A Novel Design of 1.5 GHz Low-Noise RF Amplifiers in L-BAND for Orthogonal Frequency Division Multiplexing
G. Sharmila · 2011
Communication plays very important role in day-to-day life of people. Due to fast growing age, multi carrier communication is preferred over single carrier waves for better transmission. The RF power amplifier in OFDM transmitters plays a major role in amplifying the required high frequency RF signal without distortions and other impairments which would decrease the usefulness of the signal. For narrowband & wideband operation, one may construct simple amplifiers whose noise figure and power gain are close to the theoretical optima allowed within an explicit power constraint.This paper introduces the design of a 1.5 GHz unconditionally stable Low-Noise RF amplifier in L-Band using Agilent's Advance Design Systems Software. The proposed design aims to provide an optimal gain of 12.715 dB with low Noise Figure (NF) of 1.768 dB in wideband. This paper presents a circuit topology of the Bipolar Junction Transistor Low Noise Amplifier (BJT- LNA) operating at 1.5 GHz. The circuit is constructed using AT41435 Low-Noise BJT Device. The design proposes tradeoffs between gain, noise and blocking performances (2). Agilent's ADS software in RF and microwave simulation of circuit and system has unique advantages. Some of them are friendly interface, model base of integrity, RF performance simulation and optimization of convenience. This paper just uses Agilent's ADS software for designing the Low-Noise amplifier used in IEEE 802.11b and describes in detail the methods involved in the design and simulation of Low Noise Amplifier. In Section 2, we have analyzed the basic suitability of the device for the construction of the circuit at the desired frequency range of 1.5 GHz. In the Section 3, we have analyzed and discussed the design methodology of Input Matching Network for obtaining the optimum impedance matching. Then, we design the output matching network using Microstrip-Lines in Section 4. In Section 5, we discuss the overall schematic and optimum Gain measurement at Low-Noise Figure of 1.768 dB.The simulation results and future prospects of the design are presented in Section 6.