As a result of inefficiency, radio frequency (RF) power
amplifiers typically consume high levels of current. Consequently, there have
been numerous attempts to use external circuitry in order to improve the
efficiency of RF power amplifiers located on integrated circuits (ICs); however,
these attempts have failed to provide the desired improvements in efficiency.
Specifically, because internal switching frequencies can be orders of magnitude
faster than off-chip signals, external power supplies and control circuits are
often unable to respond rapidly enough to varying load conditions. In addition,
the parasitic resistance and inductance of the interconnects between the IC and
the external circuitry can reduce voltage swing of the power amplifier, increase
power loss, and induce resonance and instability.
Electronic devices, mobile electronic devices in particular,
can greatly benefit from more efficient RF power amplifiers. Mobile electronic
devices, for example, can achieve considerable improvements in battery life by
incorporating more efficient RF power amplifiers. This can be particularly
relevant when considering other technological improvements are quickly outpacing
improvements in battery life technology.
Researchers at Arizona State University have developed an
efficiently operating RF power amplifier that is also capable of internal
integration. The RF power amplifier uses envelope elimination and restoration to
linearize a switched-mode power amplifier. The device employs a synchronous buck
DC-DC converter integrated with the switched-mode power amplifier and provides
its supply voltage while tracking the envelope of the RF input signal.
Integrating the synchronous buck DC-DC converter in proximity with the
switched-mode power amplifier can increase voltage swing, decrease power loss,
and reduce parasitic inductance and resistance.
Potential Applications
- Mixed-Signal ICs
- Memory Chips
- RF Front-End
- Signal Processors
- Microcontrollers
Benefits and Advantages
- Improves Operating Efficiency of RF Power Amplifiers
- Increases Voltage Swing
- Reduces Parasitic Inductance and Resistance
- Decreases Power Loss
- Provides Internally Integrated RF Power Amplifiers
- Improves Speed ? rapidly responds to varying load
conditions
- Reduces Cost ? reduced material requirements