CN100512391C - Circuit for generating reference voltage - Google Patents
Circuit for generating reference voltage Download PDFInfo
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- CN100512391C CN100512391C CNB2004100031114A CN200410003111A CN100512391C CN 100512391 C CN100512391 C CN 100512391C CN B2004100031114 A CNB2004100031114 A CN B2004100031114A CN 200410003111 A CN200410003111 A CN 200410003111A CN 100512391 C CN100512391 C CN 100512391C
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Abstract
The disclosed circuit is in use for supplying reference voltage needed by image sensor. The circuit includes difference amplifier, gain amplifier, source pole follower and clamping circuit. The difference amplifier receives and compares bias voltage and reference voltages. Based on comparing result, first voltage in output. The gain amplifier coupled to the difference amplifier is in use for receiving first voltage and outputting second voltage. The source pole follower coupled to the gain amplifier is in use for receiving second voltage and outputting reference voltage. The clamping circuit coupled to the source pole follower is in use for receiving reference voltage and confining the reference voltage lower than clamp voltage.
Description
Technical field
The present invention relates to a kind of generation circuit of reference voltage, particularly relate to a kind of generation circuit that is used for the reference voltage of image sensor (image sensor).
Background technology
The increasing all built-in camera function of electronic product, for example mobile phone, PDA(Personal Digital Assistant) and toy etc.In order to adapt to various different demands, especially at the demand of mobile device, we need the image sensor (image sensor) (image sensor) of low power consumption and high image quality.Seeing also shown in Figure 1A, is the calcspar of typical image sensor (image sensor).This typical case's image sensor comprises pel array (array of pixels) (pixel array) 110, row driver and voltage generator (row driver ﹠amp; Voltage reference) 120 pixel sampling circuit (sample ﹠amp; Holdcolumn circuit) 130, signal gain amplifier (gain stage) 140 and simulation/digital converter (analogy/digital converter) (pipeline A/D converter) 150.Row driver and voltage generator 120 provide each row to drive signal 121 and various reference voltage 122, and reference voltage VCL.Each row electrode (not shown) receives corresponding row respectively and drives signal 121 in the pel array 110, exports the pixel signal (pixel signal) 111 of each row (column) behind the pel array sensing image according to the sequential of row driving signal 121.Pixel sampling circuit 130 receives simultaneously, takes a sample (sample) and keeps (hold) each pixel signal 111 of going, and will keep wherein each pixel signal with series form (cascade) output pixel signal 131 then in regular turn.Signal gain amplifier 140 receives and carries out the plain signal of intensified image 131 backs and produces pixel signal 141.Simulation/digital converter 150 is generally pipeline simulation/digital converter, according to reference voltage 122 the pixel signal 141 of analog form is converted to the pixel signal 151 of numerical digit form, handles and utilization in order to subsequent conditioning circuit (among the figure only with control logic circuit 160 representatives).
In the image sensor reading circuit, the process that produces analog reference voltage is the main power consumption reason of image sensor reading circuit.This with CMOS field-effect transistor (CMOS) image sensor in pixel sampling circuit 130 be that example describes.Seeing also shown in Figure 1B, is the pixel sampling circuit schematic diagram of CMOS image sensor.For convenience of description, pel array 110 is only represented each pixel in the array with pixel 112.In addition, have many group sampling/holding circuits in the pixel sampling circuit 130, among the figure also with wherein one group be that representative describes.The CMOS image sensor needs pixels sampled voltage (pixel signal Value) and reset voltage (pixel reset value) usually, and promptly needs reference voltage VCL in sampling process.During pixels sampled voltage, sense control switch clamp and samp_sig conducting, and sense control switch samp_rst, cb and col_addr are opened circuit, be stored in capacitor C S1 sampling reset voltage during with pixel voltage and the formed potential difference of reference voltage VCL this moment, sense control switch clamp and samp_rst conducting, and causing sense control switch samp_sig, cb and col_addr to open circuit, be stored in capacitor C S2 with reset voltage and the formed potential difference of reference voltage VCL this moment.After finishing sampling, sense control switch clamp, samp_sig and samp_rst are opened circuit, will feel control switch cb conducting then, be during the maintenance during this.Pixel signal 111 of each row is stored in wherein one group of corresponding sampling/holding circuit respectively during keeping, and each group sampling/holding circuit is taken turns conducting sense control switch col_addr according to sequential, with series form output pixel signal to signal gain amplifier 140.
