A High-Gain, Low-Noise Tow-Thomas Biquad Filter for Wearable Cystic Fibrosis Sweat Analyzers in 45 nm Technology

This works presents the design, simulation, and analysis of a Tow-Thomas architecture based biquad filter that can be used in the analog front-end circuit of a sweat test analyzer for the diagnosis of Cystic Fibrosis (CF)- a life-threatening genetic disease. The biquad filter has been chosen due to its least sensitivity to the variation of passive components, which is an essential feature for sensor interface circuits like sweat tester used in CF diagnosis. The Tow-Thomas operational transconductance amplifier (OTA) is the building block of this filter. This OTA has been designed using 45 nm process technology in the Cadence environment. o be used using 45 nm technology process in Cadence environment to achieve high gain, wide output swing, low noise, and good transient response. The OTA has been optimized for a number of specifications which gain-bandwidth product, slew rate, phase margin, and power dissipation by conducting detailed AC, transient, and noise analyses. The OTA design utilizes a combination of NMOSs and PMOSs, with special consideration for minimizing the circuit size to integrate into compact wearable devices, such as a smartwatch. Challenges encountered during the project include sourcing appropriate sensors and balancing cost-efficiency with performance accuracy. The proposed design demonstrates promising results, offering a potential solution for low-power, high-performance signal amplification in CF diagnosis.