Browse > Article

A Feed-forward Method for Reducing Current Mismatch in Charge Pumps  

Lee, Jae-Hwan (Division of Electronics & Information Engineering, Chonbuk National University)
Jeong, Hang-Geun (Division of Electronics & Information Engineering, Chonbuk National University)
Publication Information
Journal of the Institute of Electronics Engineers of Korea SC / v.46, no.1, 2009 , pp. 63-67 More about this Journal
Abstract
Current mismatch in a charge pump causes degradation in spectral purity of the phase locked loops(PLLs), such as reference spurs. The current mismatch can be reduced by increasing the output resistance of the charge pump, as in a cascoded output stage. However as the supply voltage is lowered, it is hard to stack transistors. In this paper, a new method for reducing the current mismatch is proposed. The proposed method is based on a feed-forward compensation for the channel length modulation effect of the output stage. The new method has been demonstrated through simulations on typical $0.18{\mu}m$ CMOS circuits.
Keywords
Charge pump; PLL; Current matching; Current mismatch; Feed-forward;
Citations & Related Records
연도 인용수 순위
  • Reference
1 H. Arora, N. Klemmer, J. C. Morizio, and P. D. Wolf, 'Enhanced phase noise modeling of fractional-N frequency synthesizers,' IEEE Trans. Circuits Syst. I, Reg. Papers, vol. 52, no. 2, pp. 379-395, Feb. 2005   DOI   ScienceOn
2 W. Rhee, Bang-Sup Song, Akbar Ali, 'A 1.1-GHz CMOS fractional-N frequency synthesizer with a 3-b third-order $\Delta$$\Sigma$ modulator,' IEEE J. Solid-State Circuits, vol. 35, no. 10, pp. 1453-1460, Oct. 2000   DOI   ScienceOn
3 Young-Shig Choi, Dae-Hyun Han, 'Gain- boosting charge pump for current matching in phase-locked loop' IEEE Trans. Circuits Syst. II, Express Briefs, vol. 53, no. 10, pp. 1022-1025, Oct. 2006   DOI   ScienceOn
4 Jae-Shin Lee, Min-Sun Keel, Shin-Il Lim and Suki Kim, 'Charge pump with perfect current matching characteristics in phase-locked loops,' Electronics Letters, vol. 36, pp. 1907-1908, Nov. 2000   DOI   ScienceOn
5 A. Waizman, 'A delay line loop for frequency synthesis of deskewed clock,' ISSCC Digest of Technical Papers, 1994