Radiation hardening structure of a high-precision operational amplifier

Abstract

The application discloses a kind of high-precision operational amplifier's anti-radiation reinforcement structure, including the input stage circuit of operational amplifier, input differential pair tube in the input stage circuit adopts triode QD1 and triode QD2 to form input NPN pair tube;The layout structure of input NPN pair tube adopts four-tube cross structure;Triode QD1 and triode QD2 are provided with aluminium wire between emitter and collector, and the spacing between emitter and aluminium wire is 5-8 μm.Through in the input stage circuit of operational amplifier, the layout of input NPN pair tube adopts four-tube cross (common center) structure, and four-tube must be close enough on layout structure, and area margin is used to increase emitter area to reduce imbalance and noise voltage.The layout structure of input NPN pair tube is modified in the application by using existing NPN tube design area, combined with process rules, to realize the qualified parameter of domestic circuit after irradiation.The layout structure of the application is improved without affecting other performances of the circuit.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of integrated circuits, and particularly relates to an anti-radiation reinforcing structure of a high-precision operational amplifier. BACKGROUND

[0002] Operational amplifiers are everywhere in today's circuit systems, and designers always hope to design operational amplifiers with quite excellent performance in various aspects. With the increasing application of operational amplifiers in the military, the harsh environment in the military field has a significant impact on integrated circuits. The circuit performance is seriously degraded or even fails to function. How to improve the anti-radiation capability of the operational amplifier has become an urgent demand.

[0003] Due to the influence of the irradiation environment, the electrical parameters of the operational amplifier circuit will degenerate. The input stage characteristics of the operational amplifier are crucial to the entire device. However, the anti-radiation performance of the operational amplifier in the prior art cannot meet the use requirements. SUMMARY

[0004] In order to solve the problems in the prior art, the application provides an anti-radiation reinforcing structure of a high-precision operational amplifier, thereby effectively avoiding the failure mode introduced by the opening of the parasitic NMOS tube when the amplifier circuit experiences low dose rate irradiation.

[0005] To achieve the above object, the application provides the following technical scheme.

[0006] An anti-radiation reinforcing structure of a high-precision operational amplifier, comprising an input stage circuit of an operational amplifier, wherein an input differential pair tube in the input stage circuit adopts a triode QD1 and a triode QD2 to form an input NPN pair tube.

[0007] The layout structure of the input NPN pair tube adopts a four-tube cross structure; an aluminum wire is arranged between the emitter and the collector of the triode QD1 and the triode QD2, and the spacing between the emitter and the aluminum wire is 5-8 mu m.

[0008] Preferably, the spacing between the emitter and the aluminum wire between the emitter and the collector is 5 mu m.

[0009] Preferably, the input NPN pair tube of the input stage circuit comprises a capacitor C6, a resistor R12 and a resistor R11, one end of the resistor R12 is connected to a positive power supply, one end of the resistor R11 is connected to the positive power supply, one end of the capacitor C6 is connected to the positive power supply,

[0010] The other end of the resistor R12 is connected to one end of the resistor R8, one end of the capacitor C1 and the other end of the capacitor C6, and the other end of the capacitor C1 is connected to one end of the resistor 10; one end of the resistor R11 is connected to one end of the resistor R9 and the other end of the resistor R10 respectively, and the other end of the resistor R8 is connected to the collector of the transistor QD1, and one end of the resistor R9 is connected to the collector of the transistor QD2.

[0011] The bridge circuit composed of the diodes Q1, Q2, Q3 and Q4 is connected between the base of the transistor QD1 and the base of the transistor QD2, and the emitter of the transistor QD1 and the emitter of the transistor QD2 are connected to the negative power supply respectively.

[0012] Preferably, the aluminum wire is arranged between the emitter and the collector by using the photoetching technology.

[0013] Preferably, the width of the aluminum wire is 6-8 μm.

[0014] Preferably, the distance between the aluminum wire and the emitter and the collector is equal.

