Noise Reduction Technique of Switched-Capacitor Low-Pass Filter Using Adaptive Configuration

Retdian NICODIMUS  Takeshi SHIMA  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E99-A   No.2   pp.540-546
Publication Date: 2016/02/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E99.A.540
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit Techniques and Related Topics)
switched-capacitor,  low-pass filter,  low-noise,  correlated double sampling,  charge scaling,  adaptive configuration,  

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Noise and area consumption has been a trade-off in circuit design. Especially for switched-capacitor filters (SCF), kT/C noise gives a limitation to the minimum value of unit capacitance. In case of SCFs with a large capacitance spread, this limitation will result in a large area consumption due to large capacitors. This paper introduces a technique to reduce capacitance spread using charge scaling. It will be shown that this technique can reduce total capacitance of SCFs without deteriorating their noise performances. A design method to reduce the output noise of SC low-pass filters (LPF) based on the combination of cut-set scaling, charge scaling and adaptive configuration is proposed. The proposed technique can reduce the output noise voltage by 30% for small input signals.