UM E-Theses Collection (澳門大學電子學位論文庫)

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Wideband active-balun variable-gain low-noise amplifier for mobile-TV applications

English Abstract

The rapid development of wireless communications and CMOS technology has facilitated the integration of radio frequency (RF) systems as a System-on-Chip (SOC) for cost and power reductions. One of the applications is the RF TV tuner for Digital Video Broadcasting-Handheld (DVB-H). With the development of digital mobile TV industry the TV tuner system has gained wide attention recently. Variable Gain Low-Noise Amplifier (VGLNA) is one of the most important modules in the TV tuner system. The main function of a VGLNA is to provide enough gain to suppress the noise of subsequent stages as well as adding as little noise as possible. Recent works on wideband low-noise amplifiers (LNAs) based on an active-balun structure have shown reliable RF performances such as moderate noise figure (NF), high linearity and broadband input impedance matching. This structure has exhibited great potential in minimizing the required external components of multi-band mobile-TV tuners, i.e., an active-balun LNA requires just one radio frequency (RF) input pin and eliminates the need of external balun for each band, which is necessary in the current design. This thesis will propose a novel active-balun LNA with forestage and poststage gain controls. With this forestage-poststage gain controls the system noise figure and linearity can be easily traded for different gain levels. In addition, the benefits of this design allow also the decrease in circuit complexity, chip area and the power consumption. In this architecture just one Single to Differential (S2D) amplifier is required. The first part of this work will introduce the theoretical MOSFET noise model and conventional VGLNA circuits. The second part will present the circuit level design based on the proposed architecture. The VGLNA was designed with two passive attenuators inter-operating with an active core to optimize the RF performances under different reception scenarios. It was implemented in a 0.18µm CMOS process with 1.8V of voltage-supply. Finally, the simulation results of the whole circuit are presented. The VGLNA supports both VHF-III (170 to 240 MHz) and UHF (470 to 860 MHz) bands while offering low NF and S11 <-10 dB at all gain levels. The forestage and poststage gain controls flexibly befit reception at different signal-to-interferer levels. The circuit achieves good performances in the required frequency bands and satisfies the requirements of the mobile TV tuner applications.

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Lo, Keng Wai


Faculty of Science and Technology


Department of Electrical and Electronics Engineering




Radio frequency integrated circuits

Metal oxide semiconductors, Complementary

Mobile television

Automatic gain control


Mak, Pui-In

Martins, Rui Paulo

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