Rf Power Transistors

Considering the character of high-freq. Power transistor, we adopt several methods. All of that can be expressed as follows. 1. To enhance the reliability of transistor, temperature protection circuit is designed, which replaces common ballasting resistor. circuit bypasses the most of base current of RF BJT when temperature rises to 140oC, and cuts off bypass function when temperature drops to 87oC. Therefore, RF BJT comes back to normal working state. All of that aims to realize a real time protection for transistor and improve the high-freq. character of device at the same time. 2. In order to keep gain smooth, enhance output power and efficiency, reduce reflect factor and attenuation, inner matching network both at input port and at output port is needed. That can finally improve high-freq character and facilitate the transfer of power. 3. To validate different target parameters, simulation work is done by using Medici around critical electrical parameter such as cutoff frequency fT, punch through voltage BVCBO, DC current gainβetc. 4. RF BJT cell and temperature control circuit are realized at one silicon die, which is insulated from each other by a back bias PN junction circle. Layout is also drawn. Take the design of DCT260F for example, a new method based on CMOS temperature control circuit to obtain high reliability and long life RF BJT is put forward. Computer simulation and layout is completed. With subsequent continuous work, ultimately that is coming to be commercialized and enter domestic and foreign market.