[0015] Compared with the prior art, the present application has the following beneficial technical effects:

[0016] The present application provides a kind of high-precision operational amplifier's anti-radiation reinforcement structure, by in the input stage circuit of operational amplifier, the layout of input NPN pair tube adopts four-tube intersection (common center of gravity) structure, realize the symmetry matching of both, avoid the mismatch caused by process random error, temperature drift etc., the layout structure requires four tubes must be close enough and the area margin is used to increase the emitter area to reduce the mismatch and noise voltage.In the present application, the design area of existing NPN tube is utilized, the layout structure of input NPN pair tube is modified in combination with process rules, and the post-irradiation parameters of domestic circuit are qualified.The layout structure of the present application is improved without affecting other performances of the circuit. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is the common center of gravity input pair tube circuit structure;

[0018] Figure 2 It is the common center of gravity input pair tube layout structure;

[0019] Figure 3 It is the circuit structure diagram of the operational amplifier of the present application. DETAILED DESCRIPTION

[0020] The present application will be further described in detail below in conjunction with specific embodiments, which are an explanation of the present application rather than a limitation.

[0021] A high-precision operational amplifier comprises a startup and bias circuit and two amplifiers with identical structures. Each amplifier includes an input stage circuit, an intermediate stage circuit, and an output stage circuit. The input stage circuit employs a differential pair transistor structure to improve input impedance, reduce offset voltage and temperature drift, establish a good matched DC operating point, and perform input voltage buffering and initial stage amplification. The intermediate stage circuit uses a folded common-base, common-emitter structure to improve voltage gain and output swing. The output stage circuit uses transistors with identical parameters in a push-pull configuration to expand internal current, improve subsequent stage drive capability, and increase output swing. The input stage circuit includes a tuning network with multiple tuning solder joints. Different solder joints are tuned according to different measured values. This invention achieves acceptable parameters after radiation resistance testing by changing the distance between the emitter region of the input pair transistors and the aluminum wire.

[0022] To reduce offset voltage and noise, such as Figure 1 As shown, the input stage circuit of this invention uses transistors QD1 and QD2 to form an input NPN pair. The input NPN pair includes capacitor C6, resistor R12, and resistor R11. One end of resistor R12 is connected to the positive power supply, one end of resistor R11 is connected to the positive power supply, and one end of capacitor C6 is connected to the positive power supply.

[0023] The other end of resistor R12 is connected to one end of resistor R8, one end of capacitor C1 and the other end of capacitor C6. The other end of capacitor C1 is connected to one end of resistor 10. One end of resistor R11 is connected to one end of resistor R9 and the other end of resistor R10. The other end of resistor R8 is connected to the collector of transistor QD1. One end of resistor R9 is connected to the collector of transistor QD2.

[0024] A bridge circuit consisting of diodes Q1, Q2, Q3, and Q4 is connected between the base of transistor QD1 and the base of transistor QD2. The emitters of transistors QD1 and QD2 are both connected to the negative power supply.

[0025] like Figure 2As shown, the layout of the input NPN pair in the input stage circuit of the application adopts a four-transistor cross (common center) structure, which tries to realize the symmetrical matching of the two, avoids the mismatch caused by process random errors, temperature drift and other reasons, and requires that the four transistors must be close enough on the layout structure and the area margin is used to increase the emitter area to reduce the mismatch and noise voltage. But in this layout structure, the collector layout of D1 transistor must pass through D2. In order to reduce the layout area, the minimum rule design is adopted for the aluminum wire spacing, so that part of the aluminum wire will be overlapped on the emitter and base region, that is, the aluminum wire between the emitter and the collector of the NPN pair is overlapped on the emitter. During the process, the emitter and base regions exist horizontal extension, which will form the NMOS tube structure between CE. Assuming that the edge base region concentration becomes much lighter after horizontal extension, and the oxide layer charge increases after irradiation, which causes the threshold of NMOS tube to be reduced, the parasitic NMOS tube is turned on, which causes the circuit parameters to be out of tolerance after irradiation. The equivalent circuit structure is shown in Figure 1

[0026] In the application, the layout structure of the input NPN pair is modified by using the existing NPN tube design area and combining the process rules, so as to realize the qualified parameters of the domestic circuit after irradiation. And the layout structure of the application is improved without affecting other performances of the circuit.

