Design Of Power Amplifier For Vehicle EMC Testing

In recent years,the degree of vehicle electronization is deepening,to eliminate the hidden danger brought by electronic equipment,vehicle manufacturers must carry out Electromagnetic Compatibility(EMC)test for vehicle and their electronic equipment.Among them,power amplifier is the core component of vehicle EMC test system,and its performance will directly affect the effect of vehicle EMC test.With the improvement of vehicle EMC test requirements,the system puts forward higher requirements for power amplifier in bandwidth,output power,efficiency and so on.According to the above application background requirements and power amplifiers design theory,this thesis discusses and studies how to improve the bandwidth,output power,efficiency and other indicators of wideband high power amplifiers.Firstly,a balanced power amplifier working in 1?2 GHz with an output power of200 W is designed in this thesis.The power amplifier adopts a three-stage power amplifier cascade and a balanced structure to achieve a 200 W high power output,and each single-tube power amplifier adopts a Chebyshev bandpass filter structure to achieve a broadband design.The two-order Wilkinson power divider is used to expand the bandwidth of the network for both the power division network and the composite network.Finally,after testing,the power amplifier was obtained with a gain of12.5?15.1 d B,a saturated output power of 53.2?54.1 d Bm,saturated additional power efficiency of 45.2?60.4%,and gain flatness of less than ±1.5 d B in the operating band1?2 GHz,with good performance.In order to expand the application range of the vehicle EMC test power amplifier,extend the bandwidth of the power amplifier and increase its output power,another four-way power amplifier is designed in 1?2.4 GHz with an output power of 350 W in this thesis.This power amplifier adopts a four-stage power amplifier cascade and four-way power synthesis to achieve 350 W high power output.Each single-tube power amplifier adopts a modified Chebyshev bandpass filter structure to realize a wideband design,and the power division network and synthesis network are based on the Wilkinson power divider to design a four-way wideband power division network and synthesis network.Finally,the software simulation obtained that the power amplifier in the operating band 1?2.4 GHz,the gain of 14.8?16.6 d B,a saturation output power of55.4?56.5 d Bm,a saturation additional power efficiency of 53.6?63.1%,gain flatness less than ±1 d B,the performance is relatively good to meet the design index requirements.The broadband high-power amplifier designed in this thesis has certain advantages in terms of bandwidth,output power and efficiency,and is suitable for vehicle EMC test systems.At the same time,the design of this thesis can also provide corresponding theoretical reference and design experience for subsequent broadband high-power amplifiers.