Timepix

The original Timepix ASIC is a silicon chip developed at CERN by the Medipix2 Collaboration. The chip is divided into a 256×256 grid of tiny pixels, each one containing thousands of transistors that allow it to detect and analyse radiation.

Its successor, Timepix2, can be programmed to operate in one of several modes depending on the application requirement, offering increased complexity compared to the predecessor. Readout is frame-based. The arrival time (Time-of-Arrival – ToA) and charge deposit information (Time-over-Threshold – ToT) can be recorded for each hit when used in sequential read/write mode. In continuous read/write mode one can choose between ToT, ToA or event counting. There are a total of 28 bits per pixel which can be allocated depending on the read/write mode chosen and the requirements of the application.

Timepix3 is a general-purpose integrated circuit suitable for readout of both semiconductor detectors and gas-filled detectors. Compared to the original Timepix the circuit has more functionality, better time resolution and more advanced architecture for continuous sparse data readout with zero-suppression. Timepix3 can be used in a wide range of applications varying from X-rays imaging to particle track reconstruction.

Depending on the application requirements, users can choose one of three data acquisition modes. In the data driven mode both arrival time information and charge deposit information are sent off chip for each hit together with the coordinates of the active pixel. The chosen architecture allows for continuous and trigger-free readout of sparsely distributed data with the rate up to 40Mhits/s/cm2. For imaging applications and for calibrations the chip can operate in frame-based (non-continuous) data readout mode.

With Timepix4 users can choose between several data acquisition modes depending on the application requirement. In data driven mode, the arrival time (Time-of-Arrival – ToA) and charge deposit information (Time-over-Threshold – ToT), as well as coordinates of the active pixel, are provided for each hit. For imaging applications and for calibration, the ASIC can be operated in frame-based mode in either continuous read/write or sequential read/write mode.

Specifications

			Timepix (2006)	Timepix2 (2018)	Timepix3 (2013)	Timepix4 (2019)
Tech. node (nm)			IBM 250	TSMC 130	IBM 130	TSMC 65
Pixel sixe (μm)			55	55	55	55
# pixels (x x y)			256 x 256	256 x 256	256 x 256	448 x 512
Sensitive area			1.98 cm2	1.98 cm2	1.98 cm2	6.94 cm2
Number of sides for tilingusing WB			3 (87.1% active area)	3 (85.6% active area)	3 (86.7% active area)	2 (93.7% active area)
Number of sides for tilingusing TSV			No TSV ready	3 (85.6% active area)	3 (91.6% active area)	4 (99.3% active area)
Front-end		positive (h+)	Gain (16mV/kh+)(Volcano >0.8MeV/pixel)	High Gain (25mV/kh+)Logarithmic Gain (19mV/kh+)	High Gain (45mV/kh+)(Volcano >0.3MeV/pixel)	High Gain (35mV/kh+)Low Gain (20mV/kh+)Logarithmic Gain
		negative (e-)	Gain (16mV/ke–)	High Gain (25mV/ke–)	High Gain (45mV/ke–)	High Gain (35mV/ke–)Low Gain (20mV/ke–)
Minimum detectable charge			~750 e–	~600 e–	~500 e–	~500 e–
Operation Modes	Tracking(Event arrival time and/or energy)	Readout	Full Frame-based(Sequential R/W)	Full Frame-based (Sequential or Continuous R/W)	Data-driven(48-bit packet per pixel hit)	Data-driven(64-bit packet per pixel hit)
		Event Data	TOT or TOA	TOT and TOA; TOT or TOA	TOT & TOA	TOT & TOA
		TOT energy resolution	<3keV (FWHM Si)	~0.75keV (FWHM Si)	~2KeV (FWHM Si)	~1KeV (FWHM Si)
		TOA bin size	10ns (@100MHz)	10ns (@100MHz)	1.56ns (On-pixel TDC @40MHz)	195ps (On-pixel TDC @40MHz)
		TOA dynamic range	118.1µs (@100MHz)	2.62ms (@100MHz)	409.6µs (14b@40MHz)	1.63ms (16b@40MHz)
		Max Rate	<1×106 hits/cm2/s (with 300µs readout dead time)	<1×106 hits/cm2/s	43×106 hits/cm2/s	358×106 hits/cm2/s
		Max Pix Rate	33 Hz/pixel	33 Hz/pixel	1.3 KHz/pixel	10.8 KHz/pixel
	Imaging(Event counting)	Readout	Full Frame-based(Sequential R/W)	Full Frame-based (Sequential or Continuous R/W)	Zero-suppressed (with pixel addr)(Sequential R/W)	Full Frame-based(Continuous R/W)
		Counter depth	14-bits	10-bit or 14-bit	Counting (10-bit) or iTOT (14-bit)	8-bits or 16-bits
		Frame rate	100 fps @1x100Mbps 3.2 kfps @32x100Mbps	4.9 kfps @10-bit 32x100Mbps3.5 kfps @14-bit 32x100Mbps	1.62 kfps @48-bit 8x640Mbps	89.2 kfps @8-bit 16x163Gbps44.8 kfps @16-bit 16x163Gbps
		Max Count Rate	~35 x 109 hits/cm2/s	~35 x 109 hits/cm2/s	~82 x 109 hits/cm2/s	~800 x 109 hits/cm2 /s
Maximum Readout bandwidth			3.2Gbps (32 x 100MHz)	3.2Gbps (32 x 100MHz)	≤5.12Gbps(8x SLVS@640 Mbps)	≤163.84Gbps (16x @10.24 Gbps)
Power consumption			330mW/cm2 (nominal)	450mW/cm2 (nominal) 165mW/cm2 (low power mode)	625mW/cm2 (nominal)108mW/cm2 (low power)	700mW/cm2 (nominal)200mW/cm2 (low power)
Other			Out of production
Paper			https://www.sciencedirect.com/science/article/pii/S0168900207017020	https://www.sciencedirect.com/science/article/pii/S1350448719305165	https://iopscience.iop.org/article/10.1088/1748-0221/9/05/C05013	https://iopscience.iop.org/article/10.1088/1748-0221/17/01/C01044