CN209419581U - It is a kind of for detecting the integrating amplification circuit of front end - Google Patents

Abstract

The utility model discloses a kind of for detecting the integrating amplification circuit of front end, including amplifier, switch (1,2,3,4,5,6,25,26,27,10,11), switch (32,22,23,24) and capacitor (7,8,9)；Capacitor (7,8,9) is connect with switch (25,26,27) respectively, and switch (25,26,27) is shorted together；Switch (6,5,4) is connected to ground VSS with switch (22,23,24) respectively；The port that switch (25,26,27) is shorted is connect with switch 10 and amplifier output port respectively；Switch 10 is connect with VREFB, and amplifier output port is connect with switch 11, and 11 rear end of switch connects integrator output；The positive grade of amplifier is connect with VREFA；The positive and negative grade input terminal of amplifier is connected by switch 3.

Description

It is a kind of for detecting the integrating amplification circuit of front end

Technical field

The utility model relates to integrator circuit fields, amplify electricity more particularly to a kind of integral for detecting front end Road.

Background technique

The main application front end high-precision integrator circuit of the high sensitive detector front-end circuit function such as XRAY is to tiny signal It is acquired, integral amplification is changed into voltage signal and carries out subsequent processing.Sample rate current grade from PA to NA differs, therefore preceding In terminal circuit, the electric leakage of integrator itself will directly affect the precision of detector.Current domestic highly sensitive Current detector Chip does not have substantially, depends on external chip.Major technology bottleneck is technology, high precision fast A/D C technology Deng.This utility model circuit engineering is the defect for technique, utmostly reduces integrator electric leakage using circuit structure Influence to this detector precision.

Fig. 1 is traditional integrator circuit structure, and main composition includes an amplifier, the capacitor array of different capacitances and Switching circuit.Wherein 7,8,9 be three different size of capacitors, and major function is the work range for changing integrator, to adapt to Different size of integration current.In real work, 7,8,9 capacitors can be accessed entire by 6,5,4 switch controls with any combination In integrator circuit.In Fig. 1 circuit, integrator current path is mainly inputted from VIN, by 1,2 switch, then passes through 4,5 parallel, 6 switching circuits, then pass through 7,8,9 capacitors parallel, last parallel three paths are shorted to amplifier output 18.Integration current access In, uncertain leakage current can be caused to occur mainly in the switch of access above, construction of switch is made of P/N type metal-oxide-semiconductor. Wherein 4,5,6 switches are even more important, and the application switchs aiming at these three and carries out low-leakage current design.

Traditional integrator circuit, low-leakage current are designed general overriding concern technique, are reduced electric leakage using technology Stream.Followed by by reducing the device of access, reduce the electric leakage of pass device with this.In some cases due to technique, it is It not can guarantee, such as to area, to power consumption, cost, the factors such as prior art technology limit making for some special process With.And reduce pass device, such as the switch 4 above capacitive switch array, and 5,6, switch drain can be effectively solved in this way, but It is to limit the application range of integrator, range is too small, is not suitable for the application of Larger Dynamic range input.

With reference to Fig. 1, the working principle of Fig. 1 is as follows, and integrator is resetted first, and switch 1,3,10 is closed, switch 2,11 It disconnects, makes to input vin and VREFA short circuit, 20,21 ports are shorted VREFA, and output 18 and VREFB is shorted.After resetting operation, 1, 3,10 switches disconnect, and 2 close the switch.At this moment the small electric current in the end VIN charged by 1,2,4 pairs of capacitors 9 of switch (assuming that this When selection 9 channel of capacitor corresponding range, i.e. switch 4 is closed, and switch 5,6 disconnects, logical similarly if selecting 8,9 capacitor ranges Cross control to be closed switch 4,5, switch 6 disconnects), due to the effect of amplifier negative-feedback, 20,21 two-port void are shorted, i.e., and 20 Port voltage approximation etc. and 21 port voltage VREFA are constant.Capacitor plate charge conservation so that amplifier output voltage 18 from VREFB starts to gradually decrease, and reduced rate of change is related to input current and capacitor 9.Input current is bigger, and capacitor is constant, 18 decrease speed of output voltage is faster, otherwise slower.Equally constant in input current, capacitor 9 is bigger, and the variation of output voltage 18 is got over It is small, on the contrary variation is bigger.

