ADJUSTMENT METHOD, CIRCUIT, RECEIVER CIRCUIT AND TRANSMISSION EQUIPMENT OF WAVEFORM EQUALIZATION COEFFICIENT

• US 20080159460A1
• Filed: 12/28/2007
• Published: 07/03/2008
• Est. Priority Date: 12/28/2006
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kanai, Hisaaki, Chujo, Norio, Yagyu, Masayoshi
• Granted Patent: US 7,965,765 B2
• Time in Patent Office: Days
• US Class Current: 375/373
• CPC Class Codes: H04L 25/03885 adaptive

Abstract

In an adjustment method of waveform equalization coefficient, one of jitter and amplitude is measured only in a case of an arbitrary signal sequence and a waveform equalization coefficient is adjusted. Particularly, using a signal of received signals other than a 010 signal or a 101 signal, code inversion time is measured. Since the code inversion time in a case where such signals are used becomes steeper in comparison with that in the conventional technique, adjustment time of the waveform equalization coefficient can be reduced.

Claims

1. An adjustment method of waveform equalization coefficient in transmission equipment comprising a driver circuit transmitting a signal and a receiver circuit receiving the signal transmitted from the driver circuit,

wherein the signal transmitted from the driver circuit is received by the receiver circuit, measurement of one of jitter and amplitude is performed only in a case of an arbitrary signal sequence in a waveform equalization coefficient adjustment circuit in the receiver circuit and a waveform equalization coefficient of a waveform equalization circuit in the driver circuit is adjusted according to a result of the measurement.

2. The adjustment method of waveform equalization coefficient according claim 1,

wherein the arbitrary signal sequence is data other than signal sequences of 010 and 101, and

wherein the measurement of the one of the jitter and the amplitude is performed in the waveform equalization coefficient adjustment circuit using the data other than the signal sequences of 010 and 101 and the waveform equalization coefficient of the waveform equalization circuit is adjusted.

3. A receiver circuit comprising a waveform equalization coefficient adjustment circuit adjusting a waveform equalization coefficient of a waveform equalization circuit,

wherein the waveform equalization coefficient adjustment circuit comprises:

n×

2 latches having inputs of received data and composed of two stages connected in parallel;

n−

1 delay elements operating the n×

2 latches in synchronized with clocks having different timings;

n−

1 XOR gates outputting a signal when data codes of adjacent latches are inverted in the n×

2 latches;

three latches connected in series and delaying the received data by one bit respectively; and

n−

1 comparison circuits outputting no data to a counter when a code of data D₀ inputted through two latches of the

three latches and codes of data D_-1 before the data D₀ by one symbol inputted through the three latches and data D₁ after the data D₀ by one symbol inputted through one latch of the three latches are inverted, and

wherein measurement of one of jitter and amplitude is performed only when the received data is an arbitrary signal sequence and the waveform equalization coefficient of the waveform equalization circuit is adjusted according to a result of the measurement.

4. A receiver circuit receiving a signal transmitted from a driver circuit comprising:

an input buffer receiving the signal transmitted from the driver circuit;

a CDR connected to a subsequent stage of the input buffer;

a latch connected to the subsequent stage of the input buffer and using an output of the CDR as a clock; and

a waveform equalization coefficient adjustment circuit connected to the subsequent stage of the input buffer, performing measurement of one of jitter and amplitude only when received data is an arbitrary signal sequence and adjusting a waveform equalization coefficient of a waveform equalization circuit in the driver circuit according to a result of the measurement.

5. The receiver circuit according claim 4,

wherein the arbitrary signal sequence is data other than signal sequences of 010 and 101,

wherein the measurement of the one of the jitter and the amplitude is performed in the waveform equalization coefficient adjustment circuit using the data other than the signal sequences of 010 and 101 and the waveform equalization coefficient of the waveform equalization circuit is adjusted at first accuracy so as to make distribution of the one of the jitter and the amplitude small, and

wherein the measurement of the one of the jitter and the amplitude is performed in the waveform equalization coefficient adjustment circuit using data of all signal sequences and the waveform equalization coefficient of the waveform equalization circuit is adjusted at second accuracy higher than the first accuracy so as to make the distribution of the one of the jitter and the amplitude small.

6. The receiver circuit according to claim 4,

wherein the receiver circuit is formed over a semiconductor substrate and configured as an LSI.

7. Transmission equipment using the receiver circuit according to claim 6,

wherein the transmission equipment is configured using the LSI formed over the semiconductor substrate.