[0027] In the application, the layout is optimized by changing the spacing between the emitter and the aluminum wire between the emitter and the collector, which is changed to 5-8 μm, preferably 5 μm. According to the test after the irradiation test of the improved circuit, the parameters are qualified.

[0028] Through the test, when any positive or negative power supply is changed, the output voltage of the qualified circuit basically does not change with the power supply voltage. The output voltage of the failed circuit has a greater relationship with the positive power supply voltage, so it can be judged that the power supply voltage rejection ratio parameter out of tolerance has a greater relationship with the mismatch voltage parameter out of tolerance; when the positive and negative power supplies are changed at the same time, the output voltage of the qualified circuit basically does not change with the power supply voltage, and the output voltage of the failed circuit changes greatly with the power supply voltage, so it can be judged that the common mode rejection ratio parameter out of tolerance has a relationship with the mismatch voltage parameter out of tolerance.

[0029] ​According to the test results, through the analysis of the circuit, if the failure is caused by the circuit part after the input stage, if the change range is large, the voltage gain will cause great change, but through the test results, the gain does not cause great change, if the change range is small, the misadjustment will not have great fluctuation, which is inconsistent with the actual measurement results, so the problem is located at the input end of the circuit, if it is caused by the input resistor, only the change of the input misadjustment voltage parameter will be affected, the common mode rejection ratio and the power supply voltage rejection ratio will not be affected, which is inconsistent with the test results, so it should be the input tube causing the parameter out-of-tolerance, through the positioning of the layout, it is found that the aluminum wire between the emitter and the collector of the input NPN pair tube is connected to the emitter, when the base region is horizontally expanded, the concentration becomes low, the parasitic NMOS is opened, and the leakage is formed.

[0030] As shown in Figure 3 , the input stage circuit includes a resistor R1, one end of the resistor R1 is connected to a positive power supply, the other end of the resistor R1 is connected to the emitters of a transistor Q7 and a transistor Q8 respectively, the bases of the transistor Q7 and the transistor Q8 are connected to each other, the collector of the transistor Q7 is connected to the base of the transistor Q7, the emitters of a transistor Q5 and a transistor Q6 respectively, the collector of the transistor Q8 is connected to the bases of the transistor Q5 and the transistor Q6 respectively.

[0031] The collector of the transistor Q5 is connected to the base of a transistor QD1, the collector of the transistor QD1 is connected to the input end of the intermediate stage circuit and one end of a resistor R8 respectively, the other end of the resistor R8 is connected to a capacitor C1, a capacitor C6 and one end of a resistor R12 respectively, the other ends of the capacitor C6 and the resistor R12 are connected to the positive power supply, the other end of the capacitor C1 is connected to one end of a resistor R10.

[0032] The collector of the transistor Q6 is connected to the base of a transistor QD2, the collector of the transistor QD2 is connected to the input end of the intermediate stage circuit and one end of a resistor R9 respectively, the other end of the resistor R9 is connected to the other end of the resistor R10 and one end of a resistor R11 respectively, the other end of the resistor R11 is connected to the positive power supply.

[0033] A bridge circuit composed of diodes Q1, Q2, Q3 and Q4 is connected between the base of the transistor QD1 and the base of the transistor QD2, the emitters of the transistor QD1 and the transistor QD2 are connected to the collector of a transistor Q12, the base of a transistor Q9 and the base of a transistor Q42 respectively, the collector of the transistor Q9 is connected to the collector of the transistor Q8, the emitter of the transistor Q9 is connected to the emitter of the transistor Q42 and one end of a resistor R2 respectively, the other end of the resistor R2 is connected to the input end of the intermediate stage circuit.

[0034] The base of the triode Q12 is connected to one end of the resistor R5, and the other end of the resistor R5 is connected to the input of the intermediate stage circuit; the emitter of the triode Q12 is connected to one end of the resistor R6, and the other end of the resistor R6 is connected to the collector of the triode Q42 and the negative power supply. The resistance values of the resistor R11 and the resistor R12 are 33K.

