IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences
Online ISSN : 1745-1337
Print ISSN : 0916-8508
Special Section on Analog Circuit Techniques and Related Topics
Reduction of Charge Injection and Current-Mismatch Errors of Charge Pump for Phase-Locked Loop
Masahiro YOSHIOKANobuo FUJII
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2009 Volume E92.A Issue 2 Pages 381-388

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Abstract

This paper proposes a new charge pump to suppress spurious noise of phase-locked loops. The spurious noise is induced by charge injection generated from the parasitic capacitors associated with switches and the current-mismatch between the charging and discharging currents of the charge pump. A new charge pump is configured by adding an operational amplifier, a sample-and-hold circuit, and switches to a basic charge pump. During the idling time of the charge pump, the currents of the current sources are adjusted and the current-mismatch are reduced to 0.3%. Applying the proposed charge pump to a phase-locked loop, we can suppress the spurious noise by 18dB compared with a PLL using a basic one.

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© 2009 The Institute of Electronics, Information and Communication Engineers
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