title: A 2D 4×4 Channel Readout ASIC for Pixelated CdTe Detectors for Medical Imaging Applications.
abstract: We present a 16-channel readout integrated circuit (ROIC) with nanosecond-resolution time to digital converter (TDC) for pixelated Cadmium Telluride (CdTe) gamma-ray detectors. The 4 × 4 pixel array ROIC is the proof of concept of the 10 × 10 pixel array readout ASIC for positron-emission tomography (PET) scanner, positron-emission mammography (PEM) scanner, and Compton gamma camera. The electronics of each individual pixel integrates an analog front-end with switchable gain, an analog to digital converter (ADC), configuration registers, and a 4-state digital controller. For every detected photon, the pixel electronics provides the energy deposited in the detector with 10-bit resolution, and a fast trigger signal for time stamp. The ASIC contains the 16-pixel matrix electronics, a digital controller, five global voltage references, a TDC, a temperature sensor, and a band-gap based current reference. The ASIC has been fabricated with TSMC 0.25μm mixed-signal CMOS technology and occupies an area of 5.3 mm × 6.8 mm. The TDC shows a resolution of 95.5 ps, a precision of 600 ps at full width half maximum (FWHM), and a power consumption of 130μW. In acquisition mode, the total power consumption of every pixel is 200μW. An equivalent noise charge (ENC) of 160 e-RMS at maximum gain and negative polarity conditions has been measured at room temperature.
authors.affiliation: Institut de Fisica d'Altes Energies (IFAE), Barcelona E-08193, Spain.
authors.forename: Jose-Gabriel
authors.initials: JG
authors.lastname: Macias-Montero
authors.affiliation: Texas Instruments Inc., Dallas, TX 75243 USA.
authors.forename: Maher
authors.initials: M
authors.lastname: Sarraj
authors.affiliation: Institut de Fisica d'Altes Energies (IFAE), Barcelona E-08193, Spain.
authors.forename: Mokhtar
authors.initials: M
authors.lastname: Chmeissani
authors.affiliation: Instituto de Microelectronica de Barcelona (IMBCNM), Barcelona E-08193, Spain.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Martínez
authors.affiliation: Institut de Fisica d'Altes Energies (IFAE), Barcelona E-08193, Spain.
authors.forename: Carles
authors.initials: C
authors.lastname: Puigdengoles
keywords: Analog-digital conversion; application specific integrated circuits; energy resolution; gamma-ray detectors; low-power electronics; positron emission tomography; semiconductor radiation detectors