Phase-locked loop circuit
View Patent ↗Phase locked loop circuit ( 105 ) having a double entry VCO ( 158 ) and two independent charge pumps ( 171, 172 ), each connected with one of the entries of the VCO. Each of the VCO entries has a different gain coefficient, thereby allowing a better optimisation and control of the device bandwidth and a reduced phase noise. Can be employed in radio transmitters and/or receivers and allows simultaneous and precise FM modulation both inside and outside the PLL bandwidth.
1. A phase locking loop circuit, comprising:
a phase and frequency detector for receiving an input reference signal, and a feedback signal;
a voltage controlled oscillator having a first analogue voltage input for controlling a frequency produced from said voltage controlled oscillator according to a first proportionality coefficient and a second analogue voltage input, independent from said first analogue voltage input for controlling a frequency produced from said voltage controlled oscillator according to a second proportionality coefficient, different from said first proportionality coefficient;
a first charge pump receiving a signal from said frequency and phase detector and delivering a first control signal to said first voltage input of said voltage controlled oscillator;
a second charge pump receiving a signal from said frequency and phase detector and delivering a second control signal to said second voltage input of said voltage controlled oscillator; and
a feedback path for feeding a correction signal back to said phase and frequency detector;
wherein said first charge pump is connected directly to the first voltage input of the voltage controlled oscillator, without a filtering capacitor.
2. The phase locking loop of claim 1 , wherein said first voltage input is a low-sensitivity input, whereas said second voltage input is a higher-sensitivity input, for locking said output signal and following said input signal.
3. The phase locking loop circuit of claim 1 , wherein said frequency and phase detector has a first output and a second output.
4. The phase locking loop circuit of claim 1 , further comprising a capacitor for filtering said second control signal.
5. The phase locking loop circuit of claim 1 , wherein said first charge pump has an output dynamics different from an output dynamics of said second charge pump.
6. The phase locking loop circuit of claim 1 , further comprising a multiple-ratio divider for generating an output signal whose frequency is in non-integral ratio with a frequency of said input signal.
7. The phase-locking loop circuit of claim 6 , further comprising a modulation input, connected with a voltage input of said voltage controlled oscillator.
8. A frequency synthesizer, comprising a PLL circuit according to claim 1 .
9. A receiver and/or transmitter circuit, comprising a PLL circuit according to claim 1 .
10. A phase locking loop circuit, comprising:
a phase and frequency detector for receiving an input reference signal, and a feedback signal;
a voltage controlled oscillator comprising a LC oscillator with varactor diodes, said voltage controlled oscillator having a first analogue voltage input for controlling a frequency produced from said voltage controlled oscillator according to a first proportionality coefficient and a second analogue voltage input, independent from said first analogue voltage input for controlling a frequency produced from said voltage controlled oscillator according to a second proportionality coefficient, different from said first proportionality coefficient;
a first charge pump receiving a signal from said frequency and phase detector and delivering a first control signal to said first voltage input of said voltage controlled oscillator;
a second charge pump receiving a signal from said frequency and phase detector and delivering a second control signal to said second voltage input of said voltage controlled oscillator; and
a feedback path for feeding a correction signal back to said phase and frequency detector;
wherein said first charge pump is connected directly to the first voltage input of the voltage controlled oscillator, without a filtering capacitor.
11. The phase locking loop circuit of claim 10 , wherein said voltage controlled oscillator is a LC oscillator comprising an array of parallel-connected varactor diodes and providing two variable capacitors having different voltage coefficients.
12. A phase locking loop circuit, comprising:
a phase and frequency detector for receiving an input reference signal, and a feedback signal;
a voltage controlled oscillator having a first analogue voltage input for controlling a frequency produced from said voltage controlled oscillator according to a first proportionality coefficient and a second analogue voltage input, independent from said first analogue voltage input for controlling a frequency produced from said voltage controlled oscillator according to a second proportionality coefficient, different from said first proportionality coefficient;
a first charge pump receiving a signal from said frequency and phase detector and delivering a first control signal to said first voltage input of said voltage controlled oscillator;
a second charge pump receiving a signal from said frequency and phase detector and delivering a second control signal to said second voltage input of said voltage controlled oscillator;
a feedback path for feeding a correction signal back to said phase and frequency detector; and
a variable modulation source, for generating a modulation signal, that is composed with said first control signal at said first voltage input of the voltage controlled oscillator.
13. The phase locking loop circuit of claim 12 , further comprising a multiple-ratio divider for generating an output signal whose frequency is in non-integral ratio with a frequency of said input signal.
14. A receiver and/or transmitter circuit, comprising a PLL circuit according to claim 12 .