Abstract
A closed-loop protection method for a radio frequency (RF) power amplifier (PA) module applicable to mobile handsets has been introduced. The load impedance of the PA was adaptively sensed by an embedded impedance detector which was digitally controlled and the system adjusted PA power using a feedback circuit to keep the PA safe based on a load mismatch detection. For verification, a two-stage hetero junction bipolar transistor (HBT) PA module for handsets was fabricated and tested against load mismatch. Measurement results showed that the technique could help PA survive at a 0.5V larger collector bias voltage condition than when the technique was not applied for the same mismatch condition with an acceptable RF performance degradation at nominal condition.
Highlights
One of the basic requirements for radio frequency (RF) power amplifiers (PAs) in mobile devices is a sufficient ruggedness which means an ability to survive under a severe antenna mismatch condition
In previous generations of handsets, it was general to implement an isolator between the PA module and the handset antenna in order to isolate the amplifier from changes in impedance at the antenna port, which is incompatible with modern handsets due to the size and cost limits [1]
An adaptive protection circuit for mobile power amplifiers has been proposed based on a dynamic impedance detection which is digitally controlled through a mobile industry processor interface (MIPI) interface
Summary
One of the basic requirements for radio frequency (RF) power amplifiers (PAs) in mobile devices is a sufficient ruggedness which means an ability to survive under a severe antenna mismatch condition. Existing approaches have to be equipped with each solution at the same time in order to cope with various causes, which makes the system much more complicated To overcome this issue, a protection system needs to recognize the risk regardless of the type of failure. By recognizing dangerous situations and operating a feedback circuit adaptively as stated above, the PA can be protected from damages In this this paper, paper, an an adaptive adaptive protection protection method method for for PAs. In mismatch detection detection and and bias bias control control technique technique is is proposed. The conventional protection to detect both voltage and current respectively depending on situations to cope with various failure circuit must be able to detect both voltage and current respectively depending on situations to cope causes This feature may increase the complexity of protection circuits.
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