Noise Efficient Integrated Amplifier Designs for Biomedical Applications

Simmich, Sebastian; Bahr, Andreas; Rieger, Robert

doi:10.3390/electronics10131522

Cited by 13 publications

(9 citation statements)

References 84 publications

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“…The integrated amplifier presented in [ 67 ] includes operational transconductance amplifier, chopper input, folded cascode, inverter-based input, multistage amplifier, and current reuse, and the general layout is presented in Figure 24 .…”

Section: Biomedical Amplifiers From Ic and Layout Perspectivesmentioning

confidence: 99%

Amplifiers in Biomedical Engineering: A Review from Application Perspectives

Kouhalvandi

Matekovits

Peter

2023

Sensors

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Continuous monitoring and treatment of various diseases with biomedical technologies and wearable electronics has become significantly important. The healthcare area is an important, evolving field that, among other things, requires electronic and micro-electromechanical technologies. Designed circuits and smart devices can lead to reduced hospitalization time and hospitals equipped with high-quality equipment. Some of these devices can also be implanted inside the body. Recently, various implanted electronic devices for monitoring and diagnosing diseases have been presented. These instruments require communication links through wireless technologies. In the transmitters of these devices, power amplifiers are the most important components and their performance plays important roles. This paper is devoted to collecting and providing a comprehensive review on the various designed implanted amplifiers for advanced biomedical applications. The reported amplifiers vary with respect to the class/type of amplifier, implemented CMOS technology, frequency band, output power, and the overall efficiency of the designs. The purpose of the authors is to provide a general view of the available solutions, and any researcher can obtain suitable circuit designs that can be selected for their problem by reading this survey.

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Section: Biomedical Amplifiers From Ic and Layout Perspectivesmentioning

confidence: 99%

Amplifiers in Biomedical Engineering: A Review from Application Perspectives

Kouhalvandi

Matekovits

Peter

2023

Sensors

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“…However, the bandwidth was strictly limited by 200 Hz 10 . More recently, several very promising works have been published using more advanced semiconductor technologies and more complex design concepts in order to even further reduce input noise and offset, while also dealing with chopping‐related challenges 11–25 …”

Section: Utilizing Chopping For Input Noise and Input Offset Reductionmentioning

confidence: 99%

“…As mentioned before, the basic principle of chopping is widely utilized for high‐precision operational amplifiers (opamps), especially for amplifying audio 23 and weak sensor signals, for example, in medical applications, 25 of a thermopile sensors, 18 or of a micro electro‐mechanical system (MEMS) sensors 16 . For these examples, chopping or chopper stabilization is very attractive, since, for example, bio‐signals or ambient‐sensor signals are typically weak and consist of very low frequencies.…”

Section: Utilizing Chopping For Input Noise and Input Offset Reductionmentioning

confidence: 99%

“…10 More recently, several very promising works have been published using more advanced semiconductor technologies and more complex design concepts in order to even further reduce input noise and offset, while also dealing with chopping-related challenges. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] In general, one typically distinguishes between (1) pure or classical chopping as employed in this work, which is partially extended to nested chopping using several interleaved choppers 3,26 ; (2) chopper stabilization, which is a multipath amplifier approach utilizing a main amplifier and a nulling amplifier 27 ; and (3) analogous auto zeroing, for example, using switched capacitors. Although the basic principle of the latter is different, it is still related to this topic, since the inputs are switched and input offset is reduced.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

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Chopping for over 50 MHz gain‐bandwidth product current sense amplifiers achieving input noise level of 8.5 nV/√Hz

Matthus

Ellinger

2022

Circuit Theory & Apps

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An accurate, high-speed, fully differential difference amplifier for current sensing utilizing the chopper approach was implemented in a 0.18 μm complementary metal-oxide-semiconductor (CMOS) technology. Unlike state-of-the-art solutions, we use a higher chopping frequency in the MHz range due to the bandwidth requirements of the introduced circuits for the latter application, namely, low-side phase-current measurement in motor control circuits. Except the low-pass filter (LPF) effect of the output stage, no additional LPF was integrated in hardware at the output of the circuits. We show that on the other hand a digital LPF, which can be integrated in the field-programmable gatearray (FPGA) logic or microcontroller used for the motor control, offers a higher flexibility in terms of filter design. Weak input signals of only few mV can be reconstructed with a high accuracy. This is demonstrated for a 500 kHz rectangular signal and a chopping frequency of 20 MHz. Note that an inputsignal frequency of several hundreds of kHz with harmonics in the MHz region is very challenging for chopper amplifiers. Still, a significant decrease of the input-referred noise is demonstrated, especially cancelling out the 1/f-noise achieving a remaining noise floor of approximately 8.5 nV/√Hz. Overall, the input-referred noise level can be pushed far below 50 μV (root mean square).Moreover, using a quite relaxed second-order Butterworth filter with a 3 dB corner frequency of 1 MHz, input-referred noise levels of 10 μV (root mean square) can be easily achieved at the costs of reduced bandwidth. The lowest achieved input offset is 50 μV. The gain is adjusted by resistive feedback and is approximately 40 dB. Hence, the amplifier is suitable for current sensing in motor control circuits, and a significant reduction of the shunt resistance typically used for this purpose will be possible.

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“…The current-reuse technique [24] is a common analogue design to achieve low power and low noise, but at the cost of voltage headroom. Reference [30] reviews the recent developments in low-noise biomedical amplifier design based on CMOS technology, including lateral bipolar devices. In addition to biomedical amplifier design methods, signal folding with two threshold-detecting comparators [10] can keep the amplified signal varying in the fixed linear range, so it decreases supply voltage and the demand for ADC resolution.…”

Section: Introductionmentioning

confidence: 99%

A Fully Integrated 64-Channel Recording System for Extracellular Raw Neural Signals

Zhang

Chen

et al. 2021

Electronics

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This paper presents a fully integrated 64-channel neural recording system for local field potential and action potential. It mainly includes 64 low-noise amplifiers, 64 programmable amplifiers and filters, 9 switched-capacitor (SC) amplifiers, and a 10-bit successive approximation register analogue-to-digital converter (SAR ADC). Two innovations have been proposed. First, a two-stage amplifier with high-gain, rail-to-rail input and output, and dynamic current enhancement improves the speed of SC amplifiers. The second is a clock logic that can be used to align the switching clock of 64 channels with the sampling clock of ADC. Implemented in an SMIC 0.18 μm Complementary Metal Oxide Semiconductor (CMOS) process, the 64-channel system chip has a die area of 4 × 4 mm2 and is packaged in a QFN−88 of 10 × 10 mm2. Supplied by 1.8 V, the total power is about 8.28 mW. For each channel, rail-to-rail electrode DC offset can be rejected, the referred-to-input noise within 1 Hz–10 kHz is about 5.5 μVrms, the common-mode rejection ratio at 50 Hz is about 69 dB, and the output total harmonic distortion is 0.53%. Measurement results also show that multiple neural signals are able to be simultaneously recorded.

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Noise Efficient Integrated Amplifier Designs for Biomedical Applications

Cited by 13 publications

References 84 publications

Amplifiers in Biomedical Engineering: A Review from Application Perspectives

Amplifiers in Biomedical Engineering: A Review from Application Perspectives

Chopping for over 50 MHz gain‐bandwidth product current sense amplifiers achieving input noise level of 8.5 nV/√Hz

A Fully Integrated 64-Channel Recording System for Extracellular Raw Neural Signals

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