Invention Grant
US08010072B1 Charge pump current compensation for phase-locked loop frequency synthesizer systems 有权
锁相环频率合成器系统的电荷泵电流补偿

Charge pump current compensation for phase-locked loop frequency synthesizer systems
Abstract:
A technique for improving frequency synthesizer performance by frequency-compensating charge pump current in order to maintain a consistent loop bandwidth over a wide operating frequency range is described. A relationship between the capacitance value associated with a voltage controlled oscillator resonant tank and the magnitude of current pulses in a related charge pump is exploited to bound the loop bandwidth of the frequency synthesizer over both operating frequency and process variation. A control state machine generates digital coarse tune values that dynamically select a capacitance for the resonant tank, such that the voltage controlled oscillator operates within an optimal control voltage range. Each dynamically selected capacitance value is then used to determine the magnitude of current pulses in the charge pump.
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