SI4020

Si4020 Universal ISM Band FSK Transmitter DESCRIPTION Silicon Labs’ Si4020 is a single chip, low power, multi-channel FSK transmitter designed for use in applications requiring FCC or ETSI conformance for unlicensed use in the 315, 433, 868, and 915 MHz bands. Used in conjunction with IA4320, Silicon Labs’ FSK receiver, the Si4020 transmitter feature EZRadioTM technology, which produces a flexible, low cost, and highly integrated solution that does not require production alignments. All required RF functions are integrated. Only an external crystal and bypass filtering are needed for operation. The Si4020 features a completely integrated PLL for easy RF design, and its rapid settling time allows for fast frequency hopping, bypassing multipath fading and interference to achieve robust wireless links. In addition, highly stable and accurate FSK modulation is accomplished by direct closed-loop modulation with bit rates up to 256 kbps. The PLL’s high resolution allows the use of multiple channels in any of the bands. The integrated power amplifier of the transmitter has an open-collector differential output that directly drive a loop antenna with programmable output level. No additional matching network is required. An automatic antenna tuning circuit is built in to avoid costly trimming procedures and detuning due to the “hand effect”. For low-power applications, the device supports automatic activation from sleep mode. Active mode can be initiated by several wake-up events (on-...