As above-mentioned pixel sampling circuit 130, wherein required reference voltage VCL is supplied with by voltage generator 120.Voltage generator 120 also provides various reference voltage to use to other circuit of image sensor, for example signal gain amplifier 140 and simulation/digital converter 150 etc. except that pixel sampling circuit 130 required reference voltages are provided simultaneously.And reference voltage must be stable fixed voltage.With reference voltage VCL is example, please continue to consult shown in Figure 1B, and as mentioned above, the right-hand member of capacitor C S2 couples reference voltage VCL during the sampling reset voltage, and the left end of capacitor C S2 then is coupled to pixel 112 to receive reset voltage.At reset voltage at the beginning of the capacitor C S2 charging time, because of the transient response of electric capacity makes the right-hand member of capacitor C S2 produce a pulse voltage.This pulse voltage will temporarily change the accurate position of reference voltage VCL, must be absorbed this pulse voltage and be adjusted reference voltage VCL once more by voltage generator 120 to make it return former accurate position.Pixel sampling circuit 130 must be waited for after former accurate position of reference voltage VCL recurrence and electric capacity are stablized and just can enter during the maintenance.Along with pel array is increasing, just need more groups of sampling/holding circuits, that is represent the load of reference voltage VCL to strengthen, cause the accurate position of reference voltage to keep difficult.For example, it is excessive that the aforementioned pulse that transient response produced by electric capacity causes reference voltage accurate position change.Existing known generating circuit from reference voltage needs the long period to wait for that it returns former accurate position for aforementioned excessive because of the reference voltage that causes in the circuit operation process accurate position change on the sequential.It more is obviously that this shortcoming heals when big at pel array, thereby causes image sensing (sampling) speed to promote.
This shows that the generation circuit of above-mentioned existing reference voltage still has defective, and demands urgently further being improved.The problem that exists for the generation circuit that solves reference voltage, relevant manufacturer there's no one who doesn't or isn't seeks solution painstakingly, but do not see always that for a long time suitable design finished by development, and common product does not have appropriate structure to address the above problem, and this obviously is the problem that the anxious desire of relevant dealer solves.
Because the defective that the generation circuit of above-mentioned existing reference voltage exists, the inventor is based on being engaged in this type of product design manufacturing abundant for many years practical experience and professional knowledge thereof, actively studied innovation, in the hope of founding a kind of generation circuit of novel reference voltage, can improve the generation circuit of general existing reference voltage, make it have more practicality.Through constantly research, design, and after studying sample and improvement repeatedly, create the present invention who has practical value finally.
Summary of the invention
The objective of the invention is to, overcome the defective that the generation circuit of existing reference voltage exists, and a kind of generation circuit of new reference voltage is provided, technical problem to be solved is to make it can supply this required reference voltage of image sensor.Utilize clamp circuit to make, can return former accurate position within a short period of time because of the reference voltage that causes in the circuit operation process accurate position change when excessive; And utilize clamp circuit, when needing big drive current, opens reference voltage current path, otherwise close this current path, make the unnecessary power consumption of unlikely generation when other mode of operation of this circuit, therefore can provide low power reference voltage, thereby be suitable for practicality more, and have the value on the industry.
Another object of the present invention is to, a kind of generation circuit of reference voltage is provided, technical problem to be solved is to make it except above-mentioned all purposes, more form ball bearing made using and produce low power reference voltage with voltage follower and clamp circuit, and it is required to supply image sensor, thereby be suitable for practicality more.
The object of the invention to solve the technical problems realizes by the following technical solutions.The generation circuit of a kind of reference voltage that proposes according to the present invention, the reference voltage that provides an image sensor required is provided, this generation circuit comprises: a difference amplifier, be used for receiving and comparing a bias voltage and this reference voltage, and export one first voltage according to comparative result; One gain amplifier is coupled to this difference amplifier, is used to receive this first voltage, and exports one second voltage; The one source pole follower is coupled to this gain amplifier, is used to receive this second voltage and exports this reference voltage to this image sensor and this difference amplifier; And a clamp circuit, be coupled to this source follower, be used to receive this reference voltage and this reference voltage is limited in below the clamping voltage.
