High frequency low noise phase-frequency detector and phase noise reduction method and apparatus
View Patent ↗The present invention discloses a new type of extremely low-noise phase-frequency detector (PFD) 500 , broadband from DC to multi-GHz RF frequencies for PLL synthesizer applications. Free of any feedback mechanisms, thus inherently fast, it operates close to transition frequency f T of IC processes or frequency limits of discrete mixers. The PFD 500 utilizes complex SSB conversion in both the in-phase and quadrature arms, delaying the in-phase arm in 530 , beating the delayed signal 124 with the un-delayed quadrature signal 122 in mixer 126 . The output 128 contains both the frequency difference and the phase difference information between the two signals 118 and 520 , providing both the frequency-discrimination (FD) and the phase detection (PD) functions. Utilizing standard mixers the PFD 500 can achieve superior CNRs of 180 dBc/Hz at multi-GHz RF. Additionally, utilizing the FD/FM demodulation capability, the present invention improves phase noise of various signals and linearity of FM modulators.
1. A method for providing frequency discrimination/comparison and phase detection/comparison using complex single side-band (SSB) down conversion, the method comprising:
receiving a local oscillator (LO) of frequency ω o and phase θ(t), in-phase and quadrature signals;
receiving a carrier signal of carrier frequency ω c and phase φ(t), in-phase and quadrature signals;
multiplying each of said in-phase and quadrature LO signals with each of said in-phase and quadrature carrier signals, thereby generating four converted signals;
combining in two pairs said four converted signals, to produce the in-phase LSB signal and the quadrature LSB signal;
delaying one of said LSB signals by a time delay τ to produce a delayed LSB signal;
multiplying said delayed LSB signal with said other LSB signal, to produce the baseband signal BB(t); and
outputting said baseband signal BB(t), wherein said signal BB(t) has a DC voltage component substantially proportional to a frequency difference ω c −ω o , and when this frequency difference is substantially near or equal to zero then said output signal BB(t) assumes a DC voltage substantially proportional to a phase difference φ(t)−θ(t).
2. The method of claim 1 wherein the receiving a local oscillator (LO) in-phase and quadrature signals includes receiving and splitting a local oscillator (LO) signal to two signal components: the in-phase component and the quadrature component.
3. The method of claim 1 wherein the receiving carrier in-phase and quadrature signals includes receiving and splitting an input carrier signal to two signal components: the in-phase component and the quadrature component.
4. The method of claim 1 comprising an operation of adding or subtracting to effect the combining in two pairs said four converted signals.
5. The method of claim 1 further comprising controlling said time delay τ.
6. The method of claim 5 , further comprising utilizing said output BB(t) to control said time delay τ in a closed-loop circuit.
7. A device for providing frequency discrimination/comparison and phase detection/comparison using complex single side-band (SSB) down conversion, the device comprising:
an in-phase local oscillator (LO) input providing an in-phase LO signal of frequency ω o and phase θ(t);
a quadrature local oscillator (LO) input providing a quadrature component of said LO signal;
an in-phase carrier frequency signal input providing an in-phase carrier signal component of frequency ω c and phase φ(t);
a quadrature carrier frequency signal input providing a quadrature signal component of said carrier signal;
four multiplying elements multiplying respective ones of said in-phase and quadrature LO components with separate ones of said in-phase and quadrature input carrier components, generating two pairs of different converted input signals;
two combiners to combine respective ones of said two pairs of said converted signals, producing in-phase and quadrature un-delayed lower single sideband (LSB) signals;
a delay element delaying one of the two said un-delayed LSB signals by a time delay τ, to generate one delayed LSB signal;
a fifth multiplying element multiplying said delayed LSB signal with the other said un-delayed LSB signal, to generate the baseband signal BB(t); and
an output port outputting said baseband signal BB(t), wherein said signal BB(t) has a DC voltage component substantially proportional to a frequency difference ω c −ω o , and as this frequency difference approaches zero then said output signal BB(t) assumes a DC voltage substantially proportional to the phase difference φ(t)−θ(t).
8. The device of claim 7 further comprising a splitter circuit for receiving a local oscillator (LO) signal and splitting the LO signal into an in-phase and quadrature signal components.
