TED BPSK Modulator/Demodulator Integrated Circuit Development.

This program had two basic objectives to develop processing techniques suitable for the fabrication of small scale gallium arsenide GaAs integrated circuits, and to fabricate and evaluate GaAs biphase shift-keyed BPSK integrated circuit modulators and demodulators operating at 5 GHz carrier frequencies. GaAs integrated circuits require, as a minimum, field effect transistors FETs, resistors, and interconnection metals. Previous TRW studies had shown that the addition of planar, gate controlled transferred electron devices TEDs, capacitors, and multilevel metals for undercrossings would facilitate the implementation of circuits which could perform useful microwave functions with a low device count and at fairly high frequencies. The design goals for the modulator and demodulator circuits were operational at 5 GHz carrier frequency and 1 Gbps data rate with minimum dc power. The circuit designs are distinctly nonconventional, having been developed specifically for implementation with the TEDs. The TEDs are used basically as phase logic AND gates, while the FETs are used as linear amplifiers. Both circuits generally exceeded the design goals the modulator circuit operates from 4.5 to 8 GHz carrier frequency, 0 to 1.4 Gbps data rate, and 440 mW dc power the demodulator operates from 4 to 10 GHz carrier frequency, 0 to 1.6 Gbps data rate, and 235 mW dc power. The IC chips are roughly 75 mils square and are mounted in test fixtures whose volume is 0.75 cu.in.