Nyquist plots to determine $R_{phz}$

In these figures the nyquist diagram is shown of the amplifier, here the calculated value of $R_{phz}$ is equal to $11.89\Omega$ using the fllowing 2 equtions:

$R_{phz}=\dfrac{1}{2\cdot \pi \cdot f_{phz} \cdot C_{A}}$

$f_{phz} = \dfrac{B_{f}^{2}}{ \sqrt(2 B_{f}) + p_{1}+ p_{2}}$

Here $p_{1}$ and $p_{2}$ are the 2 dominant poles of the circuit.

In the nyquist plot the start value is set to $0.5 \cdot R_phz$ and this value is swept till $1.5 \cdot R_phz$ in 15 steps.

From the plot we get for the 10th step a pole position at almost $45 ^{\circ}$ angle is reached which infers a MFM characteristic, this is thus at a value of $R_{phz}=13.9\Omega$.