A 3G PMR Tetrapol-Tetra-Apco25 multi-mode analog base-band chip in CMOS 0.18 μm technology

We present a design of a complete multi-mode analog base-band chip for 3G PMR (private mobile radio) mobile terminals. To address operability into three different transmission modes, like Tetrapol, Tetra, and Acpco25, the chip makes use of special design techniques, such operation and circuits adaptation at different master clocks, and re-configurability of digital filters. The chip contains a special high-performance voice codec for PMR, which integrates three different output amplifiers, one class-AB for 32 Ohm earpiece loads, a second class-AB for 8 Ohm speaker loads, capable to deliver up to 250 mW, and a third class-D power amplifier, delivering up to 1 W output power on 4 ohm loads, and using a spread spectrum clock to alleviate any potential EMC issues. The voice codec is also capable to generate and handle both 8 ksps normal mode, and special 40 ksps MACH (mutual aided channel) mode throughputs at its PCM port. Besides the voice codec, an auxiliary codec, composed of four 10-bit 1 Msps auxiliary DAC´s, one 12-bit sigma-delta AFC DAC, one multi-port 10-bit 200 ksps ADC, and finally battery management blocks, complete the analog functions. The SOC has been designed in Atmel AT58 K CMOS 0.18 μm technology, occupies only 11.5 mm², and is currently under fabrication.