AN612

WIRELESS, RF, AND CABLE Jun 01, 2001 TD-SCDMA Radio Chipset Block Diagram for Handset Application China option for 3G cellular phone is the TD-SCDMA system. A detailed handset transceiver diagram is presented showing MAX2361 as the transmit IC, the MAX2291 as the power amplifier (PA), and the MAX2388 and MAX2309 form the receiver. A VCO buffer amplifier is used to provide isolation and maintains a clean LO signal. Overview TD-SCDMA is the third-generation (3G) cellular phone standard currently under development in China. In November 1999, the TD-SCDMA standard was adopted by the ITU as one of the options in the 3GPP mobile communication standard. TD-SCDMA combines time-division duplex (TDD) and CDMA with up-link (reverse-link) synchronization, a software radio, and a smart antenna, to increase channel capacity and improve bandwidth efficiency. In the radio section of the handset, the TD-SCDMA radio section requires fast switching time, high dynamic range, and high linearity in both the transmitter and receiver sections. Maxim's chipset delivers the highest performance, the smallest implementation size, and the least expensive radio solution available in the TD-SCDMA handset market. The following block diagram shows a typical application. Transmitter The MAX236X is a complete quadrature transmitter, including a quadrature modulator, variablegain IF and RF amplifiers, an image-rejecting upconverting mixer, a dual RF and IF synthesizer, and a dual-band power amplifier (PA) d...