A Design Method of a Cell-Based Amplifier for Body Bias Generation

Takuya KOYANAGI  Jun SHIOMI  Tohru ISHIHARA  Hidetoshi ONODERA  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E102-C   No.7   pp.565-572
Publication Date: 2019/07/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.2018CTP0014
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuits and Their Application Technologies)
Category: 
Keyword: 
body bias generator,  cell-based-design,  analog-assisted digital,  amplifier,  low power,  

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Summary: 
Body bias generators are useful circuits that can reduce variability and power dissipation in LSI circuits. However, the amplifier implemented into the body bias generator is difficult to design because of its complexity. To overcome the difficulty, this paper proposes a clearer cell-based design method of the amplifier than the existing cell-based design methods. The proposed method is based on a simple analytical model, which enables to easily design the amplifiers under various operating conditions. First, we introduce a small signal equivalent circuit of two-stage amplifiers by which we approximate a three-stage amplifier, and introduce a method for determining its design parameters based on the analytical model. Second, we propose a method of tuning parameters such as cell-based phase compensation elements and drive-strength of the output stage. Finally, based on the test chip measurement, we show the advantage of the body bias generator we designed in a cell-based flow over existing designs.