DAC module with anti-radiation reinforcement structure
By employing a triple-mode redundancy structure and a multi-layered radiation hardening structure in the DAC module, and utilizing a ring-gate MOS transistor, polysilicon resistor, and well contact protection ring manufactured using standard CMOS technology, the problem of optimizing the balance between total dose effect and single-event effect in the DAC module under space radiation environment was solved, achieving low-cost and high-reliability signal conversion.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2026-05-07
- Publication Date
- 2026-07-21
AI Technical Summary
Existing DAC modules struggle to achieve an optimal balance between total dose effect and single-event effect in space radiation environments. Existing radiation hardening solutions are costly, have limited technological maturity, and poor compatibility with standard processes, while lack synergy among the various hardening structures.
The digital control logic unit with a triple redundancy structure and the digital-to-analog converter core unit with a multi-level radiation hardening structure, including a ring gate MOS transistor, polysilicon resistors and well contact protection rings, are all manufactured using standard CMOS technology to form a closed ring structure to resist radiation effects.
It achieves effective resistance to total dose effect and single-event effect at low cost and with high process adaptability, ensuring the accuracy and stability of digital and analog signal conversion of DAC module, and improving the reliability of aerospace applications.
Smart Images
Figure CN122437541A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of circuit hardening technology, and more specifically, to a DAC module with a radiation-hardened structure. Background Technology
[0002] A digital-to-analog converter (DAC) is a key component in electronic systems, responsible for the precise conversion between digital and analog signals. It is widely used in critical functional modules such as attitude control, communication transceivers, telemetry and remote control, and scientific payloads. In space missions involving satellites, spacecraft, and deep space probes, DACs must operate stably for extended periods in complex and harsh space environments; their reliability and accuracy directly impact the overall system performance and even the success or failure of the mission. In the space environment, high-energy particle radiation (such as cosmic rays, solar particles, protons and heavy ions in the Van Allen radiation belts) is a major factor threatening the performance and reliability of DACs. Its damage mechanisms can be summarized into two categories: First, the total dose effect, that is, under the long-term cumulative ionizing radiation, the gate oxide layer of the device gradually accumulates trap charges, which leads to threshold voltage drift, transconductance degradation, and increased leakage current of the MOS transistor, ultimately causing the DAC's integral nonlinearity (INL) and differential nonlinearity (DNL) to deteriorate, reduce output accuracy, or even cause functional failure. Second, the single-event effect, that is, a single high-energy particle penetrates the sensitive area of the device and ionizes to generate a large number of electron-hole pairs in a short time, which may cause a single-event transient (SET) that causes a momentary jump in the output signal, or cause a single-event upset (SEU) that causes errors in the digital control logic state. In severe cases, it may also trigger a single-event latch-up (SEL), leading to permanent damage to the device.
[0003] In related technologies, to address the aforementioned radiation threats, DAC modules primarily employ two radiation hardening techniques: First, process hardening, which utilizes radiation-hardened manufacturing processes such as silicon-on-insulator (SOI) or special epitaxial processes to enhance the intrinsic radiation resistance of the device at the material level. However, this approach is typically costly, has limited process maturity, and poor compatibility with standard processes. Second, design hardening, which enhances radiation tolerance on the basis of conventional CMOS processes through circuit-level methods such as redundant design, guard rings, and isolation structures. However, existing design hardening schemes often exhibit fragmented characteristics, lacking systematic synergy between various hardening structures. For example, the total dose hardening of the current source array and the single-event hardening of the digital control logic often operate independently, and the layout fails to effectively isolate digital noise from analog sensitive areas, resulting in limited overall hardening effectiveness and difficulty in achieving an optimal balance between total dose tolerance, single-event immunity, and output accuracy. Summary of the Invention
[0004] The present invention aims to solve at least one of the above-mentioned problems.
