Completely first order and tone free partitioned data weighted averaging technique used in a multibit delta sigma modulator

Abstract

In order to reduce mismatch error of a DAC used in a multibit delta-sigma some dynamic element matching (DEM) algorithms have been proposed before, from which Data-Weighted-Averaging (DWA) method is more hardware efficient and widely used. Unfortunately, DWA technique loses its functionalities for periodic signals which cannot be practically avoided. Many improvements have been suggested to minimize in band tone generated by DWA algorithm, but they cause limited performance compared with an ideal first order DEM. This paper presents a new modified DWA structure, which results in a completely first order mismatch noise shaping while solving in band tone problem. Simulations are presented for a 3rd-order lowpass delta sigma. However, its modified version can also be used in bandpass applications.

A low power, high performance multi-mode Delta-Sigma ADC for GSM, WCDMA and WLAN standards

“…(6) Also the digital correction transfer (H] and H2) functions are: (7) Table III indicates the initial and fmal coefficients before and after the scaling [9]. To verify the performance of the modulator, optimize the system parameter and also extract the specifications for the analog cells, MA TLAB SIMULINK is used.…”

“…Therefore, it is necessary to reduce the Over Sampling Ratio for wideband applications because of two main drawbacks; technological limitation of the CMOS SC circuit and the power consumption consideration. Although increasing the resolution of the quantizer improves the performance of the modulator but it is inevitable to use the DAC error correction circuit in the feedback path which will increase the power consumption and circuit complexity [6]. L=3 and L=4 are optimal for multi standard wireless application because they can offer satisfied resolution and bandwidth for different standards with reasonable sampling frequency [1].…”

BandPass Dynamic Element Matching for low OSR high resolution Delta Sigma Modulators

“…PDWA was adapted for low pass DSM in [2].we here, are generalized and design Modified PDWA (MPDWA) for BP applications. Even MPDWA known as the best case of first order DEM's, and has a better function suppressing the in band tones and moving them far from band of interest by the desired filter.…”

Thermo data-weighted average dynamic element matching (DEM) encoder for current-steering DACs

“…However, for the traditional DEM encoders, such as Data-Weighted Average (DWA), a complicated encoding is necessary, which means more switch transitions [3]. For the current-steering DAC operating at high speed, switch transitions will bring additional glitches energy to the output signal of the converters and degrade the DACs' dynamic characteristics, especial the spurious-free dynamic range (SFDR) [4].…”

“…Fig. 1 (b) shows the DWA encoder [3]. When the input code changes, the status of selected elements is simply memorized by a pointer P described at end of selected unary elements.…”