[0035] The intermediate stage circuit comprises the resistor R19, one end of the resistor R19 is connected to the positive power supply, and the other end of the resistor R19 is connected to the emitters of the triodes Q22b, Q24, Q23 and Q22a and the input of the output stage circuit respectively, the bases of the triodes Q22b, Q24, Q23 and Q22a are connected to each other and the input of the output stage circuit.

[0036] The collectors of the triodes Q22b and Q24 are connected to one end of the resistor R16 and the emitter of the triode Q20 respectively, and the collectors of the triodes Q23 and Q22a are connected to one end of the resistor R15 and the emitter of the triode Q21 respectively; the other end of the resistor R16 is connected to one end of the capacitor C2 and the collector of the triode Q14, and the base of the triode Q14 is connected to the output of the input stage circuit; the other end of the resistor R15 is connected to one end of the capacitor C3 and the collector of the triode Q17, and the base of the triode Q14 is connected to the output of the input stage circuit, the emitters of the triodes Q14 and Q17 are connected to the collectors of the triodes QD3 and Q13 respectively, and the base of the triode Q17 is connected to the output of the input stage circuit.

[0037] The base of the triode QD3 is connected to the output of the input stage circuit, the base of the triode Q13 is connected to the output of the input stage circuit, the emitter of the triode QD3 is connected to the collector of the triode Q11, the collector of the triode Q10 and the base of the triode Q10 respectively, the emitter of the triode Q10 is connected to the base of the triode QD3, the emitter of the triode Q11 is connected to one end of the resistor R3, the other end of the resistor R3 is connected to the negative power supply, the base of the triode Q11 is connected to one end of the resistor R4, the other end of the resistor R4 is connected to the base of the triode Q13, and the emitter of the triode Q13 is connected to one end of the resistor R7, the other end of the resistor R7 is connected to the negative power supply.

[0038] The bases of the triodes Q20 and Q21 are connected to the input of the output stage circuit, the collector of the triode Q20 is connected to the collector and the base of the triode Q18 respectively, the emitter of the triode Q18 is connected to the collector and the base of the triode Q15, the emitter of the triode Q15 is connected to the negative power supply, and the other end of the capacitor C2 is connected to the emitter of the triode Q18.

[0039] The collector of the triode Q21 is connected to the input of the output stage circuit, the collector of the triode Q19 and one end of the capacitor C4, respectively, and the other end of the capacitor C4 is connected to one end of the resistor R14, the other end of the resistor R14 is connected to the base of the triode Q17, the base of the triode Q18 and the base of the triode Q19 are connected to each other; the emitter of the triode Q19 is connected to the other end of the capacitor C3 and the collector of the triode Q16, respectively, the base of the triode Q15 and the base of the triode Q16 are connected to each other, and the emitter of the triode Q16 is connected to the negative power supply.

[0040] The output stage circuit comprises the resistor R18, the triode Q22d and the triode Q22c, one end of the resistor R18 is connected to the positive power supply, and the other end of the resistor R18 is connected to the emitter of the triode Q28 and the collector of the triode Q32, respectively; the emitters of the triode Q22d and the triode Q22c are connected to the output of the intermediate stage circuit, the bases of the triode Q22d and the triode Q22c are connected to each other, the base of the triode Q22c is connected to the collector of the triode Q22c, the collector of the triode Q22c is connected to one end of the resistor R17, the other end of the resistor R17 is connected to the collector and the base of the triode Q27, respectively, and the base of the triode Q27 is connected to the base of the triode Q28.

[0041] The emitter of the triode Q27 is connected to the input of the intermediate stage circuit and the emitter of the triode Q25, the base of the triode Q25 is connected to the collector of the triode Q22d, the collector of the triode Q26 and one end of the capacitor C7, respectively, the other end of the capacitor C7 is connected to the negative power supply, the emitter of the triode Q26 is connected to one end of the resistor R20, and the other end of the resistor R20 is connected to the negative power supply; the collector of the triode Q25 is connected to the negative power supply.

