Design of hybrid integrated specific frequency signal generator The hybrid integrated specific frequency signal generator is mainly used in a military fuze safety control system. It plays a central nervous role in the design of the fuze, which is mainly used to realize the control of the state of the fully electronic safety system, that is, the fuze is controlled according to predetermined conditions (such as time, air pressure, instructions, etc.) under a certain logic program to correctly implement insurance. Control functions such as setting, insurance cancellation, comprehensive judgment of environmental information, and generation of specific frequency signals. The system can control the setting of the three-level insurance according to the characteristics and use requirements of the torpedo. Relying on the sensitive independent channel environment or instructions during the launch or movement of the system to release the insurance to ensure the safety during the use of the system, and at the same time select simple and mature insurance institutions to improve reliability. The design of the hybrid integrated specific frequency signal generator is mainly to use programmable logic devices for logic programming to achieve the complex logic functions required by high-performance systems. This method can greatly reduce the number of components and increase system reliability, and the working state is stable, the response speed is fast, the design cycle is short, and the system cost is low. The process adopts advanced thick film hybrid integration technology, the product has light weight, small volume, high reliability and good consistency. 1 Block diagram of circuit design The basic block diagram of this circuit is shown in Figure 1. It mainly provides a 4.096MHz frequency signal for two programmable logic devices (isp1016E) by a crystal oscillator, and generates a 1 kHz signal by frequency division, and then uses it as a counter clock trigger. The three-level switching signal (that is, the unsecured signal in the system) is sequentially added to the four photocouplers, where the first-level switching signal is used to drive the programmable logic device isp1016E-1.After the output signal is converted by the driver, the original The high-level signal at the output is converted to a low-level signal to release the first-level insurance of the system. The second-level switching signal is used to drive another programmable logic device isp1016E-2 after being isolated by the optocoupler.When the signal is judged to confirm the correct timing, the output signal of isp1016E-2 can generate a low-level signal through the driver to release the system Second level insurance. When the third-level switching signal arrives and confirms that the current three-level switching signal timing relationship is normal, the system generates a 5 V TTL signal with a specific frequency and duty cycle through isp1016E-2 to release the third-level insurance, thereby enabling the system High voltage charging, at this time the fuze is in a pending state. When the timing of the three-level switching signal is abnormal. The fourth switching signal can provide reset signals for the two isp1016E through the optocoupler isolation, so that the output terminal of the specific frequency signal has no output, so that the fuze is extinguished. 2 Scheme design Traditional digital circuits are composed of TTL and CMOS devices to form logic circuits. Most of these systems have the disadvantages of large number of logic devices, complicated circuits and huge plates. There are a large number of gate circuits (2000 gates) and flip-flops in the programmable logic device, which can be connected into various small and medium-sized digital circuits through programming. such. Circuits such as registers, counters, multiplexers, and decoders are easily implemented through programming. In addition, you can also use the macrocell library included in the supporting software of programmable logic devices to program the complex logic functions required by high-performance systems. Because the logic relationship of the hybrid integrated specific frequency signal generator is more complicated, for this reason, the programmable logic device isp1016E is used in this design to realize the logic function. To simplify the design difficulty. In this way, as long as you enter the digital circuit schematic diagram on the computer or describe the digital circuit in a hardware description language, then compile, and download the compiled data file to the programmable logic device to complete the design of the digital circuit, and the circuit structure is simple , Fewer devices, low cost, convenient design, not easy to damage, at the same time can greatly increase the reliability of the system and reduce the size of the system. 3 Software design The hybrid integrated specific frequency signal generator software is composed of isp1016E-1 chip software and isp1016E-2 chip software. It is used to realize the functions of effective environmental signal identification, timing judgment, two-level insurance cancellation, and generation of specific frequency signals. The design should first define the I / O port of the programmable logic device isp1016E, and then use Viewlogic software to simulate the system programmable logic device. After the design is compiled, the data file can be downloaded to the programmable device. IspLSI devices can be programmed on the circuit board; they can also be programmed on a dedicated programmer. 3.1 isp1016E-1 chip design The isp 1016E-1 chip is mainly used to realize the functions of effective environmental signal recognition and the release of the first-level insurance. The design idea is to first divide the frequency of the external crystal to 1 kHz to trigger it as the counter clock, and sample the first-stage switching signal (i.e., the unsecured signal) every millisecond to count the effective signal. When N times, the drive signal is sent concurrently during the count-off process, and then the low level is output to drive the first-stage safety action in the subsequent sequence, and the signal is transmitted to isp 1016E-2 at the same time. 3.2 isp1016E-2 chip design The isp 1016E-2 chip is used to complete the functions of the second and third levels of insurance release control logic, timing judgment, and the generation of specific frequency signals. The same frequency division and cumulative counting methods can be used to perform anti-interference filtering processing on the second and third level de-assertion signals. If the second-level unsecured signal is received and the timing of the first and second unsecured signals is determined to be correct, the drive signal is sent and becomes low, and the second-level insurance action is driven; if the timing is judged incorrect, the second level is closed Unlock signal receiving path (no longer received); after receiving the third-level unblocking signal from the control system and confirming that the timing relationship of the three-level unblocking signal is normal, the system will output 5 at a specific frequency and duty cycle V specific frequency signal. 