A 900mhz Front-end Design with Copper Passive Components

In this paper, we evaluate the impact of copper (Cu) passive components on RF circuit performance. A fully-differential RF Frontend is used as a test vechicle to compare the Cu 0.18 copper process with a traditional 0.25 aluminium (Al) process. The RF Front-end contains a balun and a low noise amplifier (LNA) that are designed with spiral inductors and capacitors. CMOS spiral inductor Q values range from 3 to 5 for the aluminium process and are improved with 7 to 9 for the Cu process, while the fringe capacitor Q values for the Cu process are more than twice the Q vlaues for the Al process. At the system level, the balun performance is characterized by its insertion loss and the LNA performance is defined by its gain and noise figure. The balun insertion losses are 0.6dB to 0.8dB lower for the Cu process as compared to a traditional Al process. The LNA gain is 3dB higher for the Cu process and has a sharper bandpass characteristic. The output signals from the LNA are downconverted by a Gibert cell mixer and amplified by an IF stage. The entier system has been simulated and results from measurements are included to validate our simulation result.