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SKIROC is a 64-channel front-end chip designed to read-out silicon PIN diodes for calorimetry application. It has been designed in a general framework ensuring consistent back-end of different front-end ASIC for several calorimeters (HaRDROC to read out the digital RPC HCAL prototype and SPIROC to read out the SiPM and Sci tiles HCAL prototype are the two others chip existing on that framework)

Its main characteristics are the following:

  • AMS SiGe 0.35µm technology
  • 60mm≤ (7,1mm ◊ 8,5mm) area
  • 3.3V power supply
  • Package: PQFP240

Each channel is made of a variable-gain low-noise charge preamplifier followed by both a dual shaper ñ one with a gain 1 and the other with a gain 10 - to filter the charge measurement and a trigger chain composed of a high gain fast shaper and a discriminator. The measured charge is stored in a 15-depth SCA that can be read either in an analogue way or can be connected to a multi-channel 12-bit Wilkinson ADC. Thresholds are set with a 10-bit DAC for trigger level and for automatic gain selection level. A bandgap ensures the stability versus supply voltage and temperature for all the requested reference in the analogue core.

Skiroc at a glance

   ASIC name : SKIROC (Silicon Kalorimeter Integrated Read-Out Chip)
   Current available version : 2
   Number of channel : 64 
   Polarity of input signal : positive
   Detector read out : PIN diode, compliant with GEM and RPC 
   Equivalent noise charge : 1500 e- with 20pF detector capacitance at mid-gain
   Gain : 0.15mV/fC - 23.4mV/fC
   Max input signal : 10pC at minimun gain

Skiroc2 features


PIN name

PIN type and direction

PIN description


Analogue input bus (width=64)

Charge sensitive analogue input to be connected to the detector


Multiplexed analogue output

Provides the hold value of the 64 channels, sequentially.
The selection of the SCA address is made through the SCA read register


Digital output signal

Provides a logical OR of the 64 triggers, asynchronous signal


Skiroc capabilities


SKIROC can be used either for charge measurement or time measurement. It can be used to generate a trigger for a system or tag an event. It embeds an auto-trigger feature allowing a standalone use, without any external trigger or machine clock. It can also be clocked to a system and has a an analogue memory with a depth of 15 events to reduce dead time due to read-out. It can measure charge with a 15-bit accuracy using two shaper ranges.

Skiroc characteristics

Embed measurement and perf outlook here

Skiroc in experiments

The SKIROC2 chip is currently used in the technologycal prototype of the Electromagnetic CALorimeter forseen at the ILD for the International Linear Collider