Multiband Multi-Standard LNA with CPW Transmission Line Inductor

Multiband Multi-Standard LNA with CPW Transmission Line Inductor

M. Ben Amor (University of Sfax, Tunisia), M. Loulou (University of Sfax, Tunisia), S. Quintanel (ENSEA University of Cergy Pontoise, France) and D. Pasquet (Microelectronics and Semiconductor Physics Laboratory (LaMIPS), NXP-CRISMAT-ENSICAEN, France)
DOI: 10.4018/978-1-60566-886-4.ch003
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LNA is one very essential bloc in the RF receiver. Due to the growth of the standard evolution, this component must handle several frequency bands with the best performances. This chapter presents a wide band LNA design for IEEE802.16 standard with the CMOS 0.35µm technology. In this LNA, we use a CPW transmission line to design the inductive degeneration inductor of 0.38nH. This circuit has a S21 of 12dB, a noise figure less than 3dB and an input/output reflexion coefficient less than -10dB between 2 and 6GHz. The CPW line presents a characteristic impedance of 120O, an inductance of 0.38nH, a capacitance of few fF and a resistance less than 2O on the desired frequency band.
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Receiver Architecture

In the receiver path, the main role of the RF part is the transposition of the modulated signal, which was received by the antenna, to the base band. The difference between one receiver and other in RF systems is presented in the disposition and in the number of blocs. (Super)Heterodyne, homodyne zero IF and low IF are the three existing receivers architectures. Each one has its advantages and its drawbacks.

Heterodyne Receiver

The super heterodyne architecture [L. Lévy,], Figure 1, provides the best and superior selectivity and sensitivity with the use of two down conversion steps of the desired RF signal. The first down conversion of the signal is around a fixed intermediate frequency (IF) and the second down conversion to the base band is centered on the central frequency of the desired channel. These two steps are realized with two local oscillators.

Figure 1.

Heterodyne receiver architecture

However, an undesired image signal will be created after the first mixing which has to be attenuated with an image reject filter and this last constitutes the major drawback of this architecture. RF and IF filters integrations are very difficult because the inductors have high quality factors. Moreover, this receiver requires an impedance matching between every two blocs, presents higher power consumption and it isn’t adaptable for multiband applications.

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