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US 6,172,634 B2Granted
Methods and apparatus for providing analog-fir-based line-driver with pre-equalization
AssigneeLucent Technologies Inc.
InventorsRobert H. Leonowich, Omid Shoaei, Ayal Shoval
Life of this patent
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Abstract
A line-driver receives as an input a Manchester-encoded digital data signal, which is then converted into an analog signal by a wave-shaping circuit. The wave-shaping circuit comprises a bank of current sources with a combined output, each current source being actuated by a switch controlled by a switching signal. The current sources are each scaled by a coefficient, and are actuated in a selected sequence during each input data pulse, thereby generating as a combined output a staircase pulse signal with n steps for each input data pulse.
Claims24
A line driver, comprising:
- an input for receiving a Manchester-encoded digital data signal, the data signal comprising a series of positive and negative pulse levels representing digital HI and LO, respectively;
- a wave-shaping circuit for converting the digital data signal into an analog signal, the wave-shaping circuit comprising:
- a bank of n current sources c0-cn−1 with a combined output, each current source being scaled by a coefficient,
- each current source having switches controlled by a switching signal input cnt0-cntn−1 for actuating the current sources in a selected sequence during each input data pulse, thereby generating as a combined output a staircase pulse signal with n steps for each input data pulse,
- wherein, when the Manchester-encoded input represents a binary sequence of all-ones or all-zeros data, the levels ak of the staircase pulse signal output approximate a sinusoidal curve a k = sin ( 2 π f o · T 2 · k n ) = sin ( π k n )
- where k=0 to n−1, and where f o = 1 T
- is the fundamental frequency of the input signal,
- wherein the coefficients bk used to scale the current sources are defined from the maximum peak value of the signal:
- b k = sin ( π 2 + π k n ) - sin ( π 2 + π ( k + 1 ) n )
- where k=0 to n−1,
- wherein current sources ck are scaled as follows:
- c k = 1 2 b k
- for k=0 to n−1, and
- wherein n=8 and wherein current sources c0-c7 are actuated sequentially in pairs starting from a positive or negative peak level of the input data, with pairs (c0, c7), (c1, c6), (c2, c5), and (c3, c4) being turned off sequentially in order followed by pairs (c3, c4), (c2, c5), (c1, c6), and (c0, c7) being turned on sequentially in order.
11 more elements
A line driver, comprising:
- an input for receiving a Manchester-encoded digital data signal, the data signal comprising a series of HI and LO pulse levels, the data signal including an amplitude droop by an equalization weight α, when there are two consecutive repeated positive or negative pulse levels, during the second repeated pulse level;
- a wave-shaping circuit for converting the digital data into an analog signal, the wave-shaping circuit comprising first and second sub-circuits,
- the first sub-circuit comprising a bank of n current sources (1−α)c0-(1−α)cn−1, each current source being scaled by a coefficient, each current source having a switch controlled by switching signals cnta0-cnta(n−1) for actuating the current sources in a selected sequence, thereby generating a staircase pulse signal with n steps for each input data pulse;
- and
- the second sub-circuit comprising a bank of n current sources (α)c0-(α)cn−1, each current source being scaled by a coefficient, each current source having a switch controlled by switching signals cntb0-cntb(n−1) for actuating the current sources in a selected sequence, thereby generating a staircase pulse signal with n steps for each input data pulse,
- wherein, when the Manchester-encoded pulse represent either all-ones or all-zeros data, the levels ak of the staircase pulse signal outputs Ip and In approximate a sinusoidal curve a k = sin ( 2 π f o · T 2 · k n ) = sin ( π k n )
- where k=0 to n−1, and where f o = 1 T
- is the fundamental frequency of the input signal,
- wherein current sources ck are scaled as follows:
- c k = 1 2 b k
- for k=0 to n−1,
- wherein n=8 and wherein current sources (1−α)c0-(1−α)c7 and αc0-αc7 are respectively actuated by switching signals cnta0-cnta7 and cntb0-cntb7, and
- wherein when the level of the input data pulse signal switches from the previous level to an opposite level, all control signals in the first and second sub-circuits are high and the switching signals are actuated in the following sequence where ↑ and ↓ represent, respectively, a switch turning on or off:
- (cnta0, cnta7)↓, (cnta1, cnta6)↓, (cnta2, cnta5)↓, (cnta3, cnta4)↓,
- (cnta3, cnta4)↑, (cnta2, cnta5)↑, (cnta1, cnta6)↑, (cnta0, cnta7)↑
- with every control signal in the second sub-circuit being identical to its counterpart in the first sub-circuit.
