Time-of-flight sensor, distance measuring system, and electronic device
The present application discloses a time-of-flight (TOF) sensor and a related chip, electronic device, and distance measuring system. The TOF sensor includes: a clock signal generation circuit to generate a first clock signal and a second clock signal; a transmission circuit to generate a third clock signal based on the first clock signal, wherein the third clock signal is outputted to the light-emitting module; a replicated transmission circuit to simulate the transmission circuit, and generate a fourth clock signal based on the second clock signal; a delay locked loop to generate a fifth clock signal based on one of sixth clock signals and the fourth clock signal; a clock tree to generate the plurality of sixth clock signals based on the fifth clock signal; a pixel array, having pixel columns respectively sampling the reflected light pulse based on the plurality of sixth clock signals to generate a sampling result.
1. A time-of-flight (TOF) sensor, wherein the TOF sensor controls a light-emitting module to intermittently transmit a light pulse, and the light pulse is reflected by a target to generate a reflected light pulse, wherein the TOF sensor comprises:
a clock signal generation circuit, configured to generate a first clock signal and a second clock signal, wherein the first clock signal and the second clock signal have a same frequency, and there is a predetermined phase difference between the first clock signal and the second clock signal;
a transmission circuit, configured to generate a third clock signal based on the first clock signal, wherein the third clock signal is outputted to the light-emitting module, so that the light-emitting module intermittently transmit the light pulse;
a replicated transmission circuit, configured to simulate the transmission circuit, and generate a fourth clock signal based on the second clock signal, so that the phase difference between the fourth clock signal and the third clock signal is kept the same as the predetermined phase difference;
a delay locked loop, coupled to the replicated transmission circuit and one of a plurality of sixth clock signals to generate a fifth clock signal; so that the phase difference between one of the plurality of sixth clock signals and the fourth clock signal is kept at zero;
a clock tree, configured to generate the plurality of sixth clock signals based on the fifth clock signal, wherein a plurality of phases of the plurality of sixth clock signals are all the same; and
a pixel array, having a plurality of pixel columns, wherein the plurality of pixel columns perform sampling on the reflected light pulse; respectively, based on the plurality of sixth clock signals to generate a sampling result.
2. The TOF sensor of claim 1 , wherein the clock tree comprises a plurality of paths, wherein the plurality of paths respectively include a start terminal and an end terminal, the plurality of start terminals are co-located and configured to receive the fifth clock signal, the plurality of end terminal are respectively coupled to the plurality of pixel columns, so that the fifth clock signal, starting from the source, becomes a plurality of sixth clock signals to the plurality of pixel columns via the plurality of paths, and a signal transmission distance of each of the plurality of paths matched to each other from the start terminal to the end terminal, so that phase differences between the plurality of sixth clock signals are kept at zero when temperature, bias voltage, or process changes.
3. The TOF sensor of claim 1 , wherein the TOF sensor is disposed at a first chip, and a layout of the transmission circuit is adjacent to a layout of the replicated transmission circuit.
4. The TOF sensor of claim 1 , wherein the delay locked loop generates the fifth clock signal based the fourth clock signal and on one of the plurality of sixth clock signals.
5. The TOF sensor of claim 4 , wherein the delay locked loop comprises:
a phase detector, configured to generate phase difference information between one of the plurality of sixth clock signals and the fourth clock signal;
a charge pump, configured to generate a voltage information to a filter based on the phase difference information;
the filter, configured to perform a filtering process on the voltage information to generate a voltage-controlled delay line control signal; and
a voltage-controlled delay line, configured to control the fourth clock signal to pass through the voltage-controlled delay line to generate the fifth clock signal, and the voltage-controlled delay line results in a variable phase difference between the fifth clock signal and the fourth clock signal, and the variable phase difference is under the control of the voltage-controlled delay line control signal.
6. The TOF sensor of claim 4 , wherein the delay locked loop comprises:
a phase detector, configured to generate phase difference information between one of the plurality of sixth clock signals and the fourth clock signal;
an accumulator, configured to accumulate the phase difference information to generate accumulated phase information to a filter;
the filter, configured to perform a filtering process on the accumulated phase information to generate a digital delay line control signal; and
a digital delay line, configured to control the fourth clock signal to pass through the digital delay line to generate the fifth clock signal, and the digital delay line results in a variable phase difference between the fifth clock signal and the fourth clock signal, and the variable phase difference is under the control of the digital delay line control signal.
7. The TOF sensor of claim 1 , wherein the TOE sensor further comprises:
a depth determination unit, configured to obtain a depth information based on the sampling result.
8. A time-of-flight (TOF) distance measuring system, wherein the TOF distance measuring system comprises a TOE sensor and a light-emitting module, wherein the light-emitting module is controlled by the TOF sensor to intermittently transmit a light pulse, and the light pulse is reflected by a target to generate a reflected light pulse, the TOF sensor comprises:
a clock signal generation circuit, configured to generate a first clock signal and a second clock signal, wherein the first clock signal and the second clock signal have a same frequency, and there is a predetermined phase difference between the first clock signal and the second clock signal;
a transmission circuit, configured to generate a third clock signal based on the first clock signal, wherein the third clock signal is outputted to the light-emitting module, so that the light-emitting module intermittently transmit the light pulse;
a replicated transmission circuit, configured to simulate the transmission circuit, and generate a fourth clock signal based on the second clock signal, so that the phase difference between the fourth clock signal and the third clock signal is kept the same as the predetermined phase difference;
a delay locked loop, coupled to the replicated transmission circuit and one of a plurality of sixth clock signals to generate a fifth clock signal, so that the phase difference between one of the plurality of sixth clock signals and the fourth clock signal is kept at zero;
a clock tree, configured to generate the plurality of sixth clock signals based on the fifth clock signal, wherein a plurality of phases of the plurality of sixth clock signals are all the same; and
a pixel array, having a plurality of pixel columns, wherein the plurality of pixel columns perform sampling on the reflected light pulse, respectively, based on the plurality of sixth clock signals to generate a sampling result.
