Graduate Students:
Egor Alekseev,
Youngwoo Kwon*,
Kevin Hein, and
Saeed Mohammedi
Professor
D. Pavlidis,
Dr. Jean-Oliver Plouchart
US Army Research Office DAAL-03-87-K-0007 and Daimler Benz
Microwave monolithic integrated circuits (MMICs) are being developed for many applications including receiver systems for commercial, military and space applications. These have traditionally made use of GaAs-based MESFETs and more recently HEMTs as active components. InP-based (InAlAs/InGaAs) HEMTs demonstrate the highest cutoff frequency among another three-terminal devices. HEMTs based on this material system are therefore of prime interest for millimeter-wave applications. The project addresses the optimization of submicron InAlAs/InGaAs HEMTs for improved frequency characteristics and their application to the realization of nonlinear MMICs at W-band and above.
Three different types of nonlinear monolithic circuits have been realized at various frequencies using submicron InAlAs/InGaAs HEMTs. A monolithic mixer has been designed and implemented at 94GHz yielding ~1 dB of conversion gain. This is the first demonstration of monolithic mixer with conversion gain at 94GHz. A miniaturized dual-gate HEMT mixer has been demonstrated at 94GHz with a conversion loss of 3dB. This type of mixer has the possibility of combining RF and LO signals on chip and miniaturizes the circuit. Oscillators have also been realized at Ka-band,W-band and more recently D-band. Ka-band monolithic oscillators showed a record DC-to-RF efficiency of 36%and W-band oscillators were demonstrated with an output power of 1.2mW at 77GHz out of chips with 0.1um x 36um HEMTs. The InP-based HEMT technology has been pushed to realize the fundamental monolithic source above 100GHz. A D-band dual-feedback HEMT oscillator was demonstrated with an output power of -7.9dBm at 130GHz. This represents the highest frequency fundamental oscillator using 3-terminal devices reported at the time. In order to provide signal sources well over 100GHz for space applications, 90GHz to 180GHz monolithic HEMT doublers have been realized showing a conversion loss of 6dB, which is comparable to the best hybrid diode doubler results. Various signal generation, mixing and multiplication functions are currently under study using submicron technology to extend the operation regime to subterahertz frequencies.
Other studies include PIN intergration in monolithic chips for the purpose of switching and phase shifting. Such circuit schemes are being explored for frequencies extending up to the millimeter-wave range.
High-speed circuit design issues are addressed by experimentally studying the electrical characteristics of interconnect lines used for this purpose. This includes investigation of properties such as characteristic impedance, propagation constant, coupling between adjacent lines, coplanar and microstrip designs. Frequency and time domain experiments are are carried out for this purpose. Various technologies are investigated and include CMOS, SOI, and HBT circuits designed for high speed operation.
100GHz InAlAs/InGaAs Cascode HEMT Oscillator. The cascode pair enhances the negative resistance so that more process tolerance can be achieved. The MMIC operates at 100GHz with an output power of 2dBm at a drain bias as low as 0.9V.
W-Band InAlAs/InGaAs Dual-Gate HEMT Mixer. The circuit provides on-chip RF/LO coupling and integrates the HEMT, RF/LO/IF matching circuits and bias lines. It shows a conversion loss of 3dB with 5dBm LO power.
100 GHz InAlAs/InGaAs Cascode HEMT oscillator. The cascode pair enhances
the negative resistance so that more process tolerance can be achieved.
The MMIC process at 100GHz with an output of 2dBm at a drain bias as low
as 0.9 V.
W-Band InAlAs/InGaAs Dual Gate HEMT Mixer. The circuit provides on-chip
RF/LO coupling and integrates the HEMT, RF/LO/IF matching circuits and bias
lines. It shows a conversion loss of 3dB with 5dBm LO power.