13 more elements
A line driver, comprising:
- an input for receiving a Manchester-encoded digital data signal, the data signal comprising a series of HI and LO pulse levels, the data signal including an amplitude droop by an equalization weight α, when there are two consecutive repeated positive or negative pulse levels, during the second repeated pulse level;
- a wave-shaping circuit for converting the digital data into an analog signal, the wave-shaping circuit comprising first and second sub-circuits,
- the first sub-circuit comprising a bank of n current sources (1−α)c0-(1−α)cn−1, each current source being scaled by a coefficient, each current source having a switch controlled by switching signals cnta0-cnta(n−1) for actuating the current sources in a selected sequence, thereby generating a staircase pulse signal with n steps for each input data pulse;
- and
- the second sub-circuit comprising a bank of n current sources (α)c0-(α)cn−1, each current source being scaled by a coefficient, each current source having a switch controlled by switching signals cntb0-cntb(n−1) for actuating the current sources in a selected sequence, thereby generating a staircase pulse signal with n steps for each input data pulse,
- wherein, when the Manchester-encoded pulse represent either all-ones or all-zeros data, the levels ak of the staircase pulse signal outputs Ip and In approximate a sinusoidal curve a k = sin ( 2 π f o · T 2 · k n ) = sin ( π k n )
- where k=0 to n−1, and where f o = 1 T
- is the fundamental frequency of the input signal,
- wherein current sources ck are scaled as follows:
- c k = 1 2 b k
- for k=0 to n−1,
- wherein n=8 and wherein current sources (1−α)c0-(1−α)c7 and αc0-αc7 are respectively actuated by switching signals cnta0-cnta7 and cntb0-cntb7, and
- wherein when the level of the input data pulse signal is the same as the previous one, all control signals in the first and second sub-circuits are high and the switching signals are actuated in the following sequence:
- cntb7↓, cntb6↓, cntb5↓, cntb4↓, cntb3↓, cntb2↓, cntb1↓, cntb0↓,
- (cnta0, cnta7)↓, (cnta1, cnta6)↓, (cnta2, cnta5)↓, (cnta3, cnta4)↓.
12 more elements
A line driver, comprising:
- an input for receiving a Manchester-encoded digital data signal, the data signal comprising a series of HI and LO pulse levels, the data signal including an amplitude droop by an equalization weight α, when there are two consecutive repeated positive or negative pulse levels, during the second repeated pulse level;
- a wave-shaping circuit for converting the digital data into an analog signal, the wave-shaping circuit comprising first and second sub-circuits,
- the first sub-circuit comprising a bank of n current sources (1−α)c0-(1−α)cn−1, each current source being scaled by a coefficient, each current source having a switch controlled by switching signals cnta0-cnta(n−1) for actuating the current sources in a selected sequence, thereby generating a staircase pulse signal with n steps for each input data pulse;
- and
- the second sub-circuit comprising a bank of n current sources (α)c0-(α)cn−1, each current source being scaled by a coefficient, each current source having a switch controlled by switching signals cntb0-cntb(n−1) for actuating the current sources in a selected sequence, thereby generating a staircase pulse signal with n steps for each input data pulse,
- wherein, when the Manchester-encoded pulse represent either all-ones or all-zeros data, the levels ak of the staircase pulse signal outputs Ip and In approximate a sinusoidal curve a k = sin ( 2 π f o · T 2 · k n ) = sin ( π k n )
- where k=0 to n−1, and where f o = 1 T
- is the fundamental frequency of the input signal,
- wherein current sources ck are scaled as follows:
- c k = 1 2 b k
- for k=0 to n−1,
- wherein n=8 and wherein current sources (1−α)c0-(1−α)c7 and αc0-αc7 are respectively actuated by switching signals cnta0-cnta7 and cntb0-cntb7, and
- wherein when the level of the input data pulse signal travels from zero to a peak value, all control signals in the first and second sub-circuits start at a zero level and are actuated in the following sequence where ↑ and ↓ represent, respectively, a switch turning on or off:
- (cnta0, cntb0)↑, (cnta1, cntb1)↑, (cnta2, cntb2)↑, (cnta3, cntb3)↑,
- (cnta4, cntb4)↑, (cnta5, cntb5)↑, (cnta6, cntb6)↑, (cnta7, cntb7)↑.
