Current-Mode CMOS Multifunctional Circuits for Analog Signal Processing

The paper introduces and develops the new concept of current-mode multifunctional circuit, a computational structure that is able to implement, using the same functional core, a multitude of circuit functions: amplifying, squaring, square-rooting, multiplying, exponentiation or generation of any continuous mathematical function. As a single core computes a large number of circuit functions, the original approach of analog signal processing from the perspective of multifunctional structures presents the important advantages of a much smaller power consumption and design costs per implemented function comparing with classical designs. The current-mode operation, associated with the original concrete implementation of the proposed structure increase the accuracy of computed functions and the frequency behaviour of the designed circuit. Additionally, the temperature-caused errors are almost removed by specific design techniques. It will be also shown a new method for third-order approximating the exponential function using an original approximation function. A generalization of this method will represent the functional basis for realizing an improved accuracy function synthesizer circuit with a simple implementation in CMOS technology. The proposed circuits are compatible with low-power low voltage operations.