CN104333352B - Ramp generator and imageing sensor - Google Patents
Ramp generator and imageing sensor Download PDFInfo
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- CN104333352B CN104333352B CN201410663661.2A CN201410663661A CN104333352B CN 104333352 B CN104333352 B CN 104333352B CN 201410663661 A CN201410663661 A CN 201410663661A CN 104333352 B CN104333352 B CN 104333352B
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Abstract
A kind of ramp generator and imageing sensor, ramp generator includes: operational amplifier, first electric capacity and at least one first switching capacity unit, the first switching capacity unit includes: the first switch, second switch, the 3rd switch, the 4th switch and the second electric capacity；The negative-phase input of the first end concatenation operation amplifier of the first switch and outfan, the normal phase input end of the first end concatenation operation amplifier of second switch and the first end of the first electric capacity, second end of the 3rd switch is suitable to input the first voltage, second end of the 4th switch is suitable to input the second voltage, and the magnitude of voltage of the second voltage and the first voltage is unequal；In same first switching capacity unit, the second end of the first switch connects the second end and first end of the second electric capacity of second switch, and the first end of the 3rd switch connects the first end and second end of the second electric capacity of the 4th switch；Second end ground connection of the first electric capacity；The capacitance of the first electric capacity is more than the capacitance of the second electric capacity.
Description
Technical field
The present invention relates to electronic applications, particularly relate to a kind of ramp generator and imageing sensor.
Background technology
In the image sensor, along with the continuous expansion of pixel unit array scale, traditional chip-scale analog-digital converter
Can not meet the requirement of high frame per second, so high frame rate image sensor uses the analog-digital converter of row level, wherein single-slope
Analog-digital converter (single slope analog to digital converter, SS ADC) have only need little area and
Power consumption can be achieved with high-precision feature, is widely used in the imageing sensor of high pixel high frame per second.SS ADC needs
Wanting slope (ramp) signal as the comparative level of comparator, its precision directly influences the output accuracy of SS ADC,
So how producing a high-precision ramp signal is a very important research topic.
The generation of traditional ramp signal, a kind of method is by current steer (current steering) structure, by not
Disconnected increase flows through the electric current of fixed resistance to produce ramp signal.Another kind of method is integration (integrating) structure, uses
Fixing electric current constantly charges to fixed capacity, produces a continuous print ramp signal.Both ramp signal generator pair
In time applying with heavy load at a high speed, all there is signal and set up the problem of overlong time, thus cause precision to be extremely difficult to application and want
Ask.
Summary of the invention
The problem that the present invention solves is that existing ramp signal generator is for, time at a high speed with heavy load application, existing signal and build
The problem of vertical overlong time.
For solving the problems referred to above, the present invention provides a kind of ramp generator, including: operational amplifier, the first electricity
Holding and the first switching capacity group, described first switching capacity group includes at least one first switching capacity unit, and described first opens
Pass capacitor cell includes: the first switch, second switch, the 3rd switch, the 4th switch and the second electric capacity；
First end of described first switch connects negative-phase input and the outfan of described operational amplifier, and described second opens
The first end closed connects normal phase input end and first end of the first electric capacity of described operational amplifier, the second of described 3rd switch
End is suitable to input the first voltage, and the second end of described 4th switch is suitable to input the second voltage, described second voltage and the first electricity
The magnitude of voltage of pressure is unequal；
In same first switching capacity unit, the second end of described first switch connects the second of described second switch
End and the first end of the second electric capacity, the first end of described 3rd switch connects the first end of described 4th switch and the second electric capacity
Second end；
Second end ground connection of described first electric capacity；
The capacitance of described first electric capacity is more than the capacitance of described second electric capacity.
Optionally, described ramp generator also includes: switch control unit, and described switch control unit is suitable to defeated
Go out the first control signal, the second control signal, the 3rd control signal and the 4th control signal to need the first switching capacity of work
Unit is to start described the first switching capacity unit needing work；
Described first control signal is suitable to control the closed and disconnected of described first switch, and described second control signal is suitable to
Controlling the closed and disconnected of described second switch, described 3rd control signal is suitable to control the Guan Bi of described 3rd switch and break
Opening, described 4th control signal is suitable to control the closed and disconnected of described 4th switch；
Described second control signal is the inversion signal of described first control signal, and described 4th control signal is described
The inversion signal of three control signals, described first control signal and the 3rd control signal are with frequency in-phase signal.
