Design of low cost Class-E power amplifier for HF band applications

HF band (3~30 MHz) has been widely used in many communication and other systems, in military and civil applications. Generally the circuit design in this band is not a challenge; however this is not the case in some circuits, especially in the case of power amplifier design. One of the most important parameters in power amplifier design for civil applications is the product cost. On the other hand power amplifier is the most expensive part of a transceiver or other high power RF system. Consequently low cost high performance power amplifier is very attractive in HF band. In most of designs, high power RF transistor is the most expensive circuit component. This paper presents a new design approach for Class-E power amplifier in HF band, by which the capability of RF switch is considerably improved. Thanks to the proposed approach, we have successfully designed a 30 MHz Class-E power amplifier, using the extra low cost, commercially off-the shelf (COTS) VMOS components. The reported works with COTS VMOS devices are in the range of few hundreds of kilohertz. The cost for the device used in our work is about 100 times lower than the conventional Gemini MOSFET devices. The designed PA exploits 98% power efficiency and 81% power added efficiency with 70 watts output power.