Recently, growing interest in implantable bionics and biochemical sensors spurred the research for developing non-conventional electronics with excellent device characteristics at low operation voltages and prolonged device stability under physiological conditions. Herein, we report high-performance aqueous electrolyte-gated thin-film transistors using a sol-gel amorphous metal oxide semiconductor and aqueous electrolyte dielectrics based on small ionic salts. The proper selection of channel material (i.e., indium-gallium-zinc-oxide) and precautious passivation of non-channel areas enabled the development of simple but highly stable metal oxide transistors manifested by low operation voltages within 0.5 V, high transconductance of ~1.0 mS, large current on-off ratios over 10⁷ and fast inverter responses up to several hundred hertz without device degradation even in physiologically-relevant ionic solutions. In conjunction with excellent transistor characteristics, investigation of the electrochemical nature of the metal oxide-electrolyte interface may contribute to the development of a viable bio-electronic platform directly interfacing with biological entities in vivo.

This brief presents a second-order incremental delta-sigma analog-to-digital converter (ADC) for CMOS image sensors (CISs). The ADC that employs a cascade of integrators with a feedforward architecture uses only one operational transconductance amplifier (OTA) by sharing the OTA between the first and second stages of the modulator. Further power and area savings are achieved by using a self-biasing amplifier and the proposed level-shifting technology, which allows active signal summation at the quantizer input node without using an additional OTA. Fabricated in the 0.18-μm CIS process, the 10-bit ADC occupies a die area of 0.002 mm ² and consumes 29.5 μW from a 1.8-V supply. The measured differential nonlinearity and integral nonlinearity are less than +0.22/-0.2 and +0.71/-0.89 LSB, respectively. Operating at 20 MS/s, the ADC provides signal-to-noise-distortion ratios of 57.7 and 62.3 dB for signal bandwidths of 156.25 and 78.125 kHz, respectively.

This paper presents a high full well capacity (FWC) CMOS image sensor (CIS) for space applications. The proposed pixel design effectively increases the FWC without inducing overflow of photo-generated charge in a limited pixel area. An MOS capacitor is integrated in a pixel and accumulated charges in a photodiode are transferred to the in-pixel capacitor multiple times depending on the maximum incident light intensity. In addition, the modulation transfer function (MTF) and radiation damage effect on the pixel, which are especially important for space applications, are studied and analyzed through fabrication of the CIS. The CIS was fabricated using a 0.11 μm 1-poly 4-metal CIS process to demonstrate the proposed techniques and pixel design. A measured FWC of 103,448 electrons and MTF improvement of 300% are achieved with 6.5 μm pixel pitch.