9. The device of claim 7 further comprising a splitter circuit for receiving a carrier signal and splitting the carrier signal into an in-phase and quadrature signal components.
10. The device of claim 7 wherein the two combiners use adding or subtracting means to effect the combining said two pairs of said converted signals.
11. The device of claim 7 further comprising an adjustable time delay element having a control input to control the parameters of said time delay element.
12. The device of claim 11 , comprising circuitry to couple said control input of said adjustable time delay element to said output BB(t), thereby providing a closed-loop adjustment of said time delay element.
13. The device of claim 7 , thus further comprising:
a local oscillator (LO) reference signal;
a first splitter splitting the LO reference signal into an in-phase LO component and a quadrature LO component, said in-phase LO component coupled to said in-phase LO input of said device, said quadrature LO component coupled to said quadrature LO input of said device;
a Voltage Controlled Oscillator (VCO) having one tuning voltage input port (V T ), and one output port providing a signal Vosc;
a second splitter splitting said Vosc signal into an in-phase Vosc component and a quadrature Vosc component, said in-phase Vosc component coupled to said in-phase carrier input of said device, said quadrature Vosc component coupled to said quadrature carrier input of said device, and
a loop filter, having one input coupled to said baseband output BB(t) of said device, and one output coupled to said tuning voltage input V T of said VCO, the device thereby providing a frequency-discriminator and phase-detector (PFD) function in a phase-locked loop (PLL) system.
14. The device of claim 7 , further comprising:
a local oscillator (LO) reference input providing a LO reference signal;
a first splitter splitting the LO reference signal into an in-phase LO component and a quadrature LO component, said in-phase LO component coupled to said in-phase LO input of the device, said quadrature LO component coupled to said quadrature LO input of the device;
a Voltage Controlled Oscillator (VCO) having one tuning voltage input port (V T ), and one output port providing a signal Vosc;
a second splitter splitting said Vosc signal into an in-phase Vosc component and a quadrature Vosc component, said in-phase Vosc component coupled to said in-phase carrier input of the device, said quadrature Vosc component coupled to said quadrature carrier input of the device;
an input modulating signal V mod ;
a combiner to combine said baseband signal BB(t) of the device with said input modulating signal V mod , to produce an error signal; and
a loop filter, having one input coupled to said error signal, and one output coupled to said tuning voltage input V T of said VCO, thereby providing a linearization function in an FM modulator system.
15. A feed-back system for providing phase noise-reduction (clean-up) of a Voltage Controlled Oscillator (VCO) output signal, comprising:
a VCO generating a signal Vo of frequency ω c , having a tuning voltage input V T , and separated into in-phase and quadrature Vo signal components;
a local oscillator (LO) providing an LO signal of frequency ω o close or equal to ω c +π·n/τ, where τ is a delay time and n is an integer 0,±1,±2, . . . , and separated into in-phase and quadrature LO signal components;
four multiplying elements multiplying said in-phase and quadrature LO signal components with respective ones of said in-phase and quadrature Vo signal components, generating two pairs of converted signals;
a first and a second combiner to combine respective ones of said two pairs of converted signals, producing an un-delayed lower single sideband (LSB) in-phase and un-delayed LSB quadrature signals;
a first delay element having a time delay comparable to τ, coupled to said un-delayed in-phase LSB signal, to provide a delayed LSB in-phase signal;
a second delay element having a time delay comparable to τ, coupled to said un-delayed quadrature LSB signal, to provide a delayed LSB quadrature signal;
a fifth multiplying element for multiplying said delayed LSB in-phase signal with said un-delayed LSB quadrature signal, generating a first multiplication product;
a sixth multiplying element for multiplying said delayed LSB quadrature signal with said un-delayed LSB in-phase signal, generating a second multiplication product;
a third combiner to combine said first and second multiplication products, to produce a demodulated baseband signal BB(t); and
a filter having one input port coupled to said demodulated baseband signal BB(t), and an output port coupled to said tuning voltage input V T of said VCO.
16. The feed-back system of claim 15 , comprising the first and second combiners each including a circuit to add or subtract the respective ones of said two pairs of said converted signals.
