Low-Voltage Low-Pass and Band-Pass Elliptic Filters Based on Log-Domain Approach Suitable for Biosensors
1
Department of Telecommunications Engineering, Faculty of Engineering, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand
2
Department of Electrical Engineering, Faculty of Engineering and Industrial Technology, Silpakorn University, Nakhon Pathom 73000, Thailand
3
Department of Engineering Education, Faculty of Industrial Education, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand
*
Author to whom correspondence should be addressed.
Sensors 2019, 19(24), 5581; https://doi.org/10.3390/s19245581
Received: 21 November 2019
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Revised: 11 December 2019
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Accepted: 16 December 2019
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Published: 17 December 2019
(This article belongs to the Special Issue Integrated Analog Circuits, Systems, and Sensors, and Their Applications)
This research proposes bipolar junction transistor (BJT)-based log-domain high-order elliptic ladder low-pass (LPF) and band-pass filters (BPF) using a lossless differentiator and lossless and lossy integrators. The log-domain lossless differentiator was realized by using seven BJTs and one grounded capacitor, the lossy integrator using five BJTs and one grounded capacitor, and the lossless integrator using seven BJTs and one grounded capacitor. The simplified signal flow graph (SFG) of the elliptic ladder LPF consisted of two lossy integrators, one lossless integrator, and one lossless differentiator, while that of the elliptic ladder BPF contained two lossy integrators, five lossless integrators, and one lossless differentiator. Log-domain cells were directly incorporated into the simplified SFGs. Simulations were carried out using PSpice with transistor array HFA3127. The proposed filters are operable in a low-voltage environment and are suitable for mobile equipment and further integration. The log-domain principle enables the frequency responses of the filters to be electronically tunable between 10k Hz–10 MHz. The proposed filters are applicable for low-frequency biosensors by reconfiguring certain capacitors. The filters can efficiently remove low-frequency noise and random noise in the electrocardiogram (ECG) signal.
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Keywords:
analog filter; elliptic; log-domain; low-voltage; tunable; biosensor
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MDPI and ACS Style
Prommee, P.; Wongprommoon, N.; Kumngern, M.; Jaikla, W. Low-Voltage Low-Pass and Band-Pass Elliptic Filters Based on Log-Domain Approach Suitable for Biosensors. Sensors 2019, 19, 5581. https://doi.org/10.3390/s19245581
AMA Style
Prommee P, Wongprommoon N, Kumngern M, Jaikla W. Low-Voltage Low-Pass and Band-Pass Elliptic Filters Based on Log-Domain Approach Suitable for Biosensors. Sensors. 2019; 19(24):5581. https://doi.org/10.3390/s19245581
Chicago/Turabian StylePrommee, Pipat, Natapong Wongprommoon, Montree Kumngern, and Winai Jaikla. 2019. "Low-Voltage Low-Pass and Band-Pass Elliptic Filters Based on Log-Domain Approach Suitable for Biosensors" Sensors 19, no. 24: 5581. https://doi.org/10.3390/s19245581
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