Power amplifiers are a key part of RF transmitters. Power amplifiers can be designed and fabricated using CMOS, BiCMOS, GaAs-HBT, GaN-HEMT technologies. The main performance parameters for the power amplifier are power gain, linearity, and efficiency. For a power amplifier there are two types of efficiencies known as drain efficiency and Power Added Efficiency. PAE is the most important factor for evaluation of the performance of the power amplifier. GaAs-HBT and GaN-HEMT technologies provide high output power but dissipate large amount of power and requires large chip area. CMOS power amplifiers dissipate less power as compared to other technologies due to its ability to operate at very low voltages and the total chip size is also very less. CMOS power amplifiers are also very cost effective as compared to other available technologies. Power amplifiers find themselves in many wireless applications such as WLAN, WiMAX, Bluetooth, etc. WLAN operates in RF bands of 2.4, 3.6 and 5 GHz. The RF band of 2.4 GHz is a free ISM band.
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