Triple wavelength LED driver for optical brain–computer interfaces
Soraghan , C.J. and Markham, C. and Matthews, F. and Ward, T.E. (2009) Triple wavelength LED driver for optical brain–computer interfaces. Electronics Letters, 45 (8).
A dedicated triple wavelength LED driver is presented for optical brain–computer interfacing (BCI). The solution caters for the constraints of a common-anode grounded case and modulation up to several kilohertz that allows source separation of light that has backscattered from the brain. With total harmonic distortion of 0.95% and a frequency range of ~40 kHz, the driver has application in a continuous wave optical BCI. Other modulation strategies such as time division multiplexing (TDM) are catered for, owing to input DC coupling. Linearity in the optical output is maintained by the ‘load sensing’ differential op-amp on the LED’s current limiting resistor, which is the basis for the V-I conversion.
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