Limit swing charge pump and method thereof

Details Limit swing charge pump and method thereof Limit swing charge pump and method thereof

2002-08-13

2004-06-08

Callahan, Timothy P. (Department: 2817)

Oscillators

Automatic frequency stabilization using a phase or frequency...

Particular error voltage control

C327S157000, C327S159000, C363S059000, C363S060000

Reexamination Certificate

active

06747520

ABSTRACT:

TECHNICAL FIELD
An aspect of this invention relates to charge pumps.
BACKGROUND
A charge pump circuit used in a Phase Lock Loop (PLL) generates an error signal based on a phase difference between two inputs. Within the charge pump circuit, both charge and discharge currents flow. Transient errors may occur in the output current of the charge pump circuit due to asymmetries between the charge and discharge currents. When the charge pump circuit is included in a PLL, the transient error in the output current may cause an increase in reference spurs near the carrier frequency.
SUMMARY
A charge pump comprising a charge pump core including output switches. The charge pump core, in response to a drive signal, to generate a charge pump output. A limit swing generator, in response to an input signal, to generate the drive signal to control the charge pump core. The drive signal having voltage levels including a high level and a low level. The limit swing generator including at least one voltage generator to control the voltage levels of the drive signal such that the drive signal tracks a process variable of the output switches. The at least one voltage generator including at least one diode or diode connected device.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below.


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IEEE std. 802.11b—1999,Sponsor LAN MAN Standards Committee of IEEE Computer Society, “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, Higher-Speed Physical Layer Extension in 2.4 GHz Band,”.

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