Current variation reduction for mosfet current sources

Claim 2

A metal oxide semiconductor field effect transistor (MOSFET) current source circuit comprising: a metal oxide semiconductor field effect transistor having a source terminal, a drain terminal and a gate terminal; means for connecting said source and drain terminals to an external circuit; means for applying a drive voltage between said gate and drain terminals; and means for applying a compensation current to said gate terminal, said compensation current being of substantially equivalent magnitude and opposite polarity to current flow through a source to gate capacitance within said metal oxide semiconductor field effect transistor in response to a change in voltage between said source and drain terminals, wherein said means for applying a compensation current includes first and second current mirror circuits electrically connected to each other by first and second circuit branches; said first circuit branch including a connection point electrically connected to said gate terminal; said second circuit branch including a first resistor; first and second capacitors; said first capacitor being electrically connected between a first end of said first resistor and said source terminal; and said second capacitor being electrically connected between a second end of said resistor and said source terminal.

Claim 3

A metal oxide semiconductor field effect transistor (MOSFET) current source circuit as recited in claim 1, wherein: the sum of the capacitance of said first and second capacitors is substantially equal to the source to gate capacitance of said metal oxide semiconductor field effect transistor.

Claim 4

A metal oxide semiconductor field effect transistor (MOSFET) current source circuit as recited in claim 1, wherein said first and second capacitors each comprise: a second metal oxide semiconductor field effect transistor having a gate terminal, a source terminal and a drain terminal, said gate and drain terminals of said second metal oxide semiconductor field effect transistor being electrically connected together.

Claim 5

A metal oxide semiconductor field effect transistor (MOSFET) current source circuit as recited in claim 1, wherein each of said first and second current mirror circuits comprises: a first bipolar transistor having an emitter, a base and a collector, said collector being connected to said first circuit branch; a second bipolar transistor having an emitter, a base and a collector, said collector being connected to said second circuit branch; said emitters of said first and second transistors being electrically connected together; and said base and said collector of said second transistor being electrically connected together.

Claim 6

A metal oxide semiconductor field effect transistor (MOSFET) current source circuit comprising: a metal oxide semiconductor field effect transistor having a source terminal, a drain terminal and a gate terminal; means for connecting said source and drain terminals to an external circuit; means for applying a drive voltage between said gate and drain terminals; and means for applying a compensation current to said gate terminal, said compensation current being of substantially equivalent magnitude and opposite polarity to current flow through a source to gate capacitance within said metal oxide semiconductor field effect transistor in response to a change in voltage between said source and drain terminals, wherein said means for applying a compensation current includes a first current mirror circuit electrically connected to first and second circuit branches; said first circuit branch including a first resistor and a connection point between said first resistor and said first current mirror circuit, said connection point being electrically connected to said gate terminal; said second circuit branch including a second resistor; a first capacitor; and said first capacitor being electrically connected between said source terminal and a junction point in said second circuit branch between said current mirror circuit and said second resistor.

Claim 7

A metal oxide semiconductor field effect transistor (MOSFET) current source circuit comprising: a metal oxide semiconductor field effect transistor having a source terminal, a drain terminal and a gate terminal; means for connecting said source and drain terminals to an external circuit; means for applying a drive voltage between said gate and drain terminals; and means for applying a compensation current to said gate terminal, said compensation current being of substantially equivalent magnitude and opposite polarity to current flow through a source to gate capacitance within said metal oxide semiconductor field effect transistor in response to a change in voltage between said source and drain terminals, wherein said means for applying a compensation current includes a first current mirror circuit electrically connected to first and second circuit branches; said first circuit branch including a first resistor and a connection point between said first resistor and said first current mirror circuit, said connection point being electrically connected to said gate terminal; said second circuit branch including a second resistor; a first capacitor; and said first capacitor being electrically connected between said source terminal and a junction point in said second circuit branch between said current mirror circuit and said second resistor.

Claim 8

A metal oxide semiconductor field effect transistor (MOSFET) current source circuit as recited in claim 5, wherein: the capacitance of said first capacitor is substantially equal to the source to gate capacitor of said metal oxide semiconductor field effect transistor.

Claim 9

A metal oxide semiconductor field effect transistor (MOSFET) current source circuit as recited in claim 5, wherein: said current mirror circuit is electrically connected to said drain terminal; and said first and second resistors are electrically connected to a first conductor.

Claim 10

A metal oxide semiconductor field effect transistor (MOSFET) current source circuit as recited in claim 5, wherein: said current mirror circuit is electrically connected to a first conductor; and said first and second resistors are electrically connected to said drain terminal.