High resolution small area A/D conversion circuit

Abstract

The invention discloses a digital-to-analog converting circuit which is suitable for converting an N-bit digital code into analog voltage and comprises a high-bit resistor cluster and a low-bit network connected between a current source and the ground in series, wherein the high-bit resistor cluster comprises 2<M> unit resistors R which are orderly connected in series and decoded by an M-bit digital code of a high-bit decoding unit so as to output analog voltage. The low-bit resistor network comprises a series of (N-M+2) resistors connected in parallel, and the resistance values of the seriesof resistors are gradually increased in an equal proportion mode, wherein the resistors from 2 to (N-M+2) are respectively connected with a switch in series. The (N-M)-bit digital code of a low-bit decoding unit is used for switching on and switching off (N-M+1) switches in the low-bit resistor network, thus, the low-bit resistor network has (N-M)-order resistance value to be used as the biasing of the high-bit resistor cluster, therefore, the invention can generate the analog voltage of N-bit resolution. The digital-to-analog converting circuit is suitable for forming the digital-to-analog converting circuit with high resolution and small area.

Description

High-resolution small-area digital-to-analog conversion circuit technical field The invention relates to a digital-to-analog conversion circuit, in particular to a high-resolution and small-area digital-to-analog conversion circuit. Background technique In the design of general-purpose digital-to-analog conversion circuits, resistor strings are a commonly used method. In any case, as the number of digits of digital-to-analog conversion (ie, resolution) increases, the number of resistors in the resistor string is 2N (N is the number of digits of digital-to-analog conversion circuits. ) ratio increases. Not only will this consume a large amount of semiconductor area, but it will also require a very small current source. Therefore, the traditional resistor string is only suitable for the highest 10-bit digital-to-analog conversion circuit. In order to solve this problem, some new digital-to-analog conversion circuit structures have been invented, such as a digital-to-analo...

AI Technical Summary

Problems solved by technology

However, due to the inherent matching error of the amplifier, this structure has severe INL / DNL (integral nonlinearity / differential nonlinearity) performance degradation

In fact, a 12-bit digital-to-analog conversion circuit with this structure can only get INL / DNL of a dozen LSB (LeastSignificantbit, lowest bit)

And since this structure requires two or more amplifiers, the actual semiconductor area is also limited

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