[0005] To address the above problems, this invention provides a DAC module with a radiation-hardened structure, comprising a digital control logic unit and a digital-to-analog conversion core unit; The digital control logic unit adopts a triple-modulus redundancy structure, which is used to transmit control signals to the digital-to-analog conversion core unit and shield single-particle flip errors. The digital-to-analog conversion core unit includes multiple unit current source subunits for converting the control signal into an analog signal. A trap contact protection ring is provided between adjacent unit current source subunits. Each unit current source subunit includes: A ring-gate MOS transistor, wherein the gate surrounds the active region to form a closed ring structure, and the well contact protection ring is electrically connected to the body region of the ring-gate MOS transistor. A polysilicon resistor is connected in series with the source or drain of the ring-gate MOS transistor; A parallel switch group includes at least two parallel-connected and synchronously controlled switching transistors for controlling the on / off state of the unit current source subunit; The ring gate MOS transistor, the polysilicon resistor, and the well contact protection ring are all manufactured using standard CMOS technology.
[0006] Optionally, the ring-gate MOS transistors in the plurality of unit current source sub-units are all formed in the same well region, the gate of the ring-gate MOS transistor is formed on the active region, the active region has a symmetrical polygonal structure, the gate continuously surrounds the edge of the active region to surround the channel region, and the distance between the active region and the adjacent well contact protection ring is less than or equal to a preset distance.
[0007] Optionally, the switching transistors adopt a ring gate structure, and the gates, drains, and sources of each switching transistor are shorted to each other to form a redundant conduction path; when any of the switching transistors is momentarily turned on or off due to a single particle impact, the equivalent resistance change of the remaining switching transistors in the parallel path is less than a preset threshold.
[0008] Optionally, the polysilicon resistor is disposed above the shallow trench isolation region, and its two ends are respectively connected to the metal interconnect layer through contact holes. Shallow trench isolation dielectric is provided below and around the polysilicon resistor.
[0009] Optionally, the well contact protection ring includes a first type doped region, a second type doped region, and a metal contact layer. The first type doped region is disposed in the well region and surrounds the ring gate MOS transistor. The second type doped region is disposed between the first type doped region and the well region. The metal contact layer is electrically connected to the first type doped region at a fixed potential.
[0010] Optionally, the triple redundancy structure includes three logic operation sub-modules and a majority voter. The three logic operation sub-modules receive the same input signal and perform logic operations respectively. The majority voter performs a majority vote on the output results of the three logic operation modules to obtain the control signal, and outputs the control signal to the control terminal of the unit current source sub-unit.
[0011] Optionally, an isolation ring structure is provided between the digital control logic unit and the digital-to-analog conversion core unit. The isolation ring structure includes a first annular deep well surrounding the digital control logic unit and a second annular deep well surrounding the digital-to-analog conversion core unit, and the first annular deep well and the second annular deep well are separated by a shallow trench isolation region.
[0012] Optionally, the digital-to-analog conversion core unit further includes: A reference current source, the output of which is connected to the input of each of the unit current source sub-units; The reference current source is equipped with a thermometer encoder. The output of the thermometer encoder is connected to the control terminal of each of the parallel switch groups through redundant interconnects. The redundant interconnects include at least two parallel and isolated metal lines.
[0013] Optionally, the DAC module with radiation-hardened structure further includes: The output unit is a differential amplifier, and its input terminal is connected to the output terminal of the digital-to-analog conversion core unit. The input differential pair transistors of the differential amplifier adopt a ring gate structure, and a center tap protection ring is provided between the input differential pair transistors. The center tap protection ring is electrically connected to the common mode potential.
[0014] Optionally, the digital-to-analog converter core unit is located in the central area of the module layout, the digital control logic unit and the output unit are located on both sides of the digital-to-analog converter core unit, and a protective ring isolation band is provided between the digital control logic unit and the digital-to-analog converter core unit, and between the output unit and the current-rudder type digital-to-analog converter array.
