Instrument amplifier

Abstract

The application discloses an instrument amplifier comprising a capacitance feedback structure closed loop amplifier, an input capacitor charging module, a feedback capacitor discharge module, a noise separating module and a logic controller; the capacitance feedback structure closed loop amplifier comprises a full differential operational amplifier, a first input capacitor, a second input capacitor, a first feedback capacitor and a second feedback capacitor; the input capacitor charging module is used for periodically charging the first and second input capacitors; the feedback capacitor discharge module is used for periodically discharging the first and second feedback capacitors; the noise separating module is used for separating signals from noises through the chopper modulation technology; the logic controller is respectively connected with the input capacitor charging module, the feedback capacitor discharging module and the noise separating module so as to control each module to work, thus reducing instrument amplifier power consumption, and reducing instrument amplifier noises and cost.

Description

technical field [0001] The invention relates to the technical field of high-precision measurement, and more specifically, relates to an instrument amplifier. Background technique [0002] As a high-precision amplifier used to amplify weak difference signals, instrumentation amplifiers are widely used in high-precision measurement fields such as electronic scales, pressure measurement, blood analysis, blood pressure monitors, gas analysis and measurement, power analysis and metering. [0003] figure 1 It shows an existing instrument amplifier, which realizes the set closed-loop gain amplification function by means of two single-ended output operational amplifiers Av1~Av2 and three resistors R0~R2, and has programmable amplification gain, low temperature drift, high Input impedance, high common mode rejection and other characteristics, but there are the following deficiencies: [0004] First, the circuit design of two operational amplifiers makes the instrumentation amplifie...

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Problems solved by technology

Second, the amplification gain of the instrumentation amplifier is determined by the three resistors R0~R2. The resistors themselves have thermal noise, and the larger the resistance value, the greater the thermal noise value; to achieve the low-noise design of the instrumentation amplifier, low-resistance Value resistance, but the lower the resistance value, the higher the driving capability requirements of the two operational amplifiers Av1~Av2, and the greater the power consumption of the instrumentation amplifier

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