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A fifth order operational transconductance amplifier-C(OTA-C) Butterworth type low-pass filter with highly linear range and less passband attenuation is presented for wearable bio-telemetry monitoring applications in a UWB wireless body area network.The source degeneration structure applied in typical small transconductance circuit is improved to provide a highly linear range for the OTA-C filter.Moreover,to reduce the passband attenuation of the filter,a cascode structure is employed as the output stage of the OTA.The OTA-based circuit is operated in weak inversion due to strict power limitation in the biomedical chip.The filter is fabricated in a SMIC0.18-μm CMOS process.The measured results for the filter have shown a passband gain of—6.2 dB,while the-3-dB frequency is around 276 Hz.For the 0.8 V_(PP) sinusoidal input at 100 Hz,a total harmonic distortion(THD)of-56.8 dB is obtained.An electrocardiogram signal with noise interference is fed into this chip to validate the function of the designed filter.
A fifth order operational transconductance amplifier-C (OTA-C) Butterworth type low-pass filter with highly linear range and less passband attenuation is presented for wearable bio-telemetry monitoring applications in a UWB wireless body area network. The source degeneration structure applied in typical small transconductance circuit is improved to provide a highly linear range for the OTA-C filter. Moreover, to reduce the passband attenuation of the filter, a cascode structure is employed as the output stage of the OTA. The OTA-based circuit is operated in weak inversion due to strict power limitation in the biomedical chip. The filter is fabricated in a SMIC 0.18-μm CMOS process. The measured results for the filter have shown a passband gain of-6.2 dB, while the-3-dB frequency is around 276 Hz. For the 0.8 V_ (PP) sinusoidal input at 100 Hz, a total harmonic distortion (THD) of -56.8 dB is obtained. An electrocardiogram signal with noise interference is fed into this chip to validate the function of the designed filter.