Integrated CMOS RF building blocks for 433 MHz sensor systems

摘要

The performance of low noise amplifiers (LNAs) is limited by the quality factors of the inductors used. Realising fully integrated LNAs and other radio frequency (RF) circuits requires the development of techniques to improve the quality factory of on-chip inductors. It was found that the maximum attainable tank-Q of on-chip square spiral inductors for a given technology remained fairly constant and independent of the number of turns and the width of the tracks. Based on this on-chip spiral inductors were designed for applications in resonant tank circuits. A 433 MHz Industrial, Scientific and Medical (ISM) band tank circuit was designed based on a single spiral structure with a self-resonant frequency of 433 MHz, resulting in a decrease of 3.6% in the tank-Q compared to a circuit designed for maximum tank-Q. An LNA for a wireless receiver utilising a similar structure for the tuned load has been designed with a gain of 43 dB and a bandwidth of 1.74 MHz occupying an area of 0.48 mm~2.