Low-noise chopper current feedback instrument amplification circuit

Abstract

The invention provides a low-noise chopping current feedback instrument amplification circuit which comprises a current feedback amplification circuit and a residual ripple filter circuit. The currentfeedback amplification circuit is composed of a modulation chopper CH1, an input transconductance Gm1, a feedback transconductance Gm2, a modulation chopper CH2, a demodulation chopper CH3, a modulation chopper CH4, a cascode amplifier A1, a demodulation chopper CH5, an output amplifier A2, an input resistor Rin, an output resistor Ro, a Miller compensation resistor Rm and a Miller compensation capacitor Cm. The residual ripple filter circuit is composed of filter resistors R1 and R2, filter capacitors C1 and C2 and a filter transconductance amplifier. The input amplifying circuit and the current feedback loop are combined to form the current feedback structure, 1 / f noise is effectively reduced through the two-stage chopping structure, the output ripple amplitude caused by chopping is effectively reduced through the designed residual noise filtering circuit, and the overall circuit precision is optimized.

Description

technical field [0001] The invention belongs to the field of analog integrated circuit design, and in particular relates to the design of a low-noise chopping current feedback type instrumentation amplifier circuit. Background technique [0002] With the rapid development of wearable electronic products and Internet of Things (IoT) technology, more and more practical applications require low-frequency signal measurement devices, such as EEG, EKG and EMG and other biological signals, all of which need to be transmitted through sensors Biological signals are converted into electrical signals for detection. These biological signals are very weak, as small as tens to tens of orders of magnitude, and the frequency range provided is only from DC to hundreds. At such a low frequency, they are usually affected by non-ideal conditions such as 1 / f noise and offset voltage. This non-ideal factor has been proved to be quite unfavorable to signal acquisition, so it is necessary to adopt...

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Problems solved by technology

3. Due to the influence of chopping, ripples will appear in the high-frequency band of the output signal. The idea of ​​patent No. 201410518644.X is to design a feedback loop to eliminate ripples. Although the effect is relatively good, the structure is more complicated and affects the stability of the overall system. , and this design to eliminate residual ripple filter circuit design uses a second-order Sallen-Key low-pass filter structure, the filtering effect is good without affecting the stability of the overall system

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