Analog and power management circuits 
Mixed-signal circuits and data converters Photon-starved imaging applications in astronomy, fluorescence microscopy, quantum sensing, etc., require photo-detectors with single photon detection and photon-counting ability. Existing ultra-low noise detectors like SPADs (Single Photon Avalanche Diode), EMCCDs (Electron Multiplying Charge Coupled Devices), APDs (Avalanche Photo-Diode), etc., have disadvantages like high dark count and afterpulsing, excess noise, high voltage operation, low fill factor, etc., making them unsuitable for imaging applications mentioned above.
The goal of this PhD project on the topic of "Low noise CMOS image sensor" is to develop a state-of-the-art image sensor with single photon detection and photon-counting ability using conventional CIS technology. The main objective of the research work is to reduce the readout noise significantly below 0.3 e-RMS (figure 1) without substantially compromising on other performance parameters such as readout speed, dynamic range, power, fill factor, etc.
The major bottleneck in achieving such ultra-low noise is the flicker noise of the source follower inside the pixel. Several circuit techniques and tradeoffs to reduce the flicker noise will be explored. Solutions will consist of combined efforts in multiple domains, which include CIS technology, circuit design and layout, and signal processing, to improve the noise of the complete readout chain.
