Radiation-hardened bandgap reference circuit

Abstract

The present invention relates to a radiation-resistant bandgap reference circuit, comprising a bandgap reference structure circuit for generating a reference voltage and a compensation current generating circuit for current compensation of transistors within the bandgap reference structure circuit. By performing current compensation on the transistors within the bandgap reference structure, the present invention reduces the impact of radiation effects on the transistor's current gain. While achieving radiation resistance, the present invention eliminates the need for high bias currents, effectively reducing system power consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, in particular to an anti-radiation bandgap reference source circuit. Background Art

[0002] With the development of nuclear energy and space technology, an increasing number of electronic devices are being used in various radiation environments, including electromagnetic radiation in space and radiation generated by nuclear power plants. Microelectronic devices are the fundamental building blocks of electronic equipment, and semiconductors and microelectronic devices are extremely sensitive to this radiation. Radiation can affect the performance and functionality of electronic devices to varying degrees, even causing them to fail. The demand for long life in space systems is increasing, and a key design challenge for long-life electronic devices is hardening them against total dose effects.

[0003] In space radiation environments, the radiation environment affects the minority carrier lifetime of transistors, thereby affecting their electrical parameters. Radiation-induced space charge and interface states in the oxide layer increase the surface recombination rate, reducing current gain and, in turn, affecting the accuracy of the reference voltage. For example, at 100 krad (Si), the current gain of a transistor can drop to approximately 50% of its normal value.

[0004] An accurate reference voltage is required in most electronic circuits. Bandgap reference structures are widely used as reference voltage providers due to their excellent temperature coefficient and stability. However, bandgap reference structures are primarily based on transistors. However, radiation effects can reduce the transistor's current gain, and changes in current gain directly affect the accuracy of the bandgap reference voltage. Radiation effects also generate photocurrents between PN junctions. Traditional bandgap reference structures are highly sensitive to both transistor current gain and radiation-generated photocurrents, resulting in poor radiation resistance.

[0005] Therefore, to address the impact of radiation effects on bandgap reference structures, there are two main traditional solutions: one is to develop a dedicated radiation-resistant process line that specifically optimizes the radiation effects of devices with bandgap reference structures, thereby ensuring that the current gain of the transistor does not change much under radiation conditions; the other is to bias the transistor at a higher current, at which point the current gain is relatively less affected by radiation. However, developing a customized process requires a long development cycle, high capital investment, and great development difficulty. Furthermore, when the transistor is biased at a higher current, the operating region is not the optimal operating region for the transistor, and this operating condition requires a larger bias current. The operating current of the bandgap reference circuits of common radiation-resistant devices is 2mA or above, resulting in high system power consumption.

[0006] In summary, the traditional method of solving the influence of radiation effect on the bandgap reference source structure still has the above shortcomings. Summary of the Invention

[0007] Based on this, it is necessary to provide a radiation-resistant bandgap reference source circuit to address the problems of complex process or high power consumption of traditional radiation-resistant bandgap reference source circuits.

[0008] To solve the above technical problems, the bandgap reference source structure circuit proposed in the present invention includes: a bandgap reference source structure circuit for generating a reference voltage; and a compensation current generating circuit for performing current compensation on the transistors in the bandgap reference source structure circuit.

[0009] According to a preferred embodiment of the present invention, the bandgap reference source structure circuit includes: a current mirror circuit, which includes a first MOS transistor and a second MOS transistor, wherein the two sources of the first MOS transistor and the second MOS transistor are connected, the two gates are connected, and the two drains serve as the first output arm and the second output arm of the current mirror circuit respectively; and a transistor pair consisting of a first triode and a second triode; wherein the collectors of the first triode and the second triode are connected to the first output arm and the second output arm of the current mirror circuit respectively.

[0010] According to a preferred embodiment of the present invention, the bandgap reference source structure circuit further includes a startup circuit connected to the collector of the first transistor, the gate of the first MOS transistor, and the gate of the second MOS transistor.

