Sensors · 2020 · 18 citations · 24 references
EngineeringBiomedical EngineeringElectrical EngineeringAnalog ElectronicsBioinstrumentationSensorsAnalog Integrated CircuitsBiomedical InstrumentationBiomedical SensorsCmos Circuit DesignCurrent-voltage CharacteristicsSensor Signal ConditioningChannel Length ModulationCmos Analog Integrated CircuitsCmos Operational AmplifiersLinearityOperational Transconductance AmplifiersPower ConsumptionTotal Harmonic DistortionTransconductance Amplifiers
The paper presents an operational transconductance amplifier (OTA) with low transconductance (0.62–6.28 nS) and low power consumption (28–270 nW) for the low-frequency analog front-ends in biomedical sensor interfaces. The proposed OTA implements an innovative, highly linear voltage-to-current converter based on the channel-length-modulation effect, which can be rail-to-rail driven. At 1-V supply and 1-Vpp asymmetrical input driving, the linearity error in the current-voltage characteristics is 1.5%, while the total harmonic distortion (THD) of the output current is 0.8%. For a symmetrical 2-Vpp input drive, the linearity error is 0.3%, whereas THD reaches 0.2%. The linearity is robust for the mismatch and the process-voltage-and-temperature (PVT) variations. The temperature drift of transconductance is 10 pS/°C. The prototype circuit was fabricated in 180-nanometer CMOS technology.
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