dr.ir. Qinwen Fan

1. A -121.5-dB THD Class-D Audio Amplifier With 49-dB LC Filter Nonlinearity Suppression
   Huajun Zhang; Marco Berkhout; Kofi A. A. Makinwa; Qinwen Fan;
   {IEEE} Journal of Solid-State Circuits,
   Volume 57, Issue 4, pp. 1153--1161, April 2022. DOI: 10.1109/jssc.2021.3125526
   document

2. A 121.4-dB DR Capacitively Coupled Chopper Class-D Audio Amplifier
   Huajun Zhang; Marco Berkhout; Kofi A. A. Makinwa; Qinwen Fan;
   {IEEE} Journal of Solid-State Circuits,
   Volume 57, Issue 12, pp. 3736--3745, December 2022. DOI: 10.1109/jssc.2022.3207907
   document

3. A Chopper Class-D Amplifier for PSRR Improvement Over the Entire Audio Band
   Huajun Zhang; Nuriel N. M. Rozsa; Marco Berkhout; Qinwen Fan;
   {IEEE} Journal of Solid-State Circuits,
   Volume 57, Issue 7, pp. 2035--2044, July 2022. DOI: 10.1109/jssc.2022.3161136
   document

4. A -121.5-dB THD Class-D Audio Amplifier With 49-dB LC Filter Nonlinearity Suppression
   Huajun Zhang; Marco Berkhout; Kofi A. A. Makinwa; Qinwen Fan;
   {IEEE} Journal of Solid-State Circuits,
   Volume 57, Issue 4, pp. 1153--1161, April 2022. DOI: 10.1109/jssc.2021.3125526
   document

5. A 121.4dB DR, -109.8dB THD+N Capacitively-Coupled Chopper Class-D Audio Amplifier
   Huajun Zhang; Marco Berkhout; Kofi A. A. Makinwa; Qinwen Fan;
   In Fujino, {Laura C. } (Ed.), 2022 IEEE International Solid- State Circuits Conference (ISSCC),
   United States, IEEE, pp. 484--486, 2022. Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this wo. DOI: 10.1109/ISSCC42614.2022.9731737
   
   Abstract: ...

   Class-D amplifiers (CDAs) are often used in audio applications due to their superior power efficiency. Due to the sensitivity of the human ear, a large dynamic range (DR) is desired, and audio DACs with up to 130dB DR are commercially available [1]. However, the DR of the CDAs they drive is typically much lower [2]-[4], mainly due to the thermal noise introduced by the input resistors of their resistive feedback networks. Reducing this resistance is difficult, as it reduces the CDA's input impedance and increases the required loop-filter capacitance. Alternatively, the CDA could be configured as a capacitively coupled chopper amplifier (CCCA), whose capacitive feedback network could then achieve low noise without reducing input impedance. However, the large PWM component present at its output would then saturate its input stage. By exploiting the inherent PWM filtering present in a feedback-after-LC architecture, this paper presents a capacitively coupled chopper CDA, resulting in significantly improved DR and THD+N. The prototype achieves 8V_RMS of integrated output noise (A-weighted), a 121.4dB DR, and -1 09.8dB THD+N while delivering a maximum of 15/26W into an 8/4Omega load with 93%/88% efficiency.

6. A High-Linearity and Low-EMI Multilevel Class-D Amplifier
   Huajun Zhang; Shoubhik Karmakar; Lucien J. Breems; Quino Sandifort; Marco Berkhout; Kofi A. A. Makinwa; Qinwen Fan;
   {IEEE} Journal of Solid-State Circuits,
   Volume 56, Issue 4, pp. 1176--1185, April 2021. DOI: 10.1109/jssc.2020.3043815
   document

7. A 25A Hybrid Magnetic Current Sensor with 64mA Resolution, 1.8MHz Bandwidth, and a Gain Drift Compensation Scheme
   A. Jouyaeian; Qinwen Fan; M. Motz; U. Ausserlechner; K. A. A. Makinwa;
   In Dig. Techn. Papers IEEE International Solid-State Circuits Conference (ISSCC),
   February 2021. DOI: 10.1109/ISSCC42613.2021.9365767

