Low-Voltage OTA–C Filter With an Area- and Power-Efficient OTA for Biosignal Sensor Applications

This paper presents a versatile tunable voltage-mode biquadratic filter with five inputs and three outputs. The proposed filter enjoys five single-ended output operational transconductance amplifiers (OTAs) and two grounded capacitors. The filter can be easily transformed into a quadrature oscillator. The filter with grounded capacitors is resistorless and electronically tunable. Either a voltage-mode five-input single-output biquadratic filter or a voltage-mode single-input three-output biquadratic filter can be operated by appropriate selecting input and output terminals. In the operation of five-input single-output biquadratic filter, the non-inverting lowpass, non-inverting bandpass, inverting bandpass, inverting highpass, non-inverting bandreject, inverting bandreject, and non-inverting allpass filtering responses can be realized by appropriately applying the input voltage signals. In the operation of single-input three-output biquadratic filter, the non-inverting/inverting lowpass, bandpass and bandreject filtering responses can be realized simultaneously. The circuit provides independent adjustment of the resonance angular frequency and quality factor, high-input impedance, and no inverting-type input voltage signals are imposed. The application in quadrature oscillator exhibits independent electronic tuning characteristic of the oscillation condition and the oscillation frequency. The theoretical analysis has been verified through OrCAD PSpice and furthermore by experimental measurements.

Section: Simulation and Experimental Resultsmentioning

confidence: 99%

Versatile Tunable Voltage-Mode Biquadratic Filter and Its Application in Quadrature Oscillator

Wang

Chen

et al. 2019

“…Analyzing the figures of merit (FoMs) in the literature, we found that the main parameters that are involved are power, dynamic range (DR), order of the filter (n), bandwidth (BW), and area consumption. We included in the table two FoMs defined in [31,32], as they not only take into account all the previous parameters, but also normalize the power (NP) and the area (NA) consumption to the technology used, according to:FoM1=NPn∗DR FoM2=Power∗BW∗NAn∗DR with NP = Power × [0.5/(V dd − V th )] × (1/V dd ) and NA = area(mm 2 )/Tech(µm 2 ) 2 , with V th = 0.4 V for 0.18 µm CMOS technology and 0.6 V for 0.35 µm CMOS technology.…”

Section: Lpf In a Lock-in Amplifiermentioning

confidence: 99%

“…There is a vast amount of literature on integrated low pass filters with very low-cutoff frequencies, mainly based on G m –C approach [22,23,24,25,26,27,28,29,30,31,32,33,34,35,36] and focused on biological signal processing. Therefore, besides not strictly presenting a tuneable frequency over our target sub-Hz to Hz range (5.4 kHz [22], from 2 kHz to 20 kHz [23]), some of them exhibit a power consumption rather high to be suitable to be integrated within multichannel systems ([24] consumes 75.9 µW, [25] from 59.5 µW to 90 µW, and [26] 105.3 µW including a buffer).…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, besides not strictly presenting a tuneable frequency over our target sub-Hz to Hz range (5.4 kHz [22], from 2 kHz to 20 kHz [23]), some of them exhibit a power consumption rather high to be suitable to be integrated within multichannel systems ([24] consumes 75.9 µW, [25] from 59.5 µW to 90 µW, and [26] 105.3 µW including a buffer). Among those that are power-efficient, either area is jeopardized, restricting their use within portable devices (an area of 0.336 mm 2 is reported in [27], 0.2 mm 2 in [28,29] has an external 10 nF capacitor, [30] has an area of 1 mm 2 , and an area of 0.24 mm 2 is reported in [31]), or dynamic range is jeopardized (34 dB [22] and 49.9 dB [32]), whereas others achieve such low power thanks to bias currents in the order of pA or a few nA, which are difficult to be reliably generated on-chip and are typically tuned to adjust the G m and thus adjust the cut-off frequency (from 300 pA to 900 pA [33], from 90 pA to 430 pA [34], in [35] two bias currents are used ranging from 200 pA to 4 nA and from 1 nA to 20 nA respectively, and from 250 pA to 25 nA [36]), existing on the overall power-area-dynamic range trade-off that makes their design a real challenge.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A CMOS Low Pass Filter for SoC Lock-in-Based Measurement Devices

Pérez-Bailón

Calvo

Medrano

2019

This paper presents a fully integrated Gm–C low pass filter (LPF) based on a current steering Gm reduction-tuning technique, specifically designed to operate as the output stage of a SoC lock-in amplifier. To validate this proposal, a first-order and a second-order single-ended topology were integrated into a 1.8 V to 0.18 µm CMOS (Complementary Metal-Oxide-Semiconductor) process, showing experimentally a tuneable cutoff frequency that spanned five orders of magnitude, from tens of mHz to kHz, with a constant current consumption (below 3 µA/pole), compact size (<0.0140 mm2/pole), and a dynamic range better than 70 dB. Compared to state-of-the-art solutions, the proposed approach exhibited very competitive performances while simultaneously fully satisfying the demanding requirements of on-chip portable measurement systems in terms of highly efficient area and power. This is of special relevance, taking into account the current trend towards multichannel instruments to process sensor arrays, as the total area and power consumption will be proportional to the number of channels.

“…The analog low-pass filters for ECG acquisition systems should be designed to meet specific requirements, such as high dynamic range, low-power consumption, and small chip area. There are many low-pass filters for ECG acquisition systems described in the literature [2][3][4][5][6][7][8][9][10]. The Butterworth approximation is usually used because it provides a better linear phase and flat response within each bandwidth.…”

Section: Introductionmentioning

confidence: 99%

0.5 V Fifth-Order Butterworth Low-Pass Filter Using Multiple-Input OTA for ECG Applications

Kumngern

Aupithak

Khateb

et al. 2020

This paper presents a 0.5 V fifth-order Butterworth low-pass filter based on multiple-input operational transconductance amplifiers (OTA). The filter is designed for electrocardiogram (ECG) acquisition systems and operates in the subthreshold region with nano-watt power consumption. The used multiple-input technique simplifies the overall structure of the OTA and reduces the number of active elements needed to realize the filter. The filter was designed and simulated in the Cadence environment using a 0.18 µm Complementary Metal Oxide Semiconductor (CMOS) process from Taiwan Semiconductor Manufacturing Company (TSMC). Simulation results show that the filter has a bandwidth of 250 Hz, a power consumption of 34.65 nW, a dynamic range of 63.24 dB, attaining a figure-of-merit of 0.0191 pJ. The corner (process, voltage, temperature: PVT) and Monte Carlo (MC) analyses are included to prove the robustness of the filter.