A low noise, low residual offset, chopped amplifier for mixed level applications

Sanduleanu, Mihai; Tuijl, Adrianus Johannes Maria van; Wassenaar, R.F.; Lammers, M.; Wallinga, Hans

doi:10.1109/icecs.1998.814893

Cited by 23 publications

(10 citation statements)

References 4 publications

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“…Similarly, negativefeedback around the integrator is maintained by an extra chopper, which chops the output current of the opamp's differential input pair [13].…”

Section: Implementation Of Interface Electronicsmentioning

confidence: 99%

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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“…Similarly, negativefeedback around the integrator is maintained by an extra chopper, which chops the output current of the opamp's differential input pair [13].…”

Section: Implementation Of Interface Electronicsmentioning

confidence: 99%

Interface electronics for a CMOS electrothermal frequency-locked-loop

Zhang

Makinwa

2007

ESSCIRC 2007 - 33rd European Solid-State Circuits Conference

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“…Its input is V OUT1 which is just the output of the first stage, and its output is V OUT2 . The second modulator is put at the drains of input transistors M 21 Moreover, the signal acquires more gain between the two modulators. So, the offsets and the low-frequency noises induced by transistors, which are behind the second modulator, have less influence on the signal when it is modulated back to low frequency.…”

Section: Cmos Circuit Realizationmentioning

confidence: 99%

“…3.13 to form a chopper amplifier shown in Fig. 3.12, with one at the input node and the other two at the source of cascode transistors [21]. The impedance seen from the source of transistor M 5 is written in (3.8), where g mx and r ox are the transconductance and the output resistance of transistor M x, respectively.…”

Section: Instrument Amplifier For Voltage Sensor Interfacementioning

confidence: 99%

Biomedical Signal Acquisition Circuits

Wang

Jiang

Chen

2013

CMOS IC Design for Wireless Medical and Health Care

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The biomedical sensor is one of the most significant parts in a wireless medical/ health care system. Various types of biomedical sensors are used to acquire the human body information. A modern biomedical sensor is usually a digital sensor, which means the final output of the sensor is