[0011] According to a preferred embodiment of the present invention, the bandgap reference source structure circuit further includes: a unity gain buffer connected to the base of the first transistor and the collector of the second transistor respectively.

[0012] According to a preferred embodiment of the present invention, the bandgap reference source structure circuit further includes: a base resistor connected between the bases of the first transistor and the second transistor.

[0013] According to a preferred embodiment of the present invention, the bandgap reference source structure circuit also includes a first resistor and a second resistor, wherein the first resistor and the second resistor constitute a resistor divider network, the two ends of the first resistor are respectively connected to the emitters of the first transistor and the second transistor, one end of the second resistor is connected to the emitter of the second transistor, and the other end is grounded.

[0014] According to a preferred embodiment of the present invention, the compensation current generating circuit includes a first part and a second part, the first part is used to generate a first output current I OUT1 and the second output current I OUT2 The second part is used to process the first output current and the second output current to obtain a first compensation current I CMP1 and the second compensation current I CMP2 ,

[0015] The first output current and the second output current satisfy:

[0016] I OUT1 =I B1 +I PBE1

[0017] I OUT2 =I B2 +I PBE2

[0018] I B1 is the base current of the first transistor, I PEB1 The photocurrent I between the base and emitter of the first transistor B2 is the base current of the second transistor, I PEB2 the photocurrent between the base and emitter of the second transistor;

[0019] The first compensation current I CMP1 and the second compensation current I CMP2 satisfy:

[0020] I CMP1 =I OUT2 -2×I CMP2

[0021] I CMP2 =I OUT1 -I OUT2 .

[0022] According to a preferred embodiment of the present invention, the first part of the compensation current generating circuit includes a third MOS transistor, a first compensation triode, a first output MOS transistor between the third MOS transistor and the first compensation triode, and a fourth MOS transistor, a second compensation triode, and a second output MOS transistor between the fourth MOS transistor and the second compensation triode.

[0023] According to a preferred embodiment of the present invention, the second part of the compensation current generating circuit includes a first compensation current generating circuit and a second compensation current generating circuit to generate the first compensation current I CMP1 and the second compensation current I CMP2 . BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the equivalent circuit diagram of the radiation-hardened bandgap reference circuit with photocurrent;

[0025] Figure 2 1 is an equivalent circuit diagram of a radiation-resistant bandgap reference source circuit according to an embodiment of the present invention;

[0026] Figure 3 is an equivalent circuit diagram of a compensation current generating circuit according to an embodiment of the present invention;

[0027] Figure 4 is a first compensation current I according to an embodiment of the present invention. CMP1 Generate circuit diagrams;

[0028] Figure 5 is the second compensation current I in one embodiment of the present invention CMP2 Generate circuit diagrams;

[0029] Figure 6 Schematic diagram of reference voltage changes under radiation environment of the bandgap reference source circuit according to the embodiment of the present invention and the prior art. DETAILED DESCRIPTION

[0030] In order to better understand the purpose, technical solutions and technical effects of the present invention, the present invention is further explained below with reference to the accompanying drawings and embodiments. It is also stated that the embodiments described below are only used to illustrate the present invention and are not intended to limit the present invention.

[0031] The present invention proposes a radiation-resistant method for a bandgap reference structure. This method performs current compensation on transistors in the bandgap reference structure to reduce the impact of radiation on the transistor's current gain. Specifically, current compensation can be performed on each transistor in the bandgap reference structure.

[0032] Figure 1 is the equivalent circuit diagram of the bandgap reference source circuit with photocurrent, as shown in Figure 1 As shown, the bandgap reference source structure circuit includes a current mirror circuit and a reference voltage generating circuit composed of a pair of transistors, wherein the collectors of the pair of transistors are respectively connected to the output arms of the current mirror circuit.