[0015] The beneficial effects of the DAC module with radiation-hardened structure of the present invention are: Through the synergistic effect of multi-level radiation hardening structures at the device, unit, and system levels, the radiation resistance of the DAC module is systematically improved, thereby ensuring stable and accurate conversion between digital and analog signals. At the system level, the digital control logic unit adopts a triple-modulus redundancy structure to transmit control signals, effectively shielding control signal errors caused by single-event upsets and ensuring accurate and stable control signal transmission. At the device level, the ring-gate MOS transistor, with its gate surrounding the active region to form a closed ring structure within the unit current source sub-unit, suppresses parasitic leakage current caused by total dose effects. The polysilicon resistor connected in series with its source or drain further stabilizes the output current, protecting the device itself from radiation-induced performance degradation. At the unit level, adjacent unit current source sub-units are connected to the ring-gate MOS transistor body... The well contact protection ring with electrical connection can quickly collect radiation-induced photocurrent. The parallel switch group, composed of at least two parallel synchronously controlled switching transistors, can resist output switching abnormalities caused by single-event transient effects with redundant conduction paths, ensuring stable unit output. At the same time, the ring gate MOS transistor, polysilicon resistor and well contact protection ring are all manufactured using standard CMOS technology, without the need for special radiation-hardening processes. This results in low cost and high process maturity, solving the core problems of existing radiation hardening methods for aerospace DAC modules, such as high cost, limited process maturity, poor compatibility with standard processes, fragmentation, and lack of synergy among various structures. Furthermore, it achieves effective resistance to total dose effect and single-event effect through multi-level synergistic hardening, balancing low cost, high process adaptability and the high reliability required for aerospace applications. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the structure of a DAC module with a radiation-hardened structure provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a unit current source subunit provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the layout of the trap contact protection ring provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the three-modulus redundancy structure provided in an embodiment of the present invention; Figure 5 A schematic diagram of redundant interconnection of a unit current source subunit provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the layout of a DAC module with a radiation-hardened structure provided in an embodiment of the present invention. Detailed Implementation
[0017] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.
[0018] It should be understood that the various steps described in the method embodiments of the present invention may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present invention is not limited in this respect.
[0019] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used only to distinguish different devices, modules, or units, and are not intended to limit the order of functions performed by these devices, modules, or units or their interdependencies.
[0020] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".
[0021] The names of the messages or information exchanged between the multiple devices in the embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of these messages or information.
[0022] like Figure 1 As shown, an embodiment of the present invention provides a DAC module with a radiation-hardened structure, including a digital control logic unit and a digital-to-analog conversion core unit; The digital control logic unit adopts a triple-modulus redundancy structure, which is used to transmit control signals to the digital-to-analog conversion core unit and shield single-event upset errors.
[0023] Specifically, the digital control logic unit 200 is electrically connected to the digital-to-analog converter core unit. The digital control logic unit 200 employs a triple-modulus redundancy structure 210. Its core function is to convert externally input digital signals into control signals, such as thermometer-encoded signals, and transmit the radiation-hardened control signals to the digital-to-analog converter core unit, preventing control signal transmission failure due to space radiation. In this embodiment, the triple-modulus redundancy structure 210 is the core radiation-hardened design of the digital control logic, ensuring the control signals' resistance to single-event upsets. It forms a stable electrical connection path with the digital-to-analog converter core unit, collaboratively completing the conversion control from digital to analog signals. The beneficial effect of this embodiment is that the triple-modulus redundancy structure can effectively resist control logic errors caused by single-event upsets, providing a reliable control foundation for the accurate operation of the subsequent digital-to-analog converter core unit.
[0024] The digital-to-analog conversion core unit includes multiple unit current source subunits for converting the control signal into an analog signal. A trap contact protection ring is provided between adjacent unit current source subunits. Each unit current source subunit includes: A ring-gate MOS transistor, wherein the gate surrounds the active region to form a closed ring structure, and the well contact protection ring is electrically connected to the body region of the ring-gate MOS transistor. A polysilicon resistor is connected in series with the source or drain of the ring-gate MOS transistor; A parallel switch group includes at least two parallel-connected and synchronously controlled switching transistors for controlling the on / off state of the unit current source subunit; The ring gate MOS transistor, the polysilicon resistor, and the well contact protection ring are all manufactured using standard CMOS technology.
