A two stage 14bit pipeline-SAR analog-to-digital converter includes a 5.5bit zero-crossing MDAC and a 9bit
asynchronous SAR ADC for image sensor readout circuits built in 0.18um CMOS process is described with low
power dissipation as well as small chip area. In this design, we employ comparators instead of high gain and high
bandwidth amplifier, which consumes as low as 20mW of power to achieve the sampling rate of 40MSps and 14bit
At present, single-slope analog-to-digital convertor (ADC) is widely used in the readout circuits of CMOS image sensor
(CIS) while its main drawback is the high demand for the system clock frequency. The more pixels and higher ADC
resolution the image sensor system needs, the higher system clock frequency is required. To overcome this problem in
high dynamic range CIS system, this paper presents a 12-bit 500-KS/s cyclic ADC, in which the system clock frequency
is 5MHz. Therefore, comparing with the system frequency of 2N×fS for the single-slope ADC, where fS, N is the
sampling frequency and resolution, respectively, the higher ADC resolution doesn’t need the higher system clock
frequency. With 0.18μm CMOS process, the circuit layout is realized and occupies an area of 8μm×374μm. Post
simulation results show that Signal-to-Noise-and-Distortion-Ratio (SNDR) and Efficient Number of Bit (ENOB) reaches
63.7dB and 10.3bit, respectively.
In this paper we present a 4 Megapixel high dynamic range, low dark noise and dark current CMOS image sensor, which
is ideal for high-end scientific and surveillance applications. The pixel design is based on a 4-T PPD structure. During
the readout of the pixel array, signals are first amplified, and then feed to a low- power column-parallel ADC array
which is already presented in . Measurement results show that the sensor achieves a dynamic range of 96dB, a dark
noise of 1.47e- at 24fps speed. The dark current is 0.15e-/pixel/s at -20oC.
Fabricated by four times H+ inclined implantation using tungsten wire as mask, batch vertical cavity surface emitting lasers with better characters than those of common ion implanted devices were obtained. They have the batch threshold current of less than 1.5mA, the lowest threshold current of 1.2mA which is lower than that of common oxide confinement device product, the largest light output power of about 1mW with simple TO package, and the largest 3dB modulation bandwidth of 4GHz. According to the polarization measurement result, the devices showed good 0° linear polarization character and up to 14dB polarization suppress ratio in the whole linear gain region, which is better than that of common oxide confinement devices. Spectrum measurement result showed that their wavelength was around 835nm, and they operated with single transverse mode in linear gain region. Furthermore, the fabrication technology was simple enough for the industry without photolithography and lift-off steps.