12 more elements
A line driver, comprising:
- an input for receiving a Manchester-encoded digital data signal, the data signal comprising a series of HI and LO pulse levels, the data signal including an amplitude droop by an equalization weight α, when there are two consecutive repeated positive or negative pulse levels, during the second repeated pulse level;
- a wave-shaping circuit for converting the digital data into an analog signal, the wave-shaping circuit comprising first and second sub-circuits,
- the first sub-circuit comprising a bank of n current sources (1−α)c0-(1−α)cn−1, each current source being scaled by a coefficient, each current source having a switch controlled by switching signals cnta0-cnta(n−1) for actuating the current sources in a selected sequence, thereby generating a staircase pulse signal with n steps for each input data pulse;
- and
- the second sub-circuit comprising a bank of n current sources (α)c0-(α)cn−1, each current source being scaled by a coefficient, each current source having a switch controlled by switching signals cntb0-cntb(n−1) for actuating the current sources in a selected sequence, thereby generating a staircase pulse signal with n steps for each input data pulse,
- wherein, when the Manchester-encoded pulse represent either all-ones or all-zeros data, the levels ak of the staircase pulse signal outputs Ip and In approximate a sinusoidal curve a k = sin ( 2 π f o · T 2 · k n ) = sin ( π k n )
- where k=0 to n−1, and where f o = 1 T
- is the fundamental frequency of the input signal,
- wherein current sources ck are scaled as follows:
- c k = 1 2 b k
- for k=0 to n−1,
- wherein n=8 and wherein current sources (1−α)c0-(1−α)c7 and αc0-αc7 are respectively actuated by switching signals cnta0-cnta7 and cntb0-cntb7, and
- wherein when the level of the input data pulse signal travels from a peak value to zero, all of the control signals in the first and second sub-circuits are at a peak value and are actuated in the following sequence where ↑ and ↓ represent, respectively, a switch turning on or off:
- (cnta7, cntb7)↑, (cnta6, cntb6)↑, (cnta5, cntb5)↑, (cnta4, cntb4)↑,
- (cnta3, cntb3)↑, (cnta2, cntb2)↑, (cnta1, cntb1)↑, (cnta0, cntb0)↑.
12 more elements
A line driver, comprising:
- an input for receiving a Manchester-encoded digital data signal;
- a wave-shaping circuit for converting the digital data signal into an analog signal, the wave-shaping circuit comprising:
- a bank of current sources being scaled according to a set of coefficients and sequentially actuated in predetermined pairs to generate as a combined output a staircase pulse approximating a sinusoidal curve in response to an all-ones Manchester-encoded data signal input;
- a smoothing filter for converting the staircase pulse signal into an analog signal.
1 more element
A line driver, comprising:
- an input for receiving a Manchester-encoded digital data signal;
- a wave-shaping circuit for converting the digital data into an analog signal, the wave-shaping circuit comprising:
- a first sub-circuit comprising a first bank of current sources scaled according to a first set of coefficients and sequentially actuated in predetermined pairs to generate as a combined output a first staircase pulse signal, and
- second sub-circuit comprising a second bank of current sources scaled according to a second set of coefficients and sequentially actuated in predetermined pairs to generate as a combined output a second staircase pulse signal,
- the first and second set of coefficients having values such that the steps in the first and second staircase pulse signal outputs have respective levels approximating a sinusoidal curve scaled, respectively, by (1−α) and α in response to an all-ones Manchester-encoded data signal input, where 1 is a normalized output value and α is a pre-equalization weight.
