## 3 Experimental Results  
The proposed grounded tunable active inductor was implemented using 0.13 \(\upmu\)m STMicroelectronics CMOS technology as proof of concept. Fabrication and characterization were conducted under nominal process-voltage-temperature (PVT) conditions. All presented results correspond to this typical corner. Measurements were carried out on 25 fabricated chips, which exhibited a tightly clustered performance distribution, thereby confirming the design's consistency and reliability under standard operating conditions. Figure 7 shows the die photographs of a fabricated chip, occupying an area of 400 \(\upmu\)m \(\times\) 345 \(\upmu\)m including bond pads and of 25.3 \(\upmu\)m \(\times\) 12.2 \(\upmu\)m without bond pads. The top right corner of Figure 8 depicts the active inductor during testing, while the left side illustrates the test-bench environment. To ensure accurate measurement results, performance metrics were analyzed after de-embedding the loading effects introduced by the input RF pads. The 20 pF decoupling capacitors were implemented on-chip. On-wafer measurements were performed using a Rohde & Schwarz ZVA-24 vector network analyzer (VNA) with RF and DC probing. The measurements were conducted under a 1 V supply with an input signal amplitude of -20 dBm (27\({}^{\circ}\)) at 2 GHz. The measured power consumption of the grounded active inductor was 2.0 mW, primarily attributed to the gyrator-C core. Figure 8: Experimental test-bench setup of the proposed active inductor. Figure 7: Die micrograph of the fabricated active inductor. One-port S-parameter measurements obtained from the VNA demonstrate the variation in the magnitude and self-resonant frequency of \(Z_{11}\) as functions of the control voltages V\({}_{\text{ctrl}}\) and V\({}_{\text{ctrl2}}\). As depicted in Figure 9a,b, sweeping V\({}_{\text{ctrl1}}\) from 0.3 V to 0.54 V and V\({}_{\text{ctrl2}}\) from 0.39 V to 0.47 V enables the self-resonant frequency tuning of the \(Z_{11}\) imaginary part from 1.08 GHz to 3.9 GHz and of the \(Z_{11}\) real part from 1.337 GHz to 3.96 GHz. This tunability is accompanied by variations in the magnitude of the impedance components, validating the inductor operational flexibility and the adopted reconfiguration methodology effectiveness. Figure 10 presents the measured phase of the input impedance, delineating the operational frequency range of the inductor. The circuit begins exhibiting inductive characteristics at 87 MHz (\(\omega_{\text{z}}\)), with the phase angle reaching 45\({}^{\circ}\) at 150 MHz and peaking near 89\({}^{\circ}\), maintaining inductive behavior up to 3.96 GHz (\(\omega_{\text{0}}\)), where the phase returns to 0\({}^{\circ}\). Based on the measured S-parameters, both the equivalent inductance and the quality factor Q were extracted, providing further validation of the inductor's performance. Figure 11 illustrates the influence of control voltages V\({}_{\text{ctrl1}}\) and V\({}_{\text{ctrl2}}\) on the equivalent inductance, with V\({}_{\text{DD}}\) = 1 V. Measurements were conducted under two conditions: with R\({}_{\text{f}}\) fixed and with the conductance g\({}_{\text{ds5}}\) held constant. The equivalent inductance L\({}_{\text{eq}}\) exhibits linear tuning behavior, as shown in Figure 11a,b, with the quality factor peaking at approximately 1.5 GHz and 1.9 GHz. Figure 10: Measured phase response of the input impedance for the proposed AI. Figure 9: Measured input impedance of the proposed AI: (**a**) real part and (**b**) imaginary part. Figure 12 further demonstrates that inductance values can be adjusted over a wide frequency range (668 MHz to 3.96 GHz), with corresponding inductance variation from 84.4 nH to 6.7 nH. Figure 13 presents measured quality factor values for various control voltage settings, showing high Q values (up to 50) across frequency-independent bands.