Power microwave transistors Philips Semiconductors. Powerful low-voltage microwave transistors for mobile communications. Reference data Imported RF transistors

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The current level of development of REA and its elemental base makes it possible to create completely solid-state VHF FM and television transmitters with an output power of up to 5 kW. Amplification paths based on broadband transistor amplifiers have a number of advantages compared to tube amplifiers. Solid-state transmitters are more reliable, electrically safe, convenient to use and easier to manufacture.

With a block-modular design of the transmitter, the failure of one of the terminal amplifier blocks does not lead to disruption of on-air broadcasting, since transmission will continue until the block is replaced, only with reduced power. In addition, the wideband path of the transistor amplifier does not require additional settings to a specific channel within the operating frequency band.

It is generally accepted that the reliability of a transmitter depends, first of all, on the reliability of the active components used. Thanks to the use of modern high-power linear microwave transistors, the design features and manufacturing technology of which provide a significant increase in their time between failures, the issue of increasing the reliability of solid-state transmitters has received a fundamental solution.

Growing requirements for the technical and economic indicators of VHF FM and high-power television transmitters, as well as the achieved level of domestic technology in the field of creating high-power silicon bipolar transistors stimulated the development of a new class of devices - high-power linear microwave transistors. The Research Institute of Electronic Technology (Voronezh) has developed and produces a wide range of them for use in the meter and decimeter wavelength ranges.

Transistors are specially designed for use in high-power television and radio broadcast transmitters, repeaters, in particular, in television repeaters with joint amplification of audio and image signals, as well as in multichannel signal amplifiers of base stations of a cellular communication system. These transistors meet extremely stringent requirements for linearity of the transfer characteristic, have a margin of power dissipation and, as a result, increased reliability.

Structurally, such transistors are made in metal-ceramic housings. Their appearance shown in Fig. 1 (the housings of not all transistors mentioned in the article are shown; the missing ones can be seen in the article). High linear and frequency properties of transistor structures are realized through the use of precision isoplanar technology. Diffusion layers have a submicron design standard. The width of the emitter topology elements is about 1.5 microns with an extremely developed perimeter.

In order to eliminate failures caused by secondary electrical and thermal breakdown, the transistor structure is formed on a silicon crystal with a double-layer epitaxial collector and the use of emitter stabilizing resistors. The transistors also owe their long-term reliability to the use of multilayer gold-based metallization.

Linear transistors with a power dissipation of more than 50 W (with the exception of KT9116A, KT9116B, KT9133A), as a rule, have a structurally built-in LC input matching circuit, made in the form of a microassembly based on a built-in MIS capacitor and a wire lead system. Internal matching circuits allow you to expand the operating frequency band, simplify input and output matching, and also increase the power gain CUR in the frequency band.

At the same time, these transistors are “balanced,” which means the presence of two identical transistor structures on one flange, united by a common emitter. This design and technical solution makes it possible to reduce the inductance of the common electrode output and also helps to expand the frequency band and simplify matching.

When balanced transistors are turned on push-pull, the potential of their midpoint is theoretically equal to zero, which corresponds to the condition of an artificial “ground”. This inclusion actually provides approximately a fourfold increase in the output complex impedance compared to a single-ended one at the same output signal level and effective suppression of even harmonic components in the spectrum of the useful signal.

It is well known that the quality of television broadcasting, first of all, depends on how linear the transfer characteristic of the electronic path is. The issue of linearity is especially acute when designing nodes for joint amplification of image and sound signals due to the appearance of combinational components in the frequency spectrum. Therefore, the three-tone method proposed by foreign experts for assessing the linearity of the transfer characteristic of domestic transistors based on the level of suppression of the third-order combination component was adopted.

The method is based on the analysis of real TV signal at a signal level ratio of the image carrier frequency of -8 dB. side frequency -16 dB and carrier frequency soundtrack-7 dB relative to the output power at the peak of the envelope. Transistors for joint amplification, depending on the frequency and power series, must provide a value for the coefficient of the combinational components of the MS, as a rule, no more than -53...-60 dB.

The class of microwave transistors under consideration with strict regulation of the suppression of combinational components is called superlinear transistors abroad. It should be noted that so high level Linearity is usually realized only in class A mode, where it is possible to carry out maximum mode linearization of the transfer characteristic.

In the meter range, as can be seen from the table, there are a number of transistors, represented by the KT9116A, KT91166, KT9133A and KT9173A devices with a peak output power Pvmkh.peak of 5.15, 30 and 50 W, respectively. In the decimeter wavelength range, such a range is represented by the KT983A, KT983B, KT983V, KT9150A and POZ devices with RVV1X, PIK equal to 0.5, 1.3.5, 8 and 25 W.

Superlinear transistors are usually used in joint amplifiers (in class A mode) of television repeaters and power amplifier modules of transmitters with a power of up to 100 W.

However, for the output stages of powerful transmitters, more powerful transistors are needed to provide the required level of the upper limit of the linear dynamic range when operating in a favorable energy mode. Acceptable nonlinear distortions at high level signals can be obtained using separate amplification in class AB mode.

Based on an analysis of the thermophysical operating conditions of the transistor and the peculiarities of the formation of linearity of a single-tone signal, a series of microwave transistors was specially developed for operating mode in the AB class. The linearity of the characteristics of these devices according to foreign methods is assessed by the level of compression (compression) of the gain factor based on the power of a single-tone signal - the compression factor Kszh or otherwise - the output power is determined at a certain normalized Kszh.

