Constant Conduction Angle Biasing for Class C Monolithic RF Power Amplifiers

<p>In modern wireless communication systems, a base station typically serves a few hundred users within its cell coverage. To combat the near-far problem – the situation where a nearby user’s strong cellular signal masks the cellular signal of a faraway user – base stations continually enforce power control. That is, nearby users must lower their transmit power. In CDMA technology, power control can be as large as 70-80dB. At low power outputs, this greatly impacts the performance of the RF power amplifier (PA) in the cellular device. For small RF drives, the magnitude of the output RF current approaches the magnitude of the DC current and thus the efficiency suffers. Operating the RF PA in class C operation improves the efficiency, but results in poor linearity.</p> <p>Several methods of so-called dynamic biasing have been proposed. These strategies entail lowering the bias of the PA as the RF drive increases. The proposed methods, however, fail to explain how to achieve linearity and low third-order intermodulation distortion. Additionally, the methods utilize open-loop implementations.</p> <p>This work presents a novel dynamic biasing topology that results in a much improved linear class C PA. The topology utilizes a closed loop that cleverly senses the operating conditions of the "power device." Particularly, the loop operates on the principle of keeping the conduction angle remarkably constant and thereby ensuring linearity. The work details a thorough design methodology that should provide assistance to a designer wanting to implement the topology in an RF integrated circuit. Agilent ADS simulations and laboratory results from a functional PCB prototype bring merit to the topology.</p>

Name thesis:degree_name

MS in Electrical Engineering

Discipline thesis:degree_discipline

Electrical Engineering

Year dc:date.available

2012

Author dc:creator

• Rai, Gursewak Singh

Contributors dc:contributor

• Vladimir Ivanov Prodanov

• Dynamic Biasing
• Constant Conduction Angle
• Linearized Class C
• RF Power Amplifiers
• Systems and Communications

Identifier

10.15368/theses.2012.190

OAI identifier oai:identifier

oai:digitalcommons.calpoly.edu:theses-1918