SKY74702

www.DataSheet4U.com PRODUCT SUMMARY SKY74702: Transmitter for CDMA Applications Applications CDMA phones in the cellular band: ⎯ CDMA-US ⎯ CDMA-Japan The signal enters the chip as a baseband I/Q signal, which is upconverted by an I/Q quadrature modulator. The resulting signal is fed through a VGA to provide variable output power. After leaving the open collector output of the VGA, the signal enters a switch matrix. This switch matrix allows the signal to be routed through an external filter, or it can be filtered by the tuned collector load and passed directly to the UHF image reject mixer. The image reject mixer is internally connected to the PA driver. The mixer driver combination has a variable gain control that can be used to reduce the RF gain, which improves the in-band Signal-to-Noise Ratio (SNR) at a lower output power. The PA driver amplifies the RF signal to the appropriate level for the desired output power. This is then filtered by a bandpass filter and sent to an external PA to obtain the final rated output power at the antenna. The device package and pinout for the 40-pin RF Land Grid Array (RFLGA) are shown in Figure 1. A block diagram of the SKY74702 is shown in Figure 2. Features Serial bus interface control Low power consumption in all operating modes Image reject upconverter replaces external RF SAW filter Transmit power control with 90 dB dynamic range Variable gain RF block for improved in-band SNR VHF VCO (external tank), 200 to 700 MHz ...