CN206042184U

CN206042184U - High dynamic biCMOS image sensor and pixel thereof

Info

Publication number: CN206042184U
Application number: CN201620750285.5U
Authority: CN
Inventors: 王海英; 刘强
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-07-15
Filing date: 2016-07-15
Publication date: 2017-03-22
Anticipated expiration: 2026-07-15

Abstract

The utility model provides a high dynamic biCMOS image sensor pixel which characterized in that: change voltage circuit (I3) including optical signal detection circuit (I1), current amplification circuit (I2) and electric current, optical signal detection circuit (I1) turns into the photo -signal with the received light signal, current amplification circuit (I2) carries out the self -adaptation to the photo -signal and amplifies, and wherein the current amplification multiple is S0, S1, S2 by rear end detection module feedback control, control signal, the electric current signal conversion that the electric current will change after voltage circuit (I3) will enlarge becomes voltage signal, as the output voltage signal of pixel.

Description

A kind of high dynamic BiCMOS imageing sensor and its pixel cell

Technical field

This utility model is related to field of image sensors, more particularly to a kind of high dynamic BiCMOS imageing sensor.

Background technology

Imageing sensor is a kind of semiconductor device that optical imagery is converted into the signal of telecommunication.Imageing sensor generally may be used To be divided into charge coupled cell (CCD) and complementary metal oxide semiconductors (CMOS) (CMOS) imageing sensor.Pass compared to ccd image Sensor, makes which increasingly be subject to people's attention the advantages of cmos image sensor is because of low cost, low-power consumption, high integration, Cmos image sensor has been widely used in mobile phone camera, PC computers, videophone, photographic head, video camera, safety monitoring, car Carry the fields such as phone, toy.Cmos image sensor can be additionally used in the key areas such as military surveillance, guidance, satellite in addition.

The dynamic range of imageing sensor is defined as the ratio of maximum unsaturation signal and minimum detectable signal, Larger Dynamic model The imageing sensor for enclosing can detect the scene information in the range of wider optical signal, and the details for detecting image is more rich, move State scope is the important indicator of imageing sensor image quality.

However, many results of study show that the dynamic range of conventional CMOS image sensor is much unable to reach nature field The optical dynamic range of scape, cmos image sensor open bigger city to replace ccd image sensor in more areas , must just extend its dynamic range.

It can be seen that wanting raising cmos image sensor dynamic range must just increase maximum from dynamic range definition Unsaturation signal reduces noise, and research shows, reduces circuit noise and realizes difficulty greatly and DeGrain, general by improving Maximum unsaturation signal is realizing dynamic range expansion.Concrete grammar has potential well capacity regulating (Adjusting Well Capacity) technology, partial exposure (Local Shuttering) technology, logarithmic response (Logarithmic Response) skill Art, automatic growth control (Automatic Gain Control, AGC) technology, adpative exposure adjust (Adaptive Adjusting Exposure) technology, Conditional reset (Conditional Reset) technology.Method master the more commonly used at present If logarithmic response technology, Conditional reset technology and automatic gain control.

BiCMOS (Bipolar CMOS) is CMOS and bipolar device while the technology being integrated on same chip block, on piece It is integrated with cmos device as main element circuit, add bipolar device in special circuit module.Therefore BiCMOS circuits both had There are cmos circuit high integration, low-power consumption, bipolar circuit high speed, the advantage of big driving force can be obtained again.

High dynamic BiCMOS imageing sensor of the present utility model realizes photoelectric current amplification using BiCMOS technique.Relative to Traditional output voltage gain Self Adaptive Control, BiCMOS imageing sensors of the present utility model directly carry out adaptive to photoelectric current Should amplify, the non-linear deviation occurred in avoiding photo-signal-voltage signal transformation process well.In addition, this practicality New high dynamic BiCMOS imageing sensor realizes photoelectricity using the transistor for being operated in amplification region to the amplification of electric current Banish big, the linearity is good, and can obtain very big pixel voltage output voltage swing.

The content of the invention

Core technology of the present utility model is photoelectric current self adaptation to be amplified using bipolar transistor circuit, and it is right to realize The optical signal detecting of varying strength, so as to the dynamic range of expanded images sensor.

