PLL using unbalanced quadricorrelator
A Phase Locked Loop ( 1 ) used in a data and clock recovery comprising a frequency detector ( 10 ) including a quadricorrelator ( 2 ), the quadricorrelator ( 2 ) comprising a frequency detector including double edge clocked bi-stable circuits ( 21, 22, 23, 24 ) coupled to a first multiplexer ( 31 ) and to a second multiplexer ( 32 ) being controlled by a signal having a same bitrate as the incoming signal (D), and a phase detector (DFF) controlled by a first signal pair (PQ, PQ provided by the first multiplexer ( 31 ) and by a second signal pair (PI, PI ) provided by the second multiplexer ( 32 ).
1. A Phase Locked Loop, for synchronization of a clock signal with an incoming data signal, comprising
a frequency detector including
an unbalanced quadricorrelator, the quadricorrelator including
a first multiplexer,
a second multiplexer, and
double edge clocked bi-stable circuits, supplied by incoming mutually quadrature phase shifted signals and coupled to the first multiplexer and to the second multiplexer, the first and second multiplexers controlled by a signal having a same bit-rate as the incoming signal; and
a first phase detector that includes a D flip-flop that receives, as a data input, a first signal pair provided by the first multiplexer and that is clocked by a second signal pair provided by the second multiplexer;
a first transistor pair receiving the second signal pair on respective gates for determining a state ON or OFF of a current through the first transistor pair; and
a second transistor pair biased by current through the first transistor pair and receiving the first signal pair and generating an output signal indicative for a frequency error between the incoming data signal and the clock signal.
2. A Phase Locked Loop as claimed in claim 1 , wherein the frequency detector comprises a first pair of double edge clocked bi-stable circuits coupled to the first multiplexer, and a second pair of double edge clocked bi-stable circuits coupled to the second multiplexer, wherein the first and second pairs of bi-stable circuits are supplied by mutually quadrature phase shifted signals respectively to provide the first signal pair and the second signal pair indicative for a phase difference between the incoming signal and the mutually quadrature phase shifted signals.
3. A Phase Locked Loop as claimed in claim 2 , further including a voltage controlled oscillator wherein the mutually quadrature phase shifted signals are generated by the voltage controlled oscillator.
4. A Phase Locked Loop as claimed in 3 , further including
an adder;
a first charge pump; and
a first low-pass filter,
wherein a frequency error signal produced by the quadricorrelator is inputted to a coarse control input of the voltage controlled oscillator via the first charge pump coupled to the first low-pass filter coupled to the adder.
5. A Phase Locked Loop, for synchronization with an incoming data signal, comprising
a voltage controlled oscillator generating mutually quadrature phase shifted signals,
a frequency detector including an unbalanced quadricorrelator, the quadricorrelator including
a first multiplexer,
a second multiplexer,
a first pair of double edge clocked bi-stable circuits,
a second pair of double edge clocked bi-stable circuits,
wherein the first pair and the second pair of double edge clocked bi-stable circuits are supplied by the mutually quadrature phase shifted signals, respectively, to provide a first signal pair and a second signal pair indicative of a phase difference between the incoming data signal and the mutually quadrature phase shifted signals, and
a phase detector controlled by a first signal pair provided by the first multiplexer and by a second signal pair provided by the second multiplexer;
a first low-pass filter;
a second low-pass filter;
an adder;
a first charge pump for inputting a coarse control input for the voltage controlled oscillator using a frequency error signal produced by the quadricorrelator and coupled to the first low-pass filter and to the adder;
a second charge pump; and
a further phase detector;
wherein a fine control input is controlled by a signal provided by the further phase detector coupled to the second charge pump coupled to the second low-pass filter.
6. A Phase Locked Loop, for use with an incoming data signal, comprising:
a voltage controlled oscillator having a coarse control input and a fine control input and generating mutually quadrature phase-shifted signals;
a first charge pump;
a second charge pump;
a first low-pass filter;
a second low-pass filter;
an adder;
a quadricorrelator generating a frequency error signal inputted to the coarse control input of the voltage controlled oscillator via the first charge pump coupled to the first low-pass filter coupled to the adder, the quadricorrelator including
a frequency detector including
a first multiplexer,
a second multiplexer,
a first pair of double edge clocked bi-stable circuits coupled to the first multiplexer and
a second pair of double edge clocked bi-stable circuits coupled to the second multiplexer to provide a second signal pair, the first and second pairs of bi-stable circuits being supplied by the mutually quadrature phase shifted signals, the first and second multiplexers being controlled by a signal having a same bit-rate as the incoming signal and respectively providing a first signal pair and a second signal pair indicative for a phase difference between an incoming signal and the mutually quadrature phase shifted signals;
a transistor pair; and
a phase detector controlled by the first signal pair and the second signal pair, the phase detector including
a D flip-flop receiving the first signal pair and being clocked by the second signal pair, the second signal pair being inputted to respective gates of the transistor pair for determining a state ON or OFF of a current through said transistor pair; and
a second phase detector generating a phase error inputted to the fine control input of the voltage controlled oscillator via the second charge pump coupled to the second low-pass filter.
7. The Phase Locked Loop of claim 6 , further including a third low-pass filter, wherein the phase error is further inputted to the coarse control input of the voltage controlled oscillator via the second charge pump coupled to the third low-pass filter coupled to the adder.