Narrow Band Transmitter
Tue, 11/23/2004 - 11:15am
The AS3977, the automotive-qualified ARIB transmitter ASSP (Application Specific Standard Product), was introduced by austriamicrosystems. The AS3977 multi-channel narrow band RF transmitter offers reliability of data transfer with support of FDMA and TDMA modes for redundant data transmission over distances up to one mile. It is optimal for use in RKE (Remote Keyless Entry) car access control systems and, due to its temperature resistance up to 125° C combined with low power operation modes, also for TPM (Tire Pressure Monitoring) applications. In addition it can be employed in numerous other applications such as SRD (Short Range Devices) digital radio transmission, remote control units, cordless alarm systems, remote metering and low-power telemetry. The AS3977 is a low-power, fully-integrated Frequency Shift Key (FSK)/Amplitude Shift Key (ASK) transmitter capable of operating at any user-selected ISM (Industrial, Scientific, Medical radio bands reserved for non-commercial use of RF communication) frequency from 300 to 1,000 MHz. The AS3977 is based on a sigma-delta controlled fractional-n synthesizer phase locked loop with fully-integrated voltage-controlled oscillator. The power amplifier output is programmable, capable of delivering from 20 dBm to 8 dBm. An on-chip, low drop-out regulator is available for accurate output power independent of supply voltage variation. It can support data rates up to 10 0kbps, depending on required filtering. Additional features include 2.0 - 3.6 V power supply, 4 kV ESD protection (2 kV for the RF pins), filtered FSK or ASK, FSK deviation programmable up to 64 kHz, integrated loop filter, 12 - 20 MHz crystal oscillator, digital lock detector, and low power-down current consumption.