This utility model provides a kind of high dynamic BiCMOS image sensor pixel cells, and which includes optical signal detecting electricity Road (I1), current amplification circuit (I2) and electric current turn potential circuit (I3)；Optical signal detecting circuit (I1) is by what is received Optical signal is converted into photo-signal；Current amplification circuit (I2) carries out self adaptation amplification to photo-signal, wherein electricity By rear end detection module feedback control, control signal is S0, S1, S2 to stream amplification；The electric current turns potential circuit (I3) will Current signal after amplification is converted into voltage signal, used as the output voltage signal of pixel.

Optical signal detecting circuit (I1) includes photodiode, the first PMOS (MP1) and second PMOS (MP2), the photodiode is for being converted to current signal I0 by the optical signal for receiving, then by described first and The output of two PMOS (MP1, MP2) pipes mirror image is to the current amplification circuit (I2).

Current amplification circuit (I2) include the first transistor (Q1), transistor seconds (Q2), third transistor (Q3), 3rd PMOS pipes (MP3), the 4th PMOS (MP4), the first NMOS tube (MN1), the second NMOS tube (MN2), the 3rd NMOS tube (MN3), the first transistor (Q1), transistor seconds (Q2), third transistor (Q3) cascade are as Current amplifier；Described One NMOS tube (MN1), the second NMOS tube (MN2), the 3rd NMOS tube (MN3), are current gain controlling switch, the disconnection of switch or Closure is controlled by control signal S0, S1, S2 respectively, and high level is effective.

The electric current turns potential circuit (I3) including the 5th PMOS (MP5), the 6th PMOS (MP6) and first resistor (R1), the 5th PMOS (MP5) is mirror image to pipe, and the 6th PMOS (MP6) is the enable that the electric current turns potential circuit (I3) Switch, by row selects signal control, first resistor (R1) is for being converted into electricity by the image current Ip of the 5th PMOS (MP5) Pressure.

Preferably, amplification region can be operated in order to ensure transistor, the cascade series of transistor receives supply voltage and crystalline substance Body pipe threshold voltage is limited；3rd PMOS (MP3) forms mirror image to pipe with the 5th PMOS (MP5), by electric current It is mirrored to electric current and turns potential circuit.

Preferably, in order to overcome the channel-length modulation of metal-oxide-semiconductor, mirror image needs to be designed to ratio to the channel length of pipe It is larger；4th PMOS MP4 is used as the enable of current amplification circuit and switchs, by row selects signal control, when pixel cell not During gating, current amplification circuit does not work, so as to reduce the quiescent dissipation of pel array.

This utility model additionally provides a kind of high dynamic BiCMOS imageing sensor, and which includes above-mentioned pixel cell.

This utility model additionally provides a kind of pixel output voltage sampling for high dynamic BiCMOS imageing sensor and deposits Storing up electricity road, it is characterised in which includes operational amplifier, analog to digital conversion circuit, adaptive gain control detection circuit, numeral letter Number decoding circuit and memory module；The output O of the operational amplifier is connected with input V-, as unity gain follower, will The output voltage signal equivalent inpnt of pixel is in analog-digital conversion circuit as described；Analog-digital conversion circuit as described ADC sampled pixels are defeated Go out voltage, and be converted into digital signal, output is to adaptive gain control detection circuit；The adaptive gain control System detection circuit is changed with controlling internal state for detecting whether supplied with digital signal Din meets sets requirement, output S0, S1, S2 signal control electric current gain, the adaptive gain control detection circuit also export corresponding Count of Status signal Count With the digital signal Dout of sample voltage value, the digital signal decoding circuit is for adaptive gain control detection electricity The sample voltage value digital signal of road output is decoded, and decoded pixel output is input into the memory module, institute Memory module is stated for storing the pixel output.

This utility model realizes photoelectric current amplification using transistor to the amplification of electric current.Current gain control is main logical The cascade series for crossing NMOS tube on-off control transistor is realized.Current gain adaptive control technology can realize HDR Optical signal detecting, the optical signal larger for intensity, circuit can Automatic adjusument to low current gain, it is less for intensity Optical signal, to high current gain, so either light high light is weak, and ADC can sample suitable picture for circuit meeting Automatic adjusument Plain magnitude of voltage, then by the digital signal of pixel output voltage and current amplification factor control signal combined decoding, obtain with not With the digital signal of light signal strength equity.