The object of the invention to solve the technical problems also can be applied to the following technical measures to achieve further.
The generation circuit of aforesaid reference voltage, wherein said clamp circuit comprises: one first diode, the anode of this first diode are coupled to the output of source follower and receive this reference voltage; And one second diode, the anode of this second diode is coupled to the negative electrode of this first diode, and the negative electrode of this second diode is coupled to the accurate position of a ground connection.
The generation circuit of aforesaid reference voltage, wherein said clamp circuit more comprise a sense control switch, and this sense control switch is coupled between this second diode and the accurate position of this ground connection.
The generation circuit of aforesaid reference voltage, wherein said clamp circuit comprises: one the one N transistor npn npn, the first source/drain of the gate of a N transistor npn npn and a N transistor npn npn are coupled to the output of this source follower and receive this reference voltage; And one the 2nd N transistor npn npn, the first source/drain of the gate of the 2nd N transistor npn npn and the 2nd N transistor npn npn is coupled to the second source/drain of a N transistor npn npn, and second source of the 2nd N transistor npn npn/drain is coupled to the accurate position of a ground connection.
The generation circuit of aforesaid reference voltage, wherein said clamp circuit more comprise a sense control switch, and this sense control switch is coupled between the 2nd N transistor npn npn and the accurate position of this ground connection.
The generation circuit of aforesaid reference voltage, wherein said image sensor are CMOS field-effect transistor (CMOS) image sensor.
The object of the invention to solve the technical problems also realizes by the following technical solutions.The generation circuit of a kind of reference voltage that proposes according to the present invention, the reference voltage that provides an image sensor required is provided, this generation circuit comprises: a voltage follower, be used to receive a bias voltage, and export this reference voltage and give this image sensor, and the input that this reference voltage is fed back to this voltage follower; And a clamp circuit, be coupled to this voltage follower, be used to receive this reference voltage, and this reference voltage is limited in below the clamping voltage.
The object of the invention to solve the technical problems also can be applied to the following technical measures to achieve further.
The generation circuit of aforesaid reference voltage, wherein said clamp circuit comprises: one first diode, the anode of this first diode are coupled to the output of voltage follower and receive this reference voltage; And one second diode, the anode of this second diode is coupled to the negative electrode of this first diode, and the negative electrode of this second diode is coupled to the accurate position of a ground connection.
The generation circuit of aforesaid reference voltage, wherein said clamp circuit more comprise a sense control switch, and this sense control switch is coupled between this second diode and the accurate position of this ground connection.
The generation circuit of aforesaid reference voltage, wherein said clamp circuit comprises: one the one N transistor npn npn, the first source/drain of the gate of a N transistor npn npn and a N transistor npn npn are coupled to the output of this voltage follower and receive this reference voltage; And one the 2nd N transistor npn npn, the first source/drain of the gate of the 2nd N transistor npn npn and the 2nd N transistor npn npn is coupled to the second source/drain of a N transistor npn npn, and second source of the 2nd N transistor npn npn/drain is coupled to the accurate position of a ground connection.
The generation circuit of aforesaid reference voltage, wherein said clamp circuit more comprise a sense control switch, and this sense control switch is coupled between this second diode and the accurate position of this ground connection.
The generation circuit of aforesaid reference voltage, wherein said image sensor are CMOS field-effect transistor (CMOS) image sensor.
The present invention compared with prior art has tangible advantage and beneficial effect.By above technical scheme as can be known, in order to reach aforementioned goal of the invention, major technique of the present invention thes contents are as follows:
The present invention proposes a kind of generation circuit of reference voltage, and this generation circuit is that the reference voltage that provides image sensor required is provided, and the generation circuit of this reference voltage comprises difference amplifier, gain amplifier, source follower and clamp circuit.Difference amplifier receives and compares bias voltage and reference voltage, exports first voltage according to comparative result.Gain amplifier is coupled to difference amplifier, is used to receive first voltage and exports second voltage.Source follower is coupled to gain amplifier, is used to receive second voltage and output reference voltage.Clamp circuit is coupled to source follower, is used for reference voltage is limited in below the clamping voltage.
