Fig. 1. Spectral density of the low-frequency noise in the HSB2 transistor. The bias collector current is 3.14 mA and V_ce=5 V. 1/f noise is observed below 10 kHz.

Fig. 2. Block scheme of the experimental setup. DUT indicates the device under test.

Fig. 3. Typical wavelet spectrum for f₀=316 Hz. The dashed line indicates the average value and the dashed–dotted line is the chosen threshold value. Arrows delimit the measured recurrence times.

Fig. 4. Two illustrative examples of the measured probability density function of the recurrence time τ. The line labeled as (α) is obtained in the 1/f regime (f₀=316 Hz) while line (β) belongs to the white noise regime (f₀=31 600 Hz).

Fig. 5. Double logarithmic plot of the average recurrence time as a function of the generating wavelet frequency. The experimental points are obtained with a threshold as described in the text and illustrated in Fig. 3 for all points except one (). This single point has been obtained with a higher threshold (see text for details).