Improved hybrid sige HBT class-ab power amplifier efficiency using varactor-based tunable matching networks

Abstract

This paper presents a 1.8GHz prototype class-AB power amplifier using a QUBIC4G (SiGe, ft=40GHz) handset device with adaptive inand output matching networks. The realized amplifier provides: 13dB gain, 28 dBm output power, with an efficiency greater than 33-51% over a 10dB output power control range.

Linearity and efficiency enhancement strategies for 4G wireless power amplifier designs

“…A wide range of impedances can be achieved with this technique and the high efficiency of the power amplifier can be maintained over a broad range of output powers. One example of an adaptively tuned amplifier provided 13dB gain, 27-28 dBm output power at the 900, 1800, 1900 and 2100MHz bands [43]. For the communication bands above 1GHz optimum load adaptation resulted in efficiencies between 30-55% over a 10dB output power control range, a dramatic improvement compared to constant load impedance performance.…”

“…Unfortunately, these distributed approaches require a large die area, though this can be reduced through Figure 5. A variable impedance transmission line tuner can present a variety of impedance levels to the power amplifier, so that the voltage swing across the collector remains high even at low output power levels, maximizing efficiency [43].…”

A Reconfigurable Active Array Antenna System With the Frequency Reconfigurable Amplifiers Based on Rf Mems Switches

“…Conventional reconfigurable amplifiers are commonly implemented with varactor diode as a variable capacitor to change electrical value of the capacitor in the impedance matching circuits [10]. However, varactor diodes show poor linearity, causing degradation of linearity performance, which is the most critical parameter for modern non-constant envelop communication schemes for high rate data transmission such as orthogonal frequency division multiplexing (OFDM).…”

“…Recently, MEMS capacitors have been utilized to realize reconfigurable amplifiers due to their very low insertion loss, high isolation, as well as linearity [7,13]. In the conventional variable capacitance based RMC [7,10,13], the capacitance of the varactor, however, has to be controlled with very fine and accurate with complicated control circuit for a given impedance point. Moreover, available impedance range is restricted depending on the topology of the RMC.…”

“…In this paper, a novel RMC is proposed based on L-section matching network with a shunt capacitor and a series transmission line, and a frequency reconfigurable RAA system is also presented with the RFA based on the proposed RMC topology. Moreover, the RMC, RFA, as well as RAA system proposed in this paper are realized with microelectro-mechanical-system (MEMS) switches instead of varactor diodes in the conventional reconfigurable amplifiers [10] or reconfigurable system. Since a MEMS switch shows excellent isolation, insertion loss, as well as linear characteristics [11], the RFA can be realized with maximized performance.…”