Patent ID: 7889006

Claim:
A gate voltage control circuit comprising: a first MOSFET having a gate, a source and a drain; a feedback loop comprising: a feedback transistor; a first resistance being connected in series between an emitter of the feedback transistor and the drain of the first MOSFET; a feedback resistor configured to provide a linear current at a collector of the feedback transistor, the feedback element connected with the collector of the feedback transistor; and an op amp that receives a feedback voltage originated at a node between the feedback resistor and the collector of the feedback transistor, the op amp provides an output that is used as a gate control voltage, the gate control voltage is received at the gate of the first MOSFET, the gate control voltage modulates the transconductance of the combination of first MOSFET and the first resistance; and a second MOSFET having a gate, a source and a drain, the second MOSFET matched to the first MOSFET, the gate of the second MOSFET connected to receive the gate control voltage.