage and a reference voltage at a reference current source node and that generates an output voltage that is proportional to the voltage difference; b. a reference biasing transistor that has a gate that is electrically coupled to the output voltage and that has a drain; c. a reference mirror transistor that has both a gate and a drain that are electrically coupled to the current source node, the reference mirror transistor also having a body that is electrically coupled to the drain of the reference biasing transistor, wherein the gate of the reference mirror transistor is electrically coupled to the gate of the silicon-on-insulator transistor; d. a device biasing transistor that has a gate that is electrically coupled to the output voltage and that has a drain that is electrically coupled to the body of the silicon-on-insulator transistor and that maintains a voltage at the body of the silicon-on-insulator transistor so that the silicon-on-insulator transistor has a gate-source threshold voltage that is within a predetermined range of the desired gate-source threshold voltage; and e. a body biasing element that electrically couples the body of the silicon-on-insulator transistor to a common node.