Wednesday, May 04, 2016

DEPFET Pixel Said to Beat 1/f Noise

The open source Sensor journal publishes a sub-electron sensitive image sensor paper "The DEPFET Sensor-Amplifier Structure: A Method to Beat 1/f Noise and Reach Sub-Electron Noise in Pixel Detectors" by Gerhard Lutz, Matteo Porro, Stefan Aschauer, Stefan Wölfel, and Lothar Strüder from 1 PNSENSOR GmbH, München D-81739, Germany.

"The repetitive non-destructive readout (RNDR) DEPFET is an ideal central element for an active pixel sensor (APS) pixel. The theory has been derived thoroughly and results have been verified on RNDR-DEPFET prototypes. A charge measurement precision of 0.18 electrons has been achieved. The device is well-suited for spectroscopic X-ray imaging and for optical photon counting in pixel sensors, even at high photon numbers in the same cell."

The concept of a DEPFET: The signal
electrons are collected in a potential minimum
(internal gate) located below the channel of a
FET located on top of the fully depleted bulk.

Thanks to BB for the link!

2 comments:

  1. This is another installment in the Special Issue on Photon Counting Image Sensors co-sponsored by MDPI and the Int. Image Sensor Society. About of 1/3 of the papers have been reviewed and published so far. The papers are published as soon as they are accepted. (Guest Editors Fossum, Charbon, Teranishi, Theuwissen and Stoppa)

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  2. "Due to the higher amplification a read noise of only 3.1 e− r.m.s. was obtained for a single readout and consequently a noise of 0.18 e− r.m.s. at a temperature of −55 °C was achieved after only 300 readout cycles with a readout time of 25.5 μs."

    In fact, when I analyzed the photon-counting histogram (PCH) shown in Fig 6 in this paper, I cannot obtain 0.18e- rms read noise, and instead consistently get about 0.23e- rms read noise. The authors draw just a peak and shoulders fit to obtain 0.18e- but this is generally inaccurate. I have used the VPM method (published in IEEE JEDS in May) and obtain 0.23e- rms. I have also done a full model fit to the entire PCH and also obtain 0.23e- rms. It is quite conclusive and anyone else can give it a try and see what you get using Fig. 6.

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