RF to millimeter-wave power amplifiers in CMOS SOI technology

Sultan Rifaat Helmi, Purdue University


Advancing of technology and downscaling of channel length have led to high operating frequency of CMOS transistors and have enabled their high gain at millimeter-wave (mm-wave) frequencies. CMOS transistors nowadays compete with III-V technologies for low- and medium-power RF to mm-wave applications. With advantages of low cost, high reliability, high thermal conductivity and the possibility of integration with baseband, digital and signal-processing circuits, CMOS mm-wave modules have become extremely attractive. In spite of all these advantages, realizing RF to mm-wave Si power amplifiers (PAs) that are used in transmitters is still challenging. Small transistor breakdown voltage caused by downscaling sets a hard limit on the output power and efficiency of RF to mm-wave power amplifiers. This Dissertation aims at designing wideband high power and high efficiency power amplifiers from RF to mm-wave frequencies (1.8 to 54 GHz). CMOS Silicon on Insulator (SOI) technology with electrically isolated transistors is utilized for the implementation. Dynamically-biased CMOS SOI transistors are stacked on top of each other with different combination of topologies including CS, Cascode and triple stacked transistors to increase the total output voltage swing, output impedance matching and output power without causing instability and gate oxide breakdown. Series connected transformers are used at the input to provide input signal coupling and input impedance matching. Due to finite conductivity of Si substrate, parasitic capacitances significantly degrade PA power performance especially at mm-wave frequencies. An analysis of these parasitics responsible for PA efficiency degradation is provided. Various wideband Class-AB stacked CMOS SOI power amplifiers covering different frequency bands from RF to mm-wave are implemented and fully characterized and several record power performances have been demonstrated.




Mohammadi, Purdue University.

Subject Area

Electrical engineering

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