Digital-analog converter

Abstract

The present invention provides a digital-to-analog (D / A) converter which can obtain a high converting precision and speed through a small number of resistances in series or parallel connection. A reference voltage is used by a plurality of channels, and the hardware structure of the circuit is reduced and the area of the integrated circuit silicon chip of the D / A converter is reduced. The D / A converter having a n bits of precision is composed of the bits of high bit of m, middle bit of k and low bit of j (n=m+k+j), wherein, the high bit of m data is applied on the resistance string reference voltage module 1 through the decoder 1, an one-from-plurality type export structure of partial voltage formed by a switch array composed of 2m / 2 traverse rows and 2m / 2 vertical rows; the middle bit of k is added on the resistance string reference voltage module 2 through the decoder 2, and each bit corresponds to a node voltage; the low bit of j data is added on the resistance string reference voltage module 3 through the decoder 3, and an one-from-plurality type export structure of partial voltage formed by the switch array composed of 2j / 2 traverse rows and 2j / 2 vertical rows; a n bit D / A converter is integrated by a high bit of m, a middle bit of k and a low bit of j through a multiweights circuit synthesizer, wherein, n=m+k+j.

Description

technical field [0001] The present invention relates to a set of resistor series-parallel hybrid digital-to-analog (hereinafter referred to as "D / A") converters. Background technique: [0002] In the resistor string D / A converter, resistors having the same resistance value are connected to each other in series, and the voltage of each node between the resistors is selectively output as an analog voltage corresponding to each converted data. Therefore, in order to convert data with a larger number of bits, the D / A converter is required to have a larger number of resistors. The relationship between the resistance number W and the bit number n of the D / A converter is W=2 n , it can be seen that the number of resistors must be doubled every time the conversion accuracy is increased by 1 bit. If the resistance value of the resistor remains unchanged, the conversion speed will be reduced by half for each increase in the conversion accuracy of one bit. This is highly undesirable,...

AI Technical Summary

Problems solved by technology

There are some disadvantages in this structure: 1. The MOS transistor switch as a multiplexer has a finite value of "on" state resistance, which introduces differential nonlinearity; 2. The resistance value of the second-stage ladder structure must be much greater than that of the first stage. 3. The resistance value of the two-stage ladder resistor structure and the larger second-stage ladder structure will introduce a larger settling time and reduce the conversion frequency

This structure overcomes the weakness of the previous structure, but their own disadvantage is that the number of resistors has not been reduced, the resistance of the converter occupies a large area of ​​the substrate, the cost is high, and it is impossible to form a very high-precision D / A converter.

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