Optionally, the quantity of described the first switching capacity unit needing work is multiple, and described switch control unit is suitable to
Predetermined order starts described the first switching capacity unit needing work successively.
Optionally, described predesigned order is relevant to the ramp signal slope that described ramp generator exports.
Optionally, described switch control unit is suitable to first export described second control signal and the 4th and controls signal to all
Need the first switching capacity unit of work, then be sequentially output described first control signal and the 3rd control letter by described predesigned order
Number to described the first switching capacity unit needing work.
Optionally, described first control signal and the second control signal are pulse signal, the amplitude of described pulse signal
The first terminal voltage value following described first electric capacity increases and increases.
Optionally, described ramp generator also includes second switch capacitance group, described second switch capacitance group
Including at least one second switch capacitor cell, described second switch capacitor cell includes: the 5th switch, the 6th switch, the 7th
Switch, the 8th switch and the 3rd electric capacity, the capacitance of described 3rd electric capacity is equal with the capacitance of described second electric capacity；
First end of described 5th switch connects first input end and the outfan of described operational amplifier, and the described 6th opens
The first end closed connects the second input and first end of the first electric capacity of described operational amplifier, the second of described 7th switch
End is suitable to input described first voltage, and the second end of described 8th switch is suitable to input described second voltage；
In same second switch capacitor cell, the second end of described 5th switch connects the second of described 6th switch
End and the first end of the 3rd electric capacity, the first end of described 7th switch connects the first end of described 8th switch and the 3rd electric capacity
Second end.
Optionally, described switch control unit is further adapted for exporting the 5th control signal, the 6th control signal, the 7th control letter
Number and the 8th control signal to the second switch capacitor cell needing work to start the described second switch capacitor cell needing work；
Described 5th control signal is suitable to control the closed and disconnected of described 5th switch, and described 6th control signal is suitable to
Controlling the closed and disconnected of described 6th switch, described 7th control signal is suitable to control the Guan Bi of described 7th switch and break
Opening, described 8th control signal is suitable to control the closed and disconnected of described 8th switch；
Described 5th control signal is the inversion signal of described first control signal, and described 6th control signal is described
The inversion signal of two control signals, described 7th control signal is the inversion signal of described 3rd control signal, described 8th control
Signal processed is the inversion signal of described 4th control signal.
The embodiment of the present invention also provides for a kind of imageing sensor, including: ramp generator and analog-digital converter, institute
State ramp generator and connect described analog-digital converter.
Optionally, the capacitance ratio phase of the required precision of described analog-digital converter and described first electric capacity and the second electric capacity
Close.
Compared with prior art, the ramp generator that technical scheme provides can use less etc.
Effect electric capacity carrys out discharge and recharge, reduces ramp signal and sets up the time, can meet high-precision requirement.
Accompanying drawing explanation
Fig. 1 is a structural representation of the ramp generator of the embodiment of the present invention；
Fig. 2 is the first switching capacity group structural representation of the embodiment of the present invention；
Fig. 3 is an equivalent structure schematic diagram of the ramp generator of the embodiment of the present invention；
Fig. 4 is another equivalent structure schematic diagram of the ramp generator of the embodiment of the present invention；
Fig. 5 is the waveform diagram of the ramp signal of the embodiment of the present invention；
Fig. 6 is another structural representation of the ramp generator of the embodiment of the present invention.
Detailed description of the invention
Understandable, below in conjunction with the accompanying drawings to the present invention for enabling the above-mentioned purpose of the present invention, feature and advantage to become apparent from
Specific embodiment be described in detail.
As it is shown in figure 1, the embodiment of the present invention provides a kind of ramp generator, including: operational amplifier Opamp,
First electric capacity C1 and the first switching capacity group 1.
