CMOS active image sensor with common pixel transistors and binning capability

Abstract

A lock in pinned photodiode photodetector includes a plurality of output ports which are sequentially enabled. Each time when the output port is enabled is considered to be a different bin of time. A specified pattern is sent, and the output bins are investigated to look for that pattern. The time when the pattern is received indicates the time of flightA CMOS active pixel image sensor includes a plurality of pinned photodiode photodetectors that use a common output transistor. In one configuration, the charge from two or more pinned photodiodes may be binned together and applied to the gate of an output transistor.

What is claimed is: 
     
       1. A method, comprising:
 accumulating photocarriers in each of a plurality of photocarrier integrators and successively enabling each of said plurality of photocarrier integrators to connect to a common photodiode, each of said photocarrier integrators connecting to said common photodiode through a respective photodiode output port, said plurality of photocarrier integrators accumulating photocarriers generated by said photodiode during different time periods from one another.   
     
     
       2. A method as in  claim 1 , wherein said enabling comprises actuating a gate that is connected between each said photocarrier integrator and said photodiode. 
     
     
       3. A method as in  claim 2 , further comprising, after said enabling, detecting a number of carriers accumulated in said photodiode during at least two of said time periods by detecting the number of photocarriers accumulated in at least two said photocarrier integrators. 
     
     
       4. A method as an  claim 2 , wherein said photodiode is a pinned photodiode, and further comprising, after said enabling, detecting a number of carriers accumulated in said pinned photodiode during at least two of said time periods by decting the number of photocarriers accumulated in at least two said photocarrier integrators. 
     
     
       5. A method as in  claim 1 , wherein there are four of said photocarrier integrators, and said successively enabling comprises using a first photocarrier integrator to accumulate photocarrier between times 0 and π/2, a second photocarrier integrator to accumulate photocarriers between times π/2 and π; a third photocarrier integrator to accumulate photocarriers between times π and 3π/2, and a fourth photocarrier integrator to accumulate photocarriers between times 3π/2 and 2π. 
     
     
       6. A method as in  claim 1 , further comprising detecting a phase shift of light received by said photodiode by detecting accumulated charge in at least two photocarrier integrators. 
     
     
       7. A method, comprising:
 generating photocarriers in a photodiode within a pixel during a plurality of time periods;   accumulating photocarriers in each of a plurality of photocarrier integrators within said pixel such that each photocarrier integrator accumulates photocarriers generated during a time period different from a time period in which other photocarrier integrators accumulate photocarriers; and   sampling said photocarriers from said photocarrier integrators;   determining a range of an object using said sampled photocarriers.   
     
     
       8. A method as in  claim 7 , further comprising controlling each of said photocarrier integrators to be connected to said photodiode during said different time period. 
     
     
       9. A method as in  claim 8 , wherein said controlling comprises enabling a gate, said gate being connected to said photodiode and to one of said photocarrier integrators. 
     
     
       10. A method as in  claim 9 , wherein there are four of said photocarrier integrators, and wherein said enabling comprises successively enabling a first photocarrier integrator to accumulate photocarriers between times 0 and π/2, a second photocarrier integrator to accumulate photocarriers between times π/2 and π; a third photocarrier integrator to accumulate photocarriers between times π and 3π/2, and a fourth photocarrier integrator to accumulate photocarriers between times 3π/2 and 2π. 
     
     
       11. A method as in  claim 7 , wherein there are four of said photocarriers integrators, and said sampling comprises sampling photo carriers which are 90 degrees out of phase with one another. 
     
     
       12. A method, comprising:
 sampling a plurality of different samples of light in a photodiode, each of said plurality of different samples being 90 degrees out of phase with one another; and   successively gating photocarriers representing each of said different samples from said photodiode through a respective output port, each output port associated with a respective photocarrier integrator, such that each photocarrier integrator accumulates a different sample than other of said photocarrier integrators.   
     
     
       13. A method as in  claim 12 , further comprising detecting a phase shift using said samples of light. 
     
     
       14. A method as in  claim 12 , wherein there are four different gates connected to said photodiode each gating a different sample. 
     
     
       15. A method as in  claim 12 , wherein there are four photocarrier integrators, and wherein said act of gating comprises successively enabling a first photocarrier integrator to accumulate photocarriers between times 0 and π/2, a second photocarrier integrator to accumulate photocarriers between times π/2 and π; a third photocarrier integrator to accumulate photocarriers between times π and 3π/2, and a fourth photocarrier integrator to accumulate photocarriers between times 3π/2 and 2π. 
     
