A comparison of low frequency noise in GaAs and InP-based HBTs and VCOs

The low frequency collector noise spectra for GaAs-based and InP-based HBTs have been measured and compared as a function of emitter material, bias and temperature. Al/sub 20/Ga/sub 80/As/GaAs and InAlAs/InGaAs HBTs exhibited classic 1/f noise spectra while the Al/sub 30/Ga/sub 70/As/GaAs HBTs showed a pronounced burst noise component. Identical VCO circuit topologies implemented in Al/sub 20/Ga/sub 80/As/GaAs and InAlAs/lnGaAs HBTs demonstrated a 10 dB improvement in phase noise at a 1 MHz offset over the Al/sub 30/Ga/sub 70/As/GaAs HBT-based VCO.<
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