4 System reliability and layout design In order to make the circuit work more safely and reliably, all the switching signals of each path first pass through the optocoupler and then enter the circuit. The input and output grounds are strictly separated to ensure the safety of the electronic components of the circuit; in order to reduce the interference of the external power supply, the filter capacitors should be connected between the power supply and the ground, and the working power supply of the chip for filtering Handle to ensure that the circuit works normally. Circuit programming includes comprehensive judgment of various environmental information, such as anti-jamming, anti-jitter processing, timing judgment and other functions. The comprehensive control design using "time window, timing judgment" and other technical measures can filter out ms-level interference signals, thus ensuring the system to work safely and reliably. In addition, the circuit also has the functions of single-check and re-release. Program control adopts double sets of backup and redundancy design. When a single set of inspection and joint test is required, a reset signal can be added to a set of programmed isp chips all the time, so that the function of another set of fuzes can be checked; during the system operation, if the target tracking is found after three levels of security If it is wrong, the reset signal can be received, and the security release action can be performed again through program control. In the layout design, the placement and distribution of devices should not only consider the reasonable layout of the circuit, uniform heat dissipation, but also consider the assembly production during the process. Specifically, the components can be relatively concentrated according to function; the input and output lines are placed separately and arranged in working order; when wiring, the power line and the ground line should be short and thick, and the electromagnetic interference between them should be minimized. The circuit uses two logic devices to complete the logic function. Each chip has 44 pins (PLCC package). Signals will be provided between the two chips, and between the chip and the peripheral circuit. The wiring is criss-cross, the cross-connection is complicated, and the circuit volume requirements are also strict. This will increase the difficulty of layout in the layout design process. Therefore, in the design, the placement position and direction of the two chips should be repeatedly compared and verified with drawing software to minimize the interlacing and complexity of the wiring between each other; when routing, it is best to place the vertical lines on the same level and horizontal lines At another level, dielectric insulation is used. In line routing, the wiring should be as short as possible, and the wiring should be optimized as much as possible. 5 Crafting and processing The surface processing technology of the PCB board is not selected for the process of this product, mainly because the excessive soldering connections, solder joints, connectors, etc. during PCB board assembly seriously hinder the further improvement of productivity and reliability; in addition, the work of the circuit The increase in frequency and speed also requires that the transmission delay of the signal within the system be shortened as much as possible. For this reason, the circuit specifically selected a thick film hybrid integration process, that is, a thick film multilayer wiring process to make conductive tapes and resistors; transistors, monolithic integrated circuits, etc. are assembled with bare chips using gold wire ball bonding, and the sealing is adopted Parallel seam welding technology is filled with nitrogen and sealed. The thick film process can reduce the circuit volume, improve accuracy, stability and product reliability, and facilitate mass production. In the thick film process, the capacitor should use the bonding process; the light coupling, MOS tube and other devices should use the current carrying welding process. PLCC packaged programmable logic device processing is relatively small. In the process of assembling logic devices in the initial current-carrying soldering process, because the logic device has many pins and is short (the area of ​​the soldering area is only 1.8mm × 0.4mm, the spacing between adjacent pins is about 0.3mm) The solder flow is not easy to control, and the solder can easily stick the adjacent pins together and cause a short circuit. When processing, it is often necessary to erase the solder at the short circuit and re-dispense the operation repeatedly, which will greatly affect the efficiency. After groping experiment. The author specially configures the pinhole of the spot flux with a smaller diameter to reduce the flow rate and welding area. Figure 2 shows the main process flow chart of the product. 6 Conclusion Hybrid integrated specific frequency signal generator is one of the commonly used components in a military system. In this paper, through a series of designs in software, plate-making, process, etc., the integration and miniaturization of the logic function of the device are finally achieved. It has been proved by many online tests that the device has stable performance, normal operation, and its electrical performance indicators fully meet the requirements of the system and users. At present, users have placed orders in small batches. In addition, the product can also modify the program software according to the needs of the system to output signals with different frequencies and different duty cycles. This shows that the product has the advantages of easy expansion and design upgrade. Moreover, the circuit is small in size, high in precision, light in weight, flexible in use, and has important use value and good application prospects. Power X (Qingdao) Energy Technology Co., Ltd. , https://www.qdpowerxsolar.com