17. A feed-back system for providing phase noise-reduction (clean-up) of an input signal, comprising:
an input signal having a frequency ω c ;
a phase modulator having a first input port, a second input port and one output port, the first input port coupled to said input signal, and the output port providing a signal Vo, and separated into in-phase and quadrature Vo signal components;
a local oscillator (LO) providing an LO signal of frequency ω 0 close or equal to ω c +π·n/τ, where τ is a delay time and n is an integer 0,±1,±2, . . . , and separated into in-phase and quadrature LO signal components;
four multiplying elements multiplying said in-phase and quadrature LO signal components with respective ones of said in-phase and quadrature Vo signal components, generating two pairs of converted signals;
a first and a second combiner to combine respective ones of said two pairs of converted signals, producing an un-delayed lower single sideband (LSB) in-phase and un-delayed LSB quadrature signals;
a first delay element having a time delay comparable to τ, coupled to said un-delayed in-phase LSB signal, to provide a delayed LSB in-phase signal;
a second delay element having a time delay comparable to τ, coupled to said un-delayed quadrature LSB signal, to provide a delayed LSB quadrature signal;
a fifth multiplying element for multiplying said delayed LSB in-phase signal with said un-delayed LSB quadrature signal, generating a first multiplication product;
a sixth multiplying element for multiplying said delayed LSB quadrature signal with said un-delayed LSB in-phase signal, generating a second multiplication product;
a third combiner to combine said first and second multiplication products, to produce a demodulated baseband signal BB(t); and
a filter having one input port coupled to said demodulated baseband signal BB(t), and an output port coupled to said second input of said phase modulator.
18. The feed-back system of claim 17 , comprising the first and second combiners each including a circuit to add or subtract the respective ones of said two pairs of said converted signals.
19. A feed-forward system for providing phase noise-reduction (clean-up) of an input signal, comprising:
A signal Vc having a frequency ω c ;
a phase modulator having a first input port, a second input port and one output port, the first input port coupled to said signal Vc and separated into in-phase and quadrature Vc signal components, and the output port providing a signal Vo;
a local oscillator (LO) providing an LO signal of frequency ω 0 close or equal to ω c +π·n/τ, where τ is a delay time and n an integer 0,±1,±2, . . . , and separated into in-phase and quadrature LO signal components;
four multiplying elements multiplying said in-phase and quadrature LO signal components with respective ones of said in-phase and quadrature Vc signal components, generating two pairs of converted signals;
a first and a second combiner to combine respective ones of said two pairs of converted signals, producing an un-delayed lower single sideband (LSB) in-phase and un-delayed LSB quadrature signals;
a first delay element having a time delay comparable to τ, coupled to said un-delayed in-phase LSB signal, to provide a delayed LSB in-phase signal;
a second delay element having a time delay comparable to τ, coupled to said un-delayed quadrature LSB signal, to provide a delayed LSB quadrature signal;
a fifth multiplying element for multiplying said delayed LSB in-phase signal with said un-delayed LSB quadrature signal, generating a first multiplication product;
a sixth multiplying element for multiplying said delayed LSB quadrature signal with said un-delayed LSB in-phase signal, generating a second multiplication product;
a third combiner to combine said first and second multiplication products, to produce a demodulated baseband signal BB(t); and
a filter having one input port coupled to said demodulated baseband signal BB(t), and an output port coupled to said second input of said phase modulator.
20. The feed-forward system of claim 19 , comprising the first and second combiners each including a circuit to add or subtract the respective ones of said two pairs of said converted signals.
