Proposed is the design of a linearised CMOS bidirectional distributed amplifier (DA) that greatly suppresses the third-order intermodulation (IM3) distortion. The drain and gate transmission lines are staggered to purposely mismatch their time-delay and filter out the IM3 distortion. A modified CMOS cross-coupled cascomp circuit is proposed to enhance the linearity of the gain cell with a varactor-based active post nonlinear drain capacitance compensator for wider linearisation bandwidth. The proposed linearised CMOS bidirectional DA achieves a measured IM3 reduction of 20 dB in both RF directions, with ultrawideband 0.1 to 9.5 GHz frequency of operation.Introduction: In radio-over-fibre systems, a highly linear optical transmitter is necessary to achieve the required signal dynamic range. Nonlinearities cause harmonics and unwanted intermodulation products which degenerate the transmitter performance and must be minimised. Several linearised distributed amplifiers (DAs) have been reported in the literature [1 -6], however most of the published DA linearisation methods do not provide large third-order intermodulation (IM3) distortion reduction, and they either involve system-level DA linearisation with bulky components suffering from limited linearisation over broad bandwidth, or circuit-level DA linearisation that have narrow linearised bandwidth and apply only DC-based linearisation techniques.In this Letter, we propose a linearised CMOS bidirectional DA that combines device-level with circuit-level linearisation which greatly suppresses the IM3 distortion and achieves a measured IM3 distortion reduction of 20 dB over an ultra-wideband 0.1 to 9.5 GHz frequency of operation with a two-way amplification of 4.9 dB in both RF directions.
Recent advancements in technologies enabled the development of smart cities to be more effective and possible. Smart cities depend on intelligent systems, artificial intelligence, the internet of things, control system, and many more advanced technologies. Sustainability challenges and problems worldwide, with smart and sustainability concepts, reflect almost mutual goals. It includes improving and providing the essential life services for all people efficiently while depending on sustainable, clean, and renewable energy with considerations of different economic, educational, health, social and environmental aspects in the city. In this research, a cost analysis process has been implemented to ease the implementation and resource utilization of smart and sustainable cities in Africa. The challenges and difficulties of those implementations are summarized.
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