Program and Abstract Book - SRON

19 th International Symposium on Space Terahertz Technology
7-1
Invited presentation for ISSTT2008
Pushing the limits of multiplier based local oscillator chains
Imran Mehdi, John Ward, Alain Maestrini*, Goutam Chattopadhyay, Erich Schlecht,
and John Gill
Jet Propulsion Laboratory, California Institute of Technology, Pasadena CA 91109
*Université Pierre et Marie Curie-Paris6, LISIF, Paris, France and Observatoire de Paris, LERMA, France
The successful implementation of robust
and sufficiently powerful multiplier
based sources ranging to 1900 GHz for
the Herschel Space Observatory has now
made it possible to leverage this
technology for future missions and
various other applications. Broadband,
electronically tunable sources based on
Schottky diode frequency multipliers
continue to be an ideal solution for a
number of proposed applications in the
THz range.
Fig. 1. 3D schematic view of the bottom half of the power-combined 260-
340 GHz frequency tripler based on two mirror-image integrated circuits.
Fig. 2. Close-up view of the power-combined 260-340 GHz frequency
tripler showing the two mirror-image GaAs integrated circuits. The E-field
vectors in the input and output waveguides are indicated by plain arrows.
The E-fields generated by the two sub-circuits are combined in-phase in
the output waveguide.
This talk will survey the current status of
multiplier based sources and focus on the
progress that has been made since the
delivery of HIFI local oscillator chains.
To improve device yields all chips are
now fabricated on a membrane regardless
of operating frequency. While this has
dramatically increased yields and
significantly shortened processing times,
on-chip thermal management has become
extremely important especially for the
first stage multipliers. Other objectives of
the current effort is to extend output
power and frequency range of these
sources. A simple in-phase power
combining scheme that addresses all of
these concerns has been recently
demonstrated [1]. A 300 GHz tripler
block that utilizes two in-phase planar
chips is shown in Figure 1 and 2.
Utilizing this simple approach can lead to
higher output power without sacrificing
bandwidth. Schemes that utilize even
more chips in a single block are also
being considered. Increased output
power in the drive stages allows one to
then pump later stages with sufficient
power. Using this approach can result in
multiplier based sources working up to 3
THz with sufficient power to pump single
pixel receivers.
[1] Alain Maestrini, John S. Ward, Charlotte
Tripon-Canseliet, John J. Gill, Choonsup Lee,
Hamid Javadi, Goutam Chattopadhyay, and Imran
Mehdi, “In-Phase Power-Combined Frequency
Triplers at 300 GHz,” to appear in March 2008
issue of IEEE Microwave and Wireless
Components Letters.
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