Electrochemical Impedance Spectroscopy and Its Applications

Electrochemistry has become an important and recognized field for the future since many of its approaches contemplate the establishment of stable energy supplies and the minimization of our impact on the environment. In this regard, electrochemistry can face both objectives by studying the electrode/solution interface. As a result, different electrochemical techniques can be used to study the interface to understand the electron transfer phenomena in different reactions. Considering this, one of the most useful techniques to understand the electrode/solution interface is electrochemical impedance spectroscopy. This technique allows us to describe the electrode behavior in the presence of a certain electrolyte in terms of electrical parameters such as resistances and capacitances, among others. With this information, we can infer the electrochemical behavior toward a specific reaction and the capacity of the electrode to carry on the electron transfer depending on its resistance (impedance) values. The aim of this chapter is to go from the theory, based on Ohm’s Law and its derivations, to actual applications. This will lead us to characterize the solution, electrode, and the interface between these two phases based on their electrical components by using an equivalent electrical circuit, such as the Randles equivalent circuit.

Study of coloured anodized coatings on aluminum alloy by electrochemical impedance spectroscopy

Anodizing, porous anodic alumina, electrochemical impedance spectroscopy, electrolytic coloring, hydrothermal sealing, equivalent electrical circuit, simulation.

EVALUATION OF IMPEDANCE OF CABLES IN GONIOPHOTOMETRY

In a goniophotometer system, it is often unavoidable to use long cables to connect power supply, electrical measuring instrument, and the device under test (DUT). The measurement errors caused by cable impedance should not be ignored. An equivalent electrical circuit model considering the cable impedance of a typical goniophotometer is established in this paper. The measurement errors caused by the cable impedance are analysed by simulation. In DC and low frequency circuits, the cable impedance is almost resistive, while the inductive impedance of cables is significant and may lead to considerable errors when frequency is above 1 kHz in the circuits. Cable solutions in goniophotometry are introduced and recommended.

Modulation Performance Enhancement of Directly Modulated Injection-Locked Semiconductor Lasers Using an Equivalent Electrical Circuit

We propose an equivalent electrical circuit model to evaluate the direct modulation performance of optically injection-locked (OIL) semiconductor lasers. We modeled the equivalent circuit of the OIL laser based on alternating complex envelope representations, simulated it using the Simulation Program with Integrated Circuit Emphasis (SPICE), and analyzed the frequency response of the OIL laser. Although the frequency response of the OIL laser is better than that of a free-running laser, its 3-dB modulation performance is degraded by the relaxation oscillation that occurs during direct modulation of the semiconductor laser. To overcome this limitation and maintain the maximum modulation performance within the entire locking range, we also designed an electrical filter to preprocess the electrical modulation signal and compensate for the non-flat modulation output of the OIL laser. The damping ratio of the directly modulated OIL laser increased by 0.101 (280%) and its settling time decreased by >0.037 (44%) when the electrical compensation circuit was added, exhibiting a flat 3-dB modulation bandwidth of 28.79 GHz.

On-chip interconnects modeling and timing driven buffer insertion

With the increasing effect of on-chip interconnects on nowadays [sic] VLSI design performance, modeling of interconnects becomes a necessity. GAM, TPN, and AWE are well known methods that are used to map an interconnect to an equivalent electrical circuit. In this thesis, a general approach that considers z-parameters is developed witch allows the generation of equivalent RC, RLC, and RLCG circuits for both T and ∏ configurations. The performance of these generated circuits is compared to H-spice simulations by measuring the effect of interconnects on the transition times and delays under different conditions such as input transition times, interconnect lengths and capacitive loads. As a result, the a-configuration of AWE method reveals consistently an acceptable performance which makes it a good candidate to be utilized for buffer insertion.Buffer insertion is a popular technique used to reduce the delay of a long interconnect by segmenting it and inserting buffers among these segments. Therefore, the performance of this technique depends strongly on the accuracy of the considered interconnect model. However, using a model such as the RLCG of ∏ configuration which is derived from using the AWE method is not practical due to the complexity accompanied by such model which makes the derivation of closed-form expressions very complicated. To overcome this dilemma, the selected configuration has been mapped to a simple equivalent RC circuit. As a consequence, a new RC representation of on-chip interconnects is developed. Moreover, depending on the developed RC model, the proposed buffer insertion technique shows superiority over previously published works.

On-chip interconnects modeling and timing driven buffer insertion

With the increasing effect of on-chip interconnects on nowadays [sic] VLSI design performance, modeling of interconnects becomes a necessity. GAM, TPN, and AWE are well known methods that are used to map an interconnect to an equivalent electrical circuit. In this thesis, a general approach that considers z-parameters is developed witch allows the generation of equivalent RC, RLC, and RLCG circuits for both T and ∏ configurations. The performance of these generated circuits is compared to H-spice simulations by measuring the effect of interconnects on the transition times and delays under different conditions such as input transition times, interconnect lengths and capacitive loads. As a result, the a-configuration of AWE method reveals consistently an acceptable performance which makes it a good candidate to be utilized for buffer insertion.Buffer insertion is a popular technique used to reduce the delay of a long interconnect by segmenting it and inserting buffers among these segments. Therefore, the performance of this technique depends strongly on the accuracy of the considered interconnect model. However, using a model such as the RLCG of ∏ configuration which is derived from using the AWE method is not practical due to the complexity accompanied by such model which makes the derivation of closed-form expressions very complicated. To overcome this dilemma, the selected configuration has been mapped to a simple equivalent RC circuit. As a consequence, a new RC representation of on-chip interconnects is developed. Moreover, depending on the developed RC model, the proposed buffer insertion technique shows superiority over previously published works.