[0033] Specifically, if Figure 1 As shown, the current mirror circuit includes a first MOS transistor M1 and a second MOS transistor M2. The two sources of the first MOS transistor M1 and the second MOS transistor M2 are connected, the two gates are connected, and the two drains serve as the first output arm and the second output arm of the current mirror circuit, respectively connected to the first transistor Q1 and the second transistor Q2. Figure 2 As shown, the first transistor Q1 and the second transistor Q2 form a transistor pair. That is, the collectors of the first transistor Q1 and the second transistor Q2 are respectively connected to the first output arm and the second output arm of the current mirror circuit, that is, the drain of the first MOS transistor M1 and the drain of the second MOS transistor M2.

[0034] As a preferred embodiment, the first MOS transistor M1 and the second MOS transistor M2 have the same size to offset the photocurrent in the bandgap reference source circuit.

[0035] As a preferred embodiment, Figure 1 As shown, the bandgap reference source circuit includes, in addition to the above basic circuit elements, a startup circuit connected to the collector of the first transistor Q1, the gate of the first MOS transistor M1, and the gate of the second MOS transistor M2.

[0036] As a preferred embodiment, Figure 1 As shown, the bandgap reference source circuit further includes a unit gain buffer connected to the base of the first transistor Q1 and the collector of the second transistor Q2 respectively.

[0037] Figure 2 FIG. 1 is an equivalent circuit diagram of a radiation-resistant bandgap reference source circuit according to an embodiment of the present invention. As a preferred embodiment, Figure 2 As shown, the bandgap reference source circuit further includes a base resistor R3 connected between the bases of the first transistor Q1 and the second transistor Q2.

[0038] As a preferred embodiment, Figure 1 As shown, the bandgap reference source circuit also includes a first resistor R1 and a second resistor R2. The first resistor R1 and the second resistor R2 form a resistor divider network. The two ends of the first resistor R1 are respectively connected to the emitters of the first transistor Q1 and the second transistor Q2. One end of the second resistor R2 is connected to the emitter of the second transistor Q2, and the other end is grounded.

[0039] The following describes the quantitative relationship of photocurrent under radiation environment. For the convenience of explanation, I PCS1 , I PBE1 , I PCB1 They represent the photocurrents between the collector and ground, between the base and emitter, and between the collector and base of the first transistor Q1, respectively. PCs2 , I PBE2 , I PCB2 They represent the photocurrents between the collector and ground, between the base and emitter, and between the collector and base of the second transistor Q2, respectively, and satisfy:

[0040] I PCS1 =I PCS2 , I PCB1 =I PCB2 , I pBE1 =N×I PBE2 .

[0041] According to the working principle of triode:

[0042]

[0043] I E =I C +I B

[0044]

[0045] Among them, I B is the base current of the transistor, I C is the collector current of the transistor, I E is the emitter current of the transistor, and β represents the current gain of the transistor.

[0046] For the convenience of description, the following variables are defined:

[0047] I B1 is the base current of the first transistor Q1, I C1 is the collector current of the first transistor Q1, I E1 is the emitter current of the first transistor Q1, V BE1 is the base-emitter voltage of the first transistor Q1.

[0048] I B2 is the base current of the second transistor Q2, I C2 is the collector current of the second transistor Q1, I E2 is the emitter current of the second transistor Q2, V BE2 is the base-emitter voltage of the second transistor Q1.

[0049] according to Figure 1 have:

[0050] I C1 +I PCS1 +I PCB1 =I C2 +I PCS2 +I PCB2

[0051] Since the MOS tube M1 and MOS tube M2 have the same size, I PCS1 , I PCB1 , I PCS2 , I PCB2 can be offset, so there is I C1 =I C2 , I E1 =I E2 .

[0052] make:

[0053] ΔV BE =V BE2 -V BE1

[0054]

[0055] Therefore, ΔV BE Not affected by the current gain β.

[0056] Right now:

[0057]

[0058]

[0059] So V BE2 It will be affected by the change of current gain β and photocurrent.

[0060] At this time, the reference voltage V REF for:

[0061]

[0062] It can be seen from this that the reference voltage V REF The accuracy of the device is affected by the change of the current gain β and the photocurrent, and since the current gain β and the photocurrent change with the length of time the device is exposed to radiation, its accuracy cannot be improved by trimming.

