Design Of Wideband Power Amplifier With Low Intermodulation Distortion

Ooi, Chin Chong (2015) Design Of Wideband Power Amplifier With Low Intermodulation Distortion. Project Report. UTeM, Melaka, Malaysia. (Submitted)

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Abstract

A rising of the new technology developed globally has been happening along the recent years. However, the wide range power amplifier (PA) has been designed to cover more application in the operating range of frequency of the design amplifier. Until now, the wideband PA design still maintain as an arduous part in the microwave communication system. Additionally, a conventional single stage wideband PA has been suffering for its high intermodulation distortion which able to affect the performance of the design amplifier and harder to achieve the desired specification of the wideband PA. Compared to the design of the narrow band amplifier, wide band amplifier design provides more challenging to the pass band frequency of the amplifier. The main purpose of this project is to design a wideband PA with low intermodulation distortion which combine with the parallel coupled band pass filter to allow the frequency range from 2GHz to 3GHz (S-band) pass through the PA. This amplifier is designed double stage for the microwave application which included weather radar, satellite communication (space to earth), Wireless Networking (WLAN, WiMAX, cellular network, Bluetooth), mobile TV and satellite radio. The design concept has been used the multiple stage design structure which the multiple amplifier arranged in the parallel line and two power divider (coupler) are used to combine the several stages of the amplifier at the input and output port. A voltage divider Class-A amplifier is used to design the biasing circuit of the wideband PA which the transistor used is Avago Technologies’s ATF-511P8 Gallium Arsenide (GaAs) high linearity E-pHEMT. Intermodulation Distortion (IMD3) product is used to determine the linearity of the design power amplifier. The lower the IMD3, the higher the linearity of the design amplifier. Regarding to the simulation result of design double stage PA, the IMD3 shows 65.187dBc which has lower than -33.622dBc for the single stage PA. Input and output return losses, S11 and S22 show below -10dB along the operating frequency range, whereas the gain, S21 only can achieve above 5dB which lower than the aspect result (< 10dB). The power added efficiency (PAE) able to achieve more than 30% when the output power is more than 30dBm were at the 1dB gain compression point. The input third order intercept point (IIP3) is 37.5dBm while the output third order intercept point (OIP3) is 42.0dBm.

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