With reference to Fig. 1, from working principle above it is found that when switch 4,5,6 introduces uncertain leakage current, output electricity will result in Pressure is inaccurate, causes error.4,5,6 switch leakage current uncertainties are due to output voltage 18 be as the time of integration changes, If only capacitor 9 accesses, capacitor 7,8 is not accessed, and switch 4 is closure at this time, and switch 5,6 is to disconnect.When 18 voltages become When change, since switch 5,6 disconnects, the voltage of 15,16 nodes can follow 18 node voltages to change.5,6 circuit of switch is usually by N Type MOS, the switch that p-type MOS or P/N forms MOS.The change of 15,16 node voltages causes metal-oxide-semiconductor source level or drain electricity Buckling causes substrate and source and drain pressure difference to change, so that metal-oxide-semiconductor source level or drain is made to have Weak current to flow into or out, Charge and discharge are carried out to capacitor 7,8, output voltage is caused to change.

Utility model content

The utility model mainly solving the technical problems that provide it is a kind of for detecting the integrating amplification circuit of front end, can In integral access, reduce leakage current, making switch ends voltage not will receive the variation influence of amplifier output voltage and cause Switch misses opening state.

In order to solve the above technical problems, the technical solution that the utility model uses is: before providing one kind for detecting The integrating amplification circuit at end, comprising: amplifier, switch (K1, K2, K3, K4, K5, K6, K25, K26, K27, K10, K11), switch (S32, S22, S23, S24) and capacitor (C7, C8, C9)；Input signal vin is connect with the front end switch K1, the rear end of switch K1 with Switch S32 is connected to VREFA, and the rear end of Simultaneous Switching K1 is connect with the front end switch K2, the rear end switch K2 and the negative cascade of amplifier It connects；The port that switch K2 is connect with amplifier is parallel to the front end connection of switch (K6, K5, K4), switchs the rear end (K6, K5, K4) It is connect respectively with the front end capacitor (C7, C8, C9), the rear end capacitor (C7, C8, C9) front end with switch (K25, K26, K27) respectively Connection, the switch rear end (K25, K26, K27) are shorted together；Switch the rear end (K6, K5, K4) respectively with switch (S22, S23, S24) It is connected to ground VSS or VREFA；Switch the rear end (K25, K26, K27) be shorted port respectively with the front end of switch K10 and amplification The connection of device output port；The rear end switch K10 is connect with VREFB, and amplifier output port is connect with the front end switch K11, switch K11 Rear end connects integrator output；The positive grade of amplifier is connect with VREFA；The positive and negative grade input terminal of amplifier is connected by switch K3 Come.

Further, the switch (S32, S22, S23, S24) is made of N-type metal-oxide-semiconductor；It switchs (S32, S22, S23, S24) Grid-control voltage controlled by outside, wherein switch S32, for resetting, switch (S22, S23, S24) is for different capacitor battle arrays The selection of column, to determine integrator range.

Further, the VREFA and VREFB and VSS can be true according to actual circuit situation with equipotential or different potentials It is fixed.

The beneficial effects of the utility model are: the utility model increases switch 22,23 on traditional integrating circuit, 24,25,26,27.When integrator works normally, the voltage of output end 18/17 can change always with the time, or not Different constant voltages is kept with the time, which can be coupled to integrating channel switch source level/drain, and switch source and drain is caused to have Certain pressure difference, source and drain and substrate have certain pressure difference, so that switch internal forms certain electric current.In addition in traditional structure, Switch capacitor between connect 16,15,14 voltage follows amplifier export 18 voltages variation (6,5,4 disconnection of switch Under).And 16,15,14 initial voltage is influenced by technique, and voltage is uncertain, therefore when initial voltage is relatively low, and 16,15,14 When voltage is big with 18 voltage change amplitudes of amplifier output, switch 6,5,4 can be made to be connected, circuit function error.The utility model When purpose is that amplifier is made to export 18/17 voltage change or a constant voltage, make the voltage of its capacitor array switch ends Keep equal, such source and drain and source/drain be not to having pressure drop between substrate, to reduce the internal current of switch.Simultaneously by 16, 15,14 current potential in switch OFF before, clamped down on by current potential, not by the voltage influence of amplifier output 18.