Shown in Fig. 2, described first switching capacity group 1 includes at least one first switching capacity unit.Described first
Switching capacity unit includes: the first switch, second switch, the 3rd switch, the 4th switch and the second electric capacity C2.Described first switch
The first end connect the negative-phase input of described operational amplifier Opamp and outfan bufout, the first of described second switch
End connects normal phase input end and the first end Vramp of the first electric capacity C1 of described operational amplifier Opamp, described 3rd switch
Second end is suitable to input the first voltage, and the second end of described 4th switch is suitable to input the second voltage Voft, described second voltage
The magnitude of voltage of Voft and the magnitude of voltage of the first voltage are unequal；In same first switching capacity unit, described first switch
The second end connect the second end of described second switch and first end of the second electric capacity C2, the first end of described 3rd switch connects
First end of described 4th switch and second end of the second electric capacity C2；The second end ground connection GND of described first electric capacity C1.Described
The capacitance of one electric capacity is more than the capacitance of described second electric capacity.The magnitude of voltage of the second voltage Voft is more than the value of the first voltage
Time, the ramp signal slope of ramp generator output is more than 0；The magnitude of voltage of the second voltage Voft is less than the first voltage
During value, the ramp signal slope of ramp generator output is less than 0.In order to make it easy to understand, following example are all with first
Voltage is that the magnitude of voltage of ground voltage and the second voltage Voft illustrates more than as a example by the value of the first voltage.
In Fig. 2 as a example by 4 the first switching capacity unit.First switching capacity group 1 includes: the 1st the first switching capacity
Unit 11, the 2nd the first switching capacity unit 12, the 3rd the first switching capacity unit 13 and the 4th the first switching capacity unit
14。
1st the first switching capacity unit 11 includes: the first switch Φ 11, second switch Φ 21, the 3rd switch Φ 31, the
Four switch Φ 41 and the second electric capacity C2.2nd the first switching capacity unit 12 includes: first switch Φ 12, second switch Φ 22,
3rd switch Φ the 32, the 4th switchs Φ 42 and the second electric capacity C2.3rd the first switching capacity unit 13 includes: the first switch Φ
13, second switch Φ the 23, the 3rd switch Φ the 33, the 4th switchs Φ 43 and the second electric capacity C2.4th the first switching capacity unit 14
Including: the first switch Φ 14, second switch Φ the 24, the 3rd switch Φ the 34, the 4th switchs Φ 44 and the second electric capacity C2.
The first switch in whole first switching capacity unit, the i.e. first switch Φ 11, first switchs Φ 12, first and switchs
First end of Φ 13 and the first switch Φ 14 is all connected with negative-phase input and the operational amplifier Opamp of operational amplifier Opamp
Outfan bufout.Second switch in whole first switching capacity unit, i.e. second switch Φ 21, second switch Φ 22,
First end of second switch Φ 23 and second switch Φ 24 is all connected with normal phase input end and first electric capacity of operational amplifier Opamp
The first end Vramp of C1.The 3rd switch in whole first switching capacity unit, the i.e. the 3rd switch Φ the 31, the 3rd switch Φ 32,
Second end of the 3rd switch Φ 33 and the 3rd switch Φ 34 is adapted to ground connection GND.In whole first switching capacity unit the 4th
Switch, second end of the i.e. the 4th switch Φ the 41, the 4th switch Φ the 42, the 4th switch Φ 43 and the 4th switch Φ 44 is adapted to input
Second voltage Voft.
In each first switching capacity unit, the first switch, second switch, the 3rd switch, the 4th switch and the second electricity
The annexation held is identical, as a example by the 1st the first switching capacity unit 11: second end of the first switch Φ 11 connects the
Second end of two switch Φ 21 and first end of the second electric capacity C2, first end of the 3rd switch Φ 31 connects the 4th switch Φ's 41
First end and second end of the second electric capacity C2.
Ramp generator described in the present embodiment can also include: switch control unit.
