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Z (Impedance)

Model complex impedance

  • Impedance block

RF Blockset / Circuit Envelope / Elements


The Impedance block implements the relation, vk(t) = Z(fk)*ik(t), for each simulation frequency, fk, where:

  • Z(fk) represents complex-valued impedance at a specified simulation frequency.

  • vk(t) represents the voltage across the terminals of the element at time t.

  • ik(t) represents the current through the element at time t.

Circuit envelope current and voltage signals comprise in-phase, Ik, and quadrature, Qk, components at each frequency, fk.

Frequency-dependent impedance typically cannot be realized as a physical network such as an RLC chain. You can, however, use the Impedance block to model nonphysical behavior, such as frequency-independent negative capacitance or negative inductance. You can also use this block to specify resonant frequency offsets in filter networks.


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Frequency dependency for the impedance, specified as Frequency independent or Frequency dependent.

Choose Frequency independent to apply the same impedance for all frequencies. Choose Frequency dependent to apply the impedance as a piecewise linear function.

Data Types: double

Impedance value, specified as a scalar complex number in ohms or a vector for complex numbers with each element unit in ohms.

When Impedance type is set to Frequency independent, impedance is a scalar complex number that is applied to all simulation frequencies. When Impedance type is set to Frequency dependent, impedance is a vector of complex numbers, [Z1, Z2, Z3, …]. This vector is linearly interpolated for all simulation frequencies.

Data Types: double

Frequency values for frequency dependent impedance, specified as a nonnegative scalar number in Hz or nonnegative vector number with each element unit in Hz.

When Impedance type is set to Frequency dependent, you can specify a vector of nonnegative frequencies, [f1, f2, f3, …]. The pairs, fi, Zi, define a piecewise linear function, Z(f), that is linearly interpolated for the simulation frequencies. For values outside the range, there is constant extrapolation.

Data Types: double

Version History

Introduced in R2010b

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