Presented is a new compact green design structure of distributed amplifiers in series with a common-source circuit to reduce powerdissipation and noise figure and increase gain-bandwidth. Fabricated in a 90 nm CMOS standard process, the integrated circuit prototype achieves a unity-gain cutoff frequency of 42 GHz and a gain of 8.4 dB, with a gain flatness of ± 1 dB over the bandwidth of 10-30 GHz. The noise figures are between 3.9 and 5.2 dB from 10 to 30 GHz of power consumption, and the current of the distributed amplifier is 11.13 mW, and 18.5 mA at 0.6 V supply voltage, respectively. The analytical, simulated and measured results are mutually consistent.Introduction: Ultra-wideband (UWB) systems provide a new wireless communication capable of transmitting data over a wide spectrum of frequency bands with very low power and high data rates. Distributed amplifiers (DAs) have always been one of the top choices for wide band amplification. As the energy shortage continues, green design technology has become important for low-power circuit design. Ultra-low-power design is essential for wireless mobile systems. A major concern is to be able to design an RF front-end for wideband wireless transceivers. In general, designing the RF front-end sub-system of any wideband wireless transceiver illustrates a great challenge for implementation of the whole transceiver because of the stringent requirement of the UWB radio. In this Letter, we present the first 10-30 GHz broadband CMOS DA for a low-band-worldwide interoperability for microwave access (WiMAX) (10-60 GHz) transceiver using standard 90 nm CMOS technology. It provides high power gain, wide bandwidth, improved reverse isolation and low gain ripple using a twostage DA which is in series with the common-source (CS) stage [1]. In the following Section, the design strategy and circuit simulation of various DA considerations are discussed in detail. The subsequent Section summarises the measurement results, and finally the conclusions are presented.

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A complementary metal oxide semiconductor (CMOS) downconversion mixer for ultra-wideband (UWB) applications is presented. The mixer circuit is designed using a VIS 0.25 μm radio frequency (RF) CMOS technology, working at the 0.9-10.6 GHz frequency range; it will be used in applications such as IEEE wireless fidelity (Wi-Fi), global systems for mobile (GSM) and worldwide interoperability for microwave access (WiMAX). The core of the mixer has been designed based on double-balanced cell architecture, and uses the current-bleeding method to increase the linearity and improve the conversion gain. A resistor is put on the drain of the MOS between two RF inputs, which will improve the flatness of the conversion gain. The measured conversion gain of the mixer is 8.6 ± 1 dB. The 1 dB compression point of the intermediate frequency (IF) output power is equal to −8 dBm. The RF and the local oscillator (LO) input return loss are well below −9 dB. The noise figure is 13.1 dB, whereas the IF is 100 MHz, and the mixer core dissipates 9.8 mW under a 1.8 V supply. The analytical, simulated and measured results are mutually consistent.

Purpose -The purpose of this paper is to introduce a non-uniform Chebyshev distributed low-pass filter (LPF) with dumbbell-shaped photonic bandgap structure (PBGs), implemented in the 50 V microstrip line, with improved defected ground structure. Design/methodology/approach -The non-uniform distribution of PBGs and dumbbell-shaped DGS of PBGs have been discussed in open literatures. In this study, the influence of FF of PBGs in dumbbell-shaped PBG is represented. Findings -By varying filling factor (FF) of the periodic structure from 0.25 to 0.8 of the dumbbell squares can generate better rejection band than uniform dumbbell LPF. Different FF of each square can produce different band rejection range and then yields the LPF with different cutoff. By using chirp adjustment of distance between PBGs, the band rejection performance can be optimized. Originality/value -It can be seen that the chirped and non-uniform dumbbell-shaped PBGs generate excellent bandgap performances in linearly varying period (chirped devices) than those of structures with constant period (non-chirped or uniform devices).

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