Detailed description of the invention

Fig. 1 is traditional integrator circuit schematic diagram；

Fig. 2 is that the utility model is a kind of for detecting the schematic diagram of the integrating amplification circuit of front end；

Fig. 3 is switching circuit structure schematic diagram in a kind of integrating amplification circuit for detecting front end of the utility model；

Fig. 4 is the schematic diagram of different capacitor array switched integration circuit forms.

Specific embodiment

The preferred embodiment of the utility model is described in detail with reference to the accompanying drawing, so that the advantages of the utility model It can be easier to be readily appreciated by one skilled in the art with feature, to make the protection scope of the utility model apparent clear Define.

Please see Fig. 2 to Fig. 4, the utility model embodiment includes:

It is a kind of for detecting the integrating amplification circuit of front end, comprising: amplifier circuit 31, switching circuit 1,2,3,4,5,6, 25,26,27,10,11 and capacitor array 7,8,9.Input signal vin is connect with switch 1, the other end 12 and switch of switch 1 32 are connected to VREFA, while 12 connect with 2 one end of switch, and 2 other end line 20 of switch is connect with the negative grade of amplifier 31.Port 20 are parallel to the connection of 6,5,4 one end of switch, and 6,5,4 other end line 16,15,14 of switch is connected with 7,8,9 one end of capacitor respectively, The remaining one side port of capacitor 7,8,9 is connected with switch 25,26,27 respectively again, and the remaining one side port of switch 25,26,27 is shorted one 17 are played, such as Fig. 2 line 17.6,5,4 one end 16,15,14 of switch be connected to respectively with 22,23,24N type metal-oxide-semiconductor of switch ground VSS (or Person VREFA).Line 17 is connect with 10 one end of switch respectively, and amplifier output port 18 connects.10 other end of switch and VREFB Connection, amplifier output port 18 are connect with switch 11, and 11 other end 19 of switch connects integrator output.Amplifier 31 is just End 21 is connect with VREFA.31 positive-negative input end 20,21 of amplifier is connected by a switch 3.It is switched in this illustrative circuitry 32,22,23,24 are made of N-type metal-oxide-semiconductor, their grid-control voltage is controlled by outside, wherein the effect of switch 32 is multiple Position, switch 22,23,24 is used for the selection of different capacitor arrays, to determine integrator range.In circuit VREFA and VREFB with VSS can same equipotential, can be determined according to actual circuit situation with different potentials.

This technical application is novel mainly to increase switch 22,23,24,25,26,27 on traditional integrating circuit.From It is found that when integrator works normally, the voltage of output end 18/17 can change always with the time for the principle of front, or A constant voltage is kept, which can be coupled to integrating channel switch source level/drain, switch source and drain is caused to have certain pressure The pressure difference of difference, source and drain and substrate can make switch internal form certain electric current.This technology purpose is to make 18/17 electricity of amplifier output When buckling or a constant voltage, the voltage of its capacitor array switch ends is set to keep equal, such source and drain and source/drain arrive There is no pressure drop between substrate, to reduce the internal current of switch.In addition this circuit makes 14/15/16 node voltage true It is fixed, misleading for 4,5,6 switches will not be caused because of 18 voltage change.

