High gain narrow band LNA design for Wi-max applications at 3.5GHZ

Abstract

The wireless communication has been experiencing tremendous growth in technology. The demand has been increased for low cost RFIC designs. Many researches are going on front end design of RF transceiver. The design of receiver path has become a challenging aspect, because of increased interferences around the communication path. Transmitter path design is easy because interference levels are very less compared to signal level. As the operating frequency is higher in RFIC design, receiver path also experiencing the internal noises in the system. The performance of transceiver depends on each of the individual blocks such as low noise amplifiers. In this thesis, Two RF CMOS narrow band LNAs (cascade and differential) are designed. They are designed for the IEEE 802.16 standard in the 3.5 GHz band for Wi-MAX applications. Low noise amplifier is used as the first block after the receiving antenna. This LNA is placed before the mixer in the receiver path for amplification. The LNA must have good gain and low NF to avoid further degradation of receiver path. This thesis focuses on design of a high gain LNAs with acceptable noise figure operating at 3.5GHz. Inductive Source degeneration method is used to match the circuit to source impedance in all the designs. All the circuits operate with 1.8v supply voltage. Here in this thesis, Enhanced cascode LNA exhibits a gain of 26.88dB and NF of 2.55dB and the Differential LNA exhibits a gain of 32.71dB and NF of 2.66dB. The circuits are designed using cadence 0.18µm RF CMOS technology.