According to the generation circuit of the described reference voltage of preferred embodiment of the present invention, above-mentioned clamp circuit comprises first diode and second diode.The anode of first diode is coupled to the output of source follower and receives reference voltage.The anode of second diode is coupled to the negative electrode of first diode, and the negative electrode of second diode then is coupled to the accurate position of ground connection.
According to the generation circuit of the described reference voltage of preferred embodiment of the present invention, above-mentioned clamp circuit comprises a N transistor npn npn and the 2nd N transistor npn npn.The drain of the gate of the one N transistor npn npn and a N transistor npn npn is coupled to the output of source follower and receives this reference voltage.The drain of the gate of the 2nd N transistor npn npn and the 2nd N transistor npn npn is coupled to the source electrode of a N transistor npn npn, and the source electrode of the 2nd N transistor npn npn is coupled to the accurate position of ground connection
According to the generation circuit of the described reference voltage of preferred embodiment of the present invention, above-mentioned clamp circuit more comprises sense control switch, and this sense control switch is coupled between the 2nd N transistor npn npn and the accurate position of ground connection.
The present invention proposes a kind of generation circuit of reference voltage in addition, and this generation circuit is to be used to supply image sensor required reference voltage, and the generation circuit of this reference voltage comprises voltage follower and clamp circuit.Voltage follower receives bias voltage and reference voltage, and output reference voltage.Clamp circuit is coupled to voltage follower, is used for reference voltage is limited in below the clamping voltage.
According to the generation circuit of the described reference voltage of preferred embodiment of the present invention, above-mentioned clamp circuit comprises first diode and second diode.The anode of first diode is coupled to the output of voltage follower and receives reference voltage.The anode of second diode is coupled to the negative electrode of first diode, and the negative electrode of second diode then is coupled to the accurate position of ground connection.
According to the generation circuit of the described reference voltage of preferred embodiment of the present invention, above-mentioned clamp circuit comprises a N transistor npn npn and the 2nd N transistor npn npn.The drain of the gate of the one N transistor npn npn and a N transistor npn npn is coupled to the output of voltage follower, receives reference voltage simultaneously.The drain of the gate of the 2nd N transistor npn npn and the 2nd N transistor npn npn is coupled to the source electrode of a N transistor npn npn, and the source electrode of the 2nd N transistor npn npn then is coupled to the accurate position of ground connection.
According to the generation circuit of the described reference voltage of preferred embodiment of the present invention, above-mentioned clamp circuit more comprises sense control switch, and this sense control switch is coupled between the 2nd N transistor npn npn and the accurate position of ground connection.
Via as can be known above-mentioned, the invention relates to a kind of generation circuit of reference voltage, this generation circuit is that the reference voltage that provides image sensor required is provided, and the generation circuit of this reference voltage comprises difference amplifier, gain amplifier, source follower and clamp circuit.Difference amplifier receives and compares bias voltage and reference voltage, exports first voltage according to comparative result.Gain amplifier is coupled to difference amplifier, is used to receive first voltage and exports second voltage.Source follower is coupled to gain amplifier, is used to receive second voltage and output reference voltage.Clamp circuit is coupled to source follower, is used to receive reference voltage and reference voltage is limited in below the clamping voltage.
By technique scheme, the present invention has following advantage at least: the generation circuit of reference voltage of the present invention limits the accurate position of reference voltage because of using clamp circuit, when therefore the reference voltage that causes in the circuit operation process accurate position change is excessive, can make reference voltage return former accurate position in the shortest time.Can also when needing big drive current, open reference voltage current path voluntarily by clamp circuit, otherwise close this current path, therefore make this circuit when other mode of operation, avoid unnecessary power consumption, can provide low power reference voltage and reach purpose of power saving.
