Optical receiver

Details Optical receiver Optical receiver

1998-05-14

2002-01-01

Chan, Jason (Department: 2633)

Optical: systems and elements

Deflection using a moving element

Using a periodically moving element

C359S199200, C375S317000, C375S319000

Reexamination Certificate

active

06335815

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an optical receiver and, more particularly, to an optical receiver which compensates for a phase variation due to a change in temperature of a timing extraction circuit of a tank scheme.
Generally, an optical repeater requires a 3R function, i.e., a reshaping function of converting an optical input signal into an electrical signal, amplifying the signal, and shaping the waveform of the signal, a retiming function of extracting a timing component from the signal after reshaping, and a regenerating function of identifying “1” or “0” from the signal after reshaping and regenerating it to the same signal as a transmission pulse. Japanese Patent Laid-Open No. 3-258034 discloses a technique of controlling the temperature of a SAW (Surface Acoustic Wave) filter constituting a tuning circuit necessary for extracting the timing signal for regeneration to adjust the phase of the timing signal in the optical receiver having the 3R function. This prior art will be described with reference to
FIGS. 4 and 5
.
Referring to
FIG. 4
, the optical repeater comprises an optical reception circuit
41
for converting an optical input signal into an electrical signal
45
and performing reshaping, a regenerating circuit
42
for performing regenerating for the electrical signal
45
output from the optical reception circuit
41
, a timing extraction circuit
43
for extracting the phase of a transmission pulse and supplying a timing signal
46
as a clock signal to the regenerating circuit
42
, and an optical transmission circuit
44
for converting an electrical signal output from the regenerating circuit
42
into an optical signal again and sending it.
The timing extraction circuit
43
must suppress the jitter of the regeneration output pulse output as the timing signal
46
. For this purpose, a pulse repetitive frequency component is extracted from an equalized waveform train output from the optical reception circuit
41
by a full-wave rectifier and a tuning circuit, and then amplification limitation is performed by a limiter amplifier, thereby obtaining the timing signal
46
having a small amplitude and phase error even for a wide-range mark ratio. In addition, a SAW filter is used for the tuning circuit. By controlling the temperature of the SAW filter, the phase of the timing signal
46
is adjusted.
FIG. 5
shows the arrangement of a phase adjustment circuit incorporated in the timing extraction circuit
43
shown in
FIG. 4
to control the phase of the SAW filter constituting the tuning circuit for extracting a timing signal. The phase adjustment circuit shown in
FIG. 5
comprises a SAW filter
51
, a Peltier device
52
, and a thermister
53
, which are arranged integrally with each other, and a control circuit
54
to which a reference voltage is supplied.
Since the phase of the SAW filter
51
changes in proportion to the temperature, the phase can be set at a predetermined value by controlling the temperature. When the Peltier device
52
and the thermister
53
are controlled to a temperature corresponding to an externally supplied reference voltage
55
by the control circuit
54
, the temperature of the SAW filter
51
is set to ensure a predetermined phase. In this arrangement, the temperature of the SAW filter
51
is set by adjusting the reference voltage
55
, so the phase of the timing signal
46
output from the timing extraction circuit
43
can be adjusted.
In the conventional phase adjustment circuit, since the Peltier device
52
is used to perform temperature compensation, the power consumption increases upon heating/cooling the Peltier device. For this reason, this phase adjustment circuit can hardly be applied to an optical receiver with a transmission rate of the order of Gbit/sec or less, for which reduction of power consumption is required. In addition, since only the output phase of the SAW filter is controlled, phase variations generated by a circuit device other than the SAW filter cannot be compensated for.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an optical receiver which compensates for a phase variation due to the ambient temperature of a timing extraction circuit in the optical receiver at a low power consumption.
It is another object of the present invention to provide an optical receiver which compensates for a phase variation due to the temperature of an entire timing extraction circuit.
In order to achieve the above object, according to the present invention, there is provided an optical receiver comprising photoelectric conversion means for converting input signal light into an electrical signal, reshaping means for amplifying the electrical signal output from the photoelectric conversion means and performing waveform shaping, regenerating means for regenerating data from an output from the reshaping means on the basis of a retiming signal, timing signal extraction means for extracting a timing signal from an output signal from the reshaping means, reference voltage generation means for generating a reference voltage changing in accordance with a variation in ambient temperature, and a comparator for comparing an output signal from the timing signal extraction means with the reference voltage output from the reference voltage generation means and supplying the retiming signal to the regenerating means.


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patent: 5-90887 (1993-04-01), None

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