High dynamic BiCMOS imageing sensor advantage of the present utility model：1st, realized using standard BiCMOS process, easily collected Into low in energy consumption；2nd, using current gain adaptive control technology, it is possible to achieve the optical signal detecting of HDR；3rd, this reality With current mirror is adopted between the new each circuit module of pixel cell, anti-external noise ability is strong；4th, picture of the present utility model Plain element circuit directly carries out self adaptation amplification to photoelectric current, and the linearity is good, and error is little, and the output voltage swing of pixel is big.

Description of the drawings

Fig. 1 is the theory diagram of this utility model high dynamic BiCMOS image sensor pixel cells.

Fig. 2 is the pixel cell schematic diagram of this utility model high dynamic BiCMOS imageing sensor embodiment.

Fig. 3 is the circuit module diagram of the pixel output voltage samples storage of this utility model imageing sensor.

Fig. 4 is the workflow diagram of this utility model high dynamic BiCMOS imageing sensor.

Fig. 5 is the state transition graph in Detect modules described in Fig. 3.

Specific embodiment

Fig. 1 is the theory diagram of this utility model high dynamic BiCMOS image sensor pixel cells.As shown in figure 1, this The pixel cell of utility model includes that optical signal detecting circuit I1, current amplification circuit I2 and electric current turn potential circuit I3.

Fig. 2 is the physical circuit figure of the pixel cell of this utility model high dynamic BiCMOS image sensor embodiment.Institute Stating optical signal detecting circuit I1 includes a photodiode and two PMOSs.First photodiode D1 one end is grounded GND, the drain electrode of the first PMOS MP1 of another termination, grid and the second PMOS MP2 grid；The source electrode of the first PMOS MP1 and The source electrode of the second PMOS MP2 meets power vd D, and the drain electrode of the second PMOS connects the base stage of the first transistor Q1.

The current amplification circuit I2 includes three transistors, three NMOS tubes and two PMOSs.The first transistor Q1 Base stage connect the drain electrode of the second PMOS MP2, the emitter stage of the first transistor Q1 connects drain electrode and second crystal of the first NMOS tube The base stage of pipe Q2, the emitter stage of transistor seconds Q2 connect the drain electrode of the second NMOS tube and the base stage of third transistor Q3, and is trimorphism The emitter stage of body pipe Q3 connects the drain electrode of the 3rd NMOS tube, and the colelctor electrode of transistor Q1, Q2, Q3 connects the drain electrode of the 3rd PMOS MP3； The source ground GND of NMOS tube MN1, MN2, MN3；The grid of the grid, drain electrode and the 5th PMOS MP5 of the 3rd PMOS MP3 Connect, the source electrode of the 3rd PMOS MP3 is connected with the drain electrode of the 4th PMOS MP4；The source electrode of the 4th PMOS MP4 connects power supply VDD, the grid of the 4th PMOS MP4 are connected with the grid of the 6th PMOS, are controlled by row selects signal SEL.

The electric current turns potential circuit I3 includes two PMOSs and a resistance, and the source electrode of the 6th PMOS MP6 connects electricity Source VDD, the drain electrode of the 6th PMOS MP6 connect the source electrode of the 5th PMOS MP5；The grid of the 5th PMOS MP5 meets the 3rd PMOS One termination row of the grid of pipe MP3, the drain electrode of the 5th PMOS MP5 and first resistor R1 selects metal-oxide-semiconductor M1, used as pixel cell Voltage output port, the other end ground connection GND of first resistor R1.

Fig. 3 is the circuit module of the pixel output voltage samples storage of this utility model high dynamic BiCMOS imageing sensor Diagram, including five submodular circuits, is operational amplifier OPA, analog to digital conversion circuit ADC, adaptive gain control inspection respectively Slowdown monitoring circuit Detect, digital signal decoding circuit Decode and memory module STORE RAM.The operational amplifier OPA's is defeated Go out O to connect with input V-, as unity gain follower, by the output voltage signal equivalent inpnt of pixel to analog to digital conversion circuit In ADC, ADC can be avoided from exporting the sampled voltage change for causing that directly connects with pixel；Analog-digital conversion circuit as described ADC samples Pixel output voltage, and digital signal is converted into, output is to adaptive gain control detection circuit；Described self adaptation increases Benefit control detection circuit Detect Main Functions are whether detection supplied with digital signal Din meets sets requirement, so as in controlling Portion's State Transferring, export S0, S1, S2 signal control electric current gain, to also export in addition corresponding Count of Status signal Count and The digital signal Dout of sample voltage value, the specific State Transferring of adaptive gain control detection circuit are as shown in Figure 5.

Fig. 4 is the workflow diagram of this utility model high dynamic BiCMOS imageing sensor.As shown in figure 4, this practicality is new The workflow of the imageing sensor of type is：Camera shutter is pressed first, pixel exposure, and each row pixel is selected in row gating control successively (not gated pixel is enabled and closed), the output voltage of respective pixel is input in analog to digital conversion circuit ADC by column bus to be located Reason, is converted into digital signal, and then whether adaptive gain control detection circuit Detect detection digital signals meet setting, if Do not meet, be transformed into NextState, and export corresponding control signal, after coincidence detection setting, decoding/storage is correct Pixel output, then capable choosing is transformed into next pixel repetitive operation, until completing depositing for all pixels output voltage values Storage.

Fig. 5 is the adaptive gain control detection circuit Detect state transition graphs.As shown in figure 5, initial state State0, gain control signal S0=1, S1=0, S2=0, now current amplification factor be A1, corresponding pixel output voltage V_Pixel=Ip × R1=A1 × I0 × R1；If the pixel output voltage for detecting meets setting, decode/to store pixel defeated Go out the digital signal of voltage；If magnitude of voltage is too little, State Transferring to State1.

The gain control signal of State1 states be S0=0, S1=1, S2=0, now current amplification factor be approximately equal to A1 × A2, corresponding pixel output voltage V_Pixel=Ip × R1=A1 × A2 × I0 × R1；Pixel output electricity is detected again now Pressure, if meeting setting, decodes/stores the digital signal of pixel output voltage；If magnitude of voltage is still too little, State Transferring is arrived State2。

The gain control signal of State2 states be S0=0, S1=0, S2=1, now current amplification factor be approximately equal to A1 × A2 × A3, corresponding pixel output voltage V_Pixel=A1 × A2 × A3 × I0 × R1, now because being last shape State, therefore no longer detect, directly by the digital signal decoding/storage of pixel output voltage value.After completing decoding storage, under row choosing One-row pixels, state machine return to S0 states, repeat this operation, until completing the storage of all pixels output voltage values.

This utility model is not limited to specific embodiment described here, being capable of base for this technical personnel of the field of engineering Various obvious changes are carried out in this utility model thought, is readjusted and is substituted without departing from protection model of the present utility model Enclose.Therefore, above example is simply described in further detail to this utility model, but this utility model is not only limited In above example, in the case where conceiving without departing from this utility model, more other Equivalent embodiments can also be included.

Claims

1. a kind of high dynamic BiCMOS image sensor pixel cells, it is characterised in that：Including optical signal detecting circuit (I1), electricity Current amplifier (I2) and electric current turn potential circuit (I3)；The optical signal for receiving is converted by optical signal detecting circuit (I1) For photo-signal；Current amplification circuit (I2) carries out self adaptation amplification, wherein current amplification factor to photo-signal By rear end detection module feedback control, control signal is S0, S1, S2；The electric current turns potential circuit (I3) by the electricity after amplification Stream signal is converted into voltage signal, used as the output voltage signal of pixel.

2. high dynamic BiCMOS image sensor pixel cells according to claim 1, it is characterised in that：The optical signal Detection circuit (I1) includes the first photodiode (D1), the first PMOS (MP1) and the second PMOS (MP2), the photoelectricity Diode for the optical signal for receiving is converted to current signal I0, then by first and second PMOS (MP1, MP2) output of pipe mirror image is to the current amplification circuit (I2).

3. high dynamic BiCMOS image sensor pixel cells according to claim 2, it is characterised in that：The electric current is put Big circuit (I2) include the first transistor (Q1), transistor seconds (Q2), third transistor (Q3), the 3rd PMOS (MP3), the Four PMOSs (MP4), the first NMOS tube (MN1), the second NMOS tube (MN2), the 3rd NMOS tube (MN3), the first transistor (Q1), transistor seconds (Q2), third transistor (Q3) cascade are as Current amplifier；First NMOS tube (MN1), second NMOS tube (MN2), the 3rd NMOS tube (MN3), be current gain controlling switch, and switch is opened or closed respectively by the control Signal S0, S1, S2 are controlled, and high level is effective.

4. high dynamic BiCMOS image sensor pixel cells according to claim 3, it is characterised in that：The electric current turns Potential circuit (I3) includes the 5th PMOS (MP5), the 6th PMOS (MP6) and first resistor (R1), the 5th PMOS (MP5) Be mirror image to pipe, the 6th PMOS (MP6) be the electric current turn potential circuit (I3) enable switch, controlled by row selects signal SEL System, first resistor (R1) is for being converted into voltage by the image current Ip of the 5th PMOS (MP5).

5. high dynamic BiCMOS image sensor pixel cells according to claim 4, it is characterised in that：First light Electric diode (D1) one end is grounded GND, the drain electrode of another termination the first PMOS (MP1), grid and the 2nd PMOS Pipe (MP2) grid；The source electrode of the source electrode of the first PMOS (MP1) and second PMOS (MP2) meets power vd D, institute The drain electrode for stating the second PMOS (MP2) connects the base stage of the first transistor (Q1).

6. high dynamic BiCMOS image sensor pixel cells according to claim 5, it is characterised in that：Described first is brilliant The base stage of body pipe (Q1) connects the drain electrode of the second PMOS (MP2), and the emitter stage of the first transistor (Q1) connects described The drain electrode of one NMOS tube (MN1) and the base stage of the transistor seconds (Q2), the emitter stage of transistor seconds (Q2) meet institute State the drain electrode of the second NMOS tube (MN2) and the base stage of the third transistor (Q3), the emitter stage of third transistor (Q3) The drain electrode of the 3rd NMOS tube (MN3) is connect, the colelctor electrode of described first, second, third transistor (Q1, Q2, Q3) connects described The drain electrode of the 3rd PMOS (MP3)；The source ground GND of described first, second, third NMOS tube (MN1, MN2, MN3)；It is described The grid of the 3rd PMOS (MP3), drain electrode are connected with the grid of the 5th PMOS (MP5), the 3rd PMOS (MP3) Source electrode connect with the drain electrode of the 4th PMOS (MP4)；The source electrode of the 4th PMOS (MP4) meets power vd D, described The grid of the 4th PMOS (MP4) is connected with the grid of the 6th PMOS (MP6), is controlled by row selects signal SEL.

7. high dynamic BiCMOS image sensor pixel cells according to claim 6, it is characterised in that：Described 6th The source electrode of PMOS (MP6) meets power vd D, and the drain electrode of the 6th PMOS (MP6) connects the source of the 5th PMOS (MP5) Pole；The grid of the 5th PMOS (MP5) connects the grid of the 3rd PMOS (MP3), the 5th PMOS (MP5) One termination row of drain electrode and the first resistor (R1) selects metal-oxide-semiconductor (M1), as the voltage output port of pixel cell, described the The other end ground connection GND of one resistance (R1).

8. high dynamic BiCMOS image sensor pixel cells according to claim 7, it is characterised in that：Described 3rd PMOS (MP3) forms mirror image to pipe with the 5th PMOS (MP5), and current mirror is turned potential circuit to electric current.

9. high dynamic BiCMOS image sensor pixel cells according to claim 8, it is characterised in that：Described 4th PMOS (MP4) is used as the enable of current amplification circuit and switchs, by row selects signal control, when pixel cell is not gated, electric current Amplifying circuit does not work.

10. a kind of high dynamic BiCMOS imageing sensor, which includes pixel cell as claimed in any one of claims 1-9 wherein.

A kind of pixel output voltage samples storage electricity of 11. high dynamic BiCMOS imageing sensors for described in claim 10 Road, it is characterised in which includes operational amplifier, analog to digital conversion circuit, adaptive gain control detection circuit, digital signal solution Code circuit and memory module；The output O of the operational amplifier is connected with input V-, as unity gain follower, by pixel Output voltage signal equivalent inpnt in analog-digital conversion circuit as described；Analog-digital conversion circuit as described ADC sampled pixels output electricity Pressure, and digital signal is converted into, output is to adaptive gain control detection circuit；The adaptive gain control inspection Slowdown monitoring circuit is used for detecting whether supplied with digital signal Din meets sets requirement, to control internal state conversion, output S0, S1, S2 Signal control electric current gain, the adaptive gain control detection circuit also export corresponding Count of Status signal Count and adopt The digital signal Dout of sample magnitude of voltage, the digital signal decoding circuit is for defeated to adaptive gain control detection circuit The sample voltage value digital signal for going out is decoded, and decoded pixel output is input into the memory module, described to deposit Storage module is used for storing the pixel output.