PLL circuit, radio-communication equipment and method of oscillation frequency control

• US 7,301,414 B2
• Filed: 04/07/2005
• Issued: 11/27/2007
• Est. Priority Date: 04/26/2004
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Hino, Takuo
• Primary Examiner(s): Pascal; Robert
• Assistant Examiner(s): Gannon; Levi
• Application Number:
  US11/100,896
• Publication Number:
  US 20050237125A1
• Time in Patent Office: 964 Days
• Field of Search: 331/179, 331/16, 331/40, 331/14, 331/11, 331/10
• US Class Current: 331/179
• CPC Class Codes: H03B 5/1215 the current source or degeneration circuit being in common to both transistors of the pair, e.g. a cross-coupled long-tailed pair
• CPC Class Codes: H03B 5/1231 the amplifier comprising one or more bipolar transistors
• CPC Class Codes: H03B 5/1243 the means comprising voltage variable capacitance diodes
• CPC Class Codes: H03B 5/1265 switched capacitors
• CPC Class Codes: H03B 5/1293 having means for achieving a desired tuning characteristic, e.g. linearising the frequency characteristic across the tuning voltage range
• CPC Class Codes: H03J 5/244 using electronic means
• CPC Class Codes: H03L 2207/06 Phase locked loops with a controlled oscillator having at least two frequency control terminals
• CPC Class Codes: H03L 7/0898 the source or sink current values being variable H03L7/0896 takes precedence
• CPC Class Codes: H03L 7/1072 by changing characteristics of the charge pump, e.g. changing the gain
• CPC Class Codes: H03L 7/183 a time difference being used for locking the loop, the counter counting between fixed numbers or the frequency divider dividing by a fixed number H03L7/1806 takes precedence

Abstract

A Phase-Locked Loop (PPL) circuit includes a voltage controlled oscillator (VCO), a reference signal oscillator, first and second frequency dividers, a phase comparator, a charge pump and a loop filter. The VCO has a plural number of oscillation frequency boards and oscillates according to a control voltage in a selected band. The first frequency divider frequency divides the output signal of the VCO. The second frequency divider frequency divides the reference signal outputted from the reference signal oscillator. The phase comparator detects the phase difference between the output signal of the first and second frequency dividers and outputs a phase difference signal. The charge pump inputs and outputs a current generated by a gain that was set depending on the selected band based on the phase difference signal. The loop filter increases or decreases the voltage with a specified low pass filter.

Claims

1. An oscillation frequency control method comprising:

an oscillation step of making a voltage controlled oscillator (VCO) have a plural number of bands oscillate in a selected band, the VCO having an oscillation frequency, the VCO having an output signal, the output signal of the VCO having the oscillation frequency,

a first frequency-dividing step to divide the frequency of the output signal of said voltage controlled oscillator,

a second frequency-dividing step to divide the frequency of a reference signal,

a phase comparing step of detecting a phase difference between the frequency-divided signal in said first frequency-dividing step and the frequency-divided signal in said second frequency-dividing step and of outputting a phase difference signal,

a current driving step for inputting and outputting a current generated at a gain which was set depending on the selected band based on said phase difference signal,

a control voltage generation step for generating and outputting a control voltage of said voltage controlled oscillator by increasing or decreasing the control voltage with a specified low-pass filter characteristic by the current inputted and outputted at said current driving step,

a second frequency measurement step for measuring the oscillation frequency of said voltage controlled oscillator by applying a first constant voltage as said control voltage in the selected band,

a fourth frequency measurement step for measuring the oscillation frequency of said voltage controlled oscillator by applying the output voltage of said control voltage generation step in the selected band,

a fifth frequency measurement step in which, in the selected band, when the frequency measured in the fourth frequency measurement step is higher than the frequency measured in the second frequency measurement step, a constant voltage higher by an amount of a specified voltage than said first constant voltage is selected, while when the frequency measured in the fourth frequency measurement step is lower than the frequency measured in the second frequency measurement step, a constant voltage lower by a specified voltage than said first constant voltage is selected, and then the selected constant voltage is applied as said control voltage, thereby the oscillation frequency of said voltage controlled oscillator is measured,

