Digital readout integrated circuit (DROIC) implementing time delay and integration (TDI) for scanning type infrared focal plane arrays (IRFPAs)
Ceylan, Ömer (2016) Digital readout integrated circuit (DROIC) implementing time delay and integration (TDI) for scanning type infrared focal plane arrays (IRFPAs). [Thesis]
This thesis presents a digital readout integrated circuit architecture implementing time delay and integration with an oversampling rate of 2 for scanning type infrared focal plane arrays with a charge handling capacity of 44.8 Me- while achieving quantization noise of 198 e- and power consumption of 14.5 mW. Conventional pulse frequency modulation method is supported by a single slope ramp ADC technique to have very low quantization noise together with a low power consumption. The proposed digital TDI ROIC converts the photocurrent into digital domain in two phases; in the first phase, most significant bits are generated by conventional PFM technique in the charge domain, while in the second phase least significant bits are generated by the single slope ramp ADC in the time domain. A 90x8 prototype has been fabricated and verified, showing a significantly improved signal-to-noise ratio of 51 dB for the low illumination levels (280,000 collected electrons), which is attributed to the TDI implementation method and very low quantization noise due to the single slope ADC. The proposed digital TDI ROIC proves the benefit of digital readouts for the scanning arrays enabling smaller pixel pitch, better SNR for low illumination levels and lower power consumption compared to the analog TDI readouts.
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