Low voltage low power consumption amplifier based on log domain non-linear transmission function

Abstract

The invention discloses a low voltage low power consumption amplifier based on log domain non-linear transmission function. The amplifier comprises a compression module and a non-linear conversion module; two output ends of the compression module are respectively connected with two input ends of the non-linear conversion module; the compression module comprises a PMOS pair and a NMOS pair; the PMOS pair is used for converting, in exponential form, a first differential input signal into a first voltage signal; the NMOS pair is used for converting, in exponential form, a second differential input signal into a second voltage signal; the non-linear conversion module comprises a mirror current source and conversion submodule; the mirror current source is used for generating current signals based on the inputted first voltage signal and second voltage signal; the conversion submodule is used for converting the current signals into voltage signals based on a non-linear conversion function. The inputted differential signals are converted into the voltage signals in exponential form, thereby finishing the compression conversion, executing the non-linear function, making the output expansion transistor work in a saturated area, increasing the output amplitude, and synchronously increasing the linearity and the common mode rejection ratio.

Description

technical field [0001] The invention relates to the field of biological signal processing, in particular to a low-voltage and low-power amplifier based on a logarithmic domain nonlinear transfer function. Background technique [0002] Among the daily wearable portable medical devices, in order to meet the demand for portable power supply, portable power sources such as button batteries are the main power supply sources, but their power supply capacity is limited, and it is difficult to maintain the operation of the device for a long time, which has become an increasingly serious problem, thus exacerbating the Low power requirements for daily wearable medical detection devices. Since the amplifier is the most basic module in the front-end acquisition and processing system of biological signals, this constraint increases the urgency and necessity of low power consumption of the amplifier. However, one of the most important ways to reduce power consumption is low voltage, so lo...

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Problems solved by technology

In addition, due to the very low operating current of the logarithmic amplifier, the noise tolerance of the circuit is reduced, and because there is no differential input to suppress noise, the noise performance of the circuit is further deteriorated, and the common mode rejection ratio is relatively low.

The log amp output transistor is biased in the weak inversion region and its current is very low, which limits the output current swing

And because the logarithmic amplifier needs to be converted to the logarithmic domain for nonlinear operation, this makes the linearity of the entire amplifier not high

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