8-bit high-precision DAC current source array and layout method thereof

Abstract

The invention provides an 8-bit high-precision DAC current source array and a layout method thereof. Dependence between adjacent elements in a DAC current source array is reduced, and accumulation of second-order gradient errors is prevented; gradient errors are allocated to each element uniformly, and thus linearity of a circuit can be improved very well; and the co-gravity-center layout can offset influence of first-order gradient errors. High conversion accuracy and high speed are guaranteed, and meanwhile, mismatching of the current source array due to systematic errors and random errors can be reduced, so that the DAC circuit is allowed to have good monotonicity, offset error, differential nonlinearity error (DNL), integral nonlinearity error (INL), spurious-free dynamic range (SFDR) and signal-to-noise ratio (SNR).

Description

technical field [0001] The invention belongs to the technical field of current source array layout of a current steering digital-to-analog converter, and in particular relates to a current source array suitable for 8-bit thermometer codes and a layout method. Background technique [0002] DAC is Digital-to-Analog Converter. The research and application of this module mainly focus on the research of current source structure. With dynamic characteristics, it can be applied to electronic systems such as radar, communication, and electronic countermeasures that require high sensitivity. The mismatch of DAC includes random mismatch and systematic mismatch. The random error is mainly caused by some random factors, such as component size, doping, oxide layer thickness and other microscopic fluctuations that affect component parameters. Increase the component area to reduce the adverse effects of random mismatch on the circuit; system error is also called gradient error, which is d...

AI Technical Summary

Problems solved by technology

[0003] A traditional current source array layout such as figure 1 As shown, the distribution is symmetrical and uniform along the center line, and the symmetrical layout reduces the influence of the second-order gradient error to a certain extent, but the correlation between adjacent components is too strong, which will cause the accumulation of gradient errors. Figure 9 is the MATLAB analog of the traditional layout INL, Figure 11 is the MATLAB analog of the traditional layout graph DNL, ​​from Figure 9 , Figure 11 It can be clearly seen that the accumulation of gradient errors makes INL and DNL continuously increase with the increase of input digital codes, with large fluctuations

Therefore, the current traditional current source array layout has a large gradient error, and there is a serious system mismatch problem.

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