9. The TOF distance measuring system of claim 8 , wherein the light emitting module comprises:
a light source control path, configured to generate a light source control signal based on the third clock signal; and
a light source, configured to intermittently transmit the light pulse based on the light source control signal.
10. The distance measuring system of claim 9 , wherein a phase difference between the third clock signal and the light source control signal is zero.
11. The TOF distance measuring system of claim 8 , wherein
the light-emitting module comprises:
a light source control path, configured to generate a light source control signal based on the third clock signal;
a replicated light source control path, coupled between the replicated transmission circuit and the delay locked loop, wherein the replicated light source control path is configured to simulate the light source control path, and generate a seventh clock signal to the delay locked loop of the TOF sensor based on the fourth clock signal, so that the phase difference between the light source control signal and the seventh clock signal is kept the same as a predetermined phase difference when temperature, bias voltage, or process changes; and
a light source, configured to intermittently transmit the light se based on the light source control signal.
12. The TOF distance measuring system of claim 11 , wherein the light-emitting module is disposed at a second chip, and a layout of the light source control path is adjacent to a layout of the replicated light source control path.
13. The TOF distance measuring system of claim 11 , wherein the delay locked loop comprises:
a phase detector, configured to generate phase difference information between one of the plurality of sixth clock signals and the seventh clock signal;
a charge pump, configured to generate a voltage information to a filter based on the phase difference information;
the filter, configured to perform a filtering process on the voltage information to generate a voltage-controlled delay line control signal; and
a voltage-controlled delay line, configured to control the seventh clock signal to pass through the voltage-controlled delay line to generate the fifth clock signal, and the voltage-controlled delay line results in a variable phase difference between the fifth clock signal and the seventh clock signal, and the variable phase difference is under the control of the voltage-controlled delay line control signal.
14. The TOF distance measuring system of claim 11 , wherein the delay locked loop comprises:
a phase detector, configured to generate phase difference information between one of the plurality of sixth clock signals and the seventh clock signal;
an accumulator, configured to accumulate the phase difference information to generate accumulated phase information to a filter;
the filter, configured to perform a filtering process on the accumulated phase information to generate a digital delay line control signal; and
a digital delay line, configured to control the fourth clock signal to pass through the digital delay line to generate the fifth clock signal, and the digital delay line results in a variable phase difference between the fifth clock signal and the seventh clock signal, and the variable phase difference is under the control of the digital delay line control signal.
15. The TOF distance measuring system of claim 8 , wherein the clock tree comprises a plurality of paths, wherein the plurality of paths respectively include a start terminal and an end terminal, the plurality of start terminals are co-located and configured to receive the fifth clock signal, the plurality of end terminal are respectively coupled to the plurality of pixel columns, so that the fifth clock signal, starting from the source, becomes a plurality of sixth clock signals to the plurality of pixel columns via the plurality of paths, and a signal transmission distance of each of the plurality of paths matched to each other from the start terminal to the end terminal, so that phase differences between the plurality of sixth clock signals are kept at zero when temperature, bias voltage, or process changes.
16. The TOF distance measuring system of claim 8 , wherein the TOF sensor is disposed at a first chip, and a layout of the transmission circuit is adjacent to a layout of the replicated transmission circuit.
17. The TOF distance measuring system of claim 8 , wherein the delay locked loop generates the fifth clock signal based the fourth clock signal and on one of the plurality of sixth clock signals.
18. The TOF distance measuring system of claim 17 , wherein the delay locked loop comprises:
a phase detector, configured to generate phase difference information between one of the plurality of sixth clock signals and the fourth clock signal;
a charge pump, configured to generate a voltage information to a fitter based on the phase difference information;
the filter, configured to perform a filtering process on the voltage information to generate a voltage-controlled delay line control signal; and
a voltage-controlled delay line, configured to control the fourth clock signal to pass through the voltage-controlled delay line to generate the fifth clock signal, and the voltage-controlled delay line results in a variable phase difference between the fifth clock signal and the fourth clock signal, and the variable phase difference is under the control of the voltage-controlled delay line control signal.
19. The TOF distance measuring system of claim 17 , wherein t delay locked loop comprises:
a phase detector, configured to generate phase difference information between one of the plurality of sixth clock signals and the fourth clock signal;
an accumulator, configured to accumulate the phase difference information to generate accumulated phase information to a filter;
the filter, configured to perform a filtering process on the accumulated phase information to generate a digital delay line control signal; and
a digital delay line, configured to control the fourth clock signal to pass through the digital delay line to generate the fifth clock signal, and the digital delay line results in a variable phase difference between the fifth clock signal and the fourth clock signal, and the variable phase difference is under the control of the digital delay line control signal.
20. An electronic device, comprising:
a TOF distance measuring system according to claim 8 ; and
a processor, coupled to the TOF distance measuring system.