The present invention more forms ball bearing made using and produces low power reference voltage with voltage follower and clamp circuit, and it is required to supply image sensor, thereby is suitable for practicality more.
In sum, the generation circuit of the reference voltage of special construction of the present invention, have above-mentioned many advantages and practical value, and in like product, do not see have similar structural design to publish or use and really genus innovation, no matter it structurally or bigger improvement all arranged on the function, have large improvement technically, and produced handy and practical effect, and the generation circuit of more existing reference voltage has the multinomial effect of enhancement, thereby be suitable for practicality more, and have the extensive value of industry, really be a new and innovative, progressive, practical new design.
Above-mentioned explanation only is the general introduction of technical solution of the present invention, for can clearer understanding technological means of the present invention, and can be implemented according to the content of specification, below with preferred embodiment of the present invention and conjunction with figs. describe in detail as after.
Description of drawings
Figure 1A is the calcspar of typical image sensor.
Figure 1B is the pixel sampling circuit schematic diagram of CMOS image sensor.
Fig. 2 is a kind of generating circuit from reference voltage figure that illustrates according to preferred embodiment of the present invention.
Fig. 3 is a kind of reference voltage emulation sequential chart that illustrates according to preferred embodiment of the present invention.
110: pel array (array of pixels) 111: the pixel signal of row (column)
112: pixel 120: row driver and voltage generator
121: row drive signal 122, VCL, 250: reference voltage
130: pixel sampling circuit 131,141: pixel signal
140: signal gain amplifier 150: simulation/digital converter (analogy/digital converter)
151: numerical digit pixel signal 160: control logic circuit
210: difference amplifier 220: gain amplifier
230: source follower 240: clamp circuit
260: bias voltage 270: voltage follower
M1
-M4, M7:P transistor npn npn M5
-M6, M8
-The M13:N transistor npn npn
T: setting time (settle time)
Embodiment
Below in conjunction with accompanying drawing and preferred embodiment, its embodiment of generation circuit, structure, feature and the effect thereof of the reference voltage that foundation the present invention is proposed, describe in detail as after.
Seeing also shown in Figure 2ly, is a kind of generating circuit from reference voltage figure that illustrates according to preferred embodiment of the present invention.This generating circuit from reference voltage comprises voltage follower 270 and clamp circuit 240.This voltage follower 270 is used to receive bias voltage 260 and reference voltage 250, and output reference voltage 250.In present embodiment, voltage follower 270 can comprise difference amplifier 210, gain amplifier 220 and source follower 230.Difference amplifier 210 of the present invention receives and compares bias voltage 260 and reference voltage 250, according to comparative result output voltage 211.Bias voltage 260 is between 1.3 volts to 1.5 volts for example in the present embodiment.Gain amplifier 220 is coupled to difference amplifier 210, and gain amplifier 220 receives voltage 211 and output voltage 221 source follower 230 are coupled to gain amplifier 220, and source follower 230 receives voltage 221 and output reference voltage 250.Clamp circuit 240 is coupled to source follower 230, and clamp circuit 240 receives and with the high levle of predetermined clamping voltage (for example being about 1.6 volts in the present embodiment) restriction reference voltage 250.250 outputs of this reference voltage also provide the required of image sensor (image sensor), for example provide pixel sampling circuit 130 required reference voltage VCL among Figure 1A.
Above-mentioned clamp circuit 240 can apply it with reference to present embodiment, comprises N transistor npn npn M11, N transistor npn npn M12 and N transistor npn npn M13.Drain and the gate of N transistor npn npn M11 all are coupled to reference voltage 250.The drain of N transistor npn npn M12 and gate all are coupled to the source electrode of N transistor npn npn M11.The drain of N transistor npn npn M13 is coupled to the source electrode of N transistor npn npn M12, and the source electrode of N transistor npn npn M13 is coupled to the accurate position of ground connection AGND, and the gate of N transistor npn npn M13 then is coupled to enable signal enable.Present embodiment can optionally select to make clamp circuit 240 activations or forbidden energy by N transistor npn npn M13.When selecting to make clamp circuit 240 activations, clamp circuit 240 is opened current path voluntarily when reference voltage needs big drive current, otherwise closes this current path, makes this circuit avoid unnecessary power consumption when other mode of operation.N transistor npn npn M13 can replace by the switch with other form according to the present invention.Ben is that N transistor npn npn M13 can omit and make the source electrode of N transistor npn npn M12 directly be coupled to the accurate position of ground connection AGND, its result spirit also according to the invention.In addition, present embodiment is that the N transistor npn npn M11 with secondary serial connection constitutes clamp circuit with M12, diode (not shown) replacement N transistor npn npn M11 and M12 that can also the secondary serial connection.Though present embodiment is implemented clamp circuit 240 with N transistor npn npn or diode, is to be familiar with this skill person all to know in every case, still can finish clamp circuit 240 according to alternate manner, its result also belongs to the category of technical solution of the present invention.
