ESD Circuit Impedance Measurement via Attenuation Phase Analysis
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Solution Overview
Problem
Current methods for measuring the characteristic impedance of electrostatic discharge (ESD) protecting circuits are complex and time-consuming, particularly in semiconductor and magnetic head circuits, as they require sequential application of trapezoid-shaped transmission line pulse voltages to obtain peak voltage vs. peak current characteristics, making it difficult to quickly calculate this impedance.
Innovation Solution
A method and apparatus that simultaneously measure variations in discharge voltage and current over time, calculating the characteristic impedance by taking the ratio of discharge voltage to discharge current during their attenuation phase, using a pulse generating circuit, voltage and current measuring circuits, and a controller to input data to a computer for processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TLP measurement method is used to measure characteristic impedance of ESD protecting circuit, then measurement accuracy is improved, but measurement time and operational complexity increase significantly
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the relationship between discharge voltage and discharge current in a lookup table before actual measurement. When measuring characteristic impedance, the system simply queries the pre-computed table rather than performing complex sequential TLP measurements, thus achieving accurate results quickly without the time-consuming iterative process of traditional TLP measurement methods
Solution Approach 2:
The patent changes the measurement parameter approach by using discharge voltage and discharge current characteristics during the attenuation phase instead of traditional peak voltage and peak current measurements. This parameter transformation allows characteristic impedance to be calculated from the ratio of voltage to current variations during attenuation, simplifying the measurement process while maintaining accuracy
2Measurement precision
If TLP measurement method is used to measure characteristic impedance of ESD protecting circuit, then measurement accuracy is improved, but device complexity and operational difficulty increase
Solution Approach 1:
The patent extracts the complex computational logic from the measurement process and separates it into a pre-computation phase. The complicated TLP measurement calculations are performed in advance and stored, leaving only simple data retrieval and ratio calculation for the actual measurement, thus reducing the operational complexity and making the system easier to implement while maintaining measurement accuracy
Solution Approach 2:
The patent creates a computational model (lookup table) that copies and stores the complex voltage-current relationship characteristics in advance. This computational copy allows the system to avoid repeating complex calculations during actual measurement, replacing them with simple table lookups and ratio computations, thereby reducing device complexity and operational difficulty
3Measurement precision
If sequential TLP voltage application is used to obtain peak voltage vs peak current characteristics, then characteristic impedance calculation accuracy is improved, but productivity and measurement speed decrease
Solution Approach 1:
The patent applies preliminary action by pre-computing the characteristic impedance value and storing it in a lookup table based on discharge voltage. During actual measurement, the system retrieves the pre-computed impedance value and current from the table and calculates the ratio, avoiding the need for sequential TLP voltage applications and complex real-time computations, thus achieving high measurement speed without sacrificing accuracy
Solution Approach 2:
The patent uses partial action by measuring only the discharge voltage and discharge current during the attenuation phase rather than performing complete sequential TLP measurements. This partial measurement approach, combined with pre-computed lookup tables, provides sufficient data to calculate characteristic impedance accurately while dramatically reducing measurement time and improving productivity
Data Source
AI summary
A method of quickly measuring a characteristic impedance of an ESD protecting circuit by applying a discharge voltage to the ESD protecting circuit, includes the steps of measuring a variation in discharge voltage applied to and a variation in discharge current caused to flow through the ESD protecting circuit with time; simultaneously detecting a state when both the discharge voltage and discharge current corresponding to each other are attenuated, after both the discharge voltage and discharge current sequentially rise to arrive individually to respective peak values based on an input to or an output from a computer; and taking a ratio of the variation of discharge voltage to the variation of discharge current during the attenuation as an impedance value when the ratio is nearly constant as well as an apparatus for realizing the same.