2 more elements
A line driver, comprising:
- an input for receiving a Manchester-encoded digital data signal;
- an FIR filter for shaping the digital data signal, the FIR filter including:
- a first bank of current sources scaled according to a first set of coefficients and sequentially actuated to generate as a combined output a first signal approximating a sinusoidal waveform having a peak value of (1−α) in response to an all-ones Manchester-encoded digital data signal input, where 1 is a normalized output value, and where α is a pre-equalization weight, and
- a second bank of current sources scaled according to a second set of coefficients and sequentially actuated to generate as a combined output a second signal approximating a sinusoidal waveform having a peak value of α in response to an all-ones Manchester-encoded digital data signal input;
- and
- a smoothing filter for converting the sum of the first and second signals into a continuous waveform analog output,
- wherein when two consecutive identical input pulses are received:
- the first signal makes a sinusoidal peak-to-peak transition during the first of the two consecutive identical input pulses, and then holds the peak value for the second consecutive input pulse;
- and
- the second signal has a zero value during the first half of the first input pulse followed by a sinusoidal zero-to-peak transition during the second half of the first input pulse, and then a sinusoidal peak-to-zero transition during the second input pulse,
- whereby when the first and second signals are summed, the resulting signal exhibits an amplitude droop by the pre-equalization weight α.
8 more elements
A method for converting a Manchester-encoded digital data signal into an analog signal, comprising:
- scaling a bank of current sources according to a set of coefficients having values such that in response to an all-ones Manchester-encoded digital data signal input, the current sources are actuated sequentially in predetermined pairs to generate as a combined output a staircase pulse signal approximating a sinusoidal curve;
- actuating the current sources in a predetermined sequence in response to a Manchester-encoded digital data signal input;
- converting the resulting staircase pulse signal output into an analog signal.
A method for converting a Manchester-encoded digital data signal into an analog signal, comprising:
- (a) scaling a first bank of current sources in a first sub-circuit according to a first set of coefficients;
- (b) scaling a second bank of current sources in a second sub-circuit according to a second set of coefficients, the first and second set of coefficients having values such that in response to an all-ones Manchester-encoded digital input signal, the first and second banks of current sources are actuated sequentially to generate first and second staircase pulse signals, the steps in the first and second staircase pulse signals having respective levels approximating a sinusoidal curve scaled, respectively, by (1−α) αk, and (α) αk, where 1 is a normalized output value and α is a pre-equalization weight;
- (c) actuating the first and second bank of current sources in a predetermined sequence in response to a Manchester-encoded digital signal input;
- (d) summing the first and second staircase pulse signals;
- (e) converting the summed staircase pulse signals into an analog signal.
2 more elements
A method for converting a Manchester-encoded digital data signal having an all-ones fundamental frequency ƒ0 into an analog signal, comprising:
- scaling a first bank of current sources according to a first set of coefficients having values such that when the first bank of current sources is actuated in a predetermined sequence in response to an all-ones Manchester-encoded digital data signal input, the first bank of current sources produces as a combined output a signal (t) approximating a sinusoidal waveform having the fundamental frequency ƒ0 and a peak value of 1−α, where 1 is a normalized output value, and where α is a pre-equalization weight, and
- scaling a second bank of current sources according to a second set of coefficients having values such that when the second bank of current sources is actuated in a predetermined sequence in response to an all-ones Manchester-encoded digital data signal input, the second bank of current sources produces as a combined output a second signal b(t) approximating a sinusoidal waveform having the fundamental frequency ƒ0 and a peak value of α;
- when two consecutive identical input pulses are received:
- actuating the first bank of current sources such that signal a(t) makes a sinusoidal peak-to-peak transition during the first of the two consecutive identical input pulses, and then holds the peak value for the second consecutive input pulse;
- and
- actuating the second bank of current sources such that signal b(t) has a zero value during the first half of the first input pulse followed by a sinusoidal zero-to-peak transition during the second half of the first input pulse, and then a sinusoidal peak-to-zero transition during the second input pulse,
- whereby when signals a(t) and b(t) are summed, the resulting signal exhibits an amplitude droop by the pre-equalization weight α.
4 more elements
Dependencies are inferred from the claim text.