Above-mentioned difference amplifier 210 can apply it with reference to present embodiment, comprises P transistor npn npn M1～M4 and N transistor npn npn M5～M6.The source electrode of P transistor npn npn M1 is coupled to system voltage Vdd, and the gate of transistor M1 is coupled to controlling signal vlp_amps.The source electrode of P transistor npn npn M2 is coupled to the drain of transistor M1, and the gate of transistor M2 is coupled to controlling signal pwr_en, and the drain of transistor M2 then is coupled to the source electrode of transistor M3 and the source electrode of transistor M4 simultaneously.Transistor M2 cuts off the electricity supply to save energy when being used for not using difference amplifier 210.The gate of P transistor npn npn M3 is coupled to reference voltage 250, and the gate of P transistor npn npn M4 then is coupled to bias voltage 260.Form the active formula load (active load) that NMOS current source (currentsource) then is used as difference amplifier 210 by N transistor npn npn M5 and N transistor npn npn M6.Promptly be coupled to the gate of transistor M5, the gate of transistor M6 and the drain of transistor M3 simultaneously by the drain of transistor M5, the source electrode of transistor M5 then is coupled to the accurate position of ground connection AGND.The source electrode of transistor M6 is coupled to the accurate position of ground connection AGND, and the drain of transistor M6 then is coupled to the drain of transistor M4 and draws to connect and is output as voltage 211.
Above-mentioned gain amplifier 220 can apply it with reference to present embodiment, and it comprises P transistor npn npn M7, N transistor npn npn M8, capacitor C and resistance R.The source electrode of transistor M7 is coupled to system voltage Vdd, and the gate of transistor M7 is coupled to controlling signal vlp_amps.One end of resistance R is coupled to the gate of voltage 211 and transistor M8 simultaneously, and the other end of resistance R then is coupled to an end of capacitor C.In the present embodiment, the resistance of resistance R is 5K ohm for example, and the capacitance of capacitor C is the 2p farad for example.The source electrode of transistor M8 is coupled to the accurate position of ground connection AGND, and the drain of transistor M8 then is coupled to the other end of the drain of transistor M7 and capacitor C simultaneously and draws to connect and is output as voltage 221.
Above-mentioned source follower 230 can apply it with reference to present embodiment, comprises N transistor npn npn M9 and M10.The gate of transistor M9 is coupled to voltage 221, and the drain of transistor M9 is coupled to system voltage Vdd.The gate of transistor M10 is coupled to controlling signal vln_sf, and the source electrode of transistor M10 is coupled to the accurate position of ground connection AGND, and the drain of transistor M10 then is coupled to the source electrode of transistor M9 and draws to connect and is output as reference voltage 250.