21. A method for providing frequency discrimination/comparison and phase detection/comparison using down conversion, the method comprising:
receiving a local oscillator (LO) of frequency ω o and phase θ(t), in-phase and quadrature signals;
receiving a carrier signal of carrier frequency ω c and phase φ(t), in-phase and quadrature signals;
multiplying said in-phase LO signal with said in-phase carrier signal, and said quadrature LO signal with said quadrature carrier signal, thereby generating two converted signals;
combining said two converted signals, to produce one LSB converted signal;
multiplying one of said quadrature carrier signal or in-phase carrier signal with one of said in-phase LO signal or quadrature LO signal, thereby generating one double side-band (DSB) converted signal;
delaying one of said DSB or LSB converted signals by a time delay τ to produce a delayed signal;
multiplying said delayed signal with the un-delayed one of said DSB or LSB converted signals, to produce the baseband signal BB(t); and
outputting said baseband signal BB(t), wherein said signal BB(t) has a DC voltage component substantially proportional to a frequency difference ω c −ω o , and when this frequency difference is substantially near or equal to zero then said output signal BB(t) assumes a DC voltage substantially proportional to a phase difference φ(t)−θ(t).
22. The method of claim 21 wherein the receiving a local oscillator (LO) in-phase and quadrature signals includes receiving and splitting a local oscillator (LO) signal to two signal components: the in-phase component and the quadrature component.
23. The method of claim 21 wherein the receiving carrier in-phase and quadrature signals includes receiving and splitting an input carrier signal to two signal components: the in-phase component and the quadrature component.
24. A method for providing frequency discrimination/comparison and phase detection/comparison using frequency conversion, the method comprising:
receiving a local oscillator (LO) of frequency ω o and phase θ(t);
receiving a carrier signal of carrier frequency ω c and phase φ(t), in-phase and quadrature signals;
multiplying said LO signal with said in-phase carrier signal, thereby generating a first double side-band (DSB) converted signal;
multiplying said LO signal with said quadrature carrier signal, thereby generating a second DSB converted signal;
delaying one of either first or second DSB converted signals by a time delay τ to produce a delayed signal;
multiplying said delayed signal with other un-delayed said first or second DSB signal, to produce a baseband signal BB(t); and
outputting said baseband signal BB(t), wherein said signal BB(t) has a DC voltage component substantially proportional to a frequency difference ω c −ω o , and when this frequency difference is substantially near or equal to zero then said output signal BB(t) assumes a DC voltage substantially proportional to a phase difference φ(t)−θ(t).
25. The method of claim 24 wherein the receiving a carrier in-phase and quadrature signals includes receiving and splitting a carrier signal to two signal components: the in-phase component and the quadrature component.
26. A device for providing frequency discrimination/comparison and phase detection/comparison using simple conversion, the device comprising:
a local oscillator (LO) input providing a signal of frequency ω o and phase θ(t);
an in-phase carrier signal input providing an in-phase carrier signal of frequency ω c and phase φ(t);
a quadrature carrier frequency signal input providing a quadrature carrier signal component of said carrier signal;
a multiplying element multiplying said LO signal with said in-phase carrier signal, thereby generating a first double side-band (DSB) converted signal;
a multiplying element multiplying said LO signal with said quadrature carrier signal component, thereby generating a second DSB converted signal;
a resistor-capacitor (RC) delay element delaying one of either first or second DSB converted signals to produce a delayed signal;
a multiplying element multiplying said delayed signal with other un-delayed said first or second DSB signal, to produce a baseband signal BB(t); and
an output port outputting said baseband signal BB(t), wherein said signal BB(t) has a DC voltage component substantially proportional to a frequency difference ω c −ω o , and when this frequency difference is substantially near or equal to zero then said output signal BB(t) assumes a DC voltage substantially proportional to a phase difference φ(t)−θ(t).
27. The device of claim 26 further comprising a splitter circuit for receiving a carrier signal and splitting the carrier signal into an in-phase and quadrature signal components.
28. The device of claim 26 , further comprising:
a local oscillator (LO) input providing a LO reference signal, coupled to the local oscillator (LO) input of the device;
a Voltage Controlled Oscillator (VCO) having one tuning voltage input port (V T ), and one output port providing a signal Vosc;
a splitter splitting said Vosc signal into an in-phase Vosc component and a quadrature Vosc component, said in-phase Vosc component coupled to said in-phase carrier input of the device, said quadrature Vosc component coupled to said quadrature carrier input of the device; and
a loop filter, having one input coupled to baseband signal output BB(t) of the device, and one output coupled to said tuning voltage input V T of said VCO, thereby creating a closed loop system able to provide both frequency acquisition and phase lock.