Digital/analog bit synchronizer
First Claim
1. A high speed bit synchronizer for generating a coherent clock synchronized with a received digital data stream, comprising:
- a digital phase detector having an input for receiving said digital data stream and producing a clocked data output,first summing means having a first input coupled to the clocked data output of said digital phase detector,offset eliminating means having an input coupled to the phase detector and a correction signal output coupled to a second input of said first summing means,a loop filter,said first summing means having positive inputs and a summed voltage output coupled to said loop filter,a voltage controlled oscillator having an input coupled to the filtered summed voltage output and having the coherent clock with a steady state phase offset, andthe output of said first summing means having a linear output phase offset S-curve around the lock point of said phase detector, whereby seeking is substantially eliminated.
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Abstract
A high speed bit synchronizer is provided with a digital phase detector and a digital offset eliminating circuit. The output of the digital offset eliminating circuit is summed together with the output of the digital phase detector to compensate for the DC offset voltage generated by unsymmetrical digital data received at the input of the phase detector. Further, the phase error offset voltage produced at the output of the digital phase detector is linearized so that the lock point of the phase S-curve located on a linearized portion of a phase offset S-curve, thus, substantially eliminating all seeking and jitter that normally occurs at the lock point.
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Citations
11 Claims
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1. A high speed bit synchronizer for generating a coherent clock synchronized with a received digital data stream, comprising:
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a digital phase detector having an input for receiving said digital data stream and producing a clocked data output, first summing means having a first input coupled to the clocked data output of said digital phase detector, offset eliminating means having an input coupled to the phase detector and a correction signal output coupled to a second input of said first summing means, a loop filter, said first summing means having positive inputs and a summed voltage output coupled to said loop filter, a voltage controlled oscillator having an input coupled to the filtered summed voltage output and having the coherent clock with a steady state phase offset, and the output of said first summing means having a linear output phase offset S-curve around the lock point of said phase detector, whereby seeking is substantially eliminated. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification