Shifting the sampled input signal in successive approximation register analog‐to‐digital converters to reduce the digital‐to‐analog converter switching energy and area

2020 ◽  
Vol 48 (11) ◽  
pp. 1873-1886
Author(s):  
Mahdi Momeni ◽  
Mohammad Yavari
Author(s):  
Mrs. Lakshmidevi TR ◽  
Mr. K N Jeevan Reddy ◽  
Mr. Ashrith Rao ◽  
Mr. Dhanush Kashyap S ◽  
Ms. Chandini K

In recent years, we have come across a growing need for the design of low power, long battery life Successive Approximation Register (SAR) Analog-to-Digital Converters (ADC). ADCs are the major component of all the systems which need to process an analogue signal obtained from measuring real world parameters and hence they need to be efficient enough depending on the application and power constraint of the device. Speed is also an important parameter as it is used in many real time applications. The basic components of the SAR ADC can be implemented using circuits of various logics available for the logic gates, adders, comparators utilised in it. This paper presents the working of 4-bit successive approximation register analog-to-digital converters (SAR ADC) in three different logics namely, Complementary Metal Oxide Semiconductors (CMOS), Transmission Gates (TG), and Double Pass Transistors (DPL) logics, which were used in the basic components of each major block of the ADC. The aim of this paper here is to compare the various parameters such as area, power consumption and delay between the three different technologies chosen above. The SAR ADCs were implemented for this purpose in 90nm Technology using the Cadence Virtuoso Design Tool building schematics and layouts for the same and calculating the various parameters required for the above-mentioned comparison.


Electronics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 622
Author(s):  
Ghazal A. Fahmy ◽  
Mohamed Zorkany

A memristor element has been highlighted in recent years and has been applied to several applications. In this work, a memristor-based digital to analog converter (DAC) was proposed due to the fact that a memristor has low area, low power, and a low threshold voltage. The proposed memristor DAC depends on the basic DAC cell, consisting of two memristors connected in opposite directions. This basic DAC cell was used to build and simulate both a 4 bit and an 8 bit DAC. Moreover, a sneak path issue was illustrated and its solution was provided. The proposed design reduced the area by 40%. The 8 bit memristor DAC has been designed and used in a successive approximation register analog to digital converter (SAR-ADC) instead of in a capacitor DAC (which would require a large area and consume more switching power). The SAR-ADC with a memristor-based DAC achieves a signal to noise and distortion ratio (SNDR) of 49.3 dB and a spurious free dynamic range (SFDR) of 61 dB with a power supply of 1.2 V and a consumption of 21 µW. The figure of merit (FoM) of the proposed SAR-ADC is 87.9 fj/Conv.-step. The proposed designs were simulated with optimized parameters using a voltage threshold adaptive memristor (VTEAM) model.


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