Importance

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Abstract

A high precision charge pump used in a phase-lock loop incorporating a type-IV phase/frequency detector is designed and constructed to substantially eliminate the effects of ringing and glitch errors on the charge pump output current as averaged over a pump-up and pump-down cycle by the type-IV phase/frequency detector. The high precision charge pump is constructed exclusively of transistors of a single polarity (N-channels) that are so matched as to each have the same current characteristics. The current pulse length, absolute magnitude, and waveform envelopes of the charge pumps source and sink currents are defined by matched transistors. When the type-IV phase/frequency detector is operating in quasi flywheel mode, and no phase comparisons are being made, the charge pump's source current is equal to the sink current in all significant respects such that no incremental, residual charge is left on a loop capacitor following the conclusion of a sequential pump-up and pump-down sequence.

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First Claim