A 4-MHz, 256-Channel Readout ASIC for Column-Parallel CCDs With 78.7-dB Dynamic Range

• Published in: IEEE transactions on nuclear science 2020-05, Vol.67 (5), p.823-831
• Main Authors: Grace, C. R., Denes, P., Fong, E., Goldschmidt, A., Papadopoulou, A.
• Format: Article
• Language: English
• Subjects: Acidity; Amplification; Analog circuits; Analog to digital conversion; Analog to digital converters; Application specific integrated circuits; Bonding; Capacitance; Charge coupled devices; charge-coupled devices (CCDs); CMOS; correlated double sampling (CDS); Dynamic range; Engine noise; Integrated circuits; mixed-signal IC design; Modular design; Modulation; Noise; Noise reduction; Parasitics (electronics); Pixels; Sampling; Sigma-delta modulation; Sodium channels; Soft x rays; Thermal noise; X-ray diffraction; X-ray imaging
• ISSN: 0018-9499; 1558-1578
• DOI: 10.1109/TNS.2020.2980769

A 256-channel readout application specific integrated circuit (ASIC) called the very low-noise analog sampling engine (VASE) intended for the readout of column-parallel charge-coupled devices (CP-CCDs), is presented. Each channel uses a charge-sensitive amplifier and a first-order dual-gain sigma-delta analog-to-digital converter (ADC) that act as the front end of an extended counting ADC. The extended counting ADC directly implements correlated multiple-sampling as part of its operation. To reduce the noise due to input capacitance and to ensure a compact camera, the VASE input bonding pads are pitch matched to the CP-CCD to allow chip-to-chip bonding with minimal parasitic capacitance. The chip is designed in a modular way with each 16 input channels sharing a single differential analog output and digital serializer. VASE, with a die area of 38.1 mm 2 and fabricated in 180-nm CMOS technology, achieves 22 e − equivalent noise charge (ENC) and a dynamic range of 190 ke − (78.7 dB) at a 4-MHz pixel rate (corresponding to a frame rate of 32 kfps when a 256\times256 pixel sensor is read out on both sides) while dissipating 10.1 mW per channel. The prototype has been used to successfully image X-ray diffraction at a soft X-ray synchrotron.