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AssigneeMotorola, Inc.
InventorsJaime A. Borras, Ruben J. Gonzalez, Daniel M. Smith, Jose I. Suarez, Alan M. Victor, Alfred B. Wieczorek
Estimating the term…
In a frequency synthesizer phase locked loop including a reference oscillator, a variable reference divider (.div.M), a sample and hold phase detector, a loop filter, a voltage controlled oscillator and a variable divider (.div.N), a voltage converter for controlling the voltage of a control input to the voltage controlled oscillator is disclosed. In the preferred embodiment, the voltage converter has its input connected to the output of a first reference divider in the variable reference divider (.div.M) and its output connected to a control input (varactor diode) of the voltage controlled oscillator. The voltage converter clamps the divider reference signal from the first reference divider and provides a negative voltage level output to bias the varactor diode of the voltage controlled oscillator. Thus, the tuning range of the frequency synthesizer is increased.
In a phase locked loop for a frequency synthesizer, said phase locked loop including a reference oscillator for generating a reference signal, a first divider for dividing said reference signal and generating at least one divided reference signal, a voltage controlled oscillator (VCO) having a control input, a second divider for dividing a VCO output signal, a phase detector for monitoring said divided VCO output signal and said divided reference signal and generating a first control signal to said control input of said VCO, a voltage converter, comprising:
Dependencies are inferred from the claim text.