(a) The gyrator-based circuit with the ideal gyrator connected two parallel LC tanks. (b) Opamp-based circuit configuration to obtain negative inductance and capacitance. The sensitivity of the (c), (e), real and (d), (f), imaginary parts of the eigenfrequencies to (c), (d) gyration resistance, (e), (f) positive capacitance C₁. Solid lines: solution of eigenvalue problem of Eq. (2); green-dashed lines: Puiseux series approximation truncated to its second term. Voltage of positive capacitance v₁ (t) at EPD (g) time-domain, and (h) frequency-domain. The frequency-domain result is calculated by applying an FFT with 10⁶ samples in the time window of 0 to 3 ms. (i) Root locus of zeros of Y_total (ω) = 0 showing the real versus imaginary parts of resonance frequencies by perturbing gyration resistance. At the EPD, two zero collide at ω_e and the system’s total admittance has the form of Y_total (ω) ∝ (ω − ω_e) ².