A CMOS Chopper Offset-Stabilized Opamp

Witte, J.F.; Makinwa, Kofi A. A.; Huijsing, Johan H.

doi:10.1109/esscir.2006.307605

Cited by 29 publications

(25 citation statements)

References 2 publications

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“…6). Such a S/H circuit can be readily implemented on chip [14]- [16]. This leaves the VCO as the major remaining off-chip component.…”

Section: Implementation Of Interface Electronicsmentioning

confidence: 99%

“…Due to the action of the chopper, this voltage appears as a square-wave across the OTA's output, which will charges and discharges the parasitic capacitances present there. After demodulation by the chopper, the result is a net DC current flowing into the integrator [14]. This current will be chopped by the chopper, and will again appear at the integrator's output as triangular ripple, but at the lower frequency (Fig.…”

Section: Implementation Of Interface Electronicsmentioning

confidence: 99%

“…However, this approach does not lend itself to integration. Another approach, and the one used here, is to employ a sample-and-hold (S/H) circuit as a notch-filter [14]- [16].…”

Section: Implementation Of Interface Electronicsmentioning

confidence: 99%

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Interface electronics for a CMOS electrothermal frequency-locked-loop

Zhang

Makinwa

2007

ESSCIRC 2007 - 33rd European Solid-State Circuits Conference

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Abstract-This paper describes a new implementation of a CMOS electrothermal frequency-locked-loop (FLL), whose output frequency is determined by the temperature-dependent phase shift of an electrothermal filter (ETF). The FLL maintains a constant phase shift in the ETF, and as a result drives it with a signal whose frequency is a well-defined function of temperature. Compared to a previous implementation, the FLL described here has significantly more loop gain, less electrical phase-spread, and is more suitable for full integration. Measurements on 16 samples (from one batch) show that the temperature dependence of the FLL's output frequency agrees very well with the known thermal properties of bulk silicon. The untrimmed spread of this frequency is less than 0.45% (3 ) from 40 C to 100 C, which corresponds to a temperature-sensing inaccuracy of less than 0.7 C (3 ).Index Terms-Electrothermal filter, frequency-locked-loop, synchronous demodulator, temperature sensor.

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“…6). Such a S/H circuit can be readily implemented on chip [14]- [16]. This leaves the VCO as the major remaining off-chip component.…”

Section: Implementation Of Interface Electronicsmentioning

confidence: 99%

Section: Implementation Of Interface Electronicsmentioning

confidence: 99%

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Interface electronics for a CMOS electrothermal frequency-locked-loop

Zhang

Makinwa

2007

ESSCIRC 2007 - 33rd European Solid-State Circuits Conference

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“…Although the reduction of offset due to glitches remains a difficult problem, it will not be discussed here. The reader is invited to look at the excellent work presented in [11]- [15].…”

Section: Recent Trends In Noise and Offset Reduction Techniquesmentioning

confidence: 99%

Recent trends in low-frequency noise reduction techniques for integrated circuits

Enz

Boukhayma

2015

2015 International Conference on Noise and Fluctuations (ICNF)

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Abstract-This paper presents the two main circuit techniques, namely autozeroing (AZ) and chopper stabilization (CS), that are used to reduce the 1/f noise and offset in amplifiers typically used in sensor electronics interfaces. After recalling their main properties, it looks into recent trends in circuit noise reduction techniques. First, the correlated multiple sampling (CMS) technique is presented as a generalization of AZ and correlated double sampling (CDS). Introduced in CMOS image sensors (CIS), it combines noise averaging and canceling and allows to further reduce the 1/f noise, but, like AZ, it is also ultimately limited by the aliasing of the broadband white noise. Another technique combining noise canceling and CS in a transimpedance amplifier (TIA) for bio-sensors is presented. It allows to maintain a low input impedance required by the TIA, while reducing the noise of the main transimpedance stage. CS is then used to cancel the noise of the following stages.

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“…Due to the action of the chopper, a square-wave voltage appears across the folding nodes of the amplifier. On the one hand, charges and discharges the parasitic capacitors , leading to an AC current - [17], while on the other hand, it modulates the output currents of the bottom NMOS current sources, (with finite output impedances ), leading to another AC current -. The sum of these two currents is an AC current, -, which is rectified by the chopper itself into an output current -.…”

Section: Circuit Designmentioning

confidence: 99%

A temperature-to-digital converter based on an optimized electrothermal filter

Kashmiri

Xia

Makinwa

2008

ESSCIRC 2008 - 34th European Solid-State Circuits Conference

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Abstract-This paper describes the design of a CMOS temperature-to-digital converter (TDC). It operates by measuring the temperature-dependent phase shift of an electrothermal filter (ETF). Compared to previous work, this TDC employs an ETF whose layout has been optimized to minimize the thermal phase spread caused by lithographic inaccuracy. To minimize electrical phase spread, the TDC's front-end consists of a wide bandwidth gain-boosted transconductor. The transconductor's output current is then digitized by a phase-domain 61 modulator whose phase-summing node is realized by a chopper demodulator. To minimize the residual offset caused by the demodulator's switching action, the demodulator is located at the virtual ground nodes established by the transconductor's gain-boosting amplifiers. Measurements on 16 samples (within one batch) show that the TDC has an untrimmed inaccuracy of less than 0.7 C (3 ) over the military range ( 55 C to 125 C).

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A CMOS Chopper Offset-Stabilized Opamp

Cited by 29 publications

References 2 publications

Interface electronics for a CMOS electrothermal frequency-locked-loop

Interface electronics for a CMOS electrothermal frequency-locked-loop

Recent trends in low-frequency noise reduction techniques for integrated circuits

A temperature-to-digital converter based on an optimized electrothermal filter

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