Research of V-band pHEMT Cascode Power Amplifiers
Date Issued
2011
Date
2011
Author(s)
Bai, Jing-Shian
Abstract
In this thesis, three high frequency amplifiers are designed and investigated, including a V-band buffer amplifier, a V-band power amplifier and a 67-GHz power amplifier. These three circuits are implemented using pseudomorphic high electron mobility transistor (pHEMT) technology.
The first part of this thesis describes the design of a buffer amplifier for V-band applications using 0.15-um low-noise pHEMT technology. The circuit consists of two stages cascode amplifier and designed using coplanar waveguide (CPW) structure to reduce the parasitic effect. The measured small signal gain is about 18 dB, and the measured saturation output power is about 3.5 dBm at 60 GHz.
A power amplifier with high output power in 0.15-um power pHEMT technology is presented next. This circuit is also a two-stage design adopting cacode configuration as the driver stage and common-source configuration as the power stage. The measured saturation output power is about 22 dBm at 60 GHz.
Finally, a 67-GHz power amplifier using 0.15-um low-noise pHEMT technology is presented. This circuit is realized with two-stage cascode configuration to achieve high gain and high output power. The consideration of power budget and balanced structure using Lange coupler are discussed in this chapter. There are discrepancies between simulation results and measurement results, and the reason will be discussed also.
Because of the inaccuracy of the transistor model at higher frequency, the simulation results of the circuit do not agree with the measurement results. The linear model parameters are re-generated with the measured device data provided by the foundry WIN Semiconductors. Based on the new linear model parameters and the dc-IV curves, the Angelov model is established. With the new nonlinear model, the simulation results and measurement results of the circuits show better agreement.
Subjects
Power Amplifier (PA)
V-band
pseudomorphic high electron mobility transistor (pHEMT)
Type
thesis
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