By taking Fig. 2 as an example, it is assumed that the integrator accesses capacitor 9, and 7,8 range of capacitor is bypassed.That is switch 4,27 closure conductings State, switch 24, which controls signal, makes its closing.5,6,25,26 switch off state, switch 22,23 control signal and turn it on, It is connect with ground VSS.When proper integral device works, amplifier inputs positive and negative terminal void and is shorted, i.e., port 20,21 current potentials are approximately equal VREFA, since switch 4 is connected, integration current is smaller, and 4 both sides port voltage of switch is nearly equal to VREFA, therefore switch 4 Source and drain potential voltage difference is approximately 0.Switch 5,6 is in an off state, and source and drain is not turned on, and switch 22,23 is connected and connects VREFA, therefore the voltage difference at 5,6 source and drain both ends of switch is also close to 0.When the substrate that switch 4,5,6 switchs is identical as VREFA (such as VSS), switch ends source and drain and the current potential of substrate can be effectively reduced the leakage current of switch also close to equal in this way.? In traditional circuit, the voltage change of amplifier output end 18 will have a direct impact on the voltage at 6,5,4 end 16,15,14 of switch, not have especially There is the channel of access capacitor, 15,16 initial voltage is generally determined by technique, is a uncertain value, in Fig. 1 example, such as The initial voltage of fruit 16,15 is lower, when 18 integrator output voltage of port change it is bigger, 16,15 end voltages can be made to become Switch 6,5 is connected in negative value, thus will appear circuit function error.And the circuit of Fig. 2 avoids in this way as a result, because end Mouth 16,15 is directly shorted with VREFA, and current potential is not influenced by 18 voltages of output.But disadvantage increases the electricity of output amplifier 31 Hold load, in order to overcome this disadvantage, in addition increases switch 25,26,27, the directly connection of cutting amplifier and capacitor do not increase Loading.

The above description is only the embodiments of the present invention, and therefore it does not limit the scope of the patent of the utility model, all Equivalent structure or equivalent flow shift made based on the specification and figures of the utility model, is applied directly or indirectly in Other related technical areas are also included in the patent protection scope of the utility model.

Claims (3)

1. a kind of for detecting the integrating amplification circuit of front end characterized by comprising amplifier, switch K2, is opened switch K1 It closes K3, switch K4, switch K5, switch K6, switch K25, switch K26, switch K27, switch K10, switch K11, switch S32, open Close S22, switch S23, switch S24, capacitor C7, capacitor C8, capacitor C9；Input signal vin is connect with the front end switch K1, switch K1 Rear end and switch S32 be connected to VREFA, the rear end of Simultaneous Switching K1 is connect with the front end switch K2, the rear end switch K2 with amplify The negative grade connection of device；The port that switch K2 is connect with amplifier is parallel to the front end connection of switch K6, switch K5, switch K4, switch K6, switch K5, the rear end switch K4 are connect with capacitor C7, capacitor C8, the front end capacitor C9 respectively, after capacitor C7, capacitor C8, capacitor C9 End is connect with the front end of switch K25, switch K26, switch K27 respectively, and switch K25, switch K26, the rear end switch K27 are shorted one It rises；Switch K6, switch K5, the rear end switch K4 are connected to ground VSS or VREFA with switch S22, switch S23, switch S24 respectively； The port that switch K25, switch K26, the rear end switch K27 are shorted is connect with the front end of switch K10 and amplifier output port respectively； The rear end switch K10 is connect with VREFB, and amplifier output port is connect with the front end switch K11, and the rear end switch K11 connects integrator Output；The positive grade of amplifier is connect with VREFA；The positive and negative grade input terminal of amplifier is connected by switch K3.

2. according to claim 1 a kind of for detecting the integrating amplification circuit of front end, it is characterised in that: the switch S32, switch S22, switch S23, switch S24 are made of N-type metal-oxide-semiconductor；The grid of switch S32, switch S22, switch S23, switch S24 Pole controls voltage and is controlled by outside, wherein switch S32, for resetting, switch S22, switch S23, switch S24 are used for different capacitors The selection of array, to determine integrator range.

3. according to claim 1 a kind of for detecting the integrating amplification circuit of front end, it is characterised in that: the VREFA It can be with equipotential or different potentials with VREFB and VSS.