A 8 GHz 77 % efficient discrete quarter-wavelength transmission line integrated in 0.13 μm CMOS

This paper presents a 8 GHz discrete quarter-wavelength transmission line with a characteristic impedance of 25 Ω that is integrated in a 0.13 μm CMOS technology. The proposed line transforms a 50 Ω load into 12.5 Ω. Simulations show that only three sections of on-chip integrable inductances and capacitances of respectively 0.25 nH and 0.4 pF are needed to emulate the behaviour of a traditional quarter-wavelength line. Mathematical expressions for the practical implementation of the discrete line are presented. Furthermore, a methodology based on the extraction of S-parameters is derived to determine the efficiency of the line during both the simulation and measurement phases. Using these techniques, the implemented discrete transmission line achieves both impedance matching and power combining for an efficiency of 77% while requiring only one fourth of the area of an integrated coplanar 8 GHz quarter-wavelength line.