Study On A GaAs MMIC Wideband Low Phase Shift Digital Attenuator

Wideband digital attenuators are the core chip for microwave T/R systems. Small size, light weight, high reliability make MMIC digital attenuators have been widely used in various military and commercial areas.This article describes the operating principle, circuit design and testing techniques for broadband digital attenuators. The digital attenuator development is based on PHEMT material, MMIC process and the design method combining circuit and electromagnetic simulations. High attenuation accuracy, small additional phase shift have been achieved.The main specifications of the GaAs MMIC digital attenuator are as follows:Frequency range: DC ~ 20GHz; number of bits: 5 bits; insertion loss≤5.0dB; attenuation accuracy: 0.5dB±0.15dB, 1dB±0.2dB, 2dB±0.2dB, 4dB±0.25dB, 8dB±0.6dB; additional phase shift≤±3°; VSWR≤1.5:1; switching time≤10 ns.