A new digital readout integrated circuit (DROIC) with pixel parallel A/D conversion and reduced quantization noise

Kayahan, Huseyin; Yazıcı, Melik; Ceylan, Omer; Gürbüz, Yaşar

doi:10.1016/j.infrared.2013.12.013

Cited by 20 publications

(7 citation statements)

References 21 publications

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“…However, another phase is added to the pixel's operation where value of the left-over charge on the integration capacitor is calculated using the same counter but with a different clock which is much faster than the PFM signal [5]. This phase is termed as the fine quantization phase which makes integration the coarse quantization phase.…”

Section: Pixel Based On Extended Countingmentioning

confidence: 99%

“…DROICs employing both analog and digital versions of pixel sensors can be found. While analog sensors offer a larger fill factor, digital pixels provide a direct digital output and can significantly improve the charge handling capability [5]. Generally, a DPS either consists of an in-pixel analog-to-digital converter to perform the signal conversion or it is based on a pulse frequency modulation (PFM) loop.…”

Section: Introductionmentioning

confidence: 99%

“…An extended counting technique has been proposed in [5] where the left-over charge on the integration capacitor is computed (converted to digital) in-pixel and then stored in-pixel as well. This computation is carried out by counting the number of clocks from the time when integration is stopped till the next auto-reset.…”

Section: Introductionmentioning

confidence: 99%

“…The drawback of this technique is the increase in pixel area. The design in [5] was for a 30um pixel pitch. With smaller pixel sizes, such as 15um pitch the required additional circuitry for extended counting cannot fit within the pixel area.…”

Section: Introductionmentioning

confidence: 99%

“…The paper is organized as follows: Section 2 describes a conventional PFM based pixel and provides background on the extended counting technique reported in [5], Section 3 describes the architecture of the proposed DROIC. Measurement results are shown in Section 4 and finally the concluding remarks are provided in Section 5.…”

Section: Introductionmentioning

confidence: 99%

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A PFM-based MWIR DROIC employing off-pixel fine conversion of photocharge to digital using integrated column ADCs

Abbasi

Galioğlu

Shafique

et al. 2017

Infrared Technology and Applications XLIII

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A 32x32 prototype of a digital readout IC (DROIC) for medium-wave infrared focal plane arrays (MWIR IR-FPAs) is presented. The DROIC employs in-pixel photocurrent to digital conversion based on a pulse frequency modulation (PFM) loop and boasts a novel feature of off-pixel residue conversion using 10-bit column SAR ADCs. The remaining charge at the end of integration in typical PFM based digital pixel sensors is usually wasted. Previous works employing in-pixel extended counting methods make use of extra memory and counters to convert this left-over charge to digital, thereby performing fine conversion of the incident photocurrent. This results in a low quantization noise and hence keeps the readout noise low. However, focal plane arrays (FPAs) with small pixel pitch are constrained in pixel area, which makes it difficult to benefit from in-pixel extended counting circuitry. Thus, in this work, a novel approach to measure the residue outside the pixel using column -parallel SAR ADCs has been proposed. Moreover, a modified version of the conventional PFM based pixel has been designed to help hold the residue charge and buffer it to the column ADC. In addition to the 2D array of pixels, the prototype consists of 32 SAR ADCs, a timing controller block and a memory block to buffer the residue data coming out of the ADCs. The prototype has been designed and fabricated in 90nm CMOS.

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Section: Pixel Based On Extended Countingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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