results in a resolution bandwidth of (1 $\mu$s)$^{-1}$ = .

Fig. 4(a) shows the PSDs, which contain the information of the operating frequency and linewidth of the MTJ STO’s signals as a function of $\phi_\text{ext}$. As $\phi_\text{ext}$ is increased, the operating frequency initially decreases, reaches a minimum and thereafter increases, agreeing with the measured data given in Fig. 2(a) of [@Tingsu_2014TEDI]. For different $\phi_\text{ext}$, the operating frequency and linewidth of the proposed MTJ STO model implemented in Verilog-A are in accordance with the one obtained from the theoretical analysis, as given in Fig. 2(a) and Fig. 4(a) of [@Tingsu_2014TEDI]. Particularly, as it can be noticed from Fig. 4(a), the linewidth at $\phi_\text{ext}=55^o$, is much narrower than that at $\phi_\text{ext}=40^o$, indicating less random frequency fluctuations and confirming the estimation based on Fig. 3. Moreover, as it can be observed from Fig. 4(a), the signal with comparatively large output power can be found between $40^o$ and $55^o$, which is also in agreement with the analytical and measured results in Fig. 3(a) of [@Tingsu_2014TEDI].

The dependence of $I_\text{DC}$ on the characteristics of the MTJ STO is also examined by performing transient simulations of the proposed Verilog-A model with different $I_\text{DC}$. The PSDs of 