[0025] Specifically, such as Figure 1 As shown, the core unit of the digital-to-analog conversion adopts a current-rudder type digital-to-analog converter array 100, which is used to convert the control signal into an analog signal, such as an analog current. The current-rudder type digital-to-analog converter array 100 is composed of multiple unit current source sub-units 110 arranged in rows and columns, such as... Figure 3 As shown, a trap contact protection ring 120 is provided between adjacent unit current source sub-units 110. Figure 2As shown, each unit current source sub-unit 110 integrates three core structures: a ring-gate MOS transistor 111, a polysilicon resistor 112, and a parallel switch group 113. The gate of the ring-gate MOS transistor 111 forms a closed ring structure around the active region to suppress parasitic leakage current caused by the total dose effect; the well contact protection ring 120 is electrically connected to the body region of the ring-gate MOS transistor 111 to collect radiation-induced photocurrent; the polysilicon resistor 112 is connected in series to the source or drain of the ring-gate MOS transistor 111 to stabilize the output current; the parallel switch group 113 contains at least two parallel and synchronously controlled switching transistors to control the output switching of the unit current source sub-unit 110 to resist single-event transient effects. The aforementioned ring-gate MOS transistor 111, polysilicon resistor 112, and well contact protection ring 120 are all fabricated based on standard CMOS technology and have no special process requirements. A ring-gate MOS transistor 111 serves as the core current output device, a polysilicon resistor 112 assists in stabilizing the current, a parallel switch group 113 performs on / off control, and a trap contact protection ring 120 protects against radiation interference. These four components work together to form the radiation-resistant core of the unit current source subunit 110. Using standard CMOS technology lowers the process threshold for aerospace DAC modules, and the multi-layered device structure collaboratively resists the total dose effect and single-event effect of space radiation, ensuring the current output accuracy and operational stability of the digital-to-analog conversion core unit.
[0026] For example, the DAC module can be manufactured using a bulk silicon CMOS process, the main steps of which include: forming deep well and shallow trench isolation on a P-type silicon substrate; forming a gate oxide layer and a polysilicon gate for a ring gate MOS transistor 111; forming a lightly doped drain region and sidewalls; forming source and drain doping, while simultaneously forming a doped region for a well contact guard ring 120; forming a polysilicon resistor 112 located above the shallow trench isolation region; depositing an interlayer dielectric to form contact holes and metal interconnects; forming redundant interconnects 320 and guard ring isolation bands; and finally passivating and encapsulating it in a ceramic or metal hermetically sealed housing.
[0027] In this embodiment, the radiation resistance of the DAC module is systematically improved through the synergistic effect of multi-level radiation hardening structures at the device, unit, and system levels, thereby ensuring stable and accurate conversion between digital and analog signals. At the system level, the digital control logic unit adopts a triple-modulus redundancy structure to transmit control signals, which can effectively shield control signal errors caused by single-event upsets and ensure accurate and stable control signal transmission. At the device level, the ring-gate MOS transistor, which forms a closed ring structure around the active region within the unit current source sub-unit, can suppress parasitic leakage current caused by the total dose effect. The polysilicon resistor connected in series with its source or drain can further stabilize the output current, thus resisting radiation-induced performance degradation from the device itself. At the unit level, adjacent unit current source sub-units are connected to the ring-gate MOS transistor. The trap contact protection ring, electrically connected to the body region of the tube, can quickly collect radiation-induced photocurrent. The parallel switch group, composed of at least two parallel synchronously controlled switching transistors, can resist output switching anomalies caused by single-event transient effects with redundant conduction paths, ensuring stable unit output. At the same time, the ring gate MOS transistor, polysilicon resistor, and trap contact protection ring are all manufactured using standard CMOS technology, requiring no special radiation-hardening process. This approach is low-cost and has high process maturity, solving the core problems of existing radiation hardening methods for aerospace DAC modules, such as high cost, limited process maturity, poor compatibility with standard processes, fragmentation, and lack of synergy among various structures. Furthermore, it effectively resists total dose effects and single-event effects through multi-level synergistic hardening, balancing low cost, high process adaptability, and the high reliability required for aerospace applications.
[0028] Optionally, the ring-gate MOS transistors in the plurality of unit current source sub-units are all formed in the same well region, the gate of the ring-gate MOS transistor is formed on the active region, the active region has a symmetrical polygonal structure, the gate continuously surrounds the edge of the active region to surround the channel region, and the distance between the active region and the adjacent well contact protection ring is less than or equal to a preset distance.
