RF receiver design using the direct conversion approach at 5.8 GHz band based on IEEE 802.11a standard

This thesis presents the development and analysis of a radio frequency (RF) front-end direct conversion receiver at 5.725 – 5.825 GHz where IEEE 802.11a standard is used as performance test. The RF receiver is designed based on the commercialized products (off-the-shelf) where it focuses on the system design tradeoff, rather than circuit design tradeoff. The RF receiver has been designed with the selected architecture where it is consist of low noise amplifier (LNA), radio frequency amplifier (RFA), power divider and two bandpass filters. The modeled RF receiver has been analyzed by using Advanced Design System (ADS) 2005A software for system characteristic and performance test. From the simulation, minimum sensitivity is -91 dBm at data rate 6 Mbps and -74 dBm at data rate 54 Mbps where it is comply with the IEEE 802.11a standard. The RF receiver prototype has been measured and this system produces has gain of 39 dB which is higher than the reviewed of 37.5 dB. The noise figure of this work is measured at 1.30 dB, which is better than the reviewed work at 4.6 dB. The nonlinearity characteristic such as power at 1dB compression point (P1dB) and third order intercept point (IP3) is observed. From the measurement, the RF receiver will drop 1 dB when input power (Pin) is injected above -27 dBm then it caused output power (Pout) start saturated. The third output intercept point (OIP3) and third input intercept point (IIP3) is at around 15 dBm and -24.50 dBm respectively. The RF receiver system characteristic such as sensitivity meet the standard requirement of IEEE 802.11a standard for wireless local area network (WLAN) bridge system.