8. A −121.5 dB THD Class-D Audio Amplifier with 49 dB Suppression of LC Filter Nonlinearity and Robust to +/−30% LC Filter Spread
   H. Zhang; M. Berkhout; K. Makinwa; Qinwen Fan;
   In Dig. Techn. Paper IEEE Symposium on VLSI Circuits (VLSI),
   June 2021. DOI: 10.23919/VLSICircuits52068.2021.9492441

9. A -109.1 dB/-98 dB THD/THD+N Chopper Class-D Amplifier with >83.7 dB PSRR Over the Entire Audio Band
   Huajun Zhang; Nuriel Rozsa; Marco Berkhout; Qinwen Fan;
   In ESSCIRC 2021 - IEEE 47th European Solid State Circuits Conference (ESSCIRC),
   United States, IEEE, pp. 395--398, 2021. Accepted author manuscript; ESSCIRC 2021 : IEEE 47th European Solid State Circuits Conference ; Conference date: 06-09-2021 Through 09-09-2021. DOI: 10.1109/ESSCIRC53450.2021.9567786
   
   Keywords: ...

   Class-D amplifier, PSRR, PWM, chopping, intermodulation.
   
   
   Abstract: ...

   This paper reports a chopper Class-D audio amplifier that obtains high PSRR over the entire audio band. A chopping scheme is proposed to minimize intermodulation distortion between pulse-width modulation (PWM) and chopping in the audio band. A high-voltage chopper is developed to handle a 14.4 V PWM signal. Timing matching techniques are proposed to minimize chopping nonidealities which ensure good PSRR and THD. Fabricated in a 180nm BCD process, the prototype obtains a PSRR >109 dB at 217 Hz and >83.7 dB over the entire audio band. It also achieves -109.1 dB/-98 dB THD/THD+N and can deliver a maximum of 13 W to an 8-Ω load.

10. A-121.5 dB THD Class-D Audio Amplifier with 49 dB Suppression of LC Filter Nonlinearity and Robust to +/-30% LC Filter Spread
    Huajun Zhang; Marco Berkhout; Kofi Makinwa; Qinwen Fan;
    In 2021 Symposium on VLSI Circuits,
    United States, IEEE, 2021. Green Open Access added to TU Delft Institutional Repository {\textquoteleft}You share, we take care!{\textquoteright} – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher i. DOI: 10.23919/VLSICircuits52068.2021.9492441
    
    Abstract: ...

    This paper reports a Class-D audio amplifier that uses multiloop feedback to suppress output LC filter nonlinearity by 49 dB, enabling the use of small, low-cost LC filters with ±30% spread while maintaining low distortion. Fabricated in a 180 nm BCD process, the prototype achieves a THD of-121.5 dB and a THD+N of-107.1 dB. It delivers 12W/21W into an 8-Ω/4-Ω load with 91%/87% efficiency.

11. A High-Linearity and Low-EMI Multilevel Class-D Amplifier
    H. Zhang; S. Karmakar; L. J. Breems; Q. Sandifort; M. Berkhout; K. A. A. Makinwa; Qinwen Fan;
    IEEE Journal of Solid-State Circuits,
    Volume 56, pp. 1176-1185, December 2020. DOI: 10.1109/JSSC.2020.3043815
    
    Abstract: ...

    This article presents a Class-D audio amplifier for automotive applications. Low electromagnetic interference (EMI) and, hence, smaller LC filter size are obtained by employing a fully differential multilevel output stage switching at 4.2 MHz. A modulation scheme with minimal switching activity at zero input reduces idle power, which is further assisted by a gate-charge reuse scheme. It also achieves high linearity due to the high loop gain realized by a third-order feedback loop with a bandwidth of 800 kHz. The prototype, fabricated in a 180-nm high-voltage BCD process, achieves a minimum THD+N of −107.8 dB/−102 dB and a peak efficiency of 91%/87% with 8- and 4- Ω loads, respectively, while drawing 7-mA quiescent current from a 14.4-V supply. The prototype meets the CISPR 25 Class 5 EMI standard with a 5.7-dB margin using an LC filter with a cutoff frequency of 580 kHz.

