A 1.8/2.4-GHz dual-band compact Wilkinson power divider was designed and implemented using an integrated passive device process. The design used a common inductor to match impedance in the even mode. The common inductor replaced two shunt inductors in the circuit so the circuit size was reduced. An additional complex load was then used for matching impedance in the odd mode. The circuit measurements showed reflection at all ports better than-11.9 dB, isolation at the output ports better than-14 dB and transmission coefficient better than-4.3 dB, at both operating frequencies. The circuit occupied only 0.036λ o ×0.018λ o at the higher operating frequency. INDEX TERMS Common inductor, dual band, integrated passive device, lumped transmission line, Wilkinson power divider.
This article presents the 4-bit ultra-wideband complementary metal-oxidesemiconductor (CMOS) attenuator in a standard 0.18-μm CMOS process. This design adopts switched bridge-T type topologies for each attenuation bit. Based on insertion losses and input P 1-dB considerations, the circuit performances can be optimized by the proper bit ordering arrangement. Therefore, the bit ordering 0.5-4-2-1 dB is employed in the 4-bit attenuator. Moreover, series inductors are added between each bit to further improve the input and output return losses. Measured results demonstrate that the attenuation range of the circuit is 7.5 dB with 0.5 dB step and the root-mean-square (RMS) amplitude error is between 0.11 and 0.13 dB from 3.1 to 10.8 GHz. The differences between simulated and measured RMS amplitude errors are less than 0.2 dB, which demonstrates the good agreement and feasibility of the design concept. The measured input P 1-dB is 15 dBm at 5 GHz and the chip area is 1.12 mm 2 including all testing pads.
K E Y W O R D Sattenuator, CMOS, RMS amplitude error, ultra-wideband
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