Integrated chaos generator

Abstract

With the explosion of information, the need to cater to the demands of increased number of users is of paramount importance. Spread Spectrum Technique used in wideband communications have proved to utilize the limited communication resources efficiently to meet the need of the hour. This technique requires the generation of large number of secure, orthogonal codes that can be allotted to each user. Chaotic signals being deterministic, aperiodic, broadband but dicult to predict over a longer duration qualify to be ideal candidates to generate the required pseudo random codes. <p/> <p/>This work is focussed at generating chaotic signals in continuous time as well as in discrete time simultaneously. These signals are generated by iterating through the Modified Bernoulli Map due to its simplicity, ease of physical realization and reliability. This has been implemented through switched capacitor circuits performing the sample and hold function and residue amplification. A two stage fully differential telescopic cascode Op-Amp has been designed to meet the specifications of gain, unity-gain bandwidth and slew rate as an integral part of switched capacitor circuits. The topology also incorporates a coarse analog to digital converter(ADC) along with an encoder in feedback loop to account for the discontinuities in the map. <p/> <p/>Verification of the generated chaos from the system has been done on the basis of its time domain evolution, correlation properties and power spectral density. This has also been compared with the ideal system implementing the same map on similar grounds. The work has been carried out in 0.35µm, bipolar supply, N-well technology using BSIM 3v3.1 SPICE model parameters for simulations.