An Improved Data Weighted Averaging for Segmented Current-Steering DACs

2013 ◽  
Vol 748 ◽  
pp. 868-873
Author(s):  
Dan Zheng ◽  
Wei Ni ◽  
Rui Zhang ◽  
Yong Sheng Yin
Keyword(s):  
Dynamic Performance ◽  
Weighted Averaging ◽  
Current Steering ◽  
Output Impedance ◽  
Digital To Analog Converters ◽  
Starting Position ◽  
High Level ◽  
Data Weighted Averaging ◽  
Element Sequence ◽  
Device Size

An improved DWA method for 14-bit 5+4+5 segmented current-steering digital-to-analog converters is proposed. Through to SFDR and dynamic performance of compromise consideration, this method uses two barrel shifters to control the starting position of the current element sequence every four clocks. Compared with the conventional DWA method, it features smaller device size and improves SFDR. And based on SIMULINK platform, through the establishment of high level of current steering D/A converter model with matching errors and output impedance. The simulation results show that SFDR is improved about 25dB.

SFDR Improvement Algorithms for Current-Steering DACs

2015 ◽  
Vol 643 ◽  
pp. 101-108 ◽  
Author(s):  
Shaiful Nizam Mohyar ◽  
Masahiro Murakami ◽  
Atsushi Motozawa ◽  
Haruo Kobayashi ◽  
Osamu Kobayashi ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Current Source ◽  
Weighted Averaging ◽  
Current Steering ◽  
Switching Sequence ◽  
Digital To Analog Converters ◽  
Compensation Methods ◽  
Spurious Free Dynamic Range ◽  
Data Weighted Averaging ◽  
Combined Algorithm

This paper presents algorithms for improving spurious-free dynamic range (SFDR) of current-steering digital-to-analog converters (DACs) — targeted at communication applications — by minimizing both current-source mismatches and glitches. Conventional segmented current-steering DACs suffer from static mismatches among current sources which cause nonlinearity and degrade SFDR, though glitch energy is relatively small. The data-weighted averaging (DWA) algorithm can reduce static current source mismatch effects, but it increases the effects of glitch energy. Here we investigate the use of both conventional Switching-Sequence Post-Adjustment (SSPA) calibration and One–Element-Shifting (OES) methods in order to reduce the effects of both nonlinearity and glitch energy. For further improvement, we propose and investigate a fully-digital combined algorithm to reduce static current source mismatch effects with minimal increase in the glitch energy. We also did simulations of the effect of combining these two compensation methods. Our MATLAB simulations show that the combined algorithm can improve SFDR performance by 24 dB, 22dB and 2dB compared to conventional thermometer-coded, one-element-shifting and SSPA methods respectively in some conditions. When we take current mismatch into account, the combined algorithm causes glitch energy to increase by only 0.02 to 0.2 % compared to the other three methods alone.

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