The hottest FPGA brings unique performance to test

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FPGA brings unique performance to test and measurement instruments

design engineers in the electronic industry are using FPGA in many application fields, including communication, national defense, medical treatment, education and so on. When debugging the FPGA circuit, they may not know that Agilent's measuring instrument itself also uses FPGA technology, and has in-depth cooperation with FPGA suppliers in the research and development field, and even shares some IP (intellectual property rights). Both sides have accumulated a lot of experience from the perspective of measurement and debugging. The actual design often uses FPGA and ASIC (special chip) to achieve the best effect. Agilent adopts such a comprehensive design in its oscilloscope, logic analyzer, pulse source, bit error meter and other products

there is no perfect instrument in the world. Its design is always optimized in one aspect and compromised in some aspects. Taking the oscilloscope based on Windows platform as an example, which functions are realized by software, which functions are realized by hardware, and whether the hardware part adopts a special chip or FPGA are all issues that developers need to consider. This paper gives two examples, one is the design of 9000A in the middle-end oscilloscope technology innovation integrated product MSO, and the other is the analysis and design of mipid-phy protocol

mso9000a is a three in one instrument, which integrates oscilloscope, logic analysis and protocol analysis. Its R & D team finally reached a consensus after several rounds of discussion before design. Two important points are: 1 The function of oscilloscope is the basic core, and logic analyzer and protocol analyzer are options. Whenever new protocol technology appears, the analyzer uses a variety of analysis methods such as image, computer simulation, mechanical data, etc. the analyzer must be upgraded to support new standards; 2. Protocol triggering must be real-time to ensure no signal leakage

in order to realize the real-time triggering of the protocol, windows or even linux software must not be used. At the same time, products are required to support different types of protocols. Therefore, the designer of mso9000a added an FPGA chip between the front-end input circuit and the trigger circuit of the oscilloscope to provide real-time clock recovery for the serial bus, detect the serial data packet structure, and feed the contents of the serial data packet to the trigger circuit of the oscilloscope, so that the oscilloscope can realize hardware trigger based on the serial bus protocol. When a new protocol appears in the future, it can also be supported by upgrading. Users set specific protocol trigger conditions, and mso9000 oscilloscope determines when to trigger through hardware, and performs repeated measurement or single measurement

the picture of this design is given in the figure. This product adopts a 20 layer circuit board structure, uses 27 special chips and 3 FPGAs, which are integrated into an acquisition board, and then placed vertically (not horizontally) behind the 15 inch display screen. The final mso9000a product is very thin, integrating beautiful appearance, flexibility and multi-function features

Figure 2 shows the hardware circuit photo of n4851a analyzed by mipi-dphy protocol. The function of this circuit is the data transfer and conversion center. The FPGA in the figure is the core part. The FPGA in n4851a is responsible for capturing and processing mipid-phy serial data, and then converting it into multiple low-speed parallel data for transmission to the logic analyzer. The data rate that the FPGA can capture and process is as high as 800Mbps, and N4 testing its fall resistance is also very important. The FPGA in 861a is responsible for converting the parallel data from the logic analyzer. 4. It is necessary to guide enterprises to increase scientific and technological innovation into high-speed serial mipid-phycsi/dsi signals

The application of FPGA in measuring instruments, especially in high-performance instruments, has attracted more and more attention. To make the measuring instrument unique, the analog circuit is important, but in some aspects, the application of FPGA may become the key to determine whether the product can be accepted by users. Agilent has made demonstrations in some aspects, from which we can see the application trend of FPGA in the industry in the following aspects. 1. Implementation of complex trigger circuit: such as serial signal protocol trigger, frequency domain trigger, etc., and protocol trigger of Pioneer products such as mso9000a; 2. Processing of deep storage data: it is an inevitable trend that the storage depth of the instrument is getting deeper and deeper. Processing with FPGA can give consideration to real-time and programmable. Pioneer products such as dsa90000a deep storage dedicated accelerated processing chip; 3. Processing of complex operations: equalization and de embedding technologies are digital processing technologies that must be considered in 5Gbps and faster signal testing. Because of its large amount of calculation, it will inevitably affect the response speed of the instrument, which is suitable for FPGA processing. Pioneer products such as dsa90000a n5465a and n5461a

like other devices, whether FPGA can be used well often depends on the user's deep understanding of the FPGA chip used. "Although I am very familiar with FPGA itself and my own profession, the company has cooperated with the R & D Department of FPGA suppliers for many years to share some internal IP, which has greatly improved my development efficiency." Mikebeyers, the development engineer in charge of the FPGA part of mso9000a, said, "the ATC I used in the debugging process was developed by our FPGA team. After years of repeated optimization with FPGA suppliers, this ATC and the whole FPGA debugging scheme are also open to other companies using FPGA."

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