Abstract-In this paper, analytical noise analysis of correlated double sampling (CDS) readout circuits used in CMOS active pixel image sensors is presented. Both low-frequency noise and thermal noise are considered. The results allow the computation of the output rms noise versus MOS transistor dimensions with the help of SPICE-based circuit simulators. The reset noise, the influence of floating diffusion capacitance on output noise and the detector charge-to-voltage conversion gain are also considered. Test circuits were fabricated using a standard 0.7 m CMOS process to validate the results. The analytical noise analysis in this paper emphasizes the computation of the output variance, and not the output noise spectrum, as more suitable to CDS operation. The theoretical results are compared with the experimental data.

An ideal thermographic camera could be defined as an uncooled system with high spatial and thermal resolutions featuring a video frame rate, and a short calibration process. In this paper a measurement system based on Silicon FPA operating in the Near Infrared spectral band (0.7 − 1.1 µm) is proposed. This system offers an excellent spatial resolution, a low cost and compactness. With a specific radiometric model, this system can accurately measure temperatures, in a broad temperature range, from 400 up to 1000°C. A comparison with two commercial infrared cameras is performed between 400 and 700°C.

No abstract

A new Correlated Double Sampling (CDS) method for low-noise CCD signal acquisition is presented. The method is based on the utilization of an active band-pass filter with adjustable frequency characteristics. By varying the filter parameters in sequence with the pixel readout, the signal information may be extracted while keeping the equivalent noise bandwidth low. This new acquisition method is simple to implement, offers low-noise performance (close to double integrators), and has several other advantages compared to the other acquisition systems in use. We also present the derivation of a mathematical model to simulate the signal-to-noise ratio for a given CCD output noise characteristic and pixel readout frequency. Our model considers the nonstationary nature of the signal at the sampling instant which implies that the usual way of calculating average noise power (using the filter's transfer function) is not valid. Theoretical results are compared with experimental data and the noise performance of this approach is compared with other CDS methods now in use.

CMOS active-pixel image sensors, as well as chargecoupled devices, generate both white noise and 1=f -noise over several decades depending on biasing current, operating temperature, and the characteristics of the process used, limiting the detector dynamic range. Three readout circuits, based on a fully differential cascode operational transconductance amplifier, designed and realized on a standard CMOS 0.7-m single polysilicon/double metal process, are proposed for CMOS activepixel imagers. The first is an uncompensated switched-capacitor (SC) voltage amplifier; the second, an offset-compensated SC amplifier; and the third, a commutable bandpass filter. All three amplifiers allow correlated double sampling and double delta sampling for pixel and column fixed pattern noise suppression, respectively. The amplifiers offer up to 10-Mpixels/s readout rates. A detailed theoretical analysis of the amplifiers response to white noise and low-frequency excess noise is given, considering nonstationary nature of the output signals. An original method based on diffusive Markovian representation of 1=f -noise is used. The theoretical results are compared with experimental data.