a gain setting step to set the gain at said current driving step in the band, based on a frequency difference between the measured oscillation frequency in said second frequency measurement step and the measured oscillation frequency in said fifth frequency measurement step, and

a step to make said voltage controlled oscillator oscillate by inputting and outputting the current generated at the gain that was set based on said phase difference signal in said current driving step, and then by applying the output voltage of said control voltage generation step as said control voltage.

2. The oscillation frequency control method of claim 1, further comprising:

a step to prohibit or permit the band selection action and the gain setting action in said current driving step, and wherein, only when the band selection action and the gain setting action in said current driving step are permitted, the oscillation frequency control method is executed.

3. The oscillation frequency control method of claim 1, further comprising:

a step to read and set the gain of said current driving step corresponding to the selected band from a memory storing the gain of said current driving step for respective bands.

4. The oscillation frequency control method of claim 1,

wherein when switching over from the step for measuring the oscillation frequency of said voltage controlled oscillator by applying a constant voltage as said control voltage to the step for making said voltage controlled oscillator oscillate by applying the output voltage of said control voltage generation step as said control voltage, the gain of said current driving step is transiently set high, and after a specified time lapse or after the oscillation frequency of said voltage controlled oscillator is locked in a certain specified range of error with respect to a target frequency, the gain of said current driving step is set to a value corresponding to said selected band.

5. An oscillation frequency control method comprising:

an oscillation step of making a voltage controlled oscillator (VCO) have a plural number of bands oscillate in a selected band, the VCO having an oscillation frequency, the VCO having an output signal, the output signal of the VCO having the oscillation frequency,

a first frequency-dividing step to divide the frequency of the output signal of said voltage controlled oscillator,

a second frequency-dividing step to divide the frequency of a reference signal,

a phase comparing step of detecting a phase difference between the frequency-divided signal in said first frequency-dividing step and the frequency-divided signal in said second frequency-dividing step and of outputting a phase difference signal,

a current driving step for inputting and outputting a current generated at a gain which was set depending on the selected band based on said phase difference signal,

a control voltage generation step for generating and outputting a control voltage of said voltage controlled oscillator by increasing or decreasing the control voltage with a specified low-pass filter characteristic by the current inputted and outputted at said current driving step,

a step for executing said oscillation step, said first frequency-dividing step, said second frequency-dividing step, said phase comparing step, said current driving step, and said control voltage generation step, so that said voltage controlled oscillator oscillates at a specified target frequency at a time when a power source is turned on,

a step in which, in case that a new target frequency is set, based on the new target frequency, or based on a difference between the new target frequency and said specified target frequency, the band selection and the gain setting in said current driving step are executed using a specified arithmetic expression or a specified table,

a second frequency measurement step for measuring the oscillation frequency of said voltage controlled oscillator by applying a first constant voltage as said control voltage in the selected band,

a fourth frequency measurement step for measuring the oscillation frequency of said voltage controlled oscillator by applying the output voltage of said control voltage generation step in the selected band,

a fifth frequency measurement step in which, in the selected band, when the frequency measured in the fourth frequency measurement step is higher than the frequency measured in the second frequency measurement step, a constant voltage higher by an amount of a specified voltage than said first constant voltage is selected, while when the frequency measured in the fourth frequency measurement step is lower than the frequency measured in the second frequency measurement step, a constant voltage, lower by a specified voltage than said first constant voltage is selected, and then the selected constant voltage is applied as said control voltage, thereby the oscillation frequency of said voltage controlled oscillator is measured,

a gain setting step to set the gain at said current driving step in the band, based on the frequency difference between the measured oscillation frequency in said second frequency measurement step and the measured oscillation frequency in said fifth frequency measurement step, and

a step to make said voltage controlled oscillator oscillate by inputting and outputting the current generated at the gain that was set based on said phase difference signal in said current driving step, and then by applying the output voltage of said control voltage generation step as said control voltage.

