US Patent No. 10,362,994

BIO-SENSING DEVICE WITH AMBIENT LIGHT CANCELLATION


Patent No. 10,362,994
Issue Date July 30, 2019
Title Bio-sensing Device With Ambient Light Cancellation
Inventorship Hussam Ahmed, Calicut (IN)
Jagannathan Venkataraman, Bangalore (IN)
Sandeep Kesrimal Oswal, Bangalore (IN)
Antoine Lourdes Praveen Aroul, Dallas, TX (US)
Hari Babu Tippana, Andhra Pradesh (IN)
Anand Hariraj Udupa, Bangalore (IN)
Assignee TEXAS INSTRUMENTS INCORPORATED, Dallas, TX (US)

Claim of US Patent No. 10,362,994

1. A bio-sensing device, comprising:a light source circuit;
a first photodetector;
a transimpedance amplifier coupled to the first photodetector and configured to convert a current produced by the photodetector to a voltage;
an analog-to-digital converter (ADC) coupled to the transimpedance amplifier and configured to convert the voltage from the first photodetector to a digital value; and
a controller coupled to the ADC and the light source circuit and configured to:
initiate a light source sense phase followed by a first ambient sense phase and a second ambient sense phase, wherein in the light source sense phase, the controller is configured to receive a digital value from the ADC while the light source circuit is enabled and wherein in each of the first and second ambient sense phases, the controller is configured to receive a digital value from the ADC while the light source circuit is disabled, wherein a first time period between the light source sense phase and the first ambient sense phase is equal to a second time period between the first and second ambient sense phases; and
iteratively vary the second time period, while maintaining the first and second time periods equal, until the digital value received during the first ambient sense phase is within a threshold of the digital value received during the second ambient sense phase.