Circuit for generating discrimination voltage level
First Claim
1. A circuit for generating a variable level, reference discrimination voltage used for discriminating between two adjacent logic levels of an input signal which input signal can have a plurality of different voltage levels generally corresponding to a plurality of respective, different logic levels, comprising:
- means for generating and producing, as an output, a discrimination reference voltage having a selectively variable voltage level;
an offset reference voltage generating means for generating and producing, as corresponding outputs, a plus offset reference voltage having a variable voltage level which is higher, by a predetermined offset value, than the current voltage level of the discrimination reference voltage and a minus offset reference voltage having a variable voltage level which is lower, by the same predetermined offset value, than the current voltage level of the discrimination reference voltage;
first and second eye aperture input signal detecting means, each receiving as inputs thereto the input signal and the discrimination reference voltage output of the discrimination reference voltage generating means and respectively receiving the plus and minus offset reference voltage outputs of the offset reference voltage generating means, the first eye aperture detecting means detecting and producing a first detection output corresponding to the input signal level being between the respective, current voltage levels of the discrimination reference voltage and the plus offset reference voltage and the second eye aperture detection means detecting and producing a second detection output corresponding to the input signal level being between the respective, current voltage levels of the discrimination reference voltage and the minus offset reference voltage; and
said discrimination reference voltage generating means being responsive to the respective frequencies of the first and second detection outputs of the first and second eye aperture detecting means, for the current voltage level of the discrimination reference voltage, for adjusting the voltage level thereof to an adjusted, different voltage level at which the respective frequencies of the first and second detection outputs of said corresponding first and second eye aperture detecting means are equalized.
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Accused Products
Abstract
A circuit for generating a discrimination voltage level Vref which is used as a reference voltage to discriminate between two adjacent logic levels or an input signal which can have a plurality of different voltage levels generally corresponding to a plurality of respective, different logic levels. The frequency at which the levels of the input signals lie in the upper half of the vicinity (i.e., the voltage range from the level Vref -ΔV to the level Vref +ΔV) of the discrimination voltage level (i.e., the "upper half" thereof being the voltage range from Vref to Vref +ΔV, "ΔV" being a predetermined off-set value) and the frequency at which the levels of the input signals lie in the lower half of the vicinity (i.e., as above defined) of the discrimination level (i.e., the "low half" thereof being the voltage range from Vref -ΔV to Vref) are compared, and the discrimination level is controlled so that the above two frequencies are the same.
35 Citations
9 Claims
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1. A circuit for generating a variable level, reference discrimination voltage used for discriminating between two adjacent logic levels of an input signal which input signal can have a plurality of different voltage levels generally corresponding to a plurality of respective, different logic levels, comprising:
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means for generating and producing, as an output, a discrimination reference voltage having a selectively variable voltage level; an offset reference voltage generating means for generating and producing, as corresponding outputs, a plus offset reference voltage having a variable voltage level which is higher, by a predetermined offset value, than the current voltage level of the discrimination reference voltage and a minus offset reference voltage having a variable voltage level which is lower, by the same predetermined offset value, than the current voltage level of the discrimination reference voltage; first and second eye aperture input signal detecting means, each receiving as inputs thereto the input signal and the discrimination reference voltage output of the discrimination reference voltage generating means and respectively receiving the plus and minus offset reference voltage outputs of the offset reference voltage generating means, the first eye aperture detecting means detecting and producing a first detection output corresponding to the input signal level being between the respective, current voltage levels of the discrimination reference voltage and the plus offset reference voltage and the second eye aperture detection means detecting and producing a second detection output corresponding to the input signal level being between the respective, current voltage levels of the discrimination reference voltage and the minus offset reference voltage; and said discrimination reference voltage generating means being responsive to the respective frequencies of the first and second detection outputs of the first and second eye aperture detecting means, for the current voltage level of the discrimination reference voltage, for adjusting the voltage level thereof to an adjusted, different voltage level at which the respective frequencies of the first and second detection outputs of said corresponding first and second eye aperture detecting means are equalized. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification