CN106330105A - High-linearity dynamic range photoelectric sensor applied to blood oxygen detection - Google Patents

Abstract

The invention relates to a high-linearity dynamic range photoelectric sensor applied to blood oxygen detection. The photoelectric sensor comprises a differential operational amplifier A1, a differential operational amplifier Aau, a photoelectric diode array PD, a current mirror and a pulse frequency modulator PFM. The current mirror comprises an NMOS transistor M1, an NMOS transistor M2, an NMOS transistor M3 and an NMOS transistor M4. According to the photoelectric sensor, the technology of carrying out zero offset on the photoelectric diodes and adjusting offset voltages of the amplifiers to approach 0 through an amplifier monitoring mechanism is provided, the demand for a high-linearity dynamic range can be satisfied only by employing the single photoelectric diode, the area of a photoelectric sensor chip is greatly reduced, the cost is saved, the performance is clearly improved, and the photoelectric sensor is applicable to a high-precision blood oxygen detector system.

Description

It is applied to the High Linear dynamic range photoelectric sensor of blood oxygen detection

Technical field

The invention belongs to IC design field, a kind of dynamic model of High Linear being applied to the detection of blood oxygen Enclose photoelectric sensor.

Background technology

The photoelectric sensor with High Linear dynamic range is the important composition parts of modern sensor-based system.Such as, application Photoelectric sensor in BOLD contrast, it is necessary to have high dynamic linear to respond the light of wavelength 660nm and 940nm.For high accuracy Blood oxygen concentration detector require more than 100dB opto-electronic conversion linear dynamic range.Cost-effective angle, producers are partial to use Single photodiode realizes optical sensor.But be but difficulty with when HDR expands under low-light conditions, because of Being difficult to control to for dark current in single photodiode, impact is linear.Existing routine techniques is with two photodiodes, comes Realize the light intensity frequency converter of a High Linear scope.One photodiode receives illumination, and another photodiode is then Cover with top-level metallic and only produce dark current, by current mirror, dark current is produced electric current from photosensitive photodiode Deducting, the range of linearity of photoelectric sensor can expand to low light intensity district.But the property that photoelectric sensor is under Low light intensity Photodiode matching degree and the restriction of current mirror performance can be nevertheless suffered from, especially exist when the reversed bias voltage on photodiode Time more than hundreds of millivolt, photodiode dark current at high temperature will significantly raise.Therefore, many industry products are high in low illumination Perform poor when working under the conditions of temperature.One photodiode of many uses also can dramatically increase chip area and cost, because light The area of electric diode is often several times as much as other modules, also can introduce more thermal noise.HDR can also use and adopt more Sample technology realizes, but can sacrifice the linearity.

Summary of the invention

In view of this, it is an object of the invention to provide a kind of High Linear dynamic range photoelectric transfer being applied to the detection of blood oxygen Sensor,

It is an object of the invention to be achieved through the following technical solutions, a kind of High Linear being applied to the detection of blood oxygen is dynamic Scope photoelectric sensor, including differential operational amplifier A₁, differential operational amplifier A_au, photodiode array PD, current mirror With pulse frequency modulator PFM；Described current mirror includes NMOS tube M1, NMOS tube M2, NMOS tube M3 and NMOS tube M4, described The drain electrode of NMOS tube M1 and the drain electrode of NMOS tube M2 meet power vd D, and the grid of NMOS tube M1 is connected with the grid of NMOS tube M2, The source electrode of NMOS tube M1 respectively with the grid of NMOS tube M1, the drain electrode of NMOS tube M4, differential operational amplifier A_auForward input End connects, the source electrode of described NMOS tube M2 respectively with drain electrode, the differential operational amplifier A of NMOS tube M3_auReverse input end even Connect, differential operational amplifier A_auOutfan be connected with the grid of NMOS tube M3, the source electrode of NMOS tube and pulse frequency modulator PFM connects, the grid of NMOS tube M4 and differential operational amplifier A₁Outfan connect, differential operational amplifier A₁Forward defeated Enter and hold ground connection, differential operational amplifier A₁Reverse input end be connected with the source electrode of NMOS tube M4, the source electrode of NMOS tube M4 is through light Electric diode array PD ground connection；Described differential operational amplifier A₁Outfan through load capacitance C_CGround connection.

Further, described differential operational amplifier A_auIncluding first order differential amplifier circuit, second level common source amplifying circuit, Miller-compensated electric capacity C_mWith NMOS tube M_r, described first order differential amplifier circuit includes NMOS tube M5～NMOS tube M11, described Two pole common source amplifying circuits include NMOS tube M_tipWith NMOS tube M_tin, the drain electrode of NMOS tube M5 and the drain electrode of NMOS tube M6 respectively with Power vd D connect, the grid of NMOS tube M5 is connected with the grid of NMOS tube M6, the source electrode of NMOS tube M5 respectively with NMOS tube M6 Grid, the drain electrode of NMOS tube M7 connect, the source electrode of NMOS tube M6 respectively with the grid of NMOS tube M11, the drain electrode of NMOS tube M8, NMOS tube M_rDrain electrode connect, the source electrode of NMOS tube M7 is connected with the drain electrode of NMOS tube M9 after being connected with the source electrode of NMOS tube M8, The source ground of NMOS tube M9, described NMOS tube M_rSource electrode through miller-compensated electric capacity C_mRespectively with the drain electrode of NMOS tube M10, The source electrode of NMOS tube M11, the grid of NMOS tube M9 is connected with the grid of NMOS tube M10, described NMOS tube M_rGrid and NMOS Pipe M_tipSource electrode connect, NMOS tube M_tipGrid respectively with NMOS tube M_tinDrain electrode, grid connect, NMOS tube M_tipSource electrode Ground connection, the source electrode of NMOS tube M9, the source electrode ground connection respectively of NMOS tube M10, the drain electrode of NMOS tube M11 is connected with power vd D, NMOS The grid of pipe M7 and the grid of NMOS tube M8 connect input signal, NMOS tube M_tipDrain electrode meet power vd D.

Further, described differential operational amplifier A₁Including PMOS input difference to structure and collapsible tube-in-tube structure, institute State PMOS input difference and structure is included PMOS M_r1, PMOS M_r2With PMOS M_r11, described collapsible tube-in-tube structure includes PMOS M_r3, PMOS M_r4, PMOS M_r7, PMOS M_r8, PMOS M_r11, NMOS tube M_r5, NMOS tube M_r6, NMOS tube M_r9With NMOS tube M_r10, described PMOS M_r11Source electrode be connected with power vd D, PMOS M_r11Drain electrode respectively with PMOS M_r1Source Pole, PMOS M_r2Source electrode connect；Described PMOS M_r7Source electrode, PMOS M_r8Source electrode meet power vd D respectively, described PMOS M_r7Drain electrode and PMOS M_r3Source electrode connect, PMOS M_r3Drain electrode and NMOS tube M_r5Drain electrode connect, NMOS tube M_r5Source electrode and NMOS tube M_r9Drain electrode connect, NMOS tube M_r9Source ground, described PMOS M_r8Drain electrode and PMOS M_r4Source electrode connect, PMOS M_r4Drain electrode and NMOS tube M_r6Drain electrode connect, NMOS tube M_r6Source electrode and NMOS tube M_r10Leakage Pole connects, NMOS tube M_r10Source ground, described PMOS M_r7Grid and PMOS M_r8Grid connect, PMOS M_r3's Grid and PMOS M_r4Grid connect, NMOS tube M_r5Grid and NMOS tube M_r6Grid connect, NMOS tube M_r9Grid with NMOS tube M_r10Grid connect, PMOS M_r7Grid and PMOS M_r3Drain electrode connect, described PMOS M_r1Drain electrode with PMOS M_r9Drain electrode connect, PMOS M_r2Drain electrode and NMOS tube M_r10Drain electrode connect, described PMOS M_r1Grid connect Ground, described PMOS M_r2Grid be connected with input signal Vn, described PMOS M_r11Grid and input signal V_bpConnect.

Further, described optical sensor also includes differential operational amplifier A₁Mirror image amplifier A_r1, described mirror image amplifies Device A_r1Outfan with fortune differential operational amplifier A_auPositive input connect, differential operational amplifier A_auOutput controls letter Number V_b1Regulate operational amplifier A₁Input offset voltage.

Further, described differential operational amplifier A_auOutfan be connected to mirror image amplifier A_r1, make operational amplifier A₁ Output voltage stabilization at VDD/2.

Further, described pulse frequency modulator PFM includes charging capacitor C_i, NMOS tube discharge switch SW, constant time lag Circuit, comparator A_au1And d type flip flop, described d type flip flop uses the connection of 2 frequency dividings, described comparator A_au1Reverse input end It is connected with the source electrode of NMOS tube M3, one end of charging capacitor Ci, the drain electrode of NMOS tube discharge switch SW respectively, charging capacitor Ci's The other end, source electrode ground connection, the comparator A respectively of NMOS tube discharge switch SW_au1Outfan be connected with constant time lag circuit, The grid of NMOS tube discharge switch SW is connected with the outfan of constant time lag circuit, and the outfan of constant time lag circuit triggers with D Device connects.

Owing to using above technical scheme, the invention have the advantages that

1, a photodiode is employed for the present invention relatively conventional photoelectric sensor less, a multiplex amplifier mirror Image forming control circuit controls amplifier input offset voltage, and amplifier mirror image control circuit is little compared with area for photodiode Much, chip area and production cost it are greatly saved.

2, the present invention is that the angle of suppression dark current improves photoelectric sensor in low illumination from allowing photodiode zero partially Performance under hot conditions, the performance substantially increasing the linear dynamic range of photoelectric sensor, relatively conventional photoelectric sensor has The lifting of essence.

Accompanying drawing explanation

In order to make the object, technical solutions and advantages of the present invention clearer, below in conjunction with accompanying drawing the present invention made into The detailed description of one step, wherein:

Fig. 1 is photodiode dark current and the relation of reversed bias voltage under different temperatures；

Fig. 2 is Electro-Optic Sensor System framework；

Fig. 3 is differential operational amplifier A_auStructure；

Fig. 4 is differential operational amplifier A₁Structure；

Fig. 5 is mirror image amplifier A_r1Monitoring structure figure；

Fig. 6 is pulse frequency modulator structure chart.

Detailed description of the invention

Below in conjunction with accompanying drawing, the preferred embodiments of the present invention are described in detail.

The dark current that as figure 1 shows the photodiode in P type substrate N well spends the variations in temperature model to 75 degree-25 Along with the change situation of photodiode reversed bias voltage, when as can be seen from the figure reversed bias voltage is not 0, photodiode under enclosing Change along with temperature is doubled and redoubled by dark current.But all I V characteristic curves all will be intersected in the point that reversed bias voltage is 0, That is, when photodiode reversed bias voltage is 0, photodiode dark current is the least and little with variations in temperature.This is will Photodiode dark current controls to minimum and do not vary with temperature and provide possibility.The photosensor structure of the present invention also can Photodiode reversed bias voltage on sheet is controlled to 0.

If Fig. 2 is photoelectric sensor framework proposed by the invention, it includes two differential operational amplifier A₁,A_au；One Individual photodiode array PD, a current mirror and a pulse frequency modulator.

Described current mirror includes NMOS tube M1, NMOS tube M2, NMOS tube M3 and NMOS tube M4, the drain electrode of described NMOS tube M1 Drain electrode with NMOS tube M2 meets power vd D, and the grid of NMOS tube M1 is connected with the grid of NMOS tube M2, and the source electrode of NMOS tube M1 divides Not and the grid of NMOS tube M1, the drain electrode of NMOS tube M4, differential operational amplifier A_auPositive input connect, described NMOS tube The source electrode of M2 respectively with drain electrode, the differential operational amplifier A of NMOS tube M3_auReverse input end connect, differential operational amplifier A_auOutfan be connected with the grid of NMOS tube M3, the source electrode of NMOS tube is connected with pulse frequency modulator PFM, NMOS tube M4 Grid and differential operational amplifier A₁Outfan connect, differential operational amplifier A₁Positive input ground connection, calculus of differences is put Big device A₁Reverse input end be connected with the source electrode of NMOS tube M4, the source electrode of NMOS tube M4 is through photodiode array PD ground connection； Described differential operational amplifier A₁Outfan through load capacitance C_CGround connection.

Differential operational amplifier A₁It is used for regulating NMOS tube M₄V_nTerminal voltage, simultaneously differential operational amplifier A₁And NMOS Pipe M₄, differential operational amplifier A_auWith NMOS tube M₃Constitute gain bootstrap structure, improve NMOS tube M₄With NMOS tube M₃Drain terminal Depending on entering resistance, allow current mirror closer to ideal.

Differential operational amplifier A_auStructure as it is shown on figure 3, include that first order differential amplification and second level common source amplify,

Described differential operational amplifier A_auMend including first order differential amplifier circuit, second level common source amplifying circuit, Miller Repay electric capacity C_mWith NMOS tube M_r, described first order differential amplifier circuit includes NMOS tube M5～NMOS tube M11, described second the most common Source amplifying circuit includes NMOS tube M_tipWith NMOS tube M_tin, the drain electrode of NMOS tube M5 and the drain electrode of NMOS tube M6 respectively with power supply VDD connects, and the grid of NMOS tube M5 is connected with the grid of NMOS tube M6, the source electrode of NMOS tube M5 respectively with the grid of NMOS tube M6 Pole, the drain electrode of NMOS tube M7 connect, the source electrode of NMOS tube M6 respectively with the grid of NMOS tube M11, the drain electrode of NMOS tube M8, NMOS Pipe M_rDrain electrode connect, the source electrode of NMOS tube M7 is connected with the drain electrode of NMOS tube M9 after being connected with the source electrode of NMOS tube M8, NMOS The source ground of pipe M9, described NMOS tube M_rSource electrode through miller-compensated electric capacity C_mRespectively with drain electrode, the NMOS tube of NMOS tube M10 The source electrode of M11, the grid of NMOS tube M9 is connected with the grid of NMOS tube M10, described NMOS tube M_rGrid and NMOS tube M_tip's Source electrode connects, NMOS tube M_tipGrid respectively with NMOS tube M_tinDrain electrode, grid connect, NMOS tube M_tipSource ground, The source electrode of NMOS tube M9, the source electrode ground connection respectively of NMOS tube M10, the drain electrode of NMOS tube M11 is connected with power vd D, NMOS tube M7 The grid of grid and NMOS tube M8 connect input signal, NMOS tube M_tipDrain electrode meet power vd D.

The differential operational amplifier of the present invention adds miller-compensated electric capacity C_mWith zero-regulator resistor M_rSeparate for limit, surely Determining amplifier, this amplifier has the open-loop gain of 70dB.According to the circuit structure of Fig. 2, can reverse-biased by photodiode PD Voltmeter is shown as expression formula (1), wherein V_OSIt is differential operational amplifier A₁Input offset voltage, I_phFlow through for photodiode Electric current, V_OIt is A₁Output voltage, V_nIt is the reversed bias voltage of photodiode, and K_n=μ_nC_OX(W/L)_M4.Because V_n<<V_th4, V_nExpression formula (2) can be further expressed as

$V_n=\frac{V_o}{A_1}+V_{os}=\frac{V_n+\sqrt{2I_{ph}/K_n}+V_{th4}}{A_1}+V_{os}---\left(1\right)$

$V_n\&ap;\frac{\sqrt{2I_{ph}/K_n}+V_{th4}}{A_1}+V_{os}---\left(2\right)$

From expression formula (2) it can be seen that V_nIncluding 2 two, in order to allow V_nLevel off to 0 have to these two all reduce, first Item is and photodiode current I_phRelevant item, in order to reduce this, will increase amplifier gain A as far as possible₁, the present invention The differential operational amplifier A used₁Structure such as Fig. 4, this structure have employed PMOS input difference to structure, and uses folding Formula tube-in-tube structure, open-loop gain is up to 90dB, it is possible to the item relevant with photodiode current is suppressed to below 0.1mV.Fig. 2 Structure in due on photodiode chip area very big, parasitic capacitance C of a pF level can be produced_P, therefore it is specifically added One load capacitance C_CTo amplifier A₁Output stage dominant pole is pushed lower frequency to keep loop stability.

Specifically, described differential operational amplifier A₁Including PMOS input difference to structure and collapsible tube-in-tube structure, institute State PMOS input difference and structure is included PMOS M_r1, PMOS M_r2With PMOS M_r11, described collapsible tube-in-tube structure includes PMOS M_r3, PMOS M_r4, PMOS M_r7, PMOS M_r8, PMOS M_r11, NMOS tube M_r5, NMOS tube M_r6, NMOS tube M_r9With NMOS tube M_r10, described PMOS M_r11Source electrode be connected with power vd D, PMOS M_r11Drain electrode respectively with PMOS M_r1Source Pole, PMOS M_r2Source electrode connect；Described PMOS M_r7Source electrode, PMOS M_r8Source electrode meet power vd D respectively, described PMOS M_r7Drain electrode and PMOS M_r3Source electrode connect, PMOS M_r3Drain electrode and NMOS tube M_r5Drain electrode connect, NMOS tube M_r5Source electrode and NMOS tube M_r9Drain electrode connect, NMOS tube M_r9Source ground, described PMOS M_r8Drain electrode and PMOS M_r4Source electrode connect, PMOS M_r4Drain electrode and NMOS tube M_r6Drain electrode connect, NMOS tube M_r6Source electrode and NMOS tube M_r10Leakage Pole connects, NMOS tube M_r10Source ground, described PMOS M_r7Grid and PMOS M_r8Grid connect, PMOS M_r3's Grid and PMOS M_r4Grid connect, NMOS tube M_r5Grid and NMOS tube M_r6Grid connect, NMOS tube M_r9Grid with NMOS tube M_r10Grid connect, PMOS M_r7Grid and PMOS M_r3Drain electrode connect, described PMOS M_r1Drain electrode with PMOS M_r9Drain electrode connect, PMOS M_r2Drain electrode and NMOS tube M_r10Drain electrode connect, described PMOS M_r1Grid connect Ground, described PMOS M_r2Grid be connected with input signal Vn, described PMOS M_r11Grid and input signal V_bpConnect.

Also having one in expression formula (2) is the item unrelated with photodiode current, i.e. differential operational amplifier A₁Defeated Enter offset voltage V_OS, how to produce unrelated with PVT and that amplitude is less than a 1mV input offset voltage (the least voltage Within photodiode dark current can being limited in 5pA) it is key and the difficult point of the present invention.In order to realize that calculus of differences is put Big device A₁The monitoring of input offset voltage, we used a differential operational amplifier A₁Mirror image amplifier A_r1Such as Fig. 5, it DC control signal V can be automatically generated_b1Regulate differential operational amplifier A₁Input offset voltage.This structure has two Technical essential, first ground end has all been received in PMOS Differential Input two ends by it.So when being left intact, we will be Outfan obtains mirror image amplifier A_r1Input offset voltage, if but now according to Fig. 5, introduce one at amplifier out Negative-feedback circuit, feedback signal V_b1It is used for controlling PMOS M_r3With PMOS M_r4Grid, the negative feedback being thusly-formed can be by Amplifier output voltage OUT is stable at VDD/2.So mirror image amplifier A it is achieved that_r1Input offset voltage zeroing, If we are by control signal V_b1Act on differential operational amplifier A₁Identical place can be achieved with differential operational amplifier A₁Input offset voltage zeroing.Although this loop DC gain is the highest, but it is easy to keep stable, because this loop is simply One DC control signal is provided, can be operated in extremely low bandwidth range, thus be easy to that non-dominant pole is shifted onto unit and increase Loop stability is kept beyond benefit bandwidth.Mirror image amplifier A_r1The input offset voltage with temperature and time drift can be compensated, If mirror image amplifier A in theory_r1With differential operational amplifier A₁Domain coupling good, then differential operational amplifier A₁'s Input offset voltage can significantly reduce.In order to simplify the loop stability analysis of multi-level feedback, by Fig. 5, calculus of differences is amplified Device A_auNegative terminal fix the level receiving VDD/2.So total remaining offset voltage V_os-resExpression formula can be expressed as (3) (V in formula_DDFor supply voltage, V_{th_M4}For NMOS tube M₄Pipe threshold voltage, V_OSAnd V_{OS_ra}It is respectively A₁And A_r1Input imbalance Voltage)

$V_{os\_res}=\frac{V_{DD}-2V_{th\_M4}}{2A_1}+(V_{os}-V_{os\_ra})---\left(3\right)$

The structure of pulse frequency modulator as shown in Figure 6, wherein A_au1It is the comparator of a high-gain, C_iFor charged electrical Holding, SW is NMOS tube discharge switch, and delay is the time delay that constant time lag circuit produces 150ns, and d type flip flop below uses 2 points The connection of frequency ensure that manipulator output signal dutycycle is fixed as 50%.Specifically, described pulse frequency modulator PFM includes Charging capacitor C_i, NMOS tube discharge switch SW, constant time lag circuit, comparator A_au1And d type flip flop, described d type flip flop uses 2 The connection of frequency dividing, described comparator A_au1Reverse input end respectively with the source electrode of NMOS tube M3, one end of charging capacitor Ci, The drain electrode of NMOS tube discharge switch SW connects, the other end of charging capacitor Ci, the source electrode ground connection respectively of NMOS tube discharge switch SW, Comparator A_au1Outfan be connected with constant time lag circuit, the grid of NMOS tube discharge switch SW and constant time lag circuit Outfan connects, and the outfan of constant time lag circuit is connected with d type flip flop.

During work, current mirror the image current I obtained_pfmFor C_iCharging, when reaching comparator thresholding V_bgrTime, will produce Control signal Time delay circuit produces fixing reset pulse, and reset pulse will open NMOS tube discharge switch SW, will charging Electric capacity C_iThe electric charge release of upper accumulation.If image current I_pfmFixing, then can produce the pulse reset signal of fixed cycle, warp After crossing d type flip flop two divided-frequency, produce the output signal of dutycycle 50%, and electric current I_pfmThe biggest, the output signal cycle of generation Also can be the biggest, so it is achieved that pulse frequency modulated.

The present invention is directed to traditional photoelectric sensor product, dynamic range is the highest (to be called for short technique-power supply-temperature " PVT ") sensitive, particularly under the conditions of low illumination and high-temperature, performance significant degradation, though using double photodiode design So performance increases, but significantly increases cost, introduces more noise, and creative proposes by photodiode zero partially, And regulate, by amplifier monitors mechanism, the technology that offset voltage of amplifier is close to 0, it is achieved that only with single on chip Photodiode just can meet the demand of high dynamic linear response range, substantially reduces the area of photoelectric sensor chip, saves Cost, performance also significantly improves simultaneously, is suitable among high-precision blood oxygen detection system.

Finally illustrate, preferred embodiment above only in order to technical scheme to be described and unrestricted, although logical Cross above preferred embodiment the present invention to be described in detail, it is to be understood by those skilled in the art that can be In form and it is made various change, without departing from claims of the present invention limited range in details.

Claims (6)

1. the High Linear dynamic range photoelectric sensor being applied to the detection of blood oxygen, it is characterised in that: include that calculus of differences is put Big device A₁, differential operational amplifier A_au, photodiode array PD, current mirror and pulse frequency modulator PFM；Described current mirror Including NMOS tube M1, NMOS tube M2, NMOS tube M3 and NMOS tube M4, the drain electrode of described NMOS tube M1 connects with the drain electrode of NMOS tube M2 Power vd D, the grid of NMOS tube M1 is connected with the grid of NMOS tube M2, the source electrode of NMOS tube M1 respectively with the grid of NMOS tube M1 Pole, the drain electrode of NMOS tube M4, differential operational amplifier A_auPositive input connect, the source electrode of described NMOS tube M2 respectively with The drain electrode of NMOS tube M3, differential operational amplifier A_auReverse input end connect, differential operational amplifier A_auOutfan with The grid of NMOS tube M3 connects, and the source electrode of NMOS tube is connected with pulse frequency modulator PFM, and the grid of NMOS tube M4 is transported with difference Calculate amplifier A₁Outfan connect, differential operational amplifier A₁Positive input ground connection, differential operational amplifier A₁Reverse Input is connected with the source electrode of NMOS tube M4, and the source electrode of NMOS tube M4 is through photodiode array PD ground connection；Described calculus of differences Amplifier A₁Outfan through load capacitance C_CGround connection.

A kind of High Linear dynamic range photoelectric sensor being applied to the detection of blood oxygen the most according to claim 1, its feature It is: described differential operational amplifier A_auIncluding first order differential amplifier circuit, second level common source amplifying circuit, miller-compensated electricity Hold C_mWith NMOS tube M_r, described first order differential amplifier circuit includes that NMOS tube M5～NMOS tube M11, described second pole common source are put Big circuit includes NMOS tube M_tipWith NMOS tube M_tin, the drain electrode of NMOS tube M5 and the drain electrode of NMOS tube M6 are respectively with power vd D even Connecing, the grid of NMOS tube M5 is connected with the grid of NMOS tube M6, the source electrode of NMOS tube M5 respectively with grid, the NMOS of NMOS tube M6 The drain electrode of pipe M7 connects, the source electrode of NMOS tube M6 respectively with the grid of NMOS tube M11, the drain electrode of NMOS tube M8, NMOS tube M_r's Drain electrode connects, and the source electrode of NMOS tube M7 is connected with the drain electrode of NMOS tube M9 after being connected with the source electrode of NMOS tube M8, NMOS tube M9 Source ground, described NMOS tube M_rSource electrode through miller-compensated electric capacity C_mRespectively with drain electrode, the source of NMOS tube M11 of NMOS tube M10 Pole, the grid of NMOS tube M9 is connected with the grid of NMOS tube M10, described NMOS tube M_rGrid and NMOS tube M_tipSource electrode even Connect, NMOS tube M_tipGrid respectively with NMOS tube M_tinDrain electrode, grid connect, NMOS tube M_tipSource ground, NMOS tube M9 Source electrode, the source electrode respectively ground connection of NMOS tube M10, the drain electrode of NMOS tube M11 is connected with power vd D, the grid of NMOS tube M7 and The grid of NMOS tube M8 connects input signal, NMOS tube M_tipDrain electrode meet power vd D.

A kind of High Linear dynamic range photoelectric sensor being applied to the detection of blood oxygen the most according to claim 1, its feature It is: described differential operational amplifier A₁Including PMOS input difference, structure and collapsible tube-in-tube structure, described PMOS are inputted Differential pair structure includes PMOS M_r1, PMOS M_r2With PMOS M_r11, described collapsible tube-in-tube structure includes PMOS M_r3、 PMOS M_r4, PMOS M_r7, PMOS M_r8, PMOS M_r11, NMOS tube M_r5, NMOS tube M_r6, NMOS tube M_r9With NMOS tube M_r10, Described PMOS M_r11Source electrode be connected with power vd D, PMOS M_r11Drain electrode respectively with PMOS M_r1Source electrode, PMOS M_r2Source electrode connect；Described PMOS M_r7Source electrode, PMOS M_r8Source electrode connect power vd D, described PMOS M respectively_r7Leakage Pole and PMOS M_r3Source electrode connect, PMOS M_r3Drain electrode and NMOS tube M_r5Drain electrode connect, NMOS tube M_r5Source electrode with NMOS tube M_r9Drain electrode connect, NMOS tube M_r9Source ground, described PMOS M_r8Drain electrode and PMOS M_r4Source electrode even Connect, PMOS M_r4Drain electrode and NMOS tube M_r6Drain electrode connect, NMOS tube M_r6Source electrode and NMOS tube M_r10Drain electrode connect, NMOS Pipe M_r10Source ground, described PMOS M_r7Grid and PMOS M_r8Grid connect, PMOS M_r3Grid and PMOS Pipe M_r4Grid connect, NMOS tube M_r5Grid and NMOS tube M_r6Grid connect, NMOS tube M_r9Grid and NMOS tube M_r10 Grid connect, PMOS M_r7Grid and PMOS M_r3Drain electrode connect, described PMOS M_r1Drain electrode and PMOS M_r9's Drain electrode connects, PMOS M_r2Drain electrode and NMOS tube M_r10Drain electrode connect, described PMOS M_r1Grounded-grid, described PMOS Pipe M_r2Grid be connected with input signal Vn, described PMOS M_r11Grid and input signal V_bpConnect.

A kind of High Linear dynamic range photoelectric sensor being applied to the detection of blood oxygen the most according to claim 1, its feature It is: described photoelectric sensor also includes differential operational amplifier A₁Mirror image amplifier A_r1, described mirror image amplifier A_r1Defeated Go out end and differential operational amplifier A_auPositive input connect, differential operational amplifier A_auOutput control signal V_b1Regulate Operational amplifier A₁Input offset voltage.

A kind of High Linear dynamic range photoelectric sensor being applied to the detection of blood oxygen the most according to claim 4, its feature It is: described differential operational amplifier A_auOutfan be connected to mirror image amplifier A_r1, make differential operational amplifier A₁Output Voltage stabilization is at VDD/2.

A kind of High Linear dynamic range photoelectric sensor being applied to the detection of blood oxygen the most according to claim 1, its feature It is: described pulse frequency modulator PFM includes charging capacitor C_i, NMOS tube discharge switch SW, constant time lag circuit, comparator A_au1And d type flip flop, described d type flip flop uses the connection of 2 frequency dividings, described comparator A_au1Reverse input end respectively with NMOS tube The source electrode of M3, one end of charging capacitor Ci, the drain electrode of NMOS tube discharge switch SW connect, the other end of charging capacitor Ci, NMOS Source electrode ground connection, the comparator A respectively of tube discharge switch SW_au1Outfan be connected with constant time lag circuit, NMOS tube electric discharge open The grid closing SW is connected with the outfan of constant time lag circuit, and the outfan of constant time lag circuit is connected with d type flip flop.