Abstract:
There is provided not only a radio frequency power amplifier using an SiGe HBT subject to a little amplification distortion, but also a communication system using the same. A conventional radio frequency power amplifier provides base bias paths of transistors Q1 through QN (SiGe HBT) with bias resistors R11 through R1N having resistance values three to five times higher than those of a ballast resistor attached to each transistor's base. A coil LB is provided in parallel with the bias resistor as a means for compensating a voltage drop due to direct current component IDC flowing through the bias resistor. Addition of the bias resistor suppresses non-linearity of low-frequency variations in an output current. Addition of the coil compensates for voltage drop. Accordingly, the maximum linear output power can be improved. As a result, it is possible to provide the power amplifier subject to a little amplification distortion within a wide output range.
Abstract:
With the invention, it is possible to avoid deterioration in short-channel characteristics, caused by a silicon germanium layer coming into contact with the channel of a strained SOI transistor. Further, it is possible to fabricate a double-gate type of strained SOI transistor or to implement mixedly mounting the strained SOI transistor and a conventional silicon or SOI transistor on the same wafer. According to the invention, for example, a strained silicon layer is grown on a strain-relaxed silicon germanium layer, and subsequently, portions of the silicon germanium layer are removed, thereby constituting a channel layer in the strained silicon layer.