Open AccessSporadically‐driven clock‐less in‐pixel multi‐bit energy discriminator for X‐ray spectrometry CMOS PCD imagers
Author(s) -
Kim H.S.
Publication year - 2016
Publication title -
electronics letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.375
H-Index - 146
eISSN - 1350-911X
pISSN - 0013-5194
DOI - 10.1049/el.2016.2629
Subject(s) - discriminator , cmos , comparator , detector , energy (signal processing) , encoder , pixel , power (physics) , computer science , electronic engineering , physics , computer hardware , electrical engineering , optics , engineering , voltage , quantum mechanics , operating system
A compact size and low‐power multi‐bit energy discriminator circuit is presented for X‐ray spectrometry CMOS photon‐counting detector (PCD) pixels. Because the circuit design is based on an asynchronous linear search, the discriminator with only a single‐comparator classifies a sporadically incoming photon into multiple energy‐bins, resulting in high spatial resolution and functionality of material‐selective imaging. The proposed pixel power required to perform a minimal linear search is significantly less than the power of a conventional parallel search implemented in a flash‐type discriminator. A prototype is fabricated in a 130‐nm CMOS, and a 3‐bit discriminator occupies only 23 × 60 μm 2 . The circuit dissipates a static power of 1 μW with a power supply of 3.3 V (analogue) and 1.2 V (digital). The inaccuracy of energy‐binning is measured to be 2.6–3.3 mV rms.