A VCO Design for WLAN Applications in the 2.4 to 2.5 GHz ISM Band

摘要

The increased demand for mobile network connections has lead to the establishment of RF interface standards for Wireless Local Area Networks (WLANs). The unlicensed ISM frequency band at 2.4 to 2.5 GHz has been designated for WLAN usage. Table 1 displays frequency allocations in different parts of the world for WLAN. In the US, IEEE 802.11 specifies two RF physical layer interfaces for WLAN, Direct Sequence Spread Spectrum (DSSS) and Frequency Hopped Spread Spectrum (FHSS). DSSS uses an 11-bit Barker code where each bit of information is spread within a single channel. The IEEE standard allocates 11 channels, each 22 MHz wide, with 5 MHz spacing between center frequencies in the 83.5 MHz band. This creates channels whose occupied frequencies overlap.