Title: Fast Imaging Detector Readout Circuits With In-Pixel ADCs For Fourier Transform Imaging Spectrometers
Author: David Rider
Organization: Jet Propulsion Laboratory
Co-Authors: Dmitriy Bekker, Jean-Francois Blavier, Tom Cunningham, Bruce Hancock, Richard Key, Stan Sander, Suresh Seshadri, Chao Sun
Focal plane detector arrays with high frame rates and many pixels benefit several upcoming Earth science missions including GEO-CAPE, GACM, and ACE by enabling broader spatial coverage and higher spectral resolution. Detector arrays for the PanFTS, a high spatial resolution Fourier transform spectrometer and a candidate for the GEO-CAPE mission are the focus of the developments reported here, but they have the potential to enable a variety of future measurements and instruments.
We have developed with ESTO funding a fast readout integrated circuit (ROIC) based on an innovative in-pixel analog-to-digital converter (ADC). The 128 X 128 pixel ROIC features 60 µm pixels, a 14-bit ADC in each pixel and operates at a continuous frame rate of 16 kHz with a power consumption of less than 2 W. The ROIC directly outputs the digitized data completely eliminating the bulky, power consuming signal chains associated with most detector arrays. These operating characteristics allow PanFTS to achieve complete coverage of North and South America once an hour from a geostationary orbit.
The 128 X 128 pixel ROIC has been fabricated in CMOS and is undergoing testing at the Jet Propulsion Laboratory. The current version is designed to be hybridized with PIN photodiode arrays via indium bump bonding for light detection in the visible and ultraviolet spectral regions. However, the ROIC design incorporates a small photodiode in each cell to permit detailed characterization of the ROIC performance prior to hybridization. We will describe the essential features of the ROIC design and present results of ROIC performance measurements.