Described switch control unit is suitable to export the first control signal, the second control signal, the 3rd control signal and the 4th
Control signal to the first switching capacity unit needing work to start described the first switching capacity unit needing work.Described first
Control signal is suitable to control the closed and disconnected of described first switch, and described second control signal is suitable to control described second switch
Closed and disconnected, described 3rd control signal is suitable to control the closed and disconnected of described 3rd switch, and the described 4th controls letter
Number be suitable to control the closed and disconnected of described 4th switch.
Wherein, described second control signal is the inversion signal of described first control signal, and described 4th control signal is
The inversion signal of described 3rd control signal, described first control signal and the 3rd control signal are with frequency in-phase signal.Therefore,
After first switching capacity unit is activated, the first switch and the 3rd switch are closed at or disconnect, second switch and the 4th switch
It is closed at or disconnects；First switch and the 3rd switch are then contrary with second switch and the 4th on off state, the i.e. first switch
Switch off with second switch and the 4th during the 3rd switch Guan Bi, second switch and the 4th when the first switch and the 3rd switches off
Switch Guan Bi.
First control signal, the second control signal, the 3rd control signal and the 4th control signal can be all pulse signal,
The pulse signal in one cycle has phase place 1 and phase place 2 two states, and the pulse signal in cycle is at phase place 1 and 2 two kinds of shapes of phase place
Constantly switch between state.Such as, during phase place 1, pulse signal is high level, and during phase place 2, pulse signal is low level.
Only include as a example by a first switching capacity unit 11 by ramp generator, when the first control signal and
Three control signals are phase place 1 state, the second control signal and the 4th control signal when being phase place 2 state, the first switch and
3rd switch closes and second switch and the 4th switches off, and the equivalent circuit of described ramp generator is as shown in Figure 3.
In this case, only to the second electric capacity C2 discharge and recharge.
When the first control signal and the 3rd control signal are phase place 2 state, the second control signal and the 4th control signal
State when being phase place 1, the first switch and the 3rd switches off and second switch and the 4th switch Guan Bi, and described ramp signal is sent out
The equivalent circuit of raw circuit is as shown in Figure 4.In this case, the first electric capacity C1 and the second electric capacity C2 is connected in series, equivalent capacity
Less than the second electric capacity C2.
By above-mentioned analysis it can be seen that no matter the present embodiment is in phase place 1 state or phase place 2 state, for discharge and recharge
Equivalent capacity is the least, and corresponding RC postpones the least, it is possible to achieve the quick foundation of signal.
According to the equivalent circuit shown in Fig. 3, total electrical charge Q1 being stored on the first electric capacity C1 and the second electric capacity C2 is:
Q1=Vramp (n) * (C2+C1) (formula 1)
Vramp (n) in formula 1 represents the magnitude of voltage of the first end Vramp of the first electric capacity C1, and C2 represents the second electric capacity C2
Capacitance, C1 represents the capacitance of the first electric capacity C1.
According to the equivalent circuit shown in Fig. 4, total electrical charge Q2 being stored on the first electric capacity C1 and the second electric capacity C2 is:
Q2=(Vramp (n+1)-Voft) * C2+Vramp (n+1) * C1 (formula 2)
Vramp (n+1) in formula 2 represents the magnitude of voltage of the first end Vramp of the first electric capacity C1, and Voft represents the second electricity
The magnitude of voltage of pressure Voft.
According to charge conservation theorem:
Q1=Q2 (formula 3)
Assume: △ Vramp=Vramp (n+1)-Vramp (n) (formula 4)
By formula 1 to formula 4 it follows that
△ Vramp represents the height of each step in ramp signal, by formula 5 it can be seen that by selected first electric capacity
C1 and the capacitance of the second electric capacity C2 and the magnitude of voltage of the second voltage Voft, it is possible to the slope of the shoulder height changes such as acquisition
Signal.This is it is to say, ramp signal has the best linearity, integral nonlinearity (Integral nonlinearity,
And differential nonlinearity (Differential nonlinearity, DNL) is smaller INL).
First electric capacity C1 can regard the electric capacity of a load comprising ramp generator as, can from being analyzed above
To find out that the first electric capacity C1 sets up the time, so the ramp generator of the present embodiment is permissible substantially without affect signal
Drive the biggest load.
