Full Signal Range Research Articles

A Compact Low-Power CMOS Analog FSR Model-Based CNN

A compact low-power CMOS analog circuit implementation of a Cellular Neural Network based on Full Signal Range Model (FSR-CNN) is presented. The required operations in cell definition are synapses (multiplication and summation) and saturated integration. In each synapse, a new multiplier architecture is employed with voltage and current inputs and a current output, which allows sharing building blocks and using continuously programmable weight values. Feasibility and usefulness of the proposed FSR cell architecture is verified through the simulation of two applications: the connected component detector and the border extractor.

Linear–Logarithmic CMOS Pixel With Tunable Dynamic Range

A CMOS pixel with linear-logarithmic response and programmable dynamic range (DR), based on a tunable transition point, has purposely been designed for endoscopic applications. A theoretical model of the pixel was developed and validated. A chip with a 100×100 pixel array and a 12-b digital output was fabricated in a 0.35-μm technology and was fully tested, thus demonstrating state-of-the-art performance in terms of DR and noise. Intraframe DR proved to be extendable to more than 110 dB through a logarithmic compression of the signal in the light irradiation power density (LIPD) range. The measured temporal noise (pixel noise) was less than 0.22% over the full range. The architecture presented limited fixed pattern noise (FPN) due to the scheme adopted, which allowed its correction over the full signal range: FPN was 0.83% (1.37%) in the linear (logarithmic) region. Although the test chip was designed mainly for endoscopic applications, the technology may also be applied to other fields, e.g., robotics, security and industrial automation, whenever high DR is a crucial feature.

Novel SQUID Current Sensors With High Linearity at High Frequencies

We have developed novel SQUID current sensors consisting of a sensitive 16-SQUID input stage followed by an output stage of 40, 160, or 640 low-inductance SQUIDs. A highly gradiometric design of the individual SQUIDs with ap 5 mum maximum linewidth makes the devices insensitive to external magnetic noise and allows cool-down and operation in the Earth magnetic field. Output current feedback (OCF) is used to increase the linear signal range. When driving a terminated 50 Omega coaxial cable, the sensor with 160 output SQUIDs exhibits a signal range of one flux quantum Phi0 at a power dissipation of about 100 nW. At 10 MHz and 4.2 K, a total flux noise level of 0.34 muPhi0/radic(Hz) is achieved corresponding to a dynamic range of plusmn 1.5 times 106 radic(Hz). At higher frequencies, interaction of preamplifier voltage noise with the output cable impedance increases the sensor noise (a general problem in high-speed SQUID systems). The small-signal bandwidth is >200 MHz. A very high slew rate of > 50 Phi0/mus is achieved allowing one to use the full signal range at frequencies up to 16 MHz with a total harmonic distortion below ap1%.

A VLSI-oriented continuous-time CNN model

This paper presents an analysis of the stability and convergence properties of the full signal range (FSR) CNN model. These properties are demonstrated to be similar to those of the Chua-Yang model and the I/O mapping of known applications is shown to be unaffected by the modification introduced in this new model. In this modified CNN model the dynamic range of the cell state variables equals the dynamic range of the cell output variables and is invariant with the application. This feature results in simpler circuit implementations, thus allowing higher cell densities and improving the robustness of CNN integrated circuits. The FSR CNN model is particularly well suited for programmable CNN integrated circuits.

Photoresponse Linearity of a-Si:H Imaging Pixels

Amorphous silicon imaging arrays with ∼3×105pixels have recently been developed and x-ray images of low contrast anatomical phantoms have been demonstrated. This paper reports on the linearity of response of these a-Si:H imaging pixels as a function of reverse bias voltage. The fraction of the imaging pixel's full signal range that maintains a linear response has been found to increase with increasing voltage.