This paper presents a compensation method of active inductor losses, employing passive gyrator degeneration rather than an external negative impedance converter. Theoretical analysis is confirmed by a comparative simulations of two resonators designed for 434 MHz band, using Eldo RF and Spectre and the UMC 0.18 µm 1P6M process. Presented results show that the proposed loss compensation method achieves comparable noise and large signal performance to a standard active inductor resonator and provides a significant improvement in static power consumption.
This paper presents a study of linearity in wideband CMOS low noise amplifiers (LNA) and its relationship to power consumption in context of Long Term Evolution (LTE) system. Using proposed figure of merit to compare 35 state-of-the-art LNA circuits published in recent years, the paper shows a proportional but relatively weak dependence between amplifier performance (that is combined linearity, noise figure and gain) with power consumption. As a result, the predicted increase of LNA performance, necessary to satisfy stringent linearity specifications of LTE standard, may require a significant increase in power, a critical budget planning aspect for both handheld devices and base stations operating in small cells.
This paper presents a study on different microwave structures used to integrate MEMS devices in printed circuit boards, and their effect on the linear phase response for switched delay lines applications. Three different prototypes were designed to realize the RF tracks required to integrate 0.5 mm pitch MEMS devices together with the meander delay lines. The structures includes: microstrip lines, conventional coplanar waveguides (CPW) and finite grounded coplanar waveguides (FGCPW). The three prototypes were designed to deliver a group delay of 600 ps. Simulations were carried out using CST Microwave Studio. The FGCPW proved to have the highest phase linearity with only ± 4 ps (±0.67%) delay deviations up to 2.7 GHz. The paper also presents the design of two wideband MEMS switched time delay line circuits; one used to provide a fine tuning for the group delay with a step of only 10 ps and another for coarse tuning with 50 ps delay step. Finite grounded coplanar waveguides were selected to obtain a high linearity of phase response. The simulation of the two circuits resulted in a constant delay with relatively small deviations, as well as low insertion and return losses of 0.75 dB and 20 dB, respectively for frequencies up to 5 GHz.
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