Ku-band power combining microstrip circuit design and application

Semiconductor materials and DS34LV86TM datasheet and processes as the continuous development of microwave / millimeter-wave output power of power semiconductor devices increasing magnitude, L-band power transistors has reached kW pulsed power magnitude; X-band power GaAs field Effect of pipe to tens of watts of continuous arrival, pulse power of 500W. However, limited by the physical characteristics of the semiconductor, the output power of a single solid-state device is still limited. Using chip synthesis, circuit synthesis and DS34LV86TM price and spatial power combining technology synthesis multi-output power solid-state devices with the overlay of higher output power is an effective way.

1968 Nian Josenhans first proposed the concept of chip-level power combining. Subsequently, the late 20th century, 70, Rucker implemented first in X-band multi-chip power combining circuit, and DS34LV86TM suppliers and then extend it to 40 GHz. In 1999, KohjiMatsunag, IkuoMiura and Naotaka lwata with MM IC multi-chip synthesis technology, through four separate MM IC design of the Ka-band amplifier chip in 26. 5 ~ 28. 5 GHz frequency range to obtain a 3 W continuous wave output power. This

W ilkinson carried out based on microstrip power splitter circuit of power combining to achieve a 1 W Ku-band power amplifier. Applications in satellite communications, the power amplifier required in the tens of watts to hundreds of the order of watts. Obviously, this is still such a power level of the amplifier can not be directly used as satellite communications, the power amplifier, but can be used as a traveling wave tube amplifier drives and other large and widely used. As a basis for the synthesis of 2n way power, the power involved in this synthesis is related technologies can also provide important reference value.

1 overall structure and design goals

Power combining circuit used in this block diagram shown in Figure 1. Figure 1 WPD1 as an input power divider Wilkinson power divider, and WPD2 output power as a synthesizer, another W ilkinson splitters. They chose the structure first proposed this new structure, and using the same design as described in the following approach to design. Figure 1 is the Schiffman SPS quadrature phase shifter. Figure 1 TGF2508 - SM Triquint U.S. Ku-band power amplifier chip companies, the 1 dB power compression point of power is 28 dBm, small signal gain of 25 dB, operating bandwidth for the 12 ~ 17 GHz. This article used the power of the device as a synthesis of two basic components. Synthesis of theoretical maximum power of 31 dBm. This article is designed to be as much as possible TGF2508 - SM bandwidth, to achieve as wide frequency band, the band more than 70% combining efficiency. For this purpose, Wilkinson power divider and the quadrature phase shifter Schiffman must have and TGF2508 - SM considerable bandwidth. Research under this article achieved that goal.

Figure 1 we realize the power combining circuit block diagram of the

2 Wilkinson power divider improvement

Figure 2 shows the W ilkinson general power splitter improvements.

Figure 2a Wilkinson power divider is the basic form, since the two outputs to be connected to an isolation resistor between, and this resistance are small, thus requiring the circuit in two / 4 transmission line distance between the close, resulting in mutual coupling, thus affecting the nature of the circuit bandwidth. As the basic form of W ilkinson splitters these inherent shortcomings, its working frequency higher than the X-band, bandwidth and other performance can no longer meet the requirements. Improved as shown in Figure 2b is to avoid the shortcomings of the basic model proposed above, but also the reasons for the isolation resistor, the distance between the two output ports are still very close, can not avoid mutual coupling. The circuit shown in Figure 2c to overcome these shortcomings, but because of the introduction of a longer transmission line, so bandwidth performance declined.

evolution of the structure of Figure 2 WPD Shown in Figure 2b

this paper, the improvement of the circuit shown in Figure 3a the circuit.

To overcome the above-mentioned basic and improved version of the above-mentioned shortcomings, while preserving a good broadband characteristics. Microstrip layout of the circuit shown in Figure 3b. In this paper, on the ADS circuit simulation results are shown in Figure 4, the results show that the circuit in the 12 ~ 18 GHz 3 dB within the division has a good performance, the proposed design to meet the above objectives.

Figure 3 In this paper, the Wilkinson power splitter schematics and microstrip

Figure 4 Wilkinson power splitter ADS co-simulation results

3 Schiffman quadrature phase shifter

Synthetic paper also needed to achieve the power Ku-band quadrature phase shifter. Phase shifter used in this type of double-Schiffman quadrature phase shifter. Schiffman phase shifter has a double standard Schiffman phase shifter than the smaller bandwidth, but the requirements of the coupling coefficient is greatly reduced. Quadrature with the ADS on the double Schiffman phase shifter simulation results are shown in Figure 5. Figure 5 shows the two output ports phase difference between segments in the 70 ~ 95 between. Substituting the maximum phase difference [9] in the formula:

Theory combining efficiency can be calculated more than 90%, to meet the above objectives of the proposed design.

Figure 5 Ku-band Schiffman phase shifter dual simulation results

4 circuit assembly and test

Were simulated on the design of the components later, we were prepared to design microstrip-based power combining circuit. This microstrip chosen RTDuriod 6002 as the base. Well after making the circuit board shown in Figure 6. Substrate dielectric constant 2.94, loss tangent 0.001 2, plate thickness 0. 254 mm (10 mil). Rogers used the plate in addition to the companys RT Duriod 5880, 6002 series, there Arlons DiClad, CuClad, AD and other series.

Figure 6 Ku-band two-way power combining circuit board

Coupled with combined shielding and equipped with SMA connectors on the microstrip - coaxial connector, access to a Ku-band amplifier. We tested the amplifier. Test, the amplifier is installed on a radiator, access to the output of the amplifier, a high-power attenuator, shown in Figure 7. By the Agilent 8510C vector network analyzer measured small signal gain of the amplifier shown in Figure 8, the figure connected curve contained 30 dB output attenuator, the actual gain should be the figure with the graph corresponds to the value of 30 dB . Figure 8 shows that, between the 13 ~ 16GHz, the amplifier gain is greater than 20 dB, and relatively flat.

Figure 7, the amplifier under test and test equipment

Figure 8 the measured small signal gain of the amplifier

In addition, we use the Agilent E8257D signal source and power meter compatible AgilentE4418B EPM measured amplifier saturation power, the results are shown in Table 1. Table 2 in the behavior of the measured value of saturated power amplifier, 3-line data from the single TGF2508 - SM Datasheet chip factory data capture, and subtracting the attenuation value of output connector. 4 lines 2,3 from the first line of synthetic efficiency calculated from the data.

Table 1 the measured amplifier saturation power

5 Conclusion

This paper presents a new and detailed study of the structure of W il2kinson splitters. On this basis, the further integration of dual Schiff2man quadrature phase shifter and MM IC chip, designed balanced Ku-band power combining circuit. This article also complete the circuit the processing and assembly, access to a Ku-band 1 W-class power amplifier, the saturation in the 13 ~ 16GHz power is greater than 1 W, the small signal gain is greater than 20 dB, synthesis efficiency is more than 80%. In summary, to achieve a synthesis based on 2-way power Ku-band power amplifier. Involved in related technical fields related to an important reference value, the device has obtained a certain application.