Transmitting devices are mainly divided into two forms: semiconductor solid-state devices and electric vacuum devices. As a power amplifier, electric vacuum devices have played a very important role in the history of military equipment development, and until now they are still the core components of radar, communications, electronic warfare and other systems. Before GaAs transistors came out, vacuum tubes were the only solution for power amplification and emission. Later, transistor-semiconductor solid-state devices began to replace vacuum tubes in the low frequency range. With the increase in frequency, the two competed and complemented each other. In the high frequency range, they have always been the domain of electric vacuum devices. Electric vacuum devices are the only way to realize high-
power millimeter waves.
The birth background of microwave power module
Vacuum devices and solid-state devices have their own characteristics: solid-state devices have low voltage, high current, small size, good uniformity in semiconductor process production, and are more suitable for dense active array applications, but need to overcome high-frequency single-piece power, low efficiency, and temperature Problems such as large drift and high system power consumption. Vacuum devices have high voltage, low current, high power, high efficiency, high temperature resistance, and low system cost. However, the process production consistency is not as good as solid state devices, and there are problems that need to be overcome, such as a large single piece.
Since the birth of semiconductor solid-state electronic devices, the two have begun to compete. At the same time of competition, the fusion of devices and technologies has led to the birth of microwave power modules, called MPM (Microwave Power Moudle) for short.
MPM overcomes the shortcomings of the traveling wave tube power-on difficulty, and integrates the traveling wave tube and the matched high-voltage power supply into one, which greatly facilitates the use. Users are directly facing the low and medium voltages of different platforms such as 28V, 48V, 115V and 270V. MPM combines the advantages of vacuum electronic devices and solid-state devices, and its performance exceeds that of a single solid-state amplifier and a single traveling wave tube. MPM combines the low noise performance of solid-state devices with the high power and high efficiency of traveling wave tubes; and compared with traveling wave tubes, it reduces the power requirements and weight of the power supply; compared with independent traveling wave tubes, it improves the gain And phase matching and control. MPM is called millimeter wave power module in millimeter wave frequency band, or MMPM (Millimeterwave Power Module) for short. Continue to extend to Terahertz Power Module, TPM (Terahertz Power Module) for short.
The emergence of MPM has added wings to the application of electric vacuum devices, especially traveling wave tubes. At present, the competition between the two types of devices has been mainly transformed into a competition between pure solid-state devices and
Development status of microwave power modules
Foreign MPM/MMPM and related technologies are very mature. Many companies, such as L3, Thales, Triton, CPI, Sel-exES, MITEQ, dBcontrol, e2v, etc., have launched their own MPM products with frequency coverage up to W-band and G-band, and continuous wave output power up to 250W.
Judging from the typical MPM products launched by various manufacturers, they have the characteristics of high-power low-frequency modules and high-frequency low-power modules. Among them, in the output power level of 100W, different brands and models of MPM have completely covered the range of 2-40GHz. At the same time, in the MPM products of the working frequency band 6~18GHz, the output power has reached the highest 250W. At present, the harmonic control of foreign MPM is between -11dBc~-4dBc, and the spurious control is between -60dBc~-40dBc. The overall efficiency of foreign MPMs is about 30%, and the product weight control is relatively mature, relatively concentrated between 2-3kg, and the size is different due to different heat dissipation and electromagnetic compatibility designs.
The domestic electric vacuum power device industry has achieved a leap from "tracking imitation of foreign products" to "leading the development of the industry" in the past sixty years, with continuous breakthroughs in product performance. At present, a world-class R&D center and production line have been established, high-performance devices and new equipment are booming, and a series of traveling wave tube core amplifier products that meet the new generation of weapon systems have been continuously launched. The domestic electric vacuum device industry has formed a series of 2-50GHz broadband traveling wave tubes, realizing 100% replacement of imported products, and realizing batch export of multiple products. At present, there are breakthrough developments in the three directions of high efficiency, miniaturization and high terahertz frequency.