[0029] Specifically, such as Figure 3As shown, the ring-gate MOS transistors 111 in multiple unit current source sub-units 110 are all formed in the same well region. The gate of the ring-gate MOS transistor 111 is formed on the active region. The active region adopts a symmetrical polygonal structure of rectangle or octagon. The gate continuously surrounds the edge of the active region, completely surrounding the channel region, thus completely eliminating the parasitic leakage current path at the edge of the traditional strip gate. The distance between the active region and the adjacent well contact protection ring 120 is less than or equal to the preset distance. In this embodiment, the preset distance is 1.5 times the minimum design rule. This parameter is optimized by TCAD simulation, which can make the photocurrent collection efficiency of the well contact protection ring 120 reach more than 95%. In this embodiment, the same well region ensures the consistency of the electrical characteristics of the ring-gate MOS transistor 111. The symmetrical polygonal active region, in conjunction with the continuous surrounding gate, reduces the distance between the active region and the protection ring, maximizing the radiative carrier collection efficiency. The combination of the closed ring gate and the symmetrical active region completely suppresses the parasitic leakage current caused by the total dose effect. The narrow spacing design enhances the photocurrent collection capability of the well contact protection ring 120, further improving the device's resistance to total dose and single-event latch-up. For example, the active region can be replaced with other centrally symmetrical polygonal structures such as regular hexagons or circles, and the gate continuously surrounds the edge of the symmetrical polygon, thus achieving the same anti-total dose effect by fully surrounding the channel region; the gate oxide layer thickness of the ring gate MOS transistor 111 is 5nm to 15nm.
[0030] Optionally, the switching transistors adopt a ring gate structure, and the gates, drains, and sources of each switching transistor are shorted to each other to form a redundant conduction path; when any of the switching transistors is momentarily turned on or off due to a single particle impact, the equivalent resistance change of the remaining switching transistors in the parallel path is less than a preset threshold.
[0031] Specifically, such as Figure 2As shown, the parallel switch group 113 includes two parallel-connected and synchronously controlled switching transistors. Both switching transistors employ a ring-gate structure, with their gates, drains, and sources short-circuited to form redundant conduction paths. When any switching transistor experiences a momentary on / off state due to a high-energy single-event impact, the remaining switching transistors maintain normal operation, ensuring that the change in equivalent resistance of the parallel path is less than a preset threshold. In this embodiment, the preset threshold is 5%, ensuring that the output current of the unit current source subunit 110 is not significantly disturbed and is not significantly affected by single-event transients. In this embodiment, the ring-gate structure of the switching transistors enhances their total dose resistance capability, the three-terminal short-circuiting forms a redundant conduction path, effectively resisting output disturbances caused by single-event transient effects, and the preset threshold ensures the stability of the current output. This dual reinforcement ensures the reliability of the switch control. For example, the parallel switch group 113 can employ three or more ring-gate switching transistors connected in parallel to further reduce the impact of single-event transients on the equivalent resistance. The number of redundant paths can be adaptively adjusted according to the aerospace radiation level.
[0032] Optionally, the polysilicon resistor is disposed above the shallow trench isolation region, and its two ends are respectively connected to the metal interconnect layer through contact holes. Shallow trench isolation dielectric is provided below and around the polysilicon resistor.
[0033] Specifically, such as Figure 2 As shown, a polysilicon resistor 112 is disposed on a shallow trench isolation region (STI). Both ends of the polysilicon resistor 112 are connected to a metal interconnect layer of a standard CMOS process via contact holes. The bottom and periphery of the polysilicon resistor 112 are completely surrounded by a shallow trench isolation dielectric, blocking parasitic current paths between the resistor and the substrate. In this embodiment, the shallow trench isolation dielectric completely encapsulates the polysilicon resistor 112, eliminating the resistor's sensitivity to total dose radiation. The contact holes connecting to the metal interconnect layer ensure smooth current transmission, stabilizing the output current while improving the radiation resistance of the polysilicon resistor 112, making it suitable for long-term radiation environments in aerospace. For example, the sheet resistance of the polysilicon resistor 112 is set to 100Ω to 500Ω, and the resistance range can be flexibly adjusted according to current accuracy requirements. High-resistivity polysilicon or tantalum nitride, or other standard CMOS-compatible resistor materials, can be used to replace ordinary polysilicon, achieving the same radiation-resistant resistor fabrication on the shallow trench isolation region.
