Firmenlogo IFN Home Projects About Us Contact Us Links Deutsch
Home Projects About Us Contact Us Links Deutsch
 Ordner
Current projects
 Ordner
Finished projects and references
   Ordner
Communications technology and RF applications
     Ordner

Development of a power amplifier with adjustable gain to drive an AOTF
(Acousto Optic Tunable Filter) for the Fraunhofer Institut für Chemische Technologie
as a part of a NIR (near infrared) spectrometer.

This project was done in cooperation with the Ingenieurbüro Herwig Marschelke

An acousto optic tunable filter mainly consists of a translucent crystal with piezoelectric
material on two opposite sides. This piezoelectric material bends when a voltage is applied
and therefore influences the structure of the crystal lattice. By compressing and expanding
the crystal lattice an exact selection of the wavelength of the passing light is possible.

The main difficulty when driving an AOTF is the huge and complex variations of the impedance
of the piezoelectric elements over the operating frequency range. In the present case the
impedance changed between 5 Ohms and 350 Ohms within the frequency range of 30 MHz
to 140 MHz. The power amplifier had to be unsusceptible to load variations and the output
power had to be adapted in a way that the effective power in the AOTF was constant.

picture of the pre-amplifier
The pre-amplifier

Der Leistungsverstärker
The power amplifier

Der Leistungsverstärker im Detail
A closer view of the power amplifier

back to the start of the page back to the start of the page
back to the overview of finished projects and references back to the overview of finished projects and references
back to the complete projects overview back to the complete projects overview

   

IFN Ingenieurbüro für Nachrichtentechnik Helmut Brandl,
Inhaber Helmut Brandl jun., Blarerstrasse 56, D-78462 Konstanz
Tel.: +49 (0)7531 / 91250, Fax: +49 (0)7531 / 91252,
E-Mail: info@ifn-brandl.de, Ust-Ident-Nummer DE 156 599 916
© 2008 by IFN H. Brandl, last update: 20. March, 2007