Circuit for aligning clock to parallel data
First Claim
1. A system for aligning clock and data signals comprising:
- a clock shifting circuit, receiving an incoming clock signal and outputting a shifted clock signal, comprising;
a phase locked loop (PLL) with a reference input, a feedback input, and a PLL output, wherein the incoming clock signal connected to the reference input;
a plurality of n D flip flops connected in series, each D flip flop having a D input, a clock input, a Q output, and a Q-bar output, wherein the PLL output is connected to the clock input of every D flip flop, wherein the Q output of a D flip flop is connected to the D input of a subsequent D flip flop in the series, wherein the Q-bar output of a last D flip flop in the series is connected to the D input of a first D flip flop in the series, wherein the Q-bar output of the last D flip flop in the series is buffered and connected to the feedback input, where n is an integer; and
wherein the shifted clock signal is at least one Q output from the series of D flip flops; and
a data clocking circuit, receiving the shifted clock signal and a plurality of incoming data bits and outputting a plurality of reclocked data bits.
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Accused Products
Abstract
Method and system for aligning a clock signal to parallel data are described. According to one embodiment, a clock shifting circuit shifts an incoming clock signal relative to an incoming data signal, and a data clocking circuit uses the shifted clock signal to reclock the incoming data signal. The clock shifting circuit may comprise a phase locked loop (PLL) coupled with multiple D flip flops (DFFs) connected in series. Divisional combinatorial logic may be disposed between DFFs in the series. Data clocking circuits may comprise one DFF to reclock each incoming data bit, a pair of DFFs to reclock each incoming data bit, or other circuits such as true-complement blocks to serve as local oscillators to mixers. Multiple shifted clock signals may be produced, such as those shifted 60, 90, 120, 180, 240, and 270 degrees relative to the incoming clock signal.
31 Citations
20 Claims
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1. A system for aligning clock and data signals comprising:
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a clock shifting circuit, receiving an incoming clock signal and outputting a shifted clock signal, comprising; a phase locked loop (PLL) with a reference input, a feedback input, and a PLL output, wherein the incoming clock signal connected to the reference input; a plurality of n D flip flops connected in series, each D flip flop having a D input, a clock input, a Q output, and a Q-bar output, wherein the PLL output is connected to the clock input of every D flip flop, wherein the Q output of a D flip flop is connected to the D input of a subsequent D flip flop in the series, wherein the Q-bar output of a last D flip flop in the series is connected to the D input of a first D flip flop in the series, wherein the Q-bar output of the last D flip flop in the series is buffered and connected to the feedback input, where n is an integer; and wherein the shifted clock signal is at least one Q output from the series of D flip flops; and a data clocking circuit, receiving the shifted clock signal and a plurality of incoming data bits and outputting a plurality of reclocked data bits. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system for aligning clock and data signals comprising:
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a clock shifting circuit, receiving an incoming clock signal and generating as output a first shifted clock signal and a second shifted clock signal, comprising; a phase locked loop (PLL) with a reference input, a feedback input, and a PLL output, wherein the incoming clock signal is connected to the reference input; a first D flip flop having a first D input, a first clock input, a first Q output, and a first Q-bar output, wherein the PLL output is connected to the first clock input, wherein the first Q output is the first shifted clock signal; a divisional combinatorial logic block receiving at least one input from the first D flip flop and generating at least one output; and a second D flip flop having a second D input, a second clock input, a second Q output, and a second Q-bar output, wherein the PLL output is connected to the second clock input, wherein the output of the divisional combinatorial logic block is connected to the second D input, wherein the second Q-bar output is connected to the first D input, wherein the second Q-bar output is buffered and connected to the feedback input, wherein the second Q-bar output is the second shifted clock signal; and a data clocking circuit, receiving the first and second shifted clock signals and a plurality of incoming data bits and outputting a plurality of reclocked data bits. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A method of aligning clock and data signals, comprising:
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receiving at a reference clock input of a phase locked loop (PLL) an incoming clock signal at a first frequency, generating a modified clock signal at a second frequency using the PLL, wherein the PLL also receives feedback Q signal at a feedback input, wherein the PLL multiplies the incoming clock signal so that the second frequency is greater than the first frequency; receiving the modified clock signal at a first clock input of a first D flip flop, wherein the first D flip flop also receives the feedback Q signal at a first D input; generating a shifted clock signal at a third frequency using the first D flip flop, wherein the third frequency is less than the second frequency, and wherein the shifted clock signal is phase-shifted relative to the incoming clock signal; transmitting the shifted clock signal to a second D input at a second D flip flop; receiving the modified clock signal at a second clock input of a second D flip flop; generating the feedback Q signal at a second Q-bar output of the second D flip flop; and applying the shifted clock signal to logic circuitry to which an incoming data signal is applied. - View Dependent Claims (18, 19, 20)
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Specification