[0042] The collector of the triode Q28 is connected to the emitter of the triode QD5 and the base of the triode Q34, the base of the triode QD5 is connected to one end of the capacitor C5, the output of the intermediate stage circuit and the base of the triode Q30, the other end of the capacitor C5 is connected to the negative power supply, and the collector of the triode QD5 is connected to the negative power supply.

[0043] The collector of the triode Q30 is connected to one end of the resistor R31 and the positive power supply, respectively, the other end of the resistor R31 is connected to the base of the triode Q32, the emitter of the triode Q32 is connected to one end of the resistor R23, the other end of the resistor R23 is connected to the positive power supply, the emitter of the triode Q34 is connected to one end of the resistor RX, the other end of the resistor RX is connected to the emitter of the triode QD4, the collector and the base of the triode Q36, respectively, the base of the triode QD4 is connected to the emitter of the triode Q30, and the collector of the triode QD4 is connected to the negative power supply.

[0044] The emitter of the transistor Q36 is connected to the collector and base of the transistor Q33, the base of the transistor Q33 is connected to the base of the transistor Q30, and the collector of the transistor Q33 is connected to the emitter of the transistor Q34.

[0045] The emitter of the transistor Q30 is connected to the collector of the transistor Q29, the base of the transistor Q29 is connected to one end of the resistor R22, the other end of the resistor R22 is connected to the base of the transistor Q26 and the output terminal of the intermediate circuit, and the emitter of the transistor Q29 is connected to one end of the resistor R21, the other end of the resistor R21 is connected to the negative power supply.

[0046] The starting and biasing circuit comprises the resistor R30, the transistor Q40, the transistor Q48, the transistor Q49, the transistor Q58 and the diode Q47.

[0047] One end of the resistor R30 is connected to the positive power supply, and the other end of the resistor R30 is connected to the emitter of the transistor Q63 and the emitter of the transistor Q57 respectively; the collector and base of the transistor Q40 are connected to the positive power supply, the emitter of the transistor Q40 is connected to the collector and base of the transistor Q50, the emitter of the transistor Q50 is connected to the base of the transistor Q63 and one end of the resistor R29 respectively, the other end of the resistor R29 is connected to one end of the resistor R31, and the other end of the resistor R31 is connected to the emitter of the transistor Q56.

[0048] The negative electrode of the diode Q47 is connected to the positive power supply, and the positive electrode of the diode Q47 is connected to the base of the transistor Q52 and the base of the transistor Q56, and the base of the transistor Q57 respectively; the collector and base of the transistor Q48 are connected to the positive power supply, the emitter of the transistor Q48 is connected to one end of the resistor R251, the other end of the resistor R251 is connected to one end of the resistor R252, the other end of the resistor R252 is connected to the emitter of the transistor Q52, the collector of the transistor Q52 is connected to the base of the transistor Q46 and the collector of the transistor Q45, and the emitter of the transistor Q45 is connected to the negative power supply.

[0049] The collector of the transistor Q58 is connected to the positive power supply, the collector and base of the transistor Q56 are connected to the collector and base of the transistor Q59, the base of the transistor Q58 is connected to the base of the transistor Q59, the emitter of the transistor Q58 is connected to the emitters of the transistors Q53, Q54 and Q55, the bases of the transistors Q53, Q54 and Q55 are connected to each other, the emitter of the transistor Q59 is connected to the base of the transistor Q55, the collector and base of the transistor Q62 respectively, the emitter of the transistor Q62 is connected to the collector and base of the transistor Q61, the emitter of the transistor Q61 is connected to the collector and base of the transistor Q60, the emitter of the transistor Q60 is connected to the collector and base of the transistor Q44, and the emitter of the transistor Q44 is connected to the negative power supply.

[0050] The collector of the triode Q63 is connected to the base of the triode Q45, one end of the resistor R27 is connected to the collector of the triode Q54, the other end of the resistor R27 is connected to the collector of the triode Q38 and the base of the triode Q40, the collector of the triode Q40 is connected to the negative power supply, the emitter of the triode Q40 is connected to one end of the resistor RQ37, the other end of the resistor RQ37 is connected to the output end of the output stage circuit and one end of the resistor R39, the other end of the resistor R39 is connected to the collector and base of the triode Q41, the emitter of the triode Q41 is connected to the negative power supply.

