Design Of RF Power Amplifier With Process Compensation

In wireless communication system, power amplifier is one of the essential system components, Because almost every microwave、RF and Millimeter wave systems have to use transmitter, and each one transmitter has a power amplifier, so Power amplifier has a very broad application prospect in the market. It is a trend integrating as many components as possible in wireless systems in an inexpensive technology, such as CMOS technologies. However, the implementation of high output power, high efficiency and high linearity CMOS RF power amplifier remains a formidable challenge, especially in deep-nanometer technologies. Also low supply, low breakdown voltage of thin gate oxide in devices and high silicon substrate loss deteriorate it.A RF power amplifier is designed based on HJTC0.18um CMOS process. The power amplifier stage uses cascade structure, in this structure use the superposition of two thick oxide transistors to improve the ability to withstand voltage of the circuit, Can let the circuit work under the higher power supply voltage. And also a process compensating bias circuit is designed, this bias circuit can compensate temperature and process variation to ensure the temperature and process stability of the power amplifier. All in all, this power amplifier have low sensitivity to environment and process changes, so maintain the output power in a lager range. Also a bandgap reference with low temperature and high power supply rejection ratio is designed for the bias circuit.At last, design layout for the circuit and complete post simulation. according to the results, The power amplifier can work normally under the enabling signal and modulation signal control, and can largly reject harmonic signal; when the input signal is a square wave whose fundamental frequency is315M Hz, under typical and32extreme kinds of condition, the power amplifier’s output power is all lager than lOdBm, efficiency is about50%. Because the circuit is insensitive to temperature and process variation, the power amplifier’s output power and efficiency is relatively stable.