Hier finden Sie wissenschaftliche Publikationen aus den Fraunhofer-Instituten.

A digital 25 m pixel-pitch uncooled amorphous silicon TEC-less VGA IRFPA with massive parallel Sigma-Delta-ADC readout

: Weiler, D.; Ruß, M.; Würfel, D.; Lerch, R.G.; Yang, P.; Bauer, J.; Vogt, H.


Andresen, B.F. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Infrared technology and applications XXXVI : 5-9 April 2010, Orlando, Florida, United States
Bellingham, WA: SPIE, 2010 (Proceedings of SPIE 7660)
ISBN: 978-0-8194-8124-5
Paper 76600S
Conference "Infrared Technology and Applications" <36, 2010, Orlando/Fla.>
Conference Paper
Fraunhofer IMS ()
infrared detector; IRFPA; VGA; uncooled microbolometer; amorphous silicon; Sigma-Delta-ADC on chip

This paper presents an advanced 640 x 480 (VGA) IRFPA based on uncooled microbolometers with a pixel-pitch of 25µm developed by Fraunhofer-IMS. The IRFPA is designed for thermal imaging applications in the LWIR (8 .. 14µm) range with a full-frame frequency of 30 Hz and a high sensitivity with NETD < 100 mK @ f/1. A novel readout architecture which utilizes massively parallel on-chip Sigma-Delta-ADCs located under the microbolometer array results in a high performance digital readout. Sigma-Delta-ADCs are inherently linear. A high resolution of 16 bit for a secondorder Sigma-Delta-modulator followed by a third-order digital sinc-filter can be obtained. In addition to several thousand Sigma-Delta-ADCs the readout circuit consists of a configurable sequencer for controlling the readout clocking signals and a temperature sensor for measuring the temperature of the IRFPA. Since packaging is a significant part of IRFPA's price Fraunhofer-IMS uses a chip-scaled package consisting of an IR-transparent window with antireflection coating and a soldering frame for maintaining the vacuum. The IRFPAs are completely fabricated at Fraunhofer-IMS on 8" CMOS wafers with an additional surface micromachining process. In this paper the architecture of the readout electronics, the packaging, and the electro-optical performance characterization are presented.