In this paper, different methodologies are employed to improve the linearity performance of a prototype CMOS image sensor (CIS). First, several pixel structures, including a novel pixel design based on a capacitive trans-impedance amplifier (CTIA), are proposed to achieve a higher pixel-level linearity. Furthermore, three types of digital linearity calibration methods are explored. A prototype image sensor designed in 0.18-μm, 1-poly, and 4-metal CIS technology with a pixel array of 128 × 160 is used to verify these linearity improvement techniques. The measurement results show that the proposed CTIA pixel has the best linearity result out of all pixel structures. Meanwhile, the proposed calibration methods further improved the linearity of the CIS without changing the pixel structure. The pixel mode method achieves the most significant improvement on the linearity. One type of 4T pixel attains a nonlinearity of 0.028% with pixel mode calibration, which is two times better than the state of the art. Voltage mode (VM) and current mode (CM) calibration methods get rid of the limitation on the illumination condition during calibration operation; especially, CM calibration can further suppress the nonlinearity caused by the integration capacitor C _FD on the floating diffusion node, which is remnant in VM.

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Purpose: The purpose of this paper is to demonstrate a novel 3D system-in-package (SiP) approach. This new packaging approach is based on stacked silicon submount technology. As demonstrators, a smart lighting module and a sensor systems were successfully developed by using the fabrication and assembly process described in this paper. Design/methodology/approach: The stacked module consists of multiple layers of silicon submounts which can be designed and fabricated in parallel. The 3D stacking design offers higher silicon efficiency and miniaturized package form factor. This platform consists of silicon submount design and fabrication, module packaging, system assembling and testing and analyzing. Findings: In this paper, a smart light emitting diode system and sensor system will be described based on stacked silicon submount and 3D SiP technology. The integrated smart lighting module meets the optical requirements of general lighting applications. The developed SiP design is also implemented into the miniaturization of particular matter sensors and gas sensor detection system. Originality/value: SiP has great potential of integrating multiple components into a single compact package, which has potential implementation in intelligent applications.

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This paper presents two on-chip calibration methods for improving the linearity of a CMOS image sensor (CIS). A prototype 128 × 128 pixel sensor with a size of 10 μm×12 μm is fabricated using a 0.18 μm 1P4M CIS process. Both calibration methods show obvious improvement on the linearity of the CIS. Compared with the voltage mode (VM) calibration, the pixel mode (PM) calibration method achieves better linearity results by improving the nonlinearity of the CIS 26×. This results in a minimum nonlinearity of 0.026%, which is a 2× better than the state-of-the-art. @en

This thesis provides a thorough analysis of the linearity characteristics of a CMOS image sensor. Firstly, this thesis analyzes the factors that cause the nonlinearity of the image sensors. These factors are then verified by simulation results of a proposed behavioral model and the measurements in a prototype chip. Secondly, different techniques are presented to improve the linearity of the whole imaging system; and the effectiveness of these techniques is further confirmed by measurement results of several test chips.@en

This article focuses on the effect of the operating temperature of a CMOS image sensor (CIS) on the pixel performance, especially the linearity behavior. As the temperature increases, the value of the integration capacitor C FD in the floating diffusion (FD) region increases as well. Moreover, the gain of the in-pixel voltage buffer decreases. These two factors lead to a reduced value of the conversion gain. Due to an increase in the nonlinear part of the C FD , the linearity of the CIS at a higher temperature will deteriorate. A digital calibration method proposed previously is used to improve the linearity of the CIS. Measurement results conducted on a prototype image sensor, designed with a 0.18- μ m CIS technology, agree well with an updated analytical model of the CIS and demonstrate an efficient linearity improvement at different temperatures.@en

AlGaN/GaN high electron mobility transistor (HEMT)-based sensors with catalytic platinum gate were micro-fabricated on commercially available epitaxial wafers and extensively characterized for ppm level hydrogen sulfide (H2S) detection for industrial safety applications. High operating temperature above 150 °C enabled large signal variation (ΔIDS) of 2.17 and sensing response of 112% for 90 ppm H2S in dry air as well as high stability across a wide range of biasing conditions. Transient response measurements demonstrated stable operation, superb response and recovery, with good repeatability. The measured sensing signal rise (fall) times reduced from 476 (1316) s to 219 (507) s when the temperature was increased from 200 °C to 250 °C. The response to 90 ppm H2S was 4.5x larger than to H2 and the device showed stable operation over an extended time period.@en

This paper presents a highly linear CMOS image sensor (CIS) designed in a commercial 0.18-μ m CIS technology. A new type of pixel is proposed based on the linearity analysis of a conventional 4T active pixel. The new type of pixel can mitigate the nonlinearity caused by the in-pixel source follower (SF) transistor. In addition, the optimization of the pixel design, a digitally assisted calibration method is proposed to further reduce the nonlinearity of the image sensor, especially, the nonlinearity caused by the integration capacitor (C_FD) on the floating diffusion (FD) node. A hybrid behavioral model is proposed to validate the calibration method. Experimental results show that the new type of pixel has a better linearity performance comparing with that of the typical 4T pixel. TCAD simulation results are used to help explain the spillback effect in the transfer transistor's channel. With the digital calibration, the linearity performances of the pixels in different settings have been improved.

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In this paper, we analyze the causes of the nonlinearity of a voltage-mode CMOS image sensor, including a theoretical derivation and a numerical simulation. A prototype chip designed in a 0.18 μm 1-poly 4-metal CMOS process technology is implemented to verify this analysis. The pixel array is 160 × 80 with a pitch of 15 μm, and it contains dozens of groups of pixels that have different design parameters. From the measurement results, we confirmed these factors affecting the linearity and can give guidance for a future design to realize a high linearity CMOS image sensor.@en

This paper presents a hybrid-powered wireless sensor node using enhanced triboelectric nanogenerator (TENG) as both energy harvester and air-flow sensor and two 11 cm2 solar panels as extra power supply. A low budget commercial RF microcontroller is included for data conversion, signal processing and wireless transmission. The method of flow-rate detection depends on the vibration frequency of the film inside the triboelectric generator. Experiment results show that this flow sensor is capable of detecting flow rate from 7.6 m/s to 17.1 m/s, with a standard deviation of 3.4, 3s setup time and 30s charge time. With a Raspberry Pi, the wireless signal can be received and delivered to Internet and therefore, can be monitored easily from any portable terminal with internet-access.

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This paper reports on the layout optimization of Pt-AlGaN/GaN HEMT-sensors for enhancing hydrogen sensor performance. Sensors with gate width and length ratios W_g/L_g from 0.25 to 10 were designed, fabricated and tested for the detection of hydrogen gas at 200 °C. Sensitivity, sensing current variation and transient response are directly related to the sensor gate electrode W_g/L_g ratio. The obtained results demonstrated a 217 % increase in sensitivity and 4630 % increase in sensing current variation at 500 ppm H2 for a W_g/L_g from 0.25 to 10. In addition, the detection limit was lowered to 5 ppm. Transient characteristics demonstrated faster sensor response to H2, but slower recovery rates with increasing ratio.

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