Multi-level decision circuit
First Claim
1. A multi-level signal decision circuit comprising:
- a DC level control means supplied with a multi-level amplitude signal of 2M (M being an integer equal to or greater than
2) levels, for changing, by a DC level control signal, the DC level to be superimposed on the output multi-level amplitude signal;
an AD converter connected to the output side of said DC level control means, for converting its output multi-level amplitude signal into a digital signal of N (N being an integer greater than M) bits and providing its M high-order bits as a multi-level decided output to an output terminal;
a feedback signal generating means supplied with the output of at least an (M+1)th one of (M+1)th and less significant bits of the AD converter output and at least one of its M high-order bits, for generating a DC level control feedback signal; and
a low-pass filter for integrating the DC level control feedback signal from said feedback signal generating means and feeding it as the DC level control signal back to said DC level control means, each of said feedback signal generating means and said low-pass filter constituting a part of a feedback system.
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Accused Products
Abstract
An input multi-level amplitude signal of 2M levels is supplied via a DC level controller to an AD converter for conversion into an N-bit (N being an integer greater than M) digital signal, and M high-order bits of the digital signal are provided as decided outputs. It is decided by a decision means whether a deviation of the DC level of the multi-level amplitude signal at the input side of the AD converter is in excess of a predetermined value. When the deviation of the DC level is decided less than the predetermined value, the outputs of bits less significant than the Mth bit in the digital signal are integrated for input as a DC level control signal into the DC level controller, correcting the deviation of the DC level. When it is decided by the decision means that the deviation of the DC level is greater than the predetermined value, at least one of the M high-order bit outputs in the output digital signal is integrated for input as a DC level control signal into the DC level controller, correcting the deviation of the DC level.
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Citations
13 Claims
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1. A multi-level signal decision circuit comprising:
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a DC level control means supplied with a multi-level amplitude signal of 2M (M being an integer equal to or greater than
2) levels, for changing, by a DC level control signal, the DC level to be superimposed on the output multi-level amplitude signal;an AD converter connected to the output side of said DC level control means, for converting its output multi-level amplitude signal into a digital signal of N (N being an integer greater than M) bits and providing its M high-order bits as a multi-level decided output to an output terminal; a feedback signal generating means supplied with the output of at least an (M+1)th one of (M+1)th and less significant bits of the AD converter output and at least one of its M high-order bits, for generating a DC level control feedback signal; and a low-pass filter for integrating the DC level control feedback signal from said feedback signal generating means and feeding it as the DC level control signal back to said DC level control means, each of said feedback signal generating means and said low-pass filter constituting a part of a feedback system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification