Scientists at Northeastern University in Massachusetts have devised a new method of tuning radio frequency circuits that could reduce the size and improve the performance of smartphones and other RF devices.
“Every radio-frequency resonance circuit has two components: an inductor and a capacitor. [However,] for the many decades that we’ve been using RF devices, we’ve only been able to tune the capacitor,” explains lead researcher Nian Sun, associate professor of electrical and computer engineering at Northeastern University. Tuning the other half of the circuit module—the inductor—is possible, but the power required to produce a strong enough magnetic field has rendered it an unrealistic option for execution in portable electronic devices.
Because of this limitation, multiple RF circuit modules are required in modern cell phones to handle a certain number of channels, since only capacitors—or half of each circuit module—are being tuned, Sun said. Reducing the number of circuit modules would allow for smaller devices to be manufactured, enable the batteries to last longer and lead to less RF interference.
Now, the Northeastern team has developed a new method of tuning inductors that could enable the components to share the burden, cutting the required number of circuit modules in half.
“Instead of using a current, we used voltage to tune inductance, a much more power efficient approach. You have to constantly drive a current in order to achieve magnetic field tuning of inductance, but with voltage tuning you can just charge it and inductance change will stay. This means RF circuits can be tunable on both the capacitor and inductor side [and the number of circuit modules can be significantly reduced].” Sun said. “It’s the missing link for tunable RF circuits.”
“Cell phones could be much more compact than they are right now and still be very powerful both in their performance and data rate, while also achieving a clearer signal.”
