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US 2020/0044900 A1Published application
Carrier recovery analog system for a receiver of a n-psk signal
AssigneeCommissariat A L'energie Atomique Et Aux Energies Alternatives
InventorsAlexandre SILIGARIS, Cedric DEHOS, Jose-Luis GONZALEZ JIMENEZ, Clement JANY, Baudoin MARTINEAU
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Abstract
A carrier recovery system for a receiver of a phase-modulated signal N-PSK, the system including a first pre-conditioning circuit of the signal received (S(t)), with the pre-conditioned signal (SP(t)) having a component, non-modulated in phase, at the frequency Nƒc where ƒc is the carrier used for the modulation N-PSK, and a carrier regeneration circuit to regenerate two sinusoidal signals in quadrature at the frequency ƒc, with these signals being phase locked with respect to said non-modulated component in phase of the pre-conditioned signal.
Claims13
1:
- A carrier recovery system for coherent receiver intended to receive a phase-modulated signal S(t) by means of a N-PSK modulation of said carrier where N is an even number, the carrier recovery system comprising:
- a signal pre-conditioning circuit for supplying a pre-conditioned signal having a non-modulated component with a harmonic Nƒc of the carrier frequency ƒc, said non-modulated component at Nƒc being obtained by multiplication of the phase-modulated signal and of
- K
- =
- N
- 2
- -
- 1
- delayed versions of this signal by respective delays
- k
-
- T
- c
- N
- ,
- with k=1, . . . , K, each delay being defined to the nearest integer multiple of
- T
- c
- 2
- ,
- where Tc=1/ƒc with the result of said multiplication being subjected to a quadratic function;
- and
- a carrier regeneration circuit for generating a sinusoidal signal at the carrier frequency phase locking onto said harmonic.
20 more elements
2:
- The carrier recovery system according to claim 1, wherein the signal pre-conditioning circuit obtains the pre-conditioned signal by means of
- SP
-
- (
- t
- )
- =
-
- ∏
- k
- =
- 0
- N
- 2
- -
- 1
-
-
- S
-
- (
- t
- +
- kT
- c
- N
- )
-
- .
26 more elements
3:
- The carrier recovery system according to claim 2, wherein the signal pre-conditioning circuit comprises a plurality K of stages, with each stage (k) comprising a delay (420k) of value
- T
- c
- N
- ,
- and a mixer (410k), with the mixer of a current stage (k) multiplying the signal supplied by the mixer (410k-1) of the preceding stage (k−1) with the signal at the output of the delay (420k-1) of the preceding stage, after having delayed it by the delay (420k-1) of the current stage (k), with the first stage receiving said phase-modulated signal, with the signal at the output of the mixer of the last stage (410K) being rectified by means of a rectifier in order to supply the pre-conditioned signal (SP(t)).
3 more elements
4:
- The carrier recovery system according to claim 2, wherein the signal pre-conditioning circuit comprises a plurality K of stages, with each stage (k) comprising a delay (520k) of value
- T
- c
- N
- +
- T
- c
- 2
- ,
- and a mixer (510k), with the mixer of a current stage (k) multiplying the signal supplied by the mixer (510k-1) of the preceding stage (k−1) with the signal at the output of the delay (520k-1) from the preceding stage, after having delayed it by the delay (520k) of the current stage (k), with the first stage receiving said phase-modulated signal, with the signal at the output of the mixer of the last stage (510K) being supplied to a frequency doubling circuit, followed by a band-pass filter that only allows said harmonic Nƒc to pass in order to supply the pre-conditioned signal, SP(t).
7 more elements
5:
- The carrier recovery system according to claim 2, wherein each mixer of a current stage (k) comprises a first pair of transistors and a second pair of transistors, with the gates of the transistors of the first pair and the gates of transistors of the second pair receiving in differential the output signal of the mixer of the preceding stage (k−1), with the drains of the transistors of the first pair and the drains of the transistors of the second pair receiving in differential the signal at the output of the delay (520k) of the current stage (k), the output signal of the current stage (520k) being supplied in differential by the signal on the first common terminal of the sources of the transistors of the first pair and the signal on the second common terminal of the sources of the transistors of the second pair.
6:
- The carrier recovery system according to claim 2, wherein each mixer of a current stage k=1, . . . , K comprises a first oscillating circuit between the first common terminal and the mass and a second oscillating circuit between the second commune and the mass, with the first oscillating circuit and the oscillating circuit allowing to pass only the harmonic at the frequency kƒc.
7:
- The carrier recovery system according to claim 1, wherein the carrier regeneration circuit is a frequency divider by a factor N.
8:
- The carrier recovery system according to claim 7, further comprising an injection locked frequency divider followed by at least one frequency divider using a current switching logic CML and/or at least one frequency divider with a base of CMOS flip-flops, with the product of the frequency division factors of these dividers being equal to N.
9:
- The carrier recovery system according to claim 1, wherein the carrier regeneration circuit comprises an injection locked oscillator operating at the frequency Nƒc, followed by a frequency divider by a factor N, the oscillator phase locking onto said non-modulated component at Nƒc of the pre-conditioned signal and supplying a purely sinusoidal signal at the frequency Nƒc, with the frequency divider dividing the frequency of this purely sinusoidal signal by a factor N in order to regenerate the carrier.
10:
- The carrier recovery, system according to claim 1, wherein the carrier regeneration circuit comprises an injection locked oscillator operating at the frequency
- N
- M
-
- f
- c
- ,
- where M is an N-integer divider, followed by a frequency divider by a factor
- N
- M
- ,
- with the oscillator locking in phase and in frequency on said non-modulated component at Nƒc of the pre-conditioned signal and supplying a purely sinusoidal signal at the frequency
- N
- M
-
- f
- c
- ,
- with the frequency divider dividing the frequency of this purely sinusoidal signal of a factor
- N
- M
- in order to regenerate the carrier.
19 more elements
11:
- The carrier recovery system according to claim 10, wherein the phase-modulated signal is a QPSK signal, with the injection locked oscillator being a differential cross-pair oscillator comprising a resonant circuit LC, of which the resonance frequency is close to 2ƒc, with the injection of the pre-conditioned signal being carried out in common mode, the frequency divider divides the frequency of the differential signal at the output of the oscillator by a factor 2.
12:
- The carrier recovery system according to claim 1, wherein the carrier regeneration circuit comprises an injection locked oscillator operating at the frequency ƒc, with the oscillator locking in frequency and in phase on said non-modulated component at Nƒc of the pre-conditioned signal and supplying a sinusoidal signal at the frequency ƒc in order to regenerate the carrier.
13:
- The carrier recovery system according to claim 12, wherein the frequency regeneration circuit comprises two quadrature differential cross-pair oscillators, that use resonant circuits LC, of which the resonance frequency is close to ƒc, with the quadrature oscillators injection locking in common mode, said injection in common mode being carried out by the pre-conditioning circuit, comprising a transistor polarised in such a way that its point of polarisation belongs to a non-linear portion of its characteristic drain-source current according to its gate-source voltage, said transistor receiving on its gate, through a connecting capacitor, the phase-modulated signal.