Dynamic amplifiers for analog-to-digital converters

Nandi, Timir

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https://hdl.handle.net/2142/108557 Copy

Description

Title

Dynamic amplifiers for analog-to-digital converters

Author(s)

Nandi, Timir

Issue Date

2020-05-18

Director of Research (if dissertation) or Advisor (if thesis)

Hanumolu, Pavan Kumar

Doctoral Committee Chair(s)

Hanumolu, Pavan Kumar

Committee Member(s)

• Banerjee, Arijit
• Schutt-Aine, Jose E
• Zhou, Jin

Department of Study

Electrical & Computer Eng

Discipline

Electrical & Computer Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• dynamic amplifier
• reset gain
• regeneration time
• interpolation
• pipelining
• latch
• flash ADC

Abstract

Advances in CMOS technologies have brought benefits to both digital and analog integrated circuits. However, lower output impedance and reduced supply voltage have also caused newer challenges, especially for the design of operational amplifiers (op-amps) to implement gain. In this dissertation, dynamic/latch-based/regenerative amplifiers are explored where interrupted regeneration is used to implement the gain function. First, a 6-b current-domain interpolating pipelined flash analog-to-digital converter (ADC) is presented, where a novel current-shape-amplifier (CSA) based on a simple dynamic latch stage with interrupted regeneration is used to achieve 16 X interpolation factor using four interpolating stages. Thanks to this larger interpolation factor, ADC input capacitance is greatly reduced, which significantly eases the design of ADC driver circuits. The reduction in ADC throughput that accompanies classical interpolation methods is overcome by pipelining the proposed CSA-based interpolating stages. Fabricated in a 65 nm CMOS process, the prototype ADC consumes 43.8 mW at 1/1.25 V supply and achieves 26.8 dB signal-to-noise and distortion ratio (SNDR) and 35.2 dB spurious-free dynamic range (SFDR) at 4 GS/s with a 2 GHz input. Second, a study is conducted and a fully digital technique is proposed to calibrate the offset of interpolating flash ADCs. Compared to the state-of-the-art, this technique requires fewer comparators and needs fewer sets of input differential pairs. Offset cancellation is achieved by switching references (only during calibration) without extra loading at the input or the clock generator circuitry. The efficacy of this technique is demonstrated by simulating a 4 bit interpolating flash ADC which shows an effective number of bits (ENOB) improvement of 1.5 bits. Third, the non-idealities of the ADC are described and calibration techniques are proposed to improve the performance.

Graduation Semester

2020-08

Type of Resource

Thesis

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http://hdl.handle.net/2142/108557

Copyright and License Information

© 2020 Timir Nandi

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