[0051] The base of the triode Q38 is connected to the other end of the resistor RQ37, the emitter of the triode Q38 is connected to one end of the resistor R24, the other end of the resistor R24 is connected to the negative power supply; the bases of the triodes Q53 and Q54 are connected to the emitter of the triode Q51, the collector of the triode Q51 is connected to the negative power supply; the base of the triode Q53 is connected to one end of the capacitor C8, the emitter of the triode Q53 is connected to the base of the triode Q51, the other end of the capacitor C8 and the collector of the triode Q46; the emitter of the triode Q46 is connected to the collector and base of the triode Q43 respectively, the emitter of the triode Q43 is connected to the negative power supply.

[0052] The base of the triode Q43 is connected to the base of the triode Q45, one end of the resistor R26 is connected to the bases of the triodes Q52 and Q56, the other end of the resistor R26 is connected to the negative power supply.

[0053] The collector of the triode Q55 is connected to one end of the resistor R23, the other end of the resistor R23 is connected to the base of the triode Q0 and the collector of the triode Q38-2, the collector of the triode Q0 is connected to the positive power supply, the emitter of the triode Q0 is connected to one end of the resistor R0, the other end of the resistor R0 is connected to the base of the triode Q38-2 and one end of the resistor R1 as the output end of the starting and biasing circuit.

[0054] The emitter of the triode Q38-2 is connected to one end of the resistor R24-2, the other end of the resistor R24-2 is connected to the negative power supply; the other end of the resistor R1 is connected to the collector and base of the triode Q1, the emitter of the triode Q1 is connected to the negative power supply.

[0055] In summary, the circuit of the high-precision and low-noise operational amplifier in the application has the characteristics of low offset voltage and low bias current, the application can transplant the foreign circuit to the domestic process line, and can also be transplanted in other layout structures, and the structure is completely suitable for the domestic anti-radiation process line, and has good economic and military prospects.

Claims

1. A radiation-hardened structure of a high-precision operational amplifier, characterized by, The input stage circuit comprising an operational amplifier, the input differential pair tube in the input stage circuit adopts triode QD1 and triode QD2 to form an input NPN pair tube; The layout structure of the input NPN pair tube adopts a four-tube cross structure; an aluminum wire is arranged between the emitter and the collector of the triode QD1 and the triode QD2, the spacing between the emitter and the aluminum wire is 5-8 μm, the input NPN pair tube of the input stage circuit comprises a capacitor C6, a resistor R12 and a resistor R11, one end of the resistor R12 is connected to a positive power supply, one end of the resistor R11 is connected to the positive power supply, one end of the capacitor C6 is connected to the positive power supply, the other end of the resistor R12 is connected to one end of a resistor R8, one end of a capacitor C1 and the other end of the capacitor C6, the other end of the capacitor C1 is connected to one end of a resistor 10; one end of the resistor R11 is respectively connected to one end of a resistor R9 and the other end of the resistor R10, the other end of the resistor R8 is connected to the collector of the triode QD1, one end of the resistor R9 is connected to the collector of the triode QD2; a bridge circuit composed of diodes Q1, Q2, Q3 and Q4 is connected between the base of the triode QD1 and the base of the triode QD2, the emitter of the triode QD1 and the emitter of the triode QD2 are respectively connected to a negative power supply.

2. The radiation-hardened structure of a high-precision operational amplifier according to claim 1, wherein The spacing between the emitter and the aluminum wire between the emitter and the collector is 5 μm.

3. The radiation-hardened structure of a high-precision operational amplifier according to claim 1, wherein The aluminum wire is arranged between the emitter and the collector by using a photolithography technology.

4. The radiation-hardened structure of a high-precision operational amplifier according to claim 1, wherein The width of the aluminum wire is 6-8 μm.

5. The radiation-hardened structure of a high-precision operational amplifier according to claim 1, wherein The spacing between the aluminum wire and the emitter and the collector is equal.

Images