Tx-Rx Quad-Band Front-end Module for GSM/ GPRS (824-915 MHz) (1710-1910 MHz) w/ Six Linear TRx Switch Ports
SKY77589-21 is a transmit and receive Front-End Module (FEM) with integrated power amplifier control designed in a low profile, compact form factor for quad-band cellular handsets comprising GSM850/GSM900 and DCS1800/PCS1900 operation. The SKY77589-21 offers a complete Transmit VCO-to-Antenna and Antenna-to-Receive SAW filter solution. The FEM also supports Class 12 General Packet Radio Service (GPRS) multi-slot operation and EDGE downlink.
The module consists of a GSM850/GSM900 PA block and a DCS1800/PCS1900 PA block, impedance-matching circuitry for 50 ohm input and output impedances, Tx harmonics filtering, high linearity / low insertion loss RF switch, and a Power Amplifier Control (PAC) block. One PA block supports the GSM850 / GSM900 bands and the other PA block supports the DCS1800/ PCS1900 bands. Both PA blocks share common power supply pads to distribute current. The output of each PA block and the outputs to the six receive pads are connected to the antenna pad through an RF switch. Six broadband interchangeable receive ports provide flexibility to support multimode and multiband configurations. The GaAs die, the CMOS die, the Switch die, and passive components are mounted on a multi-layer laminate substrate. The assembly is encapsulated with plastic overmold.
Band selection and control of transmit and receive are performed using four external control pads. Refer to the block diagram in Figure 1 below. The band select pad, BS1, BS2, Mode, and TxEN select GSM850, GSM900, DCS, and PCS modes of operation.
Transmit enable TxEN controls receive or transmit mode of the RF switch (Tx = logic 1). Proper timing between transmit enable TxEN and Analog Power Control VRAMP allows for high isolation between the antenna and Tx–VCO while the VCO is being tuned prior to the transmit burst.
The SKY77589-21 is compatible with logic levels from 1.2 V to 2.9 V for BS1, BS2, MODE, and TxEN pads.
Please note: SKY77589-21 is being discontinued and is not recommended for new designs.