A 65 nm CMOS Digital Phase Imager for Time-Resolved Fluorescence Imaging

作者：Guo Jian^*; Sonkusale Sameer

来源：IEEE Journal of Solid-State Circuits, 2012, 47(7): 1731-1742.

DOI：10.1109/JSSC.2012.2191335

• CMOS image sensor
• imager
• luminescence
• fluorescence
• fluorescence lifetime imaging microscopy (FLIM)
• phase contrast imaging
• time-to-digital converter (TDC)
• time interpolation
• zero-crossing detection

This paper presents a CMOS image sensor with direct digital phase output for time-resolved fluorescence imaging applications. A row-level zero-crossing detection is implemented to extract the phase-shift between the intensity modulated excitation signal and the emitted fluorescence, generating a time delay signal proportional to the fluorescence lifetime of the target analyte. A time-interpolated Time-to-Digital Converter (TDC) is subsequently used to quantize the time delay into a digital representation of the phase-shift for post-signal processing and image reconstruction. For proof-of-concept, a prototype chip consisting of a 32x32 P+/N-Well/P-Substrate photodiode array, row-level phase readout circuits, and a global TDC is implemented in a low-power 65 nm CMOS technology. The TDC features a temporal resolution of 110 ps over a 414 s range, which corresponds to a dynamic range of 132 dB. Extensive characterization results demonstrate a phase readout sensitivity of better than 0.01 degrees at a 1.2 kHz modulation frequency and 0.1 degrees at up to 1 MHz. The complete imager chip is evaluated through a sequence of phase image reconstruction experiments, and the results are presented.

• 出版日期2012-7