Communications: electrical – Condition responsive indicating system – With particular system function
Reexamination Certificate
2000-11-15
2002-11-05
Pope, Daryl (Department: 2632)
Communications: electrical
Condition responsive indicating system
With particular system function
C340S506000, C340S003100, C700S011000, C700S295000, C700S300000
Reexamination Certificate
active
06476716
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to temperature-responsive electronic devices and methods of operation. More particularly, but not by way of limitation, the present invention relates to temperature-controlled variable resistors, temperature- controlled variable current sources and temperature-controlled variable voltage sources.
BACKGROUND OF THE INVENTION
Many modern electronic devices require very precise current and/or voltage sources for proper operation. Temperature variation, however, can change the operation of a part and thereby change, for example, a required level of operating current/voltage. Present systems compensate for temperature variations in a variety of ways—none of which are completely satisfactory. In particular, these present systems often lack the necessary resolution and cannot be adjusted with enough frequency and/or accuracy.
One electronic device that requires a current source that varies with changes in temperature is a laser diode driver. Laser diodes are notoriously fickle and require a very precise operating current that will generally vary with temperature. For example, the efficiency and optical power of a laser diode above threshold increase with decreasing temperatures. This means that a laser diode that has its operating current configured at room temperature will have reduced output once it warms up past room temperature. Conversely, if the operating current is set up after the laser diode has warmed up, the laser diode may overdrive when it is operated at room temperature. Thus, a laser diode driver would be enhanced by a temperature-controlled regulation device that can adjust current or at least aid in adjusting current. Such a device would allow a laser diode to operate efficiently over a wide range of temperatures to maintain a constant output power.
Of course, laser diode drivers are not the only electronic devices that require temperature-controlled current/voltage sources. For example, transceivers may require a temperature-controlled current source, and those of skill in the art can readily identify numerous other devices that require temperature-controlled current/voltage sources. Thus, a device and method are needed to adjust or aid in adjusting current/voltage sources in response to changes in temperature.
SUMMARY OF THE INVENTION
To remedy the deficiencies of existing systems and methods, the present invention provides, among other things, a method and apparatus to regulate an electronic device in response to temperature changes. For example, one method of the present invention can control a device operable in different operational modes. This method can include the steps of sensing a temperature; accessing a table using the sensed temperature; reading an operational mode indicator from the table, wherein the operational mode indicator can, for example, correspond to the sensed temperature; and operating the device in a proper one of the operational modes, which corresponds to the operational mode indicator.
REFERENCES:
patent: 6208905 (2001-03-01), Giddings et al.
Dallas Semiconductor Corporation
Jenkens & Gilchrist
Pope Daryl
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