A 0.5-V MI-OTA-based shadow universal filter with integrated passband gain compensation and low-pass control for low-frequency applications

A 0.5-V MI-OTA-based shadow universal filter with integrated passband gain compensation and low-pass control for low-frequency applications

Článek WoS

Ultra-low-power active filters have received increasing attention in recent years due to emerging applications such as bio-signal sensing and wearable electronic devices, where they are employed in the analog front-end to eliminate interference noise. This paper presents a novel voltage-mode shadow universal filter based on multiple-input operational transconductance amplifiers (MI-OTAs). The multiple-input functionality of the OTA is implemented using the multiple-input bulk-driven MOS transistor (MIBD-MOST) technique, which enables low supply voltage operation and a wide input voltage swing. Additionally, the use of subthreshold operation contributes to the low-power consumption of the OTA. The proposed shadow filter is implemented using a voltage-mode universal filter, in which the low-pass section is employed to control the natural frequency through an external amplifier. The proposed filter provides both non-inverting and inverting transfer functions of low-pass filter (LPF), high-pass filter (HPF), band-pass filter (BPF), band-stop filter (BSF), and all-pass filter (APF). The circuit was designed and simulated using Cadence Virtuoso, utilizing TSMC's 65-nm 1P9M CMOS technology. The total silicon area of the MI-OTA measured 148 mu m x 89 mu m. Operating at a supply voltage of 0.5 V and a cutoff frequency of 31.2 Hz, the filter achieved an overall power consumption of 350 nW. Experimental validation was conducted using a prototype implemented with commercially available LM13700N integrated circuits, confirming the filter's functionality and effectiveness. The proposed design is well suited for low-voltage, low-power applications, particularly low-frequency bio-signal processing such as EEG and EGG acquisition systems, as well as sensor interface systems.

Ultra-low-power active filters have received increasing attention in recent years due to emerging applications such as bio-signal sensing and wearable electronic devices, where they are employed in the analog front-end to eliminate interference noise. This paper presents a novel voltage-mode shadow universal filter based on multiple-input operational transconductance amplifiers (MI-OTAs). The multiple-input functionality of the OTA is implemented using the multiple-input bulk-driven MOS transistor (MIBD-MOST) technique, which enables low supply voltage operation and a wide input voltage swing. Additionally, the use of subthreshold operation contributes to the low-power consumption of the OTA. The proposed shadow filter is implemented using a voltage-mode universal filter, in which the low-pass section is employed to control the natural frequency through an external amplifier. The proposed filter provides both non-inverting and inverting transfer functions of low-pass filter (LPF), high-pass filter (HPF), band-pass filter (BPF), band-stop filter (BSF), and all-pass filter (APF). The circuit was designed and simulated using Cadence Virtuoso, utilizing TSMC's 65-nm 1P9M CMOS technology. The total silicon area of the MI-OTA measured 148 mu m x 89 mu m. Operating at a supply voltage of 0.5 V and a cutoff frequency of 31.2 Hz, the filter achieved an overall power consumption of 350 nW. Experimental validation was conducted using a prototype implemented with commercially available LM13700N integrated circuits, confirming the filter's functionality and effectiveness. The proposed design is well suited for low-voltage, low-power applications, particularly low-frequency bio-signal processing such as EEG and EGG acquisition systems, as well as sensor interface systems.

Shadow filter, Universal filter, Frequency-agile filter, Operational transconductance amplifier, Active filter, Bulk-driven MOS transistor

Shadow filter, Universal filter, Frequency-agile filter, Operational transconductance amplifier, Active filter, Bulk-driven MOS transistor

KUMNGERN, M.; KHATEB, F.; KULEJ, T.; ARRBET, D.

27.10.2025

Scientific Reports

1

15

Spojené království Velké Británie a Severního Irska

1

20

20

https://doi.org/10.1038/s41598-025-21325-7

A 0.5-V MI-OTA-based shadow universal filter with integrated passband gain compensation and low-pass control for low-frequency applications