Oscillator, pll oscillator, radio apparatus

Abstract

An oscillator includes a plurality of oscillating units connected in parallel with each other, and a control unit which controls the number of parallel connections of the plurality of oscillating units based on an instruction signal indicating accuracy to be tolerated with respect to oscillation outputs of the oscillating units.

1 . A method of controlling an oscillator, comprising:
 providing a plurality of oscillating units connected in parallel with each other;   receiving an instruction signal indicating accuracy to be tolerated with respect to oscillation outputs of said oscillating units; and   controlling a number of parallel connections of said plurality of oscillating units based on the instruction signal.   
   
   
       2 . The method of  claim 1 ,
 wherein controlling the number of parallel connections is configured to increase the number of parallel connections when the instruction signal indicates higher accuracy.   
   
   
       3 . The method of  claim 1 ,
 wherein the controlling the number of parallel connections is configured to decrease the number of parallel connections when the instruction signal indicates lower accuracy.   
   
   
       4 . The method of  claim 1 ,
 wherein said oscillating unit comprises a loop oscillator formed by connecting a plurality of inverters in series   
   
   
       5 . The method of  claim 1 ,
 wherein said plurality of the oscillating units include:
 a first loop oscillating unit formed by connecting a plurality of first inverters in series in multiple stages, the first loop oscillating unit outputting an oscillation signal; and 
 a second loop oscillating unit formed by connecting a plurality of second inverters in series in multiple stages, the second loop oscillating unit being connected in parallel with the first loop oscillating unit to improve the accuracy of the oscillation signal, and 
   wherein controlling the number of parallel connections is configured to turn on/off connection between an output path of any one of the plurality of second inverters and an output path of the first inverter in a stage corresponding to the second inverter among the plurality of first inverters based on the instruction signal.   
   
   
       6 . The method of  claim 5 ,
 wherein controlling the number of parallel connections is configured to turn on the connection when the instruction signal indicates higher accuracy.   
   
   
       7 . The method of  claim 5 ,
 wherein controlling the number of parallel connections is configured to turn off the connection when the instruction signal indicates lower accuracy.   
   
   
       8 . The method of  claim 1 , further comprising
 stopping an operation of the oscillating unit which is controlled to leave the parallel connections by controlling the number of parallel connections.   
   
   
       9 . The method of  claim 8 ,
 wherein said plurality of oscillating units include:
 a first loop oscillating unit formed by connecting a plurality of first inverters in series in multiple stages, the first loop oscillating unit outputting an oscillation signal; and 
 a second loop oscillating unit formed by connecting a plurality of second inverters in series in multiple stages, the second loop oscillating unit being connected in parallel with the first loop oscillating unit to improve the accuracy of the oscillation signal, 
   wherein said method further comprises   providing a plurality of switches which open/close connection between an output path of any one of the plurality of second inverters and an output path of the first inverter in a stage corresponding to the second inverter among the plurality of first inverters to control open/closing of the parallel connection, and   wherein controlling the number of parallel connections is configured to control the switch.   
   
   
       10 . The method of  claim 9 ,
 wherein the first and second inverters are configured to receive a control voltage for controlling a frequency of the oscillation signal, and   wherein said stopping of the operation of the operation of the oscillating unit is configured to stop an oscillation of the second oscillating unit which is controlled to leave the parallel connections based on the instruction signal by stopping supply of the control voltage to the corresponding second inverters.