Claims
- 1. A virtual amplifier, comprising:
- a source follower FET having a gate connected to a reference node, a drain connected to a first voltage source, and a source connected to a source node;
- means for connecting said source node to a second voltage source during a first period;
- means connected between said reference node and said source node for accumulating a charge input on said reference node during said first period;
- means for connecting said source node to an output node during a second period; and
- means for switching connection of said source node from said second voltage source during said first period to said output node during said second period.
- 2. The virtual amplifier of claim 1, wherein said means for connecting and switching comprise:
- a first FET switch connected between said source node and said output node; and
- a second FET switch connected between said source node and said second voltage source, wherein said first and second voltage sources are equivalent.
- 3. The virtual amplifier of claim 2, wherein said means for accumulating a charge comprises a capacitor connected between said reference node and said source node.
- 4. The virtual amplifier of claim 3, wherein said reference node comprises a detector node for receiving a low current signal input to the virtual amplifier by an infrared detector.
- 5. A virtual amplification circuit, comprising:
- a reference node for receiving an input signal to be amplified;
- a source follower transistor having a gate connected to said reference node, a drain connected to a voltage source, and a source connected to a source node;
- a first FET switch connected between said source node and an output node;
- a capacitor connected between said reference node and said source node;
- a second FET switch connected between said voltage source and said source node; and
- said first and second FET switches comprising means for switching connection of said source node from said voltage source during a first period to said output node during a second period.
- 6. The virtual amplifier of claim 5, wherein said reference node comprises a detector node for receiving a low current signal input to the virtual amplifier by an infrared detector.
- 7. The virtual amplifier of claim 6, wherein the amplifier comprises a unit cell for reading an output of one detector of a focal plane array.
- 8. A method of virtual amplification of a signal, comprising the steps of:
- providing a source follower FET having a gate, a drain, and a source;
- connecting said gate to a reference node, said drain to a voltage source, and said source to a source node;
- connecting said source node to said voltage source during a first period;
- connecting a capacitance between said reference node and said source node;
- providing a low current signal on said reference node during said first period for accumulating a charge on said capacitance, said accumulated charge producing a low voltage on said reference node; and
- switching connection of said source node from said voltage source to an output node during a second period, thereby reducing said capacitance and increasing said voltage on said reference node during said second period.
- 9. The method of claim 8, wherein the steps of connecting and switching further comprise the steps of:
- connecting a first FET switch between said source node and said output node;
- connecting a second FET switch between said source node and said voltage source;
- switching said first FET switch off and said second FET switch on during said first period; and
- switching said first FET switch on and said second FET switch off during said second period.
- 10. The method of claim 9, wherein the step of providing a low current signal comprises connecting an output of an infrared detector to said reference node.
Government Interests
The United States Government has rights in this invention under contract number F29601-88-C-0075 awarded by the Department of the Air Force.
US Referenced Citations (2)