12. A 28-W, -102.2-dB THD+N Class-D Amplifier Using a Hybrid Δ Σ M-PWM Scheme
    S. Karmakar; H. Zhang; R. van Veldhoven; L. J. Breems; M. Berkhout; Qinwen Fan; K. A. A. Makinwa;
    IEEE Journal of Solid-State Circuits,
    September 2020. DOI: 10.1109/JSSC.2020.3023874
    
    Abstract: ...

    This article presents a 28-W class-D amplifier for automotive applications. The combination of a high switching frequency and a hybrid multibit Δ ΣM-PWM scheme results in high linearity over a wide range of output power, as well as low AM-band EMI. As a result, only a small (150-kHz cutoff frequency), and thus low-cost, LC filter is needed to meet the CISPR-25 EMI average limit (150 kHz-30 MHz) with 10-dB margin. At 28-W output power, the proposed amplifier achieves 91% efficiency while driving a 4-Ω load from a 14.4-V supply. It attains a peak THD+N of 0.00077% (-102.2 dB) for a 1-kHz input signal.

13. A 28-W, -102.2-dB THD$\mathplus$N Class-D Amplifier Using a Hybrid $\upDelta$$\upSigma$M-PWM Scheme
    Shoubhik Karmakar; Huajun Zhang; Robert van Veldhoven; Lucien J. Breems; Marco Berkhout; Qinwen Fan; Kofi A. A. Makinwa;
    {IEEE} Journal of Solid-State Circuits,
    Volume 55, Issue 12, pp. 3146--3156, December 2020. DOI: 10.1109/jssc.2020.3023874
    document

14. A 28W -108.9dB/-102.2dB THD/THD+N Hybrid ΔΣ−PWM Class-D Audio Amplifier with 91% Peak Efficiency and Reduced EMI Emission
    S. Karmakar; H. Zhang; R.Van Veldhoven; L. Breems; M. Berkhout; Qinwen Fan; K.A.A Makinwa;
    In Dig. Techn. Papers IEEE International Solid-State Circuits Conference (ISSCC),
    pp. 350-352, 2 2020. DOI: 10.1109/ISSCC19947.2020.9063001

15. A −107.8 dB THD+N Low-EMI Multi-Level Class-D Audio Amplifier
    H. Zhang; S. Karmakar; L. Breems; Q. Sandifort; M. Berkhout; K. Makinwa; Qinwen Fan;
    In Dig. Techn. Paper IEEE Symposium on VLSI Circuits (VLSI),
    June 2020. DOI: 10.1109/VLSICircuits18222.2020.9162793

16. A -107.8 dB THD+N Low-EMI Multi-Level Class-D Audio Amplifier
    Huajun Zhang; Shoubhik Karmakar; Lucien Breems; Quino Sandifort; Marco Berkhout; Kofi Makinwa; Qinwen Fan;
    In 2020 IEEE Symposium on VLSI Circuits,
    United States, IEEE, pp. 1--2, 2020. Green Open Access added to TU Delft Institutional Repository {\textquoteleft}You share, we take care!{\textquoteright} – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher i. DOI: 10.1109/VLSICircuits18222.2020.9162793
    
    Abstract: ...

    This paper describes a class-D audio amplifier with a multilevel output stage that reduces both EMI and idle power. High loop gain, and thus high linearity, are enabled by a relatively high (4.2 MHz) switching frequency, which relaxes the requirements on its output LC filter. Fabricated in a 180nm BCD technology, it can drive 14 W into an 8-Ω load with state-of-the-art performance: -107.8 dB THD+N, 91% peak efficiency, and 7 mA quiescent current. It meets the CISPR 25 Class 5 radiated emission standard with a low-cost 580 kHz LC filter, improving the state-of-the-art by 5.8x.

17. A 28W -108.9dB/-102.2dB THD/THD+N Hybrid ΔΣ-PWM Class-D Audio Amplifier with 91% Peak Efficiency and Reduced EMI Emission
    Shoubhik Karmakar; Huajun Zhang; {Van Veldhoven}, Robert; Lucien Breems; Marco Berkhout; Qinwen Fan; Kofi A. A. Makinwa;
    In 2020 IEEE International Solid-State Circuits Conference, ISSCC 2020,
    United States, IEEE, pp. 350--352, 2020. Green Open Access added to TU Delft Institutional Repository {\textquoteleft}You share, we take care!{\textquoteright} – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher i. DOI: 10.1109/ISSCC19947.2020.9063001
    
    Abstract: ...