6. An oscillation frequency control method comprising:

an oscillation step of making a voltage controlled oscillator (VCO) have a plural number of bands oscillate in a selected band, the VCO having an oscillation frequency, the VCO having an output signal, the output signal of the VCO having the oscillation frequency,

a first frequency-dividing step to divide the frequency of the output signal of said voltage controlled oscillator,

a second frequency-dividing step to divide the frequency of a reference signal,

a phase comparing step of detecting a phase difference between the frequency-divided signal in said first frequency-dividing step and the frequency-divided signal in said second frequency-dividing step and of outputting a phase difference signal,

a current driving step for inputting and outputting a current generated at a gain which was set depending on the selected band based on said phase difference signal,

a control voltage generation step for generating and outputting a control voltage of said voltage controlled oscillator by increasing or decreasing the control voltage with a specified low-pass filter characteristic by the current inputted and outputted at said current driving step,

a first frequency measurement step in which, under a condition that said voltage-controlled oscillator is set to a selected band and a control voltage of a constant value is applied, said reference signal or the frequency-divided signal of said reference signal and the output signal of said voltage controlled oscillator or the frequency-divided signal thereof are inputted, and based on said reference signal or the frequency-divided signal of said reference signal, the frequency of the output signal of said voltage controlled oscillator or of the frequency-divided signal thereof is measured, and

a band-selection step to select a band in which said voltage-controlled oscillator operates according to the frequency measured in said first frequency measurement step,

wherein when switching over from the first frequency measuring step to the band-selection step, the gain of said current driving step is transiently set high, and after a specified time lapses or after the oscillation frequency of said voltage controlled oscillator is locked in a certain specified range of error with respect to a target frequency, the gain of said current driving step is set to a value corresponding to said selected band.

7. An oscillation frequency control method comprising:

an oscillation step of making a voltage controlled oscillator (VCO) have a plural number of bands oscillate in a selected band, the VCO having an oscillation frequency, the VCO having an output signal, the output signal of the VCO having the oscillation frequency,

a first frequency-dividing step to divide the frequency of the output signal of said voltage controlled oscillator,

a second frequency-dividing step to divide the frequency of a reference signal,

a phase comparing step of detecting a phase difference between the frequency-divided signal in said first frequency-dividing step and the frequency-divided signal in said second frequency-dividing step and of outputting a phase difference signal,

a current driving step for inputting and outputting a current generated by a gain which was set depending on the selected band based on said phase difference signal,

a control voltage generation step for generating and outputting a control voltage of said voltage controlled oscillator by increasing or decreasing the control voltage with a specified low-pass filter characteristic by the current inputted and outputted at said current driving step,

a second frequency measurement step for measuring the oscillation frequency of said voltage controlled oscillator by applying a first constant voltage as said control voltage in the selected band,

a third frequency measurement step for measuring the oscillation frequency of said voltage controlled oscillator by applying a second constant voltage as said control voltage in the selected band,

a gain setting step to set the gain at said current driving step in the band, based on a difference between the measured oscillation frequency in said second frequency measurement step and the measured oscillation frequency in said third frequency measurement step, and

a step to make said voltage controlled oscillator oscillate by inputting and outputting the current generated at the gain that was set based on said phase difference signal in said current driving step, and by applying the output voltage of said control voltage generation step as said control voltage,

wherein when switching over from the third frequency measurement step to the step for making said voltage controlled oscillator oscillate by applying the output voltage of said control voltage generation step as said control voltage, the gain of said current driving step is transiently set high, and after a specified time lapse or after the oscillation frequency of said voltage controlled oscillator is locked in a certain specified range of error with respect to a target frequency, the gain of said current driving step is set to a value corresponding to said selected band.