[0034] Optionally, the well contact protection ring includes a first type doped region, a second type doped region, and a metal contact layer. The first type doped region is disposed in the well region and surrounds the ring gate MOS transistor. The second type doped region is disposed between the first type doped region and the well region. The metal contact layer is electrically connected to the first type doped region at a fixed potential.
[0035] Specifically, such as Figure 3As shown, the well contact protection ring 120 consists of a first-type doped region, a second-type doped region, and a metal contact layer. Taking the P-well process as an example, the first-type doped region is an N-type heavily doped region, which is disposed around the well region and surrounds the ring-gate MOS transistor 111. The second-type doped region is a P-type lightly doped region, which is disposed between the first-type doped region and the well region. The metal contact layer is electrically connected to a fixed potential such as VDD or VSS. In this embodiment, when high-energy particles are incident, the structure of the well contact protection ring 120 forms a low-impedance carrier collection path, which quickly conducts the photocurrent and prevents the parasitic bipolar transistor from turning on. Exemplarily, in the N-well process, the first-type doped region is replaced with a P-type heavily doped region, the second-type doped region is replaced with an N-type lightly doped region, and the metal contact layer is connected to the corresponding fixed potential, which also achieves a high-efficiency carrier collection effect.
[0036] Optionally, the triple redundancy structure includes three logic operation sub-modules and a majority voter. The three logic operation sub-modules receive the same input signal and perform logic operations respectively. The majority voter performs a majority vote on the output results of the three logic operation modules to obtain the control signal, and outputs the control signal to the control terminal of the unit current source sub-unit.
[0037] Specifically, such as Figure 4 As shown, the triple-modulus redundancy structure 210 of the digital control logic unit 200 includes three identical logic operation sub-modules A, B, and C, and a majority voter 212. The three logic operation sub-modules receive the same external input digital signal, independently perform logic encoding operations, and output three operation results. The majority voter 212 performs a majority vote on the three output results, and outputs the correct signal as a control signal to the control terminal of the unit current source sub-unit 110. In this embodiment, the three independent operations achieve logic redundancy, and the majority voter 212 filters the correct signal, completely shielding the transient errors in the digital control logic caused by single-event upsets, ensuring the accuracy of control signal transmission, and providing stable control commands for the current-rudder type digital-to-analog converter array 100. For example, a five-modulus redundancy structure can be used to replace the triple-modulus redundancy structure, further improving the single-event upset resistance capability and adapting to higher-level aerospace radiation environments through the cooperation of more logic operation sub-modules and the voter.
[0038] Optionally, an isolation ring structure is provided between the digital control logic unit and the digital-to-analog conversion core unit. The isolation ring structure includes a first annular deep well surrounding the digital control logic unit and a second annular deep well surrounding the digital-to-analog conversion core unit, and the first annular deep well and the second annular deep well are separated by a shallow trench isolation region.
[0039] Specifically, such as Figure 1As shown, an isolation ring structure 500 is provided between the digital control logic unit 200 and the digital-to-analog converter core unit (current-rudder type digital-to-analog converter array 100). The isolation ring structure 500 includes a first annular deep well surrounding the digital control logic unit 200 and a second annular deep well surrounding the current-rudder type digital-to-analog converter array 100. The first and second annular deep wells are completely separated by a shallow trench isolation region. In this embodiment, the double annular deep wells combined with the shallow trench isolation region form a continuous low-impedance isolation barrier, effectively blocking crosstalk of digital circuit noise to the sensitive analog core area, improving the output linearity and signal stability of the DAC module, and optimizing the analog output accuracy. For example, a deep trench isolation (DTI) structure can be used to replace the combination of annular deep wells and shallow trench isolation to further enhance the electrical isolation effect between the digital and analog areas.
[0040] Optionally, the digital-to-analog conversion core unit further includes: A reference current source, the output of which is connected to the input of each of the unit current source sub-units; The reference current source is equipped with a thermometer encoder. The output of the thermometer encoder is connected to the control terminal of each of the parallel switch groups through redundant interconnects. The redundant interconnects include at least two parallel and isolated metal lines.
