Generalized Quadrature Data Weighted Averaging

2015 ◽  
Vol 62 (3) ◽  
pp. 261-265 ◽  
Author(s):  
Marko Neitola ◽  
Timo Rahkonen
2015 ◽  
Vol 643 ◽  
pp. 101-108 ◽  
Author(s):  
Shaiful Nizam Mohyar ◽  
Masahiro Murakami ◽  
Atsushi Motozawa ◽  
Haruo Kobayashi ◽  
Osamu Kobayashi ◽  
...  

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.


Author(s):  
Ali Kerem Nahar ◽  
Ansam Subhi Jaddar ◽  
Hussain K. Khleaf ◽  
Mohmmed Jawad Mortada Mobarek

<p>In general, the noise shaping responses, a cyclic second order response is delivered by the method of data weighted averaging (DWA) in which the output of the digital-to-analog convertor (DAC) is restricted to one of two states. DWA works efficiently for rather low levels of quantizing; it begins presenting considerable difficulties when internal levels of quantizing are extended further. Though, each added bit of internal quantizing causes an exponentially increasing in power dissipation, complexity and size of the DWA logic and the DAC. This gives a controlled seconnd order response accounting for the mismatch of the elements of DAC. The multi-bit DAC is made up of numerous single-bit DACs having values thereof chosen via a digital encoder. This research presents a discussion of the influence of mismatching between unit elements of the Delta-Sigma DAC. This results in a constrained second order response accounting for mismatch of DAC elements. The results of the simulation showed how the effectiveness of DWA method is in reducing band tones. Furthermore, DWA method has proved its efficiency in solving the mismatching of DAC unit elements. The noise of the mismatching elements is enhanced 11 dB at 0.01 with the proposed DWA, thereby enhancing the efficiency of the DAC in comparison to the efficiency of the DAC with no use of the circuit of DWA</p>


2020 ◽  
Vol 105 ◽  
pp. 104905
Author(s):  
Qihui Zhang ◽  
Jing Li ◽  
Ning Ning ◽  
Qi Yu ◽  
Kejun Wu ◽  
...  

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