    Class-D amplifiers are often used in high-power audio applications due to their high power efficiency. They typically employ pulse-width modulation (PWM) at a fixed carrier frequency, which may cause electromagnetic interference (EMI). Setting this frequency fPWM) below the AM band (535 to 1605kHz) helps mitigate this, but its harmonics still contain substantial energy and must be filtered out by bulky LC filters with low cut-off frequencies (fc = 20 to 40 kHz), significantly increasing system cost and size. Stability considerations also constrain the amplifier's unity-gain frequency to be < mathrm{f} {mathrm{PWM}}/pi [1], compromising the audio-band loop gain required to suppress output-stage nonlinearity. Setting fPWM above the AM band helps increase fc and allows a higher loop gain [2]. However, this results in narrower pulses at higher power levels (higher modulation index), which cannot be faithfully produced by the output stage, thus exacerbating its non-linearity. Delta-sigma modulation (DeltaSigma M) has fixed pulse widths and does not suffer from these narrow-pulse artefacts. However, the out-of-band noise of 1bit modulators then requires larger LC filters. Moreover, high-order loop filters must be used to achieve sufficient SQNR, which then require additional techniques to maintain stability as the modulation range approaches 100% [3].

18. Design Considerations for a Mems Coriolis Mass Flow Sensing System
    A.C. de Oliveira; T. Schut; J. Groenesteijn; Qinwen Fan; R.Wiegerink; K.A.A. Makinwa;
    In MFHS,
    2019.

19. A MEMS Coriolis Mass Flow Sensing System with Combined Drive and Sense Interface
    A. de Oliveira; T. Schut; J. Groenesteijn; Qinwen Fan; R. Wiegerink; K. Makinwa;
    In Proc. IEEE Sensors,
    October 2019.

20. A MEMS Coriolis Mass Flow Sensing System with Combined Drive and Sense Interface
    A.C. de Oliveira; T. Schut; J. Groenesteijn; Qinwen Fan; R.Wiegerink; K.A.A. Makinwa;
    In Proc. IEEE SENSORS,
    10 2019. DOI: 10.1109/SENSORS43011.2019.8956695

21. Capacitively-Coupled Chopper Instrumentation Amplifiers: An Overview
    Qinwen Fan; Kofi A. A. Makinwa;
    In Proc. IEEE Sensors,
    10 2018. DOI: 10.1109/ICSENS.2018.8589958

22. Fully Capacitive Coupled Input Choppers
    J. H. Huijsing; Qinwen Fan; K. A. A. Makinwa;
    Patent, US US10033369B2, July 2018. Assignee: Maxim Integrated Products Inc.

23. Capacitively-Coupled Chopper Operational Amplifiers
    Qinwen Fan; K.A.A. Makinwa; J.H. Huising;
    Springer, , 2017.

24. Advances in Low-Offset Opamps
    Qinwen Fan; J.H. Huising; K.A.A. Makinwa;
    Switzerland: Springer, , 2016.

25. Fast-Settling Capacitive-Coupled Amplifiers
    J.H. Huijsing; Qinwen Fan; K.A.A. Makinwa; D. Fu; J. Wu; L. Zhou;
    Patent, 9,294,049, March 22 2016.

26. A 110dB SNR ADC with ±30V input common-mode range and 8¿V Offset for current sensing applications
    L. Xu; B. Gönen; Qinwen Fan; J.H. Huijsing; K.A.A. Makinwa;
    In M Romdhane; LC Fujino; J Anderson (Ed.), Proceedings of the 2015 IEEE International Solid-State Circuits Conference,
    IEEE, pp. 89-91, 2015. Harvest Session 5.2.

27. Measurement and analysis of current noise in chopper amplifiers
    J. Xu; Qinwen Fan; J.H. Huijsing; C. van Hoof; R.F. Yazicioglu; K.A.A. Makinwa;
    IEEE Journal of Solid State Circuits,
    Volume 48, Issue 7, pp. 1575-1584, 2013. Harvest.