[0041] Specifically, such as Figure 5 As shown, the core unit of the digital-to-analog converter also includes a reference current source 300. The output of the reference current source 300 is connected to the input of each unit current source subunit 110, providing a stable reference current for each subunit. The reference current source 300 integrates a thermometer encoder 310. The output of the thermometer encoder 310 is connected to the control terminals of each parallel switch group 113 via redundant interconnects 320. The redundant interconnects 320 contain at least two parallel and isolated metal lines. The two metal lines are located on different metal layers or are spaced apart in the same layer with a spacing greater than the minimum design spacing. When one metal line breaks due to radiation damage, the other can still maintain normal signal transmission, significantly improving signal transmission reliability. In this embodiment, the redundant interconnects 320, containing at least two parallel and isolated metal lines, can avoid metal line breakage due to radiation damage, ensuring stable transmission of the thermometer encoded signal to the parallel switch group 113 and maintaining the continuity and reliability of the digital-to-analog conversion. For example, the redundant interconnect 320 may employ three or more layers of parallel metal lines, or a redundant transmission structure combining metal lines and polysilicon jumpers, to further enhance the signal transmission resistance to breakage.
[0042] Optionally, the DAC module with radiation-hardened structure further includes: The output unit is a differential amplifier, and its input terminal is connected to the output terminal of the digital-to-analog conversion core unit. The input differential pair transistors of the differential amplifier adopt a ring gate structure, and a center tap protection ring is provided between the input differential pair transistors. The center tap protection ring is electrically connected to the common mode potential.
[0043] Specifically, such as Figure 1 As shown, the DAC module also includes an output unit 400. The output unit 400 adopts a differential amplifier structure, and its input terminal is connected to the output terminal of the current-controlled digital-to-analog converter array 100 to convert the analog current signal into a voltage signal for external output. The input differential pairs of the differential amplifier all adopt a ring gate structure, and a center-tapped protection ring is set between the input differential pairs. The center-tapped protection ring is electrically connected to the common-mode potential VCM. In this embodiment, the ring-gate input differential pairs can improve their total dose immunity, and the center-tapped protection ring can collect radiated carriers, suppress common-mode disturbances caused by single-event transients, and ensure the stability and purity of the output voltage signal. For example, the differential pairs can be replaced with bipolar transistors with fully enclosed gates instead of ring-gate MOSFETs, and the center-tapped protection ring 440 can adopt a double-layer doped protection ring structure to enhance the common-mode disturbance suppression effect.
[0044] Optionally, the digital-to-analog converter core unit is located in the central area of the module layout, the digital control logic unit and the output unit are located on both sides of the digital-to-analog converter core unit, and a protective ring isolation band is provided between the digital control logic unit and the digital-to-analog converter core unit, and between the output unit and the current-rudder type digital-to-analog converter array.
[0045] Specifically, such as Figure 6 As shown, the digital-to-analog converter core unit (current-rudder type digital-to-analog converter array 100) is located in the central area of the DAC module layout. The digital control logic unit 200 and the output unit (output stage 400) are respectively located on both sides of the current-rudder type digital-to-analog converter array 100. A first protective ring isolation band 610 is set between the digital control logic unit 200 and the current-rudder type digital-to-analog converter array 100, and a second protective ring isolation band 620 is set between the output unit 400 and the current-rudder type digital-to-analog converter array 100. Both protective ring isolation bands adopt a composite ring structure with deep wells and contact holes, with a width of 10μm to 50μm. In this embodiment, the centrally symmetrical layout can optimize the signal transmission path, reduce signal transmission loss and noise interference, improve the overall aerospace environment adaptability of the DAC module, and the double-sided protective ring isolation bands can block noise crosstalk, strengthen the isolation effect of each functional area, realize the partition protection of digital, analog and output units, and maximize the synergistic effect of each radiation-hardening structure. For example, the layout can use a rotationally symmetric structure to replace the centrosymmetric structure, and the protective ring isolation band can be filled with shielding medium to further improve the isolation effect.
[0046] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc. In this application, the units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of the present invention according to actual needs. Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated units can be implemented in hardware or as software functional units.
[0047] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.
