Method and apparatus to mitigate ripple in a time of flight (TOF) system
AssigneeTexas Instruments Incorporated
InventorsSubhash Chandra Venkata Sadhu, Bharath Patil
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Abstract
The disclosure provides a circuit to mitigate ripple. The circuit includes a controller that generates a PWM (pulse width modulated) clock signal. A DC/DC converter receives the PWM clock signal, and generates an output signal. A light source is coupled to the DC/DC converter, and receives the output signal. The light source transmits light pulses during an integration time. A time integral of the output signal during the integration time is constant during a plurality of quad time periods.
Claims19
A TOF (time of flight) circuit comprising:
- a controller having a controller output, the controller configured to generate a PWM (pulse width modulated) clock signal at the controller output;
- a DC/DC converter configured to receive the PWM clock signal and provide an output signal, the DC/DC converter including:
- a capacitor having first and second capacitor terminals, the first capacitor terminal coupled to a ground;
- a first inductor directly coupled to the second capacitor terminal;
- and
- a second inductor directly coupled to the second capacitor terminal;
- and
- a light source coupled to the DC/DC converter, the light source configured to receive the output signal, and transmit light pulses during an integration time period of a quad time period of a frame, each frame including quad time periods equal to a positive integer multiple of a time period of the PWM clock signal, each quad time period having a reset time period, the integration time period, a readout time period, and a dead time period.
A method comprising:
- generating, by a controller in a time of flight (TOF) system, a PWM clock signal;
- receiving, by a DC/DC converter, the PWM clock signal;
- generating, by the DC/DC converter, an output signal in response to the PWM clock signal, in which the DC/DC converter includes a first inductor directly coupled to a first terminal of a capacitor and a second inductor directly coupled to the first terminal of the capacitor, and wherein a second terminal of the capacitor is coupled to ground;
- and
- transmitting light pulses provided by a light source during an integration time of a quad time period of a frame, each frame including quad time periods equal to a positive integer multiple of a time period of the PWM clock signal, each quad time period having a reset time period, the integration time period, a readout time period, and a dead time period.
A TOF (time of flight) system comprising:
- a controller configured to generate a PWM (pulse width modulated) clock signal;
- a DC/DC converter configured to receive the PWM clock signal and provide an output signal;
- a light source coupled to the DC/DC converter, the light source configured to receive the output signal and transmit light pulses during an integration time period of a quad time of a frame, each frame of successive frames including quad time periods, each quad time period equal to a positive integer multiple of a time period of the PWM clock signal;
- and
- a sensor coupled to the controller, and configured to receive reflected light pulses and generate an image of one or more objects, the light pulses scattered by the one or more objects to provide the reflected light pulses.
Dependencies are inferred from the claim text.