Radiation source driver for accelerated modulation in an optical wireless communication system
AssigneeSignify Holding B.V.
InventorJOHAN PAUL MARIE GERARD LINNARTZ
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Abstract
This invention relates to a switched-mode light source driver with added functionality for accelerated modulation, which is beneficial for e.g. fast on-off keying (OOK) or pulse amplitude modulation (PAM). An improved output stage includes a low-cost switched-mode power supply in combination with a shunt-switch and a series-switch arrangement, which are used in combination to provide a fast modulator. Thus, two switching functions are used in the output stage, one in series with the light source(s), one in parallel to the light source(s), wherein the light source(s) can be driven between a high and a low output level by using overdriving via a switch mode driver and shorting the output via the parallel switch.
Claims15
A driver circuit for driving a semiconductor radiation source of an optical wireless communication transmitter in accordance with a digital modulation scheme for data communication comprising higher and lower states representing modulated data, the driver circuit comprising:
- a switched mode power supply for generating an overdrive current supplied to the radiation source, the overdrive current being higher than a steady-state current required for a desired radiation output level for a corresponding state of the digital modulation scheme;
- a modulator comprising a first switching element connected in series to the radiation source and a second switching element connected in parallel to the series connection of the first switching element and the radiation source;
- and
- a control circuit for controlling the switching states of the first and second switching elements to maintain a radiation output of the radiation source within a target output range for proper detection of the higher and lower states when received at an optical wireless communication receiver and for closing the second switching element to bypass the overdrive current during an open state of the first switching element.
A method of driving a semiconductor radiation source of an optical wireless communication transmitter in accordance with a digital modulation scheme for data communication comprising higher and lower states representing modulated data, the method comprising:
- supplying an overdrive current to the radiation source, the overdrive current being higher than a steady-state current required for a desired radiation output level for a corresponding state of the digital modulation scheme;
- controlling the switching states of a first switching element connected in series to the radiation source and of a second switching element connected in parallel to the series connection of the first switching element and the radiation source to maintain a radiation output of the radiation source within a target output range for proper detection of the higher and lower states when received at an optical wireless communication receiver;
- and
- closing the second switching element to bypass the overdrive current during an open state of the first switching element.
Dependencies are inferred from the claim text.