28. A multi-path chopper-stabilized capacitively coupled operational amplifier with 20V-input-common-mode range and 3μV offset
    Qinwen Fan; J.H. Huijsing; K.A.A. Makinwa;
    In A Chandrakasan (Ed.), Digest of Technical Papers - 2013 IEEE International Solid-State Circuits Conference (ISSCC 2013),
    IEEE, pp. 176-177, 2013. Harvest Session 10.

29. Capacitively coupled chopper amplifiers
    Qinwen Fan;
    PhD thesis, Delft University of Technology, 2013. Onder embargo; staat niet in de IR van de Bibliotheek.

30. A 21 nV/√ Hz chopper-stabilized multi-path current-feedback instrumentation amplifier with 2 μ v offset
    Qinwen Fan; J.H. Huijsing; K.A.A. Makinwa;
    IEEE Journal of Solid State Circuits,
    Volume 47, Issue 2, pp. 464-475, February 2012. Harvest Article number: 6112184.

31. A capacitively-coupled chopper operational amplifier with 3μV Offset and outside-the-rail capability
    Qinwen Fan; J.H. Huijsing; K.A.A. Makinwa;
    In Y. Deval; J-B Begueret; D Belot (Ed.), Proceedings 2012 38th European Solid-State Circuit Conference,
    IEEE, pp. 73-76, 2012.

32. Measurement and analysis of input current noise in chopper amplifiers
    J. Xu; Qinwen Fan; J.H. Huijsing; C. van Hoof; R.F. Yazicioglu; K.A.A. Makinwa;
    In Y. Deval; J-B Begueret; D Belot (Ed.), Proceedings 2012 38th European Solid-State Circuit Conference,
    IEEE, pp. 81-84, 2012.

33. A capacitively coupled chopper instrumentation amplifier with a ±30V common-mode range, 160dB CMRR and 5μV offset
    Qinwen Fan; J.H. Huijsing; K.A.A. Makinwa;
    In L Fujino (Ed.), Digest of Technical Papers - 2012 IEEE International Solid-state Circuits Conference,
    IEEE, pp. 374-375, 2012. Harvest Article number: 6177045.

34. A 1.8 µW 60 nV/√Hz Capacitively-Coupled Chopper Instrumentation Amplifier in 65 nm CMOS for Wireless Sensor Nodes
    Qinwen Fan; Fabio Sebastiano; Johan H. Huijsing; Kofi A.A. Makinwa;
    {IEEE} J. Solid-State Circuits,
    Volume 46, Issue 7, pp. 1534 - 1543, July 2011. DOI: 10.1109/JSSC.2011.2143610
    
    Keywords: ...

    CMOS integrated circuits;choppers (circuits);instrumentation amplifiers;wireless sensor networks;CMOS technology;CMRR;DC servo loop;PSRR;biopotential sensing;capacitively-coupled chopper instrumentation amplifier;chopping ripple;current 1.8 muA;electrode offset suppression;low-power precision instrumentation amplifier;noise efficiency factor;positive feedback loop;power 1.8 muW;rail-to-rail input common-mode range;ripple reduction loop;size 65 nm;voltage 1 V;wireless sensor nodes;Capacitors;Choppers;Impedance;Noise;Sensors;Topology;Wireless sensor networks;Bio-signal sensing;chopping;high power efficiency;low offset;low power;precision amplifier;wireless sensor nodes.
    
    
    Abstract: ...

    This paper presents a low-power precision instrumentation amplifier intended for use in wireless sensor nodes. It employs a capacitively-coupled chopper topology to achieve a rail-to-rail input common-mode range as well as high power efficiency. A positive feedback loop is employed to boost its input impedance, while a ripple reduction loop suppresses the chopping ripple. To facilitate bio-potential sensing, an optional DC servo loop may be employed to suppress electrode offset. The IA achieves 1 µV offset, 0.16% gain inaccuracy, 134 dB CMRR, 120 dB PSRR and a noise efficiency factor of 3.3. The instrumentation amplifier was implemented in a 65 nm CMOS technology. It occupies only 0.1 mm² chip area (0.2 mm² with the DC servo loop) and consumes 1.8 µA current (2.1 µA with the DC servo loop) from a 1 V supply.

