Pulse Height Analyzer and ReadOut System
PHAROS is a mixed signal integrated circuit and represents an upgraded version of ChromatIC. As a main difference with respect to ChromatIC, PHAROS gives an energy resolution of 128 levels instead of 8. PHAROS has been conceived to receive shaped signals from charge preamplifiers. It consists of 16 independent input channels. Each input channel is equipped with a Peak Detector circuit (ref. to PhantIC) and a sample and hold capacitor. The 16 input channels are grouped in 4 groups of 4 peak detectors. Each Peak Detector output is multiplexed onto a 7 bit ADC with SAR (Successive Approximation Register). The conversion time is around 250 ns. The 4 ADC can operate concurrently. This gives a maximum sustainable input rate (per channel) of about 500 kHz. The ADC output is then stored onto a 2kx10 RAM, based on two 1kx10 blocks. At the end of the acquisition time, the RAM contains the energy spectrum of the detected X-rays for each of the 16 channels. Data can be read out at the maximum speed of about 10 MByte/s. The PHAROS chips are conceived to be daisy-chained in order to service an arbitrary large number of front-end channels. The Peak Detector circuit, the Analog Multiplexer and the ADC are full custom objects. The control logic and the RAM are based on AMS library cells.
For further information, please take a look at the documents below.
- S. Cadeddu, D. Caredda, M. Caria, A. Lai, P. Randaccio - "PHAROS: a spectrometer-on-a-chip for digital radiology systems with spectral detection” - NIM A 478 (2002) 367-371
- S. Cadeddu, C. Caligiore, M. Caria, A. Lai, D. Lo Presti, C. Petta, P. Porcu, P. Randaccio, N. Randazzo, S. Reito, G. V. Russo – “A VLSI chip set for digital radiology with energy selection” - NIM A 422 (1999) 357-362
- S. Cadeddu, C. Caligiore, M. Caria, A. Lai, D. Lo Presti, S. Panebianco, C. Petta, P. Porcu, N. Randazzo, P. Randaccio, S. Reito, G. V. Russo – “The design of a system for coloured digital radiology VLSI circuits and GaAs pixel detectors.” – NIM A 419 (1998) 270-275
- Presented at Conference VCI 2001, Vienna (pdf)