Now be example so that pixel sampling circuit 130 required reference voltage VCL to be provided among Figure 1A, with convenient explanation effect of the present invention.Fig. 3 is a kind of reference voltage emulation sequential chart that illustrates according to preferred embodiment of the present invention.Please consult Figure 1B, Fig. 2 and shown in Figure 3 simultaneously.The voltage of Fig. 3 below is respectively pixels sampled voltage and sampling reset voltage to indicating two squares among the time relation figure, and it is expressed as respectively during the pixels sampled voltage of pixel sampling circuit 130 among Figure 1B and during the sampling reset voltage.We can find during to time relation figure (or the electric current I clamp of the reference voltage VCL above Fig. 3 is to time relation figure) corresponding to the reference voltage VCL in the middle of Fig. 3 (for example be the reference voltage 250 of Fig. 2 in the present embodiment) during two for this, make reference voltage VCL produce negative pulse (negative pulse) when carrying out of the transient response of pixels sampled voltage initial stage because of capacitor C S1, transistor M10 closed and provided required electric current by transistor M9 this moment, and made the reference voltage VCL standard of keeping in the center rapidly.When the initial stage of the reset voltage of taking a sample, because of the transient response of capacitor C S2 makes reference voltage VCL produce positive pulse (positive pulse), transistor M9 closed and absorbed the electric current of positive pulse by transistor M10 this moment, and made the reference voltage VCL standard of keeping in the center.Yet because power saving considers that transistor M10 is designed to less electric current motivation value usually, make reference voltage VCL need the long period standard of just keeping in the center, therefore cause the shortcoming of existing known technology.Present embodiment promptly uses clamp circuit 240 with restriction reference voltage 250, when reference voltage VCL produces positive pulse, clamp circuit 240 i.e. the electric current (this moment transistor M13 must be conducting state) of firing current path to absorb positive pulse voluntarily, and make the reference voltage VCL standard of in time being kept in the center, therefore can solve the shortcoming of known technology.Time t represents to take place to returning stable state (referring to differ less than 1 millivolt with the original position standard) required time (settle time) from positive pulse among Fig. 3, is about 1.6 microseconds according to the analog result time t of present embodiment.Clamp circuit 240 is to use two N transistor npn npn serial connections to constitute in the present embodiment, and the voltage drop of its formation is approximately 1.6 volts, and the progression of this serial connection can be decided on demand, and its result also is the category of technical solution of the present invention.
The above, it only is preferred embodiment of the present invention, be not that the present invention is done any pro forma restriction, though the present invention discloses as above with preferred embodiment, yet be not in order to limit the present invention, any those skilled in the art, in the scope that does not break away from technical solution of the present invention, when the technology contents that can utilize above-mentioned announcement is made a little change or is modified to the equivalent embodiment of equivalent variations, in every case be the content that does not break away from technical solution of the present invention, according to technical spirit of the present invention to any simple modification that above embodiment did, equivalent variations and modification all still belong in the scope of technical solution of the present invention.
Claims (12)
1, the reference voltage that provides an image sensor required is provided a kind of generation circuit of reference voltage, it is characterized in that this generation circuit comprises:
One difference amplifier is used for receiving and comparing a bias voltage and this reference voltage, exports one first voltage according to comparative result;
One gain amplifier is coupled to this difference amplifier, is used to receive this first voltage, and exports one second voltage;
The one source pole follower is coupled to this gain amplifier, is used to receive this second voltage and exports this reference voltage to this image sensor and this difference amplifier; And
One clamp circuit is coupled to this source follower, is used to receive this reference voltage and also this reference voltage is limited in below the clamping voltage.
2, the generation circuit of reference voltage according to claim 1 is characterized in that wherein said clamp circuit comprises:
One first diode, the anode of this first diode are coupled to the output of this source follower and receive this reference voltage; And
One second diode, the anode of this second diode is coupled to the negative electrode of this first diode, and the negative electrode of this second diode is coupled to the accurate position of a ground connection.
3, the generation circuit of reference voltage according to claim 2 is characterized in that wherein said clamp circuit more comprises a sense control switch, and this sense control switch is coupled between this second diode and the accurate position of this ground connection.
4, the generation circuit of reference voltage according to claim 1 is characterized in that wherein said clamp circuit comprises:
One the one N transistor npn npn, the first source/drain of the gate of a N transistor npn npn and a N transistor npn npn are coupled to the output of this source follower and receive this reference voltage; And
One the 2nd N transistor npn npn, the first source/drain of the gate of the 2nd N transistor npn npn and the 2nd N transistor npn npn is coupled to the second source/drain of a N transistor npn npn, and second source of the 2nd N transistor npn npn/drain is coupled to the accurate position of a ground connection.
