MICROTEST 6632 Impedance Analyzer｜Inductor - Impact of C1 on SRF and High-Frequency Performance

Описание: In high-frequency characterization of flat wire power inductors, an impedance analyzer is the primary instrument for evaluating frequency response and extracting parameters through equivalent-circuit modeling.
The MICROTEST 6632 Impedance Analyzer integrates equivalent-circuit model analysis using Model F (four-element model), enabling parameter interpretation based on R0, R1, L1, and C1.

Four-Element Model Interpretation (R0, R1, L1, C1)
R0 — Series Resistance
Represents low-frequency or DC winding resistance and connection losses.
Determines the starting point of impedance magnitude and low-frequency impedance level.

L1 — Inductive Component
Represents the ideal inductance of the coil.
Forms a parallel resonance with C1, defining the self-resonant frequency (SRF).

C1 — Parasitic Capacitance
Reflects parasitic capacitance between coil turns and between the coil and ground.
In parallel with L1, it forms the self-resonant point (SRF).
Directly influences high-frequency inductive extension and determines the inductive-to-capacitive transition frequency.

R1 — Loss Component (in series with C1 and then parallel with L1)
Represents high-frequency dissipation losses, including eddy-current and core losses.
By placing R1 in series with C1 and paralleling the branch with L1, the model reproduces parasitic-capacitance energy dissipation.
Significantly affects the impedance peak shape around SRF.

Impact of C1 on SRF and High-Frequency Performance
By modifying the value of C1 (parasitic capacitance), the shift of SRF can be clearly observed.
C1 determines SRF and high-frequency inductive extension, effectively controlling the inductive-to-capacitive transition point.

Sources of C1 include:
_ coupling between windings
_ dielectric constant of interlayer insulation
_ coupling to ground planes

Reducing overlapping coil areas or selecting lower-dielectric materials decreases C1, raising SRF and improving high-frequency behavior.

MICROTEST 6632 Impedance Analyzer — Catalog Download
https://www.microtest.com.tw/product_...

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