A Second Order Mixed-Mode Charge Pump Scheme for Low Phase/Duty Error and Low Power Consumption

Kyu-hyoun KIM  In-Young CHUNG  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E90-C   No.1   pp.208-211
Publication Date: 2007/01/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e90-c.1.208
Print ISSN: 0916-8516
Type of Manuscript: LETTER
Category: Integrated Electronics
Keyword: 
second order,  charge pump,  phase error,  DLL,  duty cycle corrector (DCC),  

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Summary: 
A second order charge pump (SOCP) scheme is proposed in this letter. Compared with the conventional single charge pump, the second order charge pump does not suffer phase errors caused by the output voltage dependent current mismatches. Also, the second order charge pump can be implemented in a mixed-mode type, enabling the fast lock and the various operation modes simultaneously. The proposed SOCP has been adopted into the duty cycle corrector (DCC) loops of DDR2 DRAM, and shows a much widened correction range owing to the removal of the parasitic effects.