Multiplication-type A/D (Analog/Digital) converter capable of correcting limited gain error

Abstract

The invention relates to a multiplication-type A / D (Analog / Digital) converter capable of correcting a limited gain error, which comprises an amplifying circuit unit and a limited gain error correcting circuit unit. According to the invention, two compensation capacitors and an amplifier constitute the limited gain error correcting circuit unit, part of output quantity is adjustably compensated into the input end of an operation amplifier, nonzero / virtual earth / is adjusted, and the limited gain error is greatly reduced; after the adoption of the limited gain error correcting circuit unit, the limited gain error of the whole streamlined A / D converter is reduced by one order of magnitude; and in the invention, gain of the amplifier is adjustable, and therefore the limited gain error causedby temperature and process changes is effectively offset. According to the invention, the limited gain error correcting circuit has the characteristics of small limited gain error, low power consumption and high reliability and is suitable for the fields of high-speed, high-precision, low power-consumption streamlined A / D converters.

Description

technical field [0001] The invention relates to a multiplication type digital-to-analog converter capable of correcting limited gain errors, and its direct application field is a high-speed, high-precision, low-power consumption pipeline A / D converter. Background technique [0002] The multiplying digital-to-analog converter is the sub-level core unit of the pipeline A / D converter. figure 1 The basic structure of a fully differential multiplying digital-to-analog converter is given. The advantage of this structure is that it uses the feedback principle to make the gain equal to the sampling capacitor C s with the feedback capacitor C f The ratio improves the accuracy and linearity of the gain. However, the gain error of this structure is too large, and there are two main sources: 1) the sampling capacitor C s with the feedback capacitor C f The accuracy and matching degree of the circuit are limited, so that its ratio cannot be exactly equal to the circuit design value,...

AI Technical Summary

Problems solved by technology

However, the gain error of this structure is too large, and there are two main sources: 1) the sampling capacitor C s with the feedback capacitor C f The accuracy and matching degree of the circuit are limited, so that its ratio cannot be exactly equal to the circuit design value, resulting in an inter-stage gain error

2) The DC finite gain of the operational amplifier A makes the "virtual ground" at the input of the operational amplifier equivalently non-ideal, resulting in an interstage gain error

[0003] For the above two sources of error, the first one is mainly affected by the manufacturing process; the second source of error can be solved by increasing the DC gain of the operational amplifier, but for multiplication-type analog-to-digital converters with low power consumption requirements , the DC gain of the operational amplifier must be limited and cannot be made very large. The typical value is about 60dB, so the finite gain error of the low-power multiplying digital-to-analog converter is difficult to reduce

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