Research And Design Of The Adaptive-gain RF Frequency LNA Using CMOS Technology

In the past ten years, the communication technology has developed with astonishing speed. It is estimated that the number of the wireless communication users will surpass that of line-wire communication users and achieve 1 billion up to 2010. This kind of potential market results in huge demand for the radio frequency integrated circuit. Along with the reduction of line width in CMOS technology which has low cost and low power loss, the frequency characteristic and the noise characteristic are being improved. CMOS technology has been used to design the manufacture radio frequency integrated circuit. Low noise amplifier (LNA), as the electronic device in the forefront end of radio communication system, induces the weak signal directly from the antenna receiver and enlarges it. After then, the LNA transmits the enlarged signal to the next process element. The operating frequency of the LNA is the highest among the RF commuciation modules. As one of the key modules in the entire reception channel, LNA's performance plays an important role in the performance of entire receiver.Some research and design work of the LNA module were conducted in this paper. An gain auto-adapted CMOS low noise amplifier, which is suitable for RF part of GSM/DCS 1800 dual range handset, is implemented. It avoids the output signal of rear end surpassing the linearity range of the mixer. So the LNA can work in wireless communication devices in the different environments.The realization of the gain auto-adapted low noise amplifier in this paper is based on TSMC-0.18μm CMOS technology. The results of the simulation in ADS software indicate that the LNA noise factor is 0.2dB. The range of the auto-adapted gain is from OdB to 17dB, which completely satisfies the requirement of RF part in the GSM/DCS 1800 dual range handset. In the last part of the paper, based on the radio frequency integrated circuit's layout design technique, the detail of the entire electric circuit layout with TSMC-0.18μm CMOS technology PDK is described.The LNA is implemented by changing output network impedance in this paper, which does not reduce the LNA noise factor nearly, as well as the other performance merit. The method can enhance the whole auto-adapted LNA's performance greatly.