Proceedings Article | 16 October 2019
KEYWORDS: Signal processing, Image processing, Analog electronics, Logic, Field programmable gate arrays, Digital signal processing, Transistors, Digital electronics, Logic devices, Mirrors
In this paper, we proposed a new iterative process of sorting an array of signals, which differs from the known structures of sorting signals by uniformity, versatility, which allows direct and inverse sorting of an array of analog or digital signals. The basic elements of the proposed sorting structures are simple relational nodes. Such elements can be implemented on a different element basis, including, on devices for selecting a maximum or minimum of two analog or digital signals, which are implemented on CMOS current mirrors and carry out the limited difference function of continuous logic. We offered implementation of homogeneous sorting structure on such elements, consisting of two layers and a multichannel sampling and holding device. Nine signals corresponding to a selection window of a matrix sensor are fed to this structure, we sort them in five iterative steps, and at the output we receive the signals sorted by the rank, which, using the code controlled programmable multiplexer, generates an output signal, corresponding to the selected rank. We evaluated the technical parameters of such a relational preprocessor. The base cells consist of no more than 20 CMOS 1.5μm transistors, the total power consumption of the sorting node on 10 continuously logical base cells (CL BC) is 2mW, the supply voltage is 1.8÷3.3V, the range of an input photocurrent is 0.1÷24μA, the conversion cycle is 10μs. The paper considers results of design and modeling of CL BC based on current mirrors (CM) for creating picture type image processors (IP) with matrix parallel inputs-outputs. Such sorting nodes based on them have a number of advantages: high speed and reliability, simplicity, small power consumption, high integration level. The inclusion of an iterative node for sorting signals into a modified nonlinear IP structure makes it possible to significantly simplify its design and increase the functional capabilities of such processor. The simulation results confirm the proposed approaches to the design of sorting nodes of analog signals of the iterative type, which simplify the complexity of the nodes by an order of magnitude, ensuring their uniformity, regularity and simplicity of scaling. The power consumption of the processors does not exceed 2mW, the response and processing times are 10μs and can be less by an order of magnitude, the supply voltage is 1.8÷3.3V, and the operating currents are optimally in the range of 10÷20μA. The energy efficiency of the proposed preprocessor with the iterative sorting node is 25x109 op / s•W, which corresponds to the best technical solutions. In the work we are shown, that after sorting or comparative analysis of signals by levels of selected window of image, a promising opportunity appears to implement image processors with enhanced functionality using the new method of weighting-selecting rank differences of signals. The essence of the method is that by composing the differences of the signals ordered by rank and the upper level of their range, we can simultaneously form several resulting output signals, choosing the necessary difference signals from their set according to the control commands and weighing them additionally before the summation. We are shown that using this approach and the method of processing the current window signals significantly expands the set of operations and functions for filtering images, simplifying hardware implementation of IP, especially for analog and mixed technologies. We determined set of basic possible executable instruction-functions by processors based on such a proposed method, presenting the simulation results in Mathcad, PSpice OrCad and other environments. We discussed the comparative evaluation of various modifications and options for implementing processor. We analyzed the new approach for the programmable choice of its function or set of functions, including the choice of the required differences between the ranks of signals and their weights. We show the results of design and modeling the proposed new FPGA-implementations of MIP. Simulation results show that processing time in such circuits does not exceed 25 nanoseconds. Circuits are simple, have low supply voltage (2.5 V), low power consumption (50mW), digital accuracy. Calculations show that when using an Altera FPGA chip EP3C16F484 Cyclone III family, it is possible to implement MIP with register memory for image size of 64*64 and window 3*3 in the one chip. For the chip for 2.5V and clock frequency 200MHz the power consumption will be at the level of 200mW, and the calculation time for pixel of filters will be at the level of 25ns.
