Phase lock loop (pll) with gain control

Abstract

A Phase Lock Loop (PLL) with gain control is provided. The PLL has a dual-path configuration, where a first and a second VCO control voltage are generated in response to a phase or frequency difference between a PLL input signal and an output signal. The PLL comprises a dynamic voltage gain control (DVGC) unit and a voltage-to-current (V2I) unit, where the DVGC creates a baseline reference current in response to the first VCO control voltage and the V2I provides a substantially linear current in response to the second VCO control voltage. The currents from the DVGC and V2I are combined and fed into a current-controlled oscillator, which generates a PLL output frequency signal. Frequency gain of the VCO is substantially reduced, thus providing a PLL with improved tuning precision.

Description

technical field [0001] The present invention relates to the structure of a voltage controlled oscillator (VCO) in a phase locked loop (PLL), and more particularly to the structure of a VCO with gain control. Background technique [0002] A phase-locked loop is an electronic system that locks the phase and frequency of the output signal to the phase and frequency of the input signal. PLLs are widely used in communication system applications such as FM demodulation, stereo demodulation, tone detectors, and frequency synthesizers. PLLs are also commonly used in digital applications that require high-frequency periodic signals to synchronize events between high-performance digital circuits. For various application areas, PLLs are especially best implemented on advanced very large scale integrated circuit (VLSI) manufacturing technologies, as well as integrated semiconductor integrated circuits (ICs). [0003] FIG. 1 is a system diagram illustrating the architectural block of a...

AI Technical Summary

Problems solved by technology

PLLs with VCO frequency gain, such as the above, provide too coarse tuning accuracy to meet the needs of these applications

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