     
       16. A method of operating a range finding sensor, the method comprising;
 providing a plurality of photodiodes, each photodiode having a first output port for switchably coupling each respective photodiode to a first photocarrier integrator in a same pixel as said photodiode and a second output port for switchably coupling each photodiode to a second photocarrier integrator in a same pixel as said photodiode;   generating first photocarriers in said photodiodes in response to light received during a first time period;   transferring said first photocarriers to respective first photocarrier integrators via said first output ports;   generating second photocarriers in said photodiodes in response to light received during a second time period; and   transferring said second photocarriers to respective second photocarrier integrators via said second output ports.   
     
     
       17. The method of  claim 16 , further comprising outputting said first photocarriers from first photocarrier integrators and outputting said second photocarriers from second photocarrier integrators. 
     
     
       18. The method of  claim 17 , wherein the act of outputting said first photocarriers comprises summing outputs of all of said first photocarrier integrators, and wherein the act of outputting said second photocarriers comprises summing outputs of all of said second photocarrier integrators. 
     
     
       19. The method of  claim 16 , further comprising counting the amount of photocarriers in said first photocarriers integrator and counting the amount of said second photocarriers in said second photocarrier integrator. 
     
     
       20. The method of  claim 19 , further comprising determining a range of an object using the results of said acts of counting. 
     
     
       21. The method of  claim 16 , wherein said act of providing a plurality of photodiodes includes providing said plurality of photodiodes within a common pixel. 
     
     
       22. The method of  claim 16 , wherein said act of transferring said first photocarriers comprises transferring said first photocarriers to respective first output drains by operating first gates connected to said photodiodes and said first output drains, and wherein said act of transferring said second photocarriers comprises transferring said second photocarriers to respective second output drains by operating second gates connected to said photodiodes and said second output drains. 
     
     
       23. The method of  claim 16 , wherein each photodiode further has a third output port for switchably coupling each photodiode to a third photocarrier integrator in a same pixel as said photodiode and a fourth output port for switchably coupling each photodiode to a fourth photocarrier integrator in a same pixel as said photodiode, and further comprising:
 generating third photocarriers in said photodiodes in response to light received during a third time period;   transferring said third photocarriers to respective third photocarrier integrators via said third output ports;   generating fourth photocarriers in said photodiodes in response to light received during a fourth time period; and   transferring said fourth photocarriers to respective fourth photocarrier integrators via said fourth output ports.   
     
     
       24. The method of  claim 23 , further comprising outputting said first photocarriers from said first photocarrier integrators, outputting said second photocarriers from said second photocarrier integrators, outputting said third photocarriers from said third photocarrier integrators, and outputting said fourth photocarriers from said fourth photocarrier integrators. 
     
     
       25. The method of  claim 24 , wherein the act of outputting said first photocarriers comprises summing outputs of all of said first photocarrier integrators, wherein the act of outputting said second photocarriers comprises summing outputs of all of said second photocarrier integrators, wherein the act of outputting said third photocarriers comprises summing outputs of all of said third photocarrier integrators, and wherein the act of outputting said fourth photocarriers comprises summing outputs of all of said fourth photocarrier integrators. 
     
     
       26. A CMOS active image sensor comprising:
 a first pinned photodiode of a first pixel for accumulating charge therein wherein the first pinned photodiode of the first pixel occupies a first row of an array of photodiodes;   a first transistor for transferring charge from the first pinned photodiode directly to a first diffusion region;   a second pinned photodiode of a second pixel for accumulating charge therein wherein the second pinned photodiode of the second pixel occupies a second row, below the first row, of the array;   a second transistor for transferring charge from the second pinned photodiode directly to the first diffusion region;   a third pinned photodiode of a third pixel for accumlating charge therein wherein the third pinned photodiode of the third pixel occupies a third row, below the second row, of the array;   a third transistor for transferring charge from the third pinned photodiode directly to a second diffusion region, separate from the first diffusion region;   a fourth pinned photodiode of a fourth pixel that accumulates charge therein wherein the fourth pinned photodiode of the fourth pixel occupies a fourth row, below the third row, of the array;   a fourth transistor that transfers charge from the fourth pinned photodiode directly to the second diffusion region;   the first diffusion region configured to apply charge to a gate of a fifth transistor coupled between a supply voltage and an output; and   the second diffusion region configured to apply charge to the gate of the fifth transistor, wherein the fifth transistor is an in-pixel buffer transistors common to the first, second, third, and fourth pixels.   
     
     
       27. The CMOS active image sensor of claim 26 wherein the first transistor and the second transistor are configured to be turned on during a same period of time during operation of the image sensor. 
     
     
       28. The CMOS active image sensor of claim 27, wherein the third transistor and the fourth transistor are configured to be turned on during a same period of time during operation of the image sensor. 
     
     
       29. The CMOS active image sensor of claim 26, wherein the first and second diffusion regions are reset via a single reset transistor. 
     
     
       30. The CMOS active image sensor of claim 29 further comprising in-pixel selection transistors. 
     
     
       31. The CMOS active image sensor of claim 26 further comprising in-pixel selection transistors.