5, the generation circuit of reference voltage according to claim 4 is characterized in that wherein said clamp circuit more comprises a sense control switch, and this sense control switch is coupled between the 2nd N transistor npn npn and the accurate position of this ground connection.
6, the generation circuit of reference voltage according to claim 1 is characterized in that wherein said image sensor is a CMOS field-effect transistor image sensor.
7, the reference voltage that provides an image sensor required is provided a kind of generation circuit of reference voltage, it is characterized in that this generation circuit comprises:
One voltage follower is used to receive a bias voltage, and exports this reference voltage and give this image sensor, and the input that this reference voltage is fed back to this voltage follower; And
One clamp circuit is coupled to this voltage follower, is used to receive this reference voltage, and this reference voltage is limited in below the clamping voltage.
8, the generation circuit of reference voltage according to claim 7 is characterized in that wherein said clamp circuit comprises:
One first diode, the anode of this first diode are coupled to the output of this voltage follower and receive this reference voltage; And
One second diode, the anode of this second diode is coupled to the negative electrode of this first diode, and the negative electrode of this second diode is coupled to the accurate position of a ground connection.
9, the generation circuit of reference voltage according to claim 8 is characterized in that wherein said clamp circuit more comprises a sense control switch, and this sense control switch is coupled between this second diode and the accurate position of this ground connection.
10, the generation circuit of reference voltage according to claim 7 is characterized in that wherein said clamp circuit comprises:
One the one N transistor npn npn, the first source/drain of the gate of a N transistor npn npn and a N transistor npn npn are coupled to the output of this voltage follower and receive this reference voltage; And
One the 2nd N transistor npn npn, the first source/drain of the gate of the 2nd N transistor npn npn and the 2nd N transistor npn npn is coupled to the second source/drain of a N transistor npn npn, and second source of the 2nd N transistor npn npn/drain is coupled to the accurate position of a ground connection.
11, the generation circuit of reference voltage according to claim 10 is characterized in that wherein said clamp circuit more comprises a sense control switch, and this sense control switch is coupled between this second diode and the accurate position of this ground connection.
12, the generation circuit of reference voltage according to claim 7 is characterized in that wherein said image sensor is a CMOS field-effect transistor image sensor.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2004100031114A CN100512391C (en) | 2004-02-04 | 2004-02-04 | Circuit for generating reference voltage |
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|---|---|---|---|
| CNB2004100031114A CN100512391C (en) | 2004-02-04 | 2004-02-04 | Circuit for generating reference voltage |
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| CN100512391C true CN100512391C (en) | 2009-07-08 |
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| CNB2004100031114A Expired - Fee Related CN100512391C (en) | 2004-02-04 | 2004-02-04 | Circuit for generating reference voltage |
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| CN (1) | CN100512391C (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI502989B (en) * | 2013-09-18 | 2015-10-01 | Silicon Optronics Inc | Image sensor and adjustment method thereof |
| TWI753526B (en) * | 2019-08-16 | 2022-01-21 | 英商思睿邏輯國際半導體股份有限公司 | Voltage control |
| US11522528B2 (en) | 2019-08-16 | 2022-12-06 | Cirrus Logic, Inc. | Voltage control |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101425806B (en) * | 2007-10-31 | 2010-12-08 | 联咏科技股份有限公司 | Analog electricity saving device for electric charge allocation and method thereof |
| US9042172B2 (en) * | 2013-05-02 | 2015-05-26 | Windbond Electronics Corporation | Flash memory having dual supply operation |
| CN113496718B (en) * | 2020-04-07 | 2024-02-13 | 华邦电子股份有限公司 | Reference voltage holding circuit and sense amplifier circuit having the same |
-
2004
- 2004-02-04 CN CNB2004100031114A patent/CN100512391C/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI502989B (en) * | 2013-09-18 | 2015-10-01 | Silicon Optronics Inc | Image sensor and adjustment method thereof |
| TWI753526B (en) * | 2019-08-16 | 2022-01-21 | 英商思睿邏輯國際半導體股份有限公司 | Voltage control |
| US11522528B2 (en) | 2019-08-16 | 2022-12-06 | Cirrus Logic, Inc. | Voltage control |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1652578A (en) | 2005-08-10 |
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