Superposed operation circuit and floating voltage digital-to-analog conversion circuit

Abstract

The present invention provides a superposed operation circuit and a floating voltage digital-to-analog conversion circuit, and adopts the principle of superposition of indirect current to realize the superposition of analog quantities. The negative phase input end and the output end of a first operational amplifier are connected to make the first operational amplifier possess the characteristics of a voltage follower and its output end clamped to the voltage inputted from the positive-phase input end, that is, the analog quantity to be superimposed. Then, a current generating circuit converts a voltage signal into a current signal, wherein the current signal produces a voltage drop across a first resistor connected to the output end of the first operational amplifier. The voltage drop is superimposed with the voltage signal outputted by the first operational amplifier. Therefore, the output operation point of the first operational amplifier in the superposed operation circuit is always fixed to the analog quantities to be superimposed, thereby ensuring the output precision of the operational amplifier. Furthermore, the high-precision current superposed quantity is obtained from the conversion of the low absolute precision voltage signal instead of being generated directly from the digital-to-analog conversion circuit, relaxing the input accuracy of the current generating circuit and further reducing the requirement of the current generating circuit on power consumption and the size.

Description

technical field [0001] The invention belongs to the field of electronic technology, and in particular relates to a superposition operation circuit and a floating voltage digital-to-analog conversion circuit. Background technique [0002] In electronic control applications, in many cases, an analog quantity needs to be superimposed and adjusted with another digital control analog quantity. The digital control analog quantity can be obtained through a digital-to-analog converter (Digital Analog Converter, DAC). See figure 1 , showing a schematic diagram of a principle that requires superposition of analog quantity A and analog quantity B, such as figure 1 As shown, the DAC generates the corresponding analog quantity A after receiving the digital control signal, and the analog quantity is superimposed with the analog quantity B to be superimposed through the superposition operation circuit to obtain the signal C required in the final application, that is, C=A+B. [0003] The ...

AI Technical Summary

Problems solved by technology

Excluding the inherent error of the inconsistency between VS and VDAC, in the case of a large change in VDAC, the input voltage has a great influence on the state change of the MOS tube, and the change in the state of the MOS tube will cause gm to change, which in turn will lead to a non-linear error of the superimposed amount. It can be seen that the voltage superimposition circuit is simple and has low power consumption, but the achievable absolute accuracy is low, at the mV level

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