A 13nV/✓Hz 4.5μW Chopper Instrumentation Amplifier with Robust Ripple Reduction and Input Impedance Boosting Techniques

Fang, Liang; Gui, Ping

doi:10.1109/cicc48029.2020.9075876

Cited by 9 publications

(5 citation statements)

References 3 publications

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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%

“…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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Section: Utilizing Chopping For Input Noise and Input Offset Reductionmentioning

confidence: 99%

Section: Theoretical Backgroundmentioning

confidence: 99%

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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“…Amperometric readout circuit with 140 dB detec-tion range was implemented in [13], [14], while it does not have programmable bias voltage generator for potentiostat sensors. In [15], a three-electrode AFE chip with a current detection dynamic range of 120 dB is proposed, it can basically meet the detection of heavy metal ions in liquid. However, the chip cannot convert multiple input types of signals, and the system linearity is low, which makes it difficult to apply to a comprehensive water quality inspection system.…”

Section: Introductionmentioning

confidence: 99%

A Multi-Channel CMOS Analog Front-End Interface IC with 157.8 dB Current Detection Dynamic Range

Wang,

Xu,

Zhang

et al. 2024

Chinese J. Elect.

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A high dynamic range and low-noise CMOS (complementary metal-oxide-semiconductor transistor) front-end interface integrated circuit (IC) with multi-channel detection is presented in this paper. Two different current detection channels, composed of a trans-impedance amplifier (TIA) and an integrator-differentiator TIA, are used to boost the current detection range. A capacitance-coupled instrument amplifier (CCIA) is also included to realize high precision voltage detection. A fourth-order sigma-delta modulator using a second-order loop filter and a second-order noise shaping integral quantizer is adopted to realize effective number of bits above 16 bits. The presented interface IC is implemented in 0.18-μm CMOS process with supply voltage of 3.3 V, and a proto-type electrochemical sensor platform with miniaturized sensor array is developed to verify the functionality of the interface IC. Measurement results indicate that the designed interface IC achieves 157.8 dB current detection dynamic range, and the measured input-referred current noise and voltage noise floor are 1.04 pA and 58.4 nV within 10 kHz integration bandwidths, respectively.

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“…In addition, it can be implemented in a relatively small area compared to the 3-opamp IA [16]. However, the input impedance is low due to the input capacitance, thus an input impedance boosting circuit with positive feedback is needed [17]. An input impedance boosting circuit based on positive feedback can increase the input impedance of the CCIA, but can damage the stability of the circuit.…”

Section: Introductionmentioning

confidence: 99%

Low-Noise Resistive Bridge Sensor Analog Front-End Using Chopper-Stabilized Multipath Current Feedback Instrumentation Amplifier and Automatic Offset Cancellation Loop

et al. 2022

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Resistive bridge sensors are used in many application areas to measure changes in physical parameters. To amplify the resistive changes from sensing elements with high precision, various offset contributors in the resistive bridge and amplifiers should be minimized. This study proposes a low-noise resistive bridge sensor analog front-end (AFE) using a chopper-stabilized multipath current feedback instrumentation amplifier (CFIA) and an automatic offset cancellation loop. The proposed circuit exploits a multipath chopper-stabilized architecture for obtaining low noise performance and wide bandwidth characteristics. This circuit can minimize the offsets in the bridge and the high frequency and low frequency amplifiers, while achieving high precision resistive signal acquisition. The high frequency path of the multipath amplifier uses the CFIA topology with class-AB output stage. The offset in the high frequency path is stabilized by the low frequency path amplifier with a high gain and low noise chopper amplifier. The up-modulated offset in the low frequency chopper amplifier path is reduced by the AC-coupled ripple reduction loop (RRL). An automatic offset calibration loop (AOCL) circuit was designed to calibrate the offset due to the bridge mismatch. The AOCL reduces the bridge offset using a successive approximation register (SAR)-based binary-search algorithm. The gain of the proposed circuit is adjustable from 15.56 dB to 44.14 dB. The AFE is implemented in a 0.18 μm CMOS process and draws 123 μA current from a 3.3 V supply. The input referred noise and noise efficiency factor (NEF) are 14.6 nV/√Hz and 6.1, respectively.INDEX Resistive analog front-end, current feedback instrumentation amplifier (CFIA), multipath amplifier, automatic offset calibration loop (AOCL)

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A 13nV/✓Hz 4.5μW Chopper Instrumentation Amplifier with Robust Ripple Reduction and Input Impedance Boosting Techniques

Cited by 9 publications

References 3 publications

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

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

A Multi-Channel CMOS Analog Front-End Interface IC with 157.8 dB Current Detection Dynamic Range

Low-Noise Resistive Bridge Sensor Analog Front-End Using Chopper-Stabilized Multipath Current Feedback Instrumentation Amplifier and Automatic Offset Cancellation Loop

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