Asynchronous front-end asic for X-ray medical imaging applications implemented in CMOS 0.18μm technology

An idea as well as a CMOS implementation of the novel multi-channel readout front-end ASIC for nuclear X-ray imaging system has been presented in the paper. The circuit has been designed in an example configuration with eight equal channels, but the modular structure enables an easy realization of larger systems with even hundreds of channels. Various new circuit solutions have been proposed by author and used in the circuit, such as: an asynchronous output multiplexer, a pulse shaper and a peak detector with a built-in clock generator, which activates the circuit only in the situation when a new impulse occurs at the input. This technique allows for very low power dissipation. In the worst case scenario, i.e. when all channels would be active at the same time, the power dissipation is kept below 2 mW. By introducing an efficient RESET mechanism that turns off a given channel just after reading out the information, the counting rate of a single channel has been increased to about 3 MSps. The proposed circuit solutions allow for a very low chip area usage that for a single channel is equal to 0.021 mm², while the total chip area is equal to 0.17 mm².