35. Input characteristics of a chopped multi-path current feedback instrumentation amplifier
    Qinwen Fan; J.H. Huijsing; K.A.A. Makinwa;
    In {De Venuto}, D; L Benini (Ed.), 4th IEEE International Workshop on Advances in Sensors and Interfaces (IWASI),
    IEEE, pp. 61-66, 2011.

36. A 2.1 µW Area-Efficient Capacitively-Coupled Chopper Instrumentation Amplifier for ECG Applications in 65 nm CMOS
    Qinwen Fan; Fabio Sebastiano; Johan H. Huijsing; Kofi A.A. Makinwa;
    In Proc. Asian Solid-State Circuits Conference,
    Beijing, China, pp. 1 - 4, November8--10 2010. DOI: 10.1109/ASSCC.2010.5716624
    
    Keywords: ...

    CMOS integrated circuits;amplifiers;biomedical electrodes;choppers (circuits);electrocardiography;CMOS technology;DC servo loop;ECG application;area efficient chopper instrumentation amplifier;capacitive feedback network;capacitively coupled chopper instrumentation amplifier;electrocardiography;electrode-tissue interface;power 2.1 muW;switched capacitor integrator;Choppers;DSL;Earth Observing System;Electrocardiography;Impedance;Instruments;Noise.
    
    
    Abstract: ...

    This paper describes a capacitively-coupled chopper instrumentation amplifier for use in electrocardiography (ECG). The amplifier's gain is accurately defined by a capacitive feedback network, while a DC servo loop rejects the DC offset generated by the electrode-tissue interface. The high-pass corner frequency established by the servo loop is realized by an area-efficient switched-capacitor integrator. Additional feedback loops are employed to boost the amplifier's input-impedance to 80 MΩ and to suppress the chopper ripple. Implemented in a 65 nm CMOS technology, the amplifier draws 2.1 µA from a 1 V supply and occupies 0.2 mm².

37. A 21nV/¿Hz chopper-stabilized multipath current-feedback instrumentation amplifier with 2µV offset
    Qinwen Fan; J.H. Huijsing; K.A.A. Makinwa;
    In H Hidaka; B. Nauta (Ed.), Digest of Technical Papers - 2010 IEEE International Solid-State Circuits Conference,
    IEEE, pp. 80-81, 2010.

38. A 1.8µW 1-µV-offset capacitively-coupled chopper instrumentation amplifier in 65nm CMOS
    Qinwen Fan; Fabio Sebastiano; Johan H. Huijsing; Kofi A.A. Makinwa;
    In Proc. European Solid-State Circuits Conference,
    Sevilla, Spain, pp. 170 - 173, September14--16 2010. DOI: 10.1109/ESSCIRC.2010.5619902
    
    Keywords: ...

    CMOS integrated circuits;instrumentation amplifiers;CMOS;input impedance;noise efficiency factor;positive feedback loop;precision capacitively-coupled chopper instrumentation amplifier;rail-to-rail DC common-mode input range;ripple reduction loop;size 65 nm;Accuracy;Choppers;Impedance;Instruments;Noise;Resistors;Topology.
    
    
    Abstract: ...

    This paper describes a precision capacitively-coupled chopper instrumentation amplifier (CCIA). It achieves 1µV offset, 134dB CMRR, 120dB PSRR, 0.16% gain accuracy and a noise efficiency factor (NEF) of 3.1, which is more than 3x better than state-of-the-art. It has a rail-to-rail DC common-mode (CM) input range. Furthermore, a positive feedback loop (PFL) is used to boost the input impedance, and a ripple reduction loop (RRL) is used to reduce the ripple associated with chopping. The CCIA occupies only 0.1mm² in a 65nm CMOS technology. It can operate from a 1V supply, from which it draws only 1.8µA.

39. A chopper instrumentation amplifier for biopotential applications
    Qinwen Fan;
    PhD thesis, Delft University of Technology, 2008.

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