Tunable IF Aids Bluetooth Flexibility

摘要

This novel programmable intermediate-frequency (IF) filter providesrnperformance that can be adapted to changing needs, whether to savernpower or deliver high rejection of unwanted signals.rnBluetooth has evolved from a low-throughput-rate (723 kb/s) short-range wireless link at 2.40 to 2.4835 GHz transmit-ting simple frequency-hopped, Gaussian frequency-shift-keying (FSK) modulated signal. This early version of the unlicensed wireless standard (Bluetooth 1.2) shifts carriers by ±160 kHz to represent the data bit, using frequency hopping at 1600 times/second onto one of 79 channels, each spaced 1 MHz apart. Newer versions of Bluetooth employ more complex modulation to increase the throughput rate. As a result, compatibility with the different Bluetooth formats requires a radio with a flexible intermediate-frequency (IF) section for the different spectral masks.