RF109

The RF109, a fully integrated transceiver device, provides the transmit, receive, and frequency synthesis functions for 2400 MHz digital spread spectrum systems operating in the 24002483.5 MHz portion of the ISM (Industrial, Scientific, Medical) band. The device has a direct conversion architecture that minimizes circuit complexity and cost.

The receive path of the RF109 provides complete RF-to-baseband I/Q demodulation, including an LNA, double-balanced quadrature mixers, fully integrated baseband filters, and baseband variable-gain amplifiers. The transmit path is a variable-gain direct conversion modulator. Figure 1 shows the RF109's pin signals. Figure 2 shows the RF109 block diagram.

The RF109 generates the Local Oscillator (LO) frequencies using a Phase Lock Loop (PLL) frequency synthesizer and an external 2.4 GHz Voltage Controlled Oscillator (VCO). The PLL provides a full frequency range of 2392.22505.6 MHz.

The RF109 features low-voltage operation (3.04.5V) for low power consumption. A complete RF system solution for 2.4 GHz cordless telephone applications can be constructed with the RF109, a power amplifier, a differential 2.4 GHz frequency source and a Transmit/Receive (T/R) switch.