Smart Tuning Capacitor

What is a tuning capacitor?

Join us as we uncover the intricacies and significance of tuning capacitors in this enlightening journey. Tuning capacitors are adjustable electronic components crucial for fine-tuning resonant circuits to specific frequencies. They consist of two conductive plates separated by a dielectric, allowing for capacitance adjustment.

Why do tunable capacitors have a high tuning ratio?

The high tuning ratio is due to double side metallization of silicon structure layer, which reduces the out of plane stresses and bending of the tunable capacitor. Furthermore, when implementing the tunable capacitor into a two-pole UHF filter, tuning over a 225–400 MHz range was achieved with a loss below 6.2 dB.

How does a tunable capacitor work?

The tunable capacitor consists of separate RF and DC electrodes, which are fabricated underneath a circular diaphragm, as shown in figure 10. The design increases both the restoring force, and the RF self-actuation voltage, resulting in improved power-handling capabilities. The prototype requires a small pull-in voltage of only 24–28 V.

What is the tuning range of electrostatically actuated tunable capacitors?

The tuning range of capacitor is only 29%. Thus the resonance frequencies tuning ranges can be improved by using higher tuning range capacitors. Table 1 shows the comparison summary of the electrostatically actuated tunable capacitors used in RF communication industry, electronics, and biomedical industry.

What is the tuning range of a capacitor?

The resonance frequencies of 3.9 GHz and 7.35 GHz are tuned to 3.65 GHz and 6.6 GHz, respectively. The tuning range of capacitor is only 29%. Thus the resonance frequencies tuning ranges can be improved by using higher tuning range capacitors.

How tunable capacitor is actuated with lateral comb drive system?

The tunable capacitor is actuated with lateral comb drive system and is sensed using parallel-plate capacitor, as shown in figure 9 (b). A tunability of 172% was achieved with the voltage range of −120 V to 120 V. The Q factor of 0.35 was achieved at 1 GHz. This Q factor is very low due to the RF losses in the silicon material.