[0063] In this embodiment, if Figure 2 As shown, the radiation-resistant bandgap reference source circuit of this embodiment also includes a compensation current generating circuit. The compensation current generating circuit includes a current source circuit for generating a compensation current. The two ends of the compensation current are respectively connected to the emitters of the first transistor Q1 and the second transistor Q2. The compensation currents generated are respectively as follows: Figure 2 The first compensation current I CMP1 and the second compensation current I CMP2 .

[0064] at this time:

[0065]

[0066] According to I PBE1 =N×I PBE2 , when R3=R1, I CMP1 =(N-1)I PBE2 , then:

[0067]

[0068] Visible I C2 It is not affected by the current gain β and the photocurrent, so V BE2 Not affected by current gain β and photocurrent.

[0069] at the same time:

[0070] V REF =V BE2 +(I E2 +I PBE2 +I cmp2 +I E1 +I PBE1-I cmp1 )×R2

[0071] Take I CMP2 =2×I B2 -2×I PBE2 , will I E2 =I E1 , I PBE1 =N×I PBE2 , I CMP1 =(N-1)×I PBE2 Bring in:

[0072]

[0073] It can be seen that the reference voltage V REF Both terms of are not affected by the current gain β and the photocurrent, so the reference voltage V REF Not affected by current gain β and photocurrent.

[0074] Figure 3 FIG. 1 is an equivalent circuit diagram of a compensation current generating circuit according to an embodiment of the present invention. Figure 3 As shown, the compensation current generating circuit of this embodiment includes a first part and a second part, the first part is used to generate a first output current I OUT1 and the second output current I OUT2 The second part is used to process the first output current and the second output current to obtain a first compensation current I CMP1 and the second compensation current I CMP2 .

[0075] like Figure 3 As shown, the first part includes a third MOS transistor M3, a first compensation transistor Q1A, a first output MOS transistor M1A between the third MOS transistor M3 and the first compensation transistor Q1A, and a fourth MOS transistor M4, a second compensation transistor Q2A, and a second output MOS transistor M2A between the fourth MOS transistor M4 and the second compensation transistor Q2A.

[0076] Substituting the photocurrent radiation model of the transistor into the equation, we can obtain:

[0077] I CQ1A =I C1

[0078] I OUT1 =I B1A +I PBE1A

[0079] I OUT2 =I B2A +I PBE2A

[0080] As a preferred embodiment, the first compensation transistor Q1A and the first transistor Q1 have the same size and shape, so I B1A =I B1 , I PBE1A =I PBE1 The second compensation transistor Q2A and the second transistor Q2 have the same size and shape, then I B2A =I B2 , I PBE2A =I PBE2 ;thus,

[0081] I OUT1 =I B1 +I PBE1

[0082] I OUT2 =I B2 +I PBE2

[0083] Because I PBE1 =N×I PBE2 , I B1 =I B2 , by the first output current I OUT1 and the second output current I OUT2 After processing, the first compensation current I CMP1 and the second compensation current I CMP2 .

[0084] I CMP2 =(N-1)×I PBE2

[0085] =IO UT1 -I OUT2

[0086]

[0087] The second part of the compensation current generating circuit includes a first compensation current generating circuit and a second compensation current generating circuit to obtain a first compensation current I that meets the above conditions. CMr1 and the second compensation current I CMP2 .

[0088] Figure 4 is a first compensation current I in one embodiment of the present invention CMP1 The circuit diagram of the production process. Figure 4 As shown, the first compensation current I CMP1 The generating circuit is composed of four MOS transistors constituting a current source circuit. The four MOS transistors are paired with each other. The sources of the two MOS transistors in a pair are connected, and the drain of one of the MOS transistors is used to output the first compensation current I CMP1 .

[0089] Figure 5 I is the second compensation current of an embodiment of the present invention CMP2 Generate a circuit diagram. Figure 5 As shown, the second compensation current I CMP2 The generating circuit is composed of four MOS transistors constituting a current source circuit. The four MOS transistors are paired with each other. The sources of the two MOS transistors in a pair are connected, and the drain of one of the MOS transistors is used to output the second compensation current I CMP2 .