For use in the meter wavelength range in class AB mode, there are now KT9151A transistors with an output power of 200 W and KT9174A transistors with an output power of 300 W. For the decimeter range, transistors 2T9155A, KT9142A, 2T9155B, KT9152A, 2T9155V, KT9182A with output power from 15 to 150 W have been developed.

For the first time, the possibility of creating modular solid-state transmitters in the decimeter range with combined amplification of image and audio signals with a power of 100 W was demonstrated by NEC specialists. Later, similar transmitters were created using domestic high-power microwave transistors 12, 9]. In particular, it describes original research to expand the scope of use of high-power transistors KT9151A and KT9152A when creating 100-watt joint amplification modules in class A mode. It is shown that in this mode it is possible to suppress combinational components when their power is underutilized by 3...4 times from nominal in class AB mode.

Specialists from the Novosibirsk State Technical University have conducted research on the use of domestic high-power microwave transistors in television power amplifier modules with separate amplification.

In Fig. Figure 2 shows a block diagram of an image signal power amplifier for television channels 1 - 5 with 250 W peak output power. The amplifier is designed according to the circuit of separate amplification of image and sound signals. For channels 6 - 12, the amplifier is made according to a similar circuit with the addition of an intermediate stage on a KT9116A transistor operating in class A mode to obtain the required gain.

In the output stage, KT9151A transistors operate in class AB. It is assembled according to a balanced push-pull circuit. This allows you to obtain the rated output power with fairly simple matching circuits in the complete absence of “feeder echo” and the level of even harmonic components no more than -35 dB. The nonlinearity of the amplitude characteristic of the amplifier is established for a small signal by selecting the shift of the operating point in each stage, as well as by adjusting the nonlinearity in the exciter video modulator.

The block diagram of a power amplifier for television channels 21 - 60 is shown in Fig. 3. The output stage of the amplifier is also made according to a balanced push-pull circuit.

To ensure broadband matching and transition from an asymmetrical to a symmetrical load, a two-link low-pass filter is used as a correction circuit in the output stages of the amplifiers of channels 6 - 12, 21 - 60. The inductance of the first link of the matching circuit is implemented in the form of sections of strip microlines on elements of the general topology of the printed circuit board. The coils of the second link are the terminals of the transistor base.

The structure of these amplifiers corresponds to Fig. 2 and 3. The division of power at the input of the amplification stages and its addition at their output, as well as the matching of inputs and outputs with a standard load, is carried out using three-dB directional couplers. Structurally, each coupler is made in the form of bifilar windings (quarter-wave lines) on a frame placed in a shielding casing.

Thus, modern domestic linear microwave transistors make it possible to create powerful - up to 250 W - television amplifier modules. Using batteries of such modules, it is possible to increase the output power supplied to the antenna-feeder path to 2 kW. As part of the transmitters, the developed amplifiers meet all modern requirements for electrical characteristics and reliability.

Powerful linear microwave transistors have recently begun to be widely used in the construction of power amplifiers for base stations of a cellular communication system.

In my own way technical level The high-power microwave linear transistors developed by NIIET can be used as an elemental base for the creation of modern radio broadcasting, television and other national economic and amateur radio equipment.

Material prepared
A. Assessorov, V. Assessors, V. Kozhevnikov, S. Matveev, Voronezh

LITERATURE
1. Hlraoka K., FuJIwara S., IkegamI T. etc. Hig power all solid-state UHF transmitters.- NEC Pes. & Develop. 1985. to 79, p. 61 -69.
2. Assessor V., Kozhevnikov V., Kosoy A. Scientific search for Russian engineers. Trend in the development of high-power microwave transistors - Radio, 1994, No. 6, p. 2.3.
3. Broadband radio transmitting devices. Ed. Alekseeva O. A. - M.: Svyaz, 1978, p. 304.
4. FuJIwurdS., IkegamI T., Maklagama I. etc. SS series solid-state television transmitter. -NEC Res. & Develop. 1989. No. 94, p. 78-89.
5. Acessorov V., Kozhevnikov V., Kosoy A. Trend in the development of high-power microwave transistors for use in radio broadcasting, television and communications.
- Electronics industry. 1994. No. 4, p. 76-80.
6. Assessor V., Kozhevnikov V.. Kosoy A. New microwave transistors. - Radio. 1996. No. 5, p. 57. 58.
7. Mipler O. Superlinear high-power transistors of the decimeter range for wire television - TIIER, 1970. v. 58. No. 7. With. 138-147.
8. Kojlwara Y., Hlrakuwa K., Sasaki K. etc UHF high power transistor amplifier with high-dielectric substrate. - NEC Res- & Develop. 1977. No. 45, p. 50-57.
9. Grebennikov A., Nikiforov V., Ryzhikov A. Powerful transistor amplifier modules for VHF FM and TV broadcasting. - Telecommunications. 1996, no. 3, p. 28-31.

The table uses the following designations for the electrical parameters of transistors:

Ikbo- reverse collector current (collector-base), in the numerator, with voltage between the collector and base, in the denominator.
Iebo- reverse current of the emitter (emitter - base), in the numerator, at a voltage between the emitter and base, in the denominator.
h21e- static current transfer coefficient (gain).
Fgr- upper limit frequency of the transistor transmission coefficient.
Sk- capacitance of the collector junction, tk - circuit time constant feedback(no more).
Ukb max- the maximum permissible voltage between the collector and the base.
Uke max- maximum permissible voltage between collector and emitter
Web max- maximum permissible voltage between emitter and base.
Iк max- maximum collector current.
Ik imp.- maximum pulse collector current.
Ib max- maximum base current.
Рmax- maximum power without heat sink.
RT max- maximum power with heat sink.