Variable gain amplification circuit for pressure-sensitive touch control

Abstract

The invention discloses a variable gain amplification circuit for pressure-sensitive touch. The circuit comprises an operational amplification module, a gain configuration module and a clock control module; the clock control module is used for generating a control clock; the gain configuration module is used for configuring gain and output bias voltage according to the control signal, so that an input signal is amplified through reverse operation, superposed with fixed bias voltage and then output; according to the invention, the gain of the amplification circuit is adjusted by adjusting the capacitance value ratio of the input end of an operational amplifier to a feedback branch; the fixed bias amount of the output voltage is changed by adjusting the capacitance value ratio of the input of the operational amplifier to a reference voltage branch; the output signal is only related to the reference voltage, the gain and the input, accurate amplification is obtained when the voltage of the input signal is close to zero, and the problem in amplification when the input signal is close to zero (ground) during light touch in a pressure-resistance change-voltage sensing-based touch schemeis solved.

Description

technical field [0001] The invention relates to a signal amplifying circuit, in particular to a variable gain amplifying circuit based on a pressure-sensitive touch array composed of force-sensitive materials when the input signal to the ground is close to zero when the pressure is small. Background technique [0002] The pressure sensing network based on high-sensitivity force-sensitive materials can be applied in the design of human-computer interaction. The circuit of the pressure-sensing grid of force-sensitive materials is equivalent to a pressure variable resistor. This resistance-based touch solution It has the advantages of anti-electromagnetic interference, waterproof, anti-oil pollution, foldable and easy to expand, which are not available in capacitive touch solutions. [0003] The voltage characteristic of the output signal of the sensor network equivalent to a variable resistance network is that the greater the pressure, the higher the voltage output, and when n...

AI Technical Summary

Problems solved by technology

[0006] (1) For the input, the input resistance is R1, because the touch network cannot drive the resistive load, which directly affects the input voltage;

[0007] (2) The operational amplifier needs to drive a resistive load, which requires continuous consumption of additional current;

[0008] (3) When the input is zero, the output bias voltage changes with the gain configuration, which is easy to cause output saturation, and it is not friendly to the subsequent signal or data processing after ADC conversion, and the gain cannot be switched arbitrarily during use;

[0009] (4) The problem can be solved by using a negative power supply, but the power consumption and cost will also increase

[0011] That is to say, when VIN=0, VOUT=VB, when it is necessary to configure different output bias voltages at zero input, it is necessary to change the VB voltage value, but this requires that the input range of the operational amplifier is large enough, and may be used depending on requirements Only rail-to-rail operational amplifiers can cover the full bias voltage range, which increases the complexity and difficulty of operational amplifier design

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