[0090] Figure 6 The figure shows the reference voltage variation under radiation conditions for an embodiment of the present invention and a conventional bandgap reference circuit. Using the radiation-hardened bandgap reference circuit of the embodiment of the present invention, the compensated reference voltage variation is only 3mV, indicating minimal radiation impact. The uncompensated reference voltage variation, on the other hand, reaches 20mV. This shows that the radiation-hardened bandgap reference circuit of the present invention improves the accuracy of the bandgap reference circuit under radiation conditions by compensating for variations in transistor current gain β and photocurrent.

[0091] As described above, the radiation-resistant bandgap reference circuit of the present invention incorporates a compensation current generation circuit to compensate for the transistors in the bandgap reference circuit structure. This achieves radiation resistance while avoiding high bias currents and effectively reducing system power consumption. Therefore, the present invention can shorten development cycles, reduce capital investment, and ease development difficulty.

[0092] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0093] The above embodiments merely represent specific implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be based on the appended claims.

Claims

1. A radiation-resistant bandgap reference source circuit, characterized in that: It includes a bandgap reference source structure circuit and a compensation current generating circuit, wherein: The bandgap reference source structure circuit is used to generate a reference voltage; The bandgap reference source structure circuit includes a current mirror circuit, a transistor pair consisting of a first transistor and a second transistor, a first resistor and a second resistor; The current mirror circuit includes a first MOS transistor and a second MOS transistor, wherein the two sources of the first MOS transistor and the second MOS transistor are connected, the two gates are connected, and the two drains serve as the first output arm and the second output arm of the current mirror circuit respectively; The collectors of the first transistor and the second transistor are connected to the first output arm and the second output arm of the current mirror circuit respectively; The first resistor and the second resistor form a resistor voltage divider network, wherein both ends of the first resistor are connected to the emitters of the first transistor and the second transistor respectively, one end of the second resistor is connected to the emitter of the second transistor, and the other end is grounded; The compensation current generating circuit is used to perform current compensation on the transistor in the bandgap reference source structure circuit; The compensation current generating circuit includes a first part and a second part, the first part is used to generate a first output current I OUT1 and the second output current I OUT2 The second part is used to process the first output current and the second output current to obtain a first compensation current I CMP1 and the second compensation current I CMP2 , The first part of the compensation current generating circuit includes a third MOS transistor, a first compensation triode, a first output MOS transistor between the third MOS transistor and the first compensation triode, and a fourth MOS transistor, a second compensation triode, and a second output MOS transistor between the fourth MOS transistor and the second compensation triode; The second part of the compensation current generating circuit includes a first compensation current generating circuit and a second compensation current generating circuit to generate the first compensation current I CMP1 and the second compensation current I CMP2 ; The first output current and the second output current satisfy: I OUT1 =I B1 +I PBE1 I OUT2 =I B2 +I PBE2 I B1 is the base current of the first transistor, I PEB1 The photocurrent I between the base and emitter of the first transistor B2 is the base current of the second transistor, I PEB2 the photocurrent between the base and emitter of the second transistor; The first compensation current I CMP1 and the second compensation current I CMP2 satisfy: I CMP1 =I OUT2 -2×I CMP2 I CMP2 =I OUT1 -I OUT2 。 2. The radiation-resistant bandgap reference source circuit according to claim 1, wherein: The bandgap reference source structure circuit also includes: A startup circuit connected to the collector of the first transistor, the gate of the first MOS transistor, and the gate of the second MOS transistor.

3. The radiation-resistant bandgap reference source circuit according to claim 2, wherein: The bandgap reference source structure circuit also includes: A unity gain buffer is connected to the base of the first transistor and the collector of the second transistor respectively.

4. The radiation-resistant bandgap reference source circuit according to claim 3, wherein: The bandgap reference source structure circuit also includes: A base resistor is connected between the bases of the first transistor and the second transistor.

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