Parallel-to-serial converter
First Claim
1. A parallel-to-serial converter receiving incoming data words each having M parallel bits from a digital processing device for converting them into serialized bits transmitted at a first frequency in a transmission medium, comprisinga time base receiving a clock signal at said first frequency and producing(1)--a loading clock signal at a second frequency M times less than said first frequency to rhythm a loading of said incoming data words which are received and which are previously transferred to outputs of a parallel-to-parallel register in a parallel-to-serial register,(2)--a first clock signal at said second frequency transmitted to said digital processing device to synchronize said digital processing device, and(3)--two second clock signals at said second frequency and substantially in opposition of phase to each other, anda phase analyzing means for analyzing the phase of said incoming data words compared to the phase of said first clock signal in order to select one of said two second clock signals according to whether said incoming data words and said first clock signal are approximately in phase and in opposition of phase, respectively, in a selected clock signal which rhythms a transfer of said incoming data words to said outputs of the parallel-to-parallel register.
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Abstract
Typically, a parallel-to-serial converter comprises a parallel-to-parallel register and a parallel-to-serial register. According to the prior art, a first clock signal the transfer of incoming parallel data words to outputs of the parallel-to-parallel register whereas the loading of the parallel-to-parallel register is rhythmed by a second clock signal which is independent of the first clock signal. According to the invention, a local base time produces the second loading clock signal and two clock signals substantially in phase-opposition so that there is time dependence between these signals. A phase analyzing circuit derives a control signal for selecting one of the two clock signals which are in phase-opposition as a function of a phase shift between the incoming parallel data words and the first clock signal.
29 Citations
12 Claims
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1. A parallel-to-serial converter receiving incoming data words each having M parallel bits from a digital processing device for converting them into serialized bits transmitted at a first frequency in a transmission medium, comprising
a time base receiving a clock signal at said first frequency and producing (1)--a loading clock signal at a second frequency M times less than said first frequency to rhythm a loading of said incoming data words which are received and which are previously transferred to outputs of a parallel-to-parallel register in a parallel-to-serial register, (2)--a first clock signal at said second frequency transmitted to said digital processing device to synchronize said digital processing device, and (3)--two second clock signals at said second frequency and substantially in opposition of phase to each other, and a phase analyzing means for analyzing the phase of said incoming data words compared to the phase of said first clock signal in order to select one of said two second clock signals according to whether said incoming data words and said first clock signal are approximately in phase and in opposition of phase, respectively, in a selected clock signal which rhythms a transfer of said incoming data words to said outputs of the parallel-to-parallel register.
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4. A parallel-to-serial converter receiving incoming data words each having M parallel bits from a digital processing device for converting them into serialized bits transmitted at a first frequency in a transmission medium, comprising
(a) a time base receiving a clock signal at said first frequency and producing (1) a loading clock signal at a second frequency M times less than said first frequency to rhythm a loading of said incoming data words which are received and which are previously transferred to outputs of a parallel-to-parallel register in a parallel-to-serial register, (2) a first clock signal at said second frequency transmitted to said digital processing device to synchronize said digital processing device, and (3) two second clock signals at said second frequency and substantially in opposition of phase to each other, a first of said second clock signals being produced directly and a second of said second clock signals being produced through a logic inverter receiving said first of said second clock signals, and (b) a phase analyzing means for analyzing the phase of said incoming data words compared to the phase of said first clock signal in order to select one of said two second clock signals according to whether said incoming data words and said first clock signal are approximately in phase and in opposition of phase, respectively, in a selected clock signal which rhythms a transfer of said incoming data words to said outputs of the parallel-to-parallel register.
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5. A parallel-to-serial converter receiving incoming data words each having M parallel bits for a digital processing device for converting them into serialized bits transmitted at a first frequency in a transmission medium, comprising
(a) a time base receiving a clock signal at said first frequency and producing (1) a loading clock signal at a second frequency M times less than said first frequency to rhythm a loading of said incoming data words which are received and which are previously transferred to outputs of a parallel-to-parallel register in a parallel-to-serial register, (2) a first clock signal at said second frequency transmitted to said digital processing device to synchronize said digital processing device, and (3) two second clock signals at said second frequency and substantially in opposition of phase to each other, and (b) a phase analyzing means for analyzing the phase of said incoming data words compared to the phase of said first clock signal in order to select one of said two second clock signals according to whether said incoming data words and said first clock signal are approximately in phase and in opposition of phase, respectively, in a selected clock signal which rhythms a transfer of said incoming data words to said outputs of the parallel-to-parallel register, said phase analyzing means comprising (1) several cascade-connected delay means imposing delays the sum of which defines a predetermined phase analysis duration, to delay one of predetermined of M bit signals relative to said M parallel bits in said incoming data words in several delayed signals, respectively, said analysis duration being less than a half-period of said clock signals at the second frequency, (2) several sampling means for sampling said first clock signal in response to predetermined logic transitions in said one predetermined of the M bit signal and said delayed signals in order to produce several sampling signals respectively, and (3) a logic means for generating as a function of two of said several sampling signals a control signal whose two logic states select said two second clock signals, respectively.
Specification