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This paper presents chaotic oscillation-based built-in self-test (BIST) for CMOS operational amplifier. The proposed BIST technique is based on the use of designed operational amplifier (op-amp) in the unity gain buffer of discrete time chaotic oscillator as circuit under test (CUT) of BIST. The presented BIST detected faults by using a differentiation of chaotic output signal among fault free and faulty CUT. The circuit is simulated in 0.18/lm CMOS technology. The simulation results on circuit-level are presented to examine the feasibility and efficiency to detecting faults in op-amp.

Detection of parametric faults is a crucial issue due to the large variation of the fabrication process, which provide a range of acceptable parameter deviations in analog circuits. This paper presents a phase difference analysis technique, which is sensitive to the parametric deviations and allows a tolerance band of passive analog components. Test operations can be simply achieved by comparing the phase difference between a reference clock signal and a reconfigured circuit-under-test (CUT) as an oscillator. The difference of phase characteristics between the two signals can be utilized as an indicator for a fault signature, which can be characterized by a compact digital circuit comprising a counter and logic components. Simulation of faults detection reveals a high faults coverage, high-speed testing, and tolerance band controllability. The proposed technique has offered a fully on-chip BIST in 0.18-µm CMOS standard technology with no external test equipment required.

The search for generation approaches to robust chaos has received considerable attention due to potential applications in cryptography or secure communications. This paper is of interest regarding a 1-D sigmoidal chaotic map, which has never been distinctly investigated. This paper introduces a generic form of the sigmoidal chaotic map with three terms, i.e., x n+1 = ∓Af NL (Bx n) ± Cx n ± D, where A, B, C, and D are real constants. The unification of modified sigmoid and hyperbolic tangent (tanh) functions reveals the existence of a "unified sigmoidal chaotic map" generically fulfilling the three terms, with robust chaos partially appearing in some parameter ranges. A simplified generic form, i.e., x n+1 = ∓f NL (Bx n) ± Cx n , through various S-shaped functions, has recently led to the possibility of linearization using (i) hardtanh and (ii) signum functions. This study finds a linearized sigmoidal chaotic map that potentially offers robust chaos over an entire range of parameters. Chaos dynamics are described in terms of chaotic waveforms, histogram, cobweb plots, fixed point, Jacobian, and a bifurcation structure diagram based on Lyapunov exponents. As a practical example, a true random bit generator using the linearized sigmoidal chaotic map is demonstrated. The resulting output is evaluated using the NIST SP800-22 test suite and TestU01.