A 1.0-μm CMOS 60-MBaud single-chip QAM processor for digital radio applications

A QAM processor for applications in QAM demodulators with modulation schemes of up to 1024 QAM and baud rates of up to 60 Mbaud has been implemented on a single chip. The chip performs all digital base-band signal processing of a high-capacity QAM demodulator including the digital parts of the timing and carrier recovery as well as the controlling and biasing functions for the proceeding A/D converters. The chip can be operated in half-baud spaced mode and can also be used for cross-polarisation interference cancellation in systems using co-channel transmission modes. The computational power of the QAM processor exceeds 5 gigamultiply-accumulate operations per second. The 800 k-transistor chip has been implemented on a chip area of 185 mm² using a 1.0-μm CMOS technology and has a power consumption of 4.4 W at 60 MHz clock frequency.