VIRTUAL AMPLIFIER

Abstract

A virtual amplifier comprises a typical switched source follower circuit plus an additional switch of minimum size to perform a virtual amplification function. A capacitor is connected between the gate, which comprises a detector node, and the source, which comprises a source node, of a source follower FET. The source node is connected to the output by a first FET switch. The source node is also connected to a voltage source by a second FET switch. The voltage on the detector node is manipulated by pumping a charge into or out of the capacitor. Charge pumping is accomplished by first accumulating charge on the detector node while the source node is connected to the voltage source, and then switching the first FET switch on and the second FET switch off so that the effective capacitance of the detector node is reduced. Thus, the low voltage that is generated during charge accumulation, and which is desirable for maintaining a constant detector bias, is greatly increased for readout by capacitive charge pumping without power dissipation or noise penalty.

Source: Google Patents

35 USC §181 Secrecy Order

Inventor

• 1SHY-SHIUN CHERN

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