Switched capacitor adjustable gain amplifier with high gain and low noise

Abstract

The invention provides a switched capacitor adjustable gain amplifier with high gain and low noise. The switched capacitor adjustable gain amplifier comprises an external signal source, a square wavegenerator, a switched capacitor integrator and a feedback circuit with a signal amplification function, wherein the external signal source and the square wave generator are connected to the switched capacitor integrator, the switched capacitor integrator outputs through the feedback circuit, the switched capacitor integrator comprises seven COMS switching tubes opened by forward pulses, a samplingcapacitor, an adjustable feedback capacitor and an integrating capacitor, and the feedback circuit comprises an operational amplifier. According to the switched capacitor adjustable gain amplifier, the time-reduced integrated frequency of the feedback capacitor is equivalent to the reduction of the capacitance value of the feedback capacitor; the noise of the PGA is reduced while the high gain isrealized; meanwhile, the layout area of the circuit is not increased, the power consumption and the cost are reduced, the detection precision and the detection efficiency of the circuit are improved,and the switched capacitor adjustable gain amplifier is suitable for various sensor interfaces, signal conditioning chips and signal links and has a great market development prospect in automotive electronics, white household appliances, industrial automation and the Internet-of-things.

Description

technical field [0001] The invention relates to the field of integrated circuit design, in particular to a high-gain and low-noise switched capacitor adjustable gain amplifier. Background technique [0002] A switched capacitor adjustable gain amplifier (programmable gain amplifier, PGA) is often used in sensor signal detection, analog-to-digital signal conversion (ADC) and digital-to-analog (DAC) conversion circuits. However, the currently commonly used switched capacitor PGA circuit usually increases the ratio of the input capacitor and the feedback capacitor of the switched capacitor amplifier when achieving a higher gain, or uses a method of cascading two switched capacitor amplifiers. The former achieves high gain while amplifying the noise of switched capacitors a lot, while the latter is insufficient in terms of power consumption and occupied chip area. [0003] Such as figure 1 The commonly used single-ended output switched capacitor PGA is shown as an example. The...

AI Technical Summary

Problems solved by technology

The result must be a significant increase in chip area and cost

[0016] 2. If the capacitances of 108 and 104 increase at the same time, the power consumption will also increase at the same time, because the charge and discharge current required by the op amp 111 to complete the integration increases significantly and the power consumption of the chip increases

[0017] In practical applications, it is mostly a PGA with a fully differential structure, and the principle has not changed.

Images