Patent ID: 6218875
Filing Date: 2001-04-17
Classification: H03L

Abstract:
A circuitry for controlling a response speed of a phase locked loop circuit, said circuitry comprising:a response speed switching circuit having at least one resistive element with a resistance; anda switching operation control circuit being connected to a phase comparator in said phase locked loop circuit for receiving output signals from said phase comparator, and said switching operation control circuit being also connected to said response speed switching circuit for transmitting selected one of first and second switching control signals to said response speed switching circuit,so that if said response speed switching circuit receives said first switching control signal from said switching operation control circuit, then said response speed switching circuit becomes connected to said phase locked loop circuit, whereby both ends of said at least one resistive element becomes connected to said phase locked loop circuit so as to place said phase locked loop circuit into a high speed response state, andso that if said response speed switching circuit receives said second switching control signal from said switching operation control circuit, then said response speed switching circuit becomes disconnected from said phase locked loop circuit, whereby one end of said at least one resistive element becomes disconnected from said phase locked loop circuit so as to place said phase locked loop circuit into a low speed response state.