The ramp generator of the present embodiment can be applied in the image sensor, is connected with analog-digital converter, institute
Stating analog-digital converter can be single slope analog-to-digital converter.When ramp generator connection mode number converter, described
The capacitance ratio of one electric capacity C1 and the second electric capacity C2 can be relevant to the required precision of described analog-digital converter.It is assumed that modulus
Transducer needs to reach the precision of 11, and accessible range of signal is 1V, then the height △ of each step in ramp signal
Vramp just approximates 0.5mV.When the magnitude of voltage of the second voltage Voft is 0.4V, the first electric capacity C1 can be obtained according to formula 5
It is 799:1 with the capacitance ratio of the second electric capacity C2.
All there is photon shot noise (photon shot noise) in imageing sensor, it can be along with the increasing of input signal
Add and increase.And the quantizing noise of analog-digital converter, do not change with input signal.So, when input signal is bigger, photon shot
Noise will be occupied an leading position, and now the performance of analog-digital converter is higher than required value, can reduce precision.On ramp signal
Performance be exactly: when input signal is bigger the slope of ramp signal can more than input signal less time ramp signal slope.
So for identical signal processing scope, the conversion time of analog-digital converter can be reduced, be preferably suitable for imageing sensor
High speed high pixel application.To this end, ramp generator can produce the ramp signal shown in Fig. 5.Oblique by shown in Fig. 5
Slope signal is divided into three intervals, and the ramp signal slope in each interval is different.
When the capacitance of the first electric capacity C1 is much larger than the capacitance of the second electric capacity C2, formula 5 can be reduced to:
From formula 6 it can be seen that realize tiltedly by changing the quantity of the second electric capacity C2 work the first switching capacity group
The change of slope signal slope.Therefore, the quantity needing the first switching capacity unit of work described in the embodiment of the present invention can be many
Individual, switch control unit is suitable to predetermined order and starts described the first switching capacity unit needing work successively.Described predetermined time
Sequence can determine according to the ramp signal slope of required output.
Still, as a example by the ramp signal shown in Fig. 5, when first is interval, ramp generator starts one first
Switching capacity unit, i.e. accesses a second electric capacity C2；When second is interval, ramp generator starts two first and opens
Close capacitor cell, i.e. access two the second electric capacity C2；When the 3rd is interval, ramp generator starts four first switches
Capacitor cell, i.e. accesses four the second electric capacity C2.
Concrete, in conjunction with Fig. 2 and Fig. 5, during t0 to the t1 moment, switch control unit exports the first control letter respectively
Number, first opening of controlling signal in the 1st the first switching capacity unit 11 of the second control signal, the 3rd control signal and the 4th
Close Φ 11, second switch Φ the 21, the 3rd switch Φ the 31, the 4th and switch Φ 41, to start the 1st the first switching capacity unit 11,
Thus access a second electric capacity C2.During t1 to the t2 moment, switch control unit again by the first control signal produced, the
Two control signals, the 3rd control signal and the output of the 4th control signal are opened to first in the 2nd the first switching capacity unit 12
Close Φ 12, second switch Φ the 22, the 3rd switch Φ the 32, the 4th and switch Φ 42, to start the 2nd the first switching capacity unit 12,
Thus add a second electric capacity C2.During t2 to the t3 moment, switch control unit again by produce the first control signal,
Second control signal, the 3rd control signal and the 4th control signal export first to the 3rd the first switching capacity unit 13
In switch Φ 13, second switch Φ the 23, the 3rd switch Φ the 33, the 4th switch Φ 43 and the 4th the first switching capacity unit 14
First switch Φ 14, second switch Φ the 24, the 3rd switch Φ the 34, the 4th switch Φ 44, to start the 3rd the first switching capacity
Unit 13 and the 4th the first switching capacity unit 14, thus add again two the second electric capacity C2.
In above process, described switch control unit can also first export described second control signal and the 4th control letter
Number to all needing the first switching capacity unit of work, then it is sequentially output described first control signal and by described predesigned order
Three control signal to described the first switching capacity unit needing work.
