The possibility of using application specific integrated circuits has several advantages in particle measurements. The small size may allow additional functionality included. This functionality would otherwise require several discrete components.

• The ASICs may include filters and pre-processing circuitry. If the amount of generated data is huge, this circuitry will reduce the data set by only forwarding the most promising data.
• When filtering and pre-processing are done in parallel in each front-end circuit, the total time for processing is reduced.  Hence the final results may be delivered faster.
• The ASICs may include memory for temporary storage. In this way the output peaks of data may be smoothed down allowing a lower data rate on data buses.
• Some times naked, integrated circuits are the only possibility due to limited space, harsh environment etc.

Front end integrated circuits have advantages in addition to those coming from smaller size and higher integration. When a circuit is designed for a specific system the circuit design may be optimised to improve one or more specific parameters. Examples are low noise or low power. This will give better results than what can be achieved through discrete components. This requires special skills.
 
SINTEF has been working on readout ASICs for many years and has achieved significant experience in this field. Circuits designed in CHICSi system by SINTEF have been used at CERN (European Nuclear Research Centre in Switzerland) in connection with the Atlas detector. One of these readout circuits has 128 channels, an area of 85mm² with more than 100 000 transistors. Noise has been measured to 366e + 22.6 e/pF. This experience has been acknowledged with orders from several research institutes, such as the University of Oslo in Norway and the University of Lund in Sweden. 

For more information contact: Joar Martin Østby