An analog synchronous QPSK demodulator for ultra-high rate wireless communications

In this paper, the authors present a monolithic integrated QPSK demodulator, which performs carrier phase and frequency synchronization in the analog domain. Analog synchronization eliminates the need for high speed and high resolution analog to digital converters (ADC), which makes the presented demodulator especially promising for communication links exceeding gigabits-per-second data rates. Within this paper, analog carrier recovery, and successful synchronous demodulation is experimentally demonstrated for data rates up to 3.5 Gbit/s. The presented MMIC is realized in Telefunken SiGe2RF HBT technology (f_T and f_max ≈ 80GHz), and operates at an intermediate frequency of 5GHz. The IC is supplied from a single 2.5 V DC source and consumes 110mA current.