Single-Chip Transceiver Aids TDMA/AMPS

Self proclaimed as the industry’s most compact and cost-effective off-the-shelf cell phone radio chip for second-generation TDMA/AMPS digital networks, the ZLTM20200 is also said to be the first commercial device to integrate call receive and transmit circuitry on the same silicon. The device uses advanced architectural partitioning and a two-stage receiver design to address isolation issues associated with this level of integration. Its receiver mixes incoming IF voice signals with synthesized LO signals from an on-chip VHF VCO and down converts them to the baseband frequency. With 100 dB of gain control, AMPS FM demodulation capability, and baseband filters, the receiver allows direct connection of the transceiver to most commercial baseband processors without external circuitry. The transmitter section is a linear circuit with a quadrature modulator, IF gain control, and a single-ended output that delivers enough power to directly drive a two-stage power amplifier, eliminating the need for an external balun. The transceiver operates in the 850 MHz frequency band in TDMA and AMPS modes and in the 1,900 MHz PCS band in TDMA mode and is compliant with the TIA/EIA IS-136 specification. Available in a 56-pin MLP measuring 8 mm x 8 mm, price is less than $5 each in volume. An evaluation board and API software are also available. ZARLINK SEMICONDUCTOR, Ottawa, Canada. (613) 270-7115.