Fully Differential Current Amplifier Circuit

Abstract

The invention provides a fully-differential current amplifying circuit. The fully-differential current amplifying circuit comprises a current gain circuit and a differential output circuit, wherein the current gain circuit is constructed to amplify or shrink two paths of differential input current respectively by a preset gain through two same translinear loops; and the differential output circuit is connected with the current gain circuit, and constructed to equally divide and perform a subtracting operation on the amplified or shrunk differential input current and output differential current from which background current is eliminated through a current copy circuit and a current mirror which are arranged symmetrically. The fully-differential current amplifying circuit can directly process a weak current signal, and has a simple structure. A whole system works in a subthreshold area, so that a power voltage and working current are very low, and the power consumption is lowered greatly. A fully-differential structure is adopted, so that common-mode noise can be restrained well. The background current is counteracted at an output end, and only pure signal current is output, so that greater convenience is brought to cascade connection. MOS (Metal Oxide Semiconductor) devices in the subthreshold area are easier to integrate. Linear adjustment of the gain can be realized through externally biased current.

Description

technical field [0001] The present application relates to the technical field of fully differential current amplifying circuits, in particular to a fully differential current amplifying circuit. Background technique [0002] In recent years, MOS transistors operating in the subthreshold region have gradually attracted people's attention due to their great potential in the field of low voltage and low power consumption. However, due to the small signal and slow switching speed processed by circuits operating in the subthreshold region, they have not been well reused in the field of high-frequency signals. In the field of biomedicine, due to the low frequency and small amplitude of bioelectrical signals, for example, the current amplitude of PPG signals is on the order of nA and the frequency is several Hertz, so that MOS tubes working in the subthreshold region can exert their great advantages. In addition, MOS transistors working in the subthreshold region have exponential ...

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Problems solved by technology

[0005] The problem of the above implementation scheme is: (1) The output voltage signal of the transimpedance amplifier must have a contradictory relationship between the output swing and the power supply voltage, which cannot be used in low-voltage design, and the power consumption is large; and the noise effect of the transimpedance circuit itself In this case, small current signals are not easy to transmit, which requires very high noise requirements for transimpedance amplifiers.

(4) The circuit adopts the method of first extracting the square and then square, which makes the circuit structure very complicated and also increases the power consumption

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