Claims
1. A DAC module with a radiation-hardened structure, characterized in that, Includes digital control logic units and digital-to-analog conversion core units; The digital control logic unit adopts a triple-modulus redundancy structure, which is used to transmit control signals to the digital-to-analog conversion core unit and shield single-particle flip errors. The digital-to-analog conversion core unit includes multiple unit current source subunits for converting the control signal into an analog signal. A trap contact protection ring is provided between adjacent unit current source subunits. Each unit current source subunit includes: A ring-gate MOS transistor, wherein the gate surrounds the active region to form a closed ring structure, and the well contact protection ring is electrically connected to the body region of the ring-gate MOS transistor. A polysilicon resistor is connected in series with the source or drain of the ring-gate MOS transistor; A parallel switch group includes at least two parallel-connected and synchronously controlled switching transistors for controlling the on / off state of the unit current source subunit; The ring gate MOS transistor, the polysilicon resistor, and the well contact protection ring are all manufactured using standard CMOS technology.
2. The DAC module with radiation-hardened structure according to claim 1, characterized in that, The ring-gate MOS transistors in the multiple unit current source sub-units are all formed in the same well region. The gate of the ring-gate MOS transistor is formed on the active region. The active region has a symmetrical polygonal structure. The gate continuously surrounds the edge of the active region to surround the channel region. The distance between the active region and the adjacent well contact protection ring is less than or equal to a preset distance.
3. The DAC module with radiation-hardened structure according to claim 1, characterized in that, The switching transistors adopt a ring gate structure, and the gates, drains, and sources of each switching transistor are shorted to each other to form a redundant conduction path. When any of the switching transistors is momentarily turned on or off due to a single particle impact, the equivalent resistance change of the remaining switching transistors in the parallel path is less than a preset threshold.
4. The DAC module with radiation-hardened structure according to claim 1, characterized in that, The polysilicon resistor is disposed above the shallow trench isolation region, and its two ends are respectively connected to the metal interconnect layer through contact holes. Shallow trench isolation dielectric is provided below and around the polysilicon resistor.
5. The DAC module with radiation-hardened structure according to claim 1, characterized in that, The well contact protection ring includes a first type doped region, a second type doped region, and a metal contact layer. The first type doped region is disposed in the well region and surrounds the ring gate MOS transistor. The second type doped region is disposed between the first type doped region and the well region. The metal contact layer is electrically connected to the first type doped region at a fixed potential.
6. The DAC module with radiation-hardened structure according to claim 1, characterized in that, The triple redundancy structure includes three logic operation sub-modules and a majority voter. The three logic operation sub-modules receive the same input signal and perform logic operations respectively. The majority voter performs a majority vote on the output results of the three logic operation modules to obtain the control signal, and outputs the control signal to the control terminal of the unit current source sub-unit.
7. The DAC module with radiation-hardened structure according to claim 1, characterized in that, An isolation ring structure is provided between the digital control logic unit and the digital-to-analog conversion core unit. The isolation ring structure includes a first annular deep well surrounding the digital control logic unit and a second annular deep well surrounding the digital-to-analog conversion core unit. The first annular deep well and the second annular deep well are separated by a shallow trench isolation region.
8. The DAC module with radiation-hardened structure according to claim 1, characterized in that, The digital-to-analog conversion core unit also includes: A reference current source, the output of which is connected to the input of each of the unit current source sub-units; The reference current source is equipped with a thermometer encoder. The output of the thermometer encoder is connected to the control terminal of each of the parallel switch groups through redundant interconnects. The redundant interconnects include at least two parallel and isolated metal lines.
9. The DAC module with radiation-hardened structure according to claim 1, characterized in that, Also includes: The output unit is a differential amplifier, and its input terminal is connected to the output terminal of the digital-to-analog conversion core unit. The input differential pair transistors of the differential amplifier adopt a ring gate structure, and a center tap protection ring is provided between the input differential pair transistors. The center tap protection ring is electrically connected to the common mode potential.
10. The DAC module with radiation-hardened structure according to claim 9, characterized in that, The digital-to-analog converter core unit is located in the central area of the module layout. The digital control logic unit and the output unit are located on both sides of the digital-to-analog converter core unit. Protective ring isolation bands are provided between the digital control logic unit and the digital-to-analog converter core unit, and between the output unit and the current-rudder type digital-to-analog converter array.