Davis Advanced RF Technologies Lab

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News

» [23 May 2018] » Songjie Defended his PhD Degree
» [20 Jan 2018] » DART Lab to Advance to Phase 2 of the DARPA SPAR Program
» [07 Mar 2017] » DART Lab Awarded NSF STTR Phase II Project on Developing a Radar-based Wearable Heart Health Monitoring Device
» [08 Nov 2016] » DART Lab to Participate in DARPA SPAR program
» [24 Aug 2016] » DART Lab Awarded a Humanitarian Innovation Fund Grant on Developing Autonomous Aerial Vehicles for Unexploded Ordnance Detection
» [27 Jan 2016] » DART Lab Awarded a Catalyst Foundation Supplementary Grant on Developing an Extremely Low Power RF Wake-up Front-end

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Welcome to the Davis Advanced RF Technologies (DART) lab

Maker Fair RF-MEMS Drone RF-MEMS Prof. Liu Oscillator

We are a group of researchers with a keen interest in many exciting areas of high frequency electronics. Our research interests include:

Critical to our scientific research efforts is a pursuit of fundamental understanding of the engineering principles of high frequency electronics. A major mission of our work is to formulate and disseminate such understanding through university education as well as community outreach.

Blog

[10 Jun 2018] » High-Efficiency mmW/THz Oscillator Design - 2: Some Historic Perspectives

Turns out that people have been thinking about this problem from very early on.

In 1968, Vehovec documented in his book a method for optimizing the output power of a transistor oscillator circuit. He formulated the problem in terms of the complex voltage gain across the transistor. Shown in the following figure, a transistor oscillator is considered as a combination of an active device and a passive feedback network. The ratio between the voltage at the output and the input port of the active device is defined as the voltage gain. In the steady state, we use phasors to represent the voltages and therefore the voltage gain is complex.

\begin{equation} A=A_R+jA_I=\frac{V_2}{V_1}, \end{equation} where $A_R$ and $A_I$ are the real and imaginary parts of $A$, respectively.

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