Concrete, during t0 to the t1 moment, switch control unit is by the first control signal produced, the second control letter
Number, the 3rd control signal and the output of the 4th control signal to the first switch Φ 11 in the 1st the first switching capacity unit 11, the
Two switch Φ the 21, the 3rd switch Φ the 31, the 4th switch Φ 41, to start the 1st the first switching capacity unit 11, and will produce
The second control signal and the output of the 4th control signal to second switch Φ 22 and the 4th in the 2nd the first switching capacity unit 12
Second switch Φ 23 and the 4th switch Φ 43 in switch Φ 42, the 3rd the first switching capacity unit 13 and the 4th first leave
Close the second switch Φ 24 and the 4th switch Φ 44 in capacitor cell 14.During t1 to the t2 moment, switch control unit again will
The first switch Φ 12 that the first control signal produced and the 3rd control signal export to the 2nd the first switching capacity unit 12
Φ 32 is switched, to start the 2nd the first switching capacity unit 12 with the 3rd.During t2 to the t3 moment, switch control unit is again
The first switch Φ that the first control signal produced and the 3rd control signal are exported to the 3rd the first switching capacity unit 13
13 and the 3rd switch the first switch Φ 14 and the 3rd switch Φ 34 in Φ 33 and the 4th the first switching capacity unit 14, with
Start the 3rd the first switching capacity unit 13 and the 4th the first switching capacity unit 14.This mode can be in the shorter time
Interior startup the first switching capacity unit.
The first switch, second switch, the 3rd switch and the 4th switch described in the present embodiment can be metal-oxide-semiconductor.
The grid of the first switch and second switch receives the first control signal and the second control signal, and source electrode connects the first electricity
Holding the first end Vramp and the outfan bufout of operational amplifier Opamp of C1, the two terminal voltage is all along with the first electric capacity C1
The first end Vramp capacitance become big and become big.Along with the magnitude of voltage of the first end Vramp of the first electric capacity C1 is increasing, execute
The voltage being added to the first switch and second switch source electrode is the most increasing, and this causes the conducting resistance of metal-oxide-semiconductor the biggest.
In order to solve the problems referred to above, the first control signal of the present embodiment switch control unit generation and the second control signal
Pulse amplitude follow described first electric capacity C1 first end Vramp magnitude of voltage increase and increase.That is, the first of the first electric capacity C1
End Vramp magnitude of voltage increases how many, and the pulse amplitude of the first control signal just increases how many so that the electricity between grid and source electrode
Pressure difference Vgs keeps constant, thus conducting resistance keeps constant, reduces the non-linear of switch.
Owing to the 3rd switch and the 4th switch are all connected on fixed potential, conducting resistance is constant, so the present embodiment institute
The 3rd control signal stated and the 4th control signal can use the current potential lower than supply voltage, thus reduce the 3rd switch and the
The Charge injection effect of four switches and clock feed-through effect.
For the consideration identical with the 4th switch with the 3rd switch, between the first switch and the grid of second switch and source electrode
Voltage difference Vgs might be less that supply voltage, and the first switch and second switch are made in DEEP NWELL, substrate
It is connected together with source electrode, reduces body bias effect, such that it is able to reduce the voltage difference Vgs between grid and source electrode further and open
Close is non-linear.
As shown in Figure 6, the ramp generator described in the present embodiment can also include: second switch capacitance group 2.
Described second switch capacitance group 2 includes at least one second switch capacitor cell, described second switch capacitor cell
Including: the 5th switch, the 6th switch, the 7th switch, the 8th switch and the 3rd electric capacity, the capacitance of described 3rd electric capacity is with described
The capacitance of the second electric capacity is equal.
First end of described 5th switch connects first input end and the outfan of described operational amplifier, and the described 6th opens
The first end closed connects the second input and first end of the first electric capacity of described operational amplifier, the second of described 7th switch
End is suitable to input described first voltage, and the second end of described 8th switch is suitable to input described second voltage.Same second
In switching capacity unit, the second end of described 5th switch connects second end and the first of the 3rd electric capacity of described 6th switch
End, the first end of described 7th switch connects the first end and second end of the 3rd electric capacity of described 8th switch.
The first switch, second switch, the 3rd switch and the 4th switch described in the present embodiment can opening by same size
Close and realize, described 5th switch, the 6th switch, the 7th switch and the 8th switch also with the first switch, second switch, the 3rd open
Close identical with the specification of the 4th switch.So, second switch capacitance group 2 and the composition of the first switching capacity group 1 and connected mode
The most identical.The increase of second switch capacitance group 2 can realize the mode of operation of duplex.
Concrete, described switch control unit is further adapted for exporting the 5th control signal, the 6th control signal, the 7th control letter
Number and the 8th control signal to the second switch capacitor cell needing work to start the described second switch capacitor cell needing work.
Described 5th control signal is suitable to control the closed and disconnected of described 5th switch, and it is described that described 6th control signal is suitable to control
The closed and disconnected of the 6th switch, described 7th control signal is suitable to control the closed and disconnected of described 7th switch, and described the
Eight control signals are suitable to control the closed and disconnected of described 8th switch.Described 5th control signal is described first control signal
Inversion signal, described 6th control signal is the inversion signal of described second control signal, and described 7th control signal is institute
Stating the inversion signal of the 3rd control signal, described 8th control signal is the inversion signal of described 4th control signal.
When only first switching capacity group 1 works, the magnitude of voltage of first electric capacity C1 the first end Vramp only controls first
Just increase when signal is phase place 2, keep constant during phase place 1.And the first switching capacity group 1 and second switch capacitance group 2 all work
Time, the second electric capacity and the 3rd electric capacity are alternately to the first electric capacity charging, and the magnitude of voltage of first electric capacity C1 the first end Vramp can be the
One control signal is all to increased when phase place 1 and phase place 2, so for given clock frequency and range of signal, and the first electricity
The rise time of the magnitude of voltage holding C1 the first end Vramp reduces half.And for given working time and range of signal, clock
Frequency can reduce by one times, say, that the time set up for signal in each phase place doubles.
Although present disclosure is as above, but the present invention is not limited to this.Any those skilled in the art, without departing from this
In the spirit and scope of invention, all can make various changes or modifications, therefore protection scope of the present invention should be with claim institute
Limit in the range of standard.
Claims (9)
1. a ramp generator, it is characterised in that including: operational amplifier, the first electric capacity and the first switching capacity
Group, described first switching capacity group includes that at least one first switching capacity unit, described first switching capacity unit include: the
One switch, second switch, the 3rd switch, the 4th switch and the second electric capacity, switch control unit；
First end of described first switch connects negative-phase input and the outfan of described operational amplifier, described second switch
First end connects normal phase input end and first end of the first electric capacity of described operational amplifier, and the second end of described 3rd switch is fitted
In inputting the first voltage, the second end of described 4th switch is suitable to input the second voltage, described second voltage and the first voltage
Magnitude of voltage is unequal；
In same first switching capacity unit, described first switch second end connect described second switch the second end and
First end of the second electric capacity, the first end of described 3rd switch connects first end and the second of the second electric capacity of described 4th switch
End；
Second end ground connection of described first electric capacity；
The capacitance of described first electric capacity is more than the capacitance of described second electric capacity；
Described switch control unit is suitable to export the first control signal, the second control signal, the 3rd control signal and the 4th control
Signal is to needing the first switching capacity unit of work to start described the first switching capacity unit needing work；
Described first control signal is suitable to control the closed and disconnected of described first switch, and described second control signal is suitable to control
The closed and disconnected of described second switch, described 3rd control signal is suitable to control the closed and disconnected of described 3rd switch, institute
State the 4th control signal and be suitable to control the closed and disconnected of described 4th switch；
Described second control signal is the inversion signal of described first control signal, and described 4th control signal is described 3rd control
The inversion signal of signal processed, described first control signal and the 3rd control signal are with frequency in-phase signal.
2. ramp generator as claimed in claim 1, it is characterised in that described the first switching capacity list needing work
The quantity of unit is multiple, and described switch control unit is suitable to predetermined order and starts described the first switching capacity needing work successively
Unit.
3. ramp generator as claimed in claim 2, it is characterised in that described predesigned order and described ramp signal
The ramp signal slope that circuit output occurs is correlated with.
4. ramp generator as claimed in claim 2, it is characterised in that described switch control unit is suitable to first export
Described second control signal and the 4th controls signal to all need the first switching capacity unit of work, then by described predesigned order
It is sequentially output described first control signal and the 3rd and controls signal to described the first switching capacity unit needing work.
5. ramp generator as claimed in claim 1, it is characterised in that described first control signal and second controls
Signal is pulse signal, and the amplitude of described pulse signal follows the first terminal voltage value of described first electric capacity to be increased and increase.
6. the ramp generator as described in claim 1 to 5 any claim, it is characterised in that also include second
Switching capacity group, described second switch capacitance group includes at least one second switch capacitor cell, described second switch electric capacity list
Unit includes: the 5th switch, the 6th switch, the 7th switch, the 8th switch and the 3rd electric capacity, the capacitance of described 3rd electric capacity and institute
The capacitance stating the second electric capacity is equal；
First end of described 5th switch connects first input end and the outfan of described operational amplifier, described 6th switch
First end connects the second input and first end of the first electric capacity of described operational amplifier, and the second end of described 7th switch is fitted
In inputting described first voltage, the second end of described 8th switch is suitable to input described second voltage；
In same second switch capacitor cell, described 5th switch second end connect described 6th switch the second end and
First end of the 3rd electric capacity, the first end of described 7th switch connects first end and the second of the 3rd electric capacity of described 8th switch
End.
7. ramp generator as claimed in claim 6, it is characterised in that described switch control unit is further adapted for output
5th control signal, the 6th control signal, the 7th control signal and the 8th control signal to need the second switch electric capacity list of work
Unit is to start the described second switch capacitor cell needing work；
Described 5th control signal is suitable to control the closed and disconnected of described 5th switch, and described 6th control signal is suitable to control
The closed and disconnected of described 6th switch, described 7th control signal is suitable to control the closed and disconnected of described 7th switch, institute
State the 8th control signal and be suitable to control the closed and disconnected of described 8th switch；
Described 5th control signal is the inversion signal of described first control signal, and described 6th control signal is described second control
The inversion signal of signal processed, described 7th control signal is the inversion signal of described 3rd control signal, and the described 8th controls letter
It number it is the inversion signal of described 4th control signal.
8. an imageing sensor, it is characterised in that including: described in analog-digital converter and claim 1 to 7 any claim
Ramp generator, described ramp generator connect described analog-digital converter.
9. imageing sensor as claimed in claim 8, it is characterised in that the required precision of described analog-digital converter and described the
The capacitance ratio of one electric capacity and the second electric capacity is correlated with.
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| CN110418082B (en) * | 2018-04-28 | 2021-11-12 | 比亚迪半导体股份有限公司 | Column-level analog-to-digital converter and analog-to-digital conversion method applied to column-level analog-to-digital converter |
| CN110913152B (en) * | 2019-11-25 | 2022-02-15 | Oppo广东移动通信有限公司 | Image sensor, camera assembly and mobile terminal |
| CN115223498A (en) * | 2021-04-14 | 2022-10-21 | 孙丽娜 | Gamma voltage generating circuit, display device and gamma voltage generating method |
| CN115174882B (en) * | 2022-09-07 | 2022-12-02 | 天宜微电子(北京)有限公司 | Ramp signal module and gamma correction circuit |
| CN115550625B (en) * | 2022-10-10 | 2023-06-30 | 天宜微电子(北京)有限公司 | Ramp signal module and gamma correction circuit |
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| CN101924555A (en) * | 2009-06-15 | 2010-12-22 | 夏普株式会社 | A/D converter, solid-state image capturing device and electronic message unit |
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| US7907079B1 (en) * | 2008-02-21 | 2011-03-15 | Foveon, Inc. | Delta sigma modulator for analog-to-digital converter |
| CN101924555A (en) * | 2009-06-15 | 2010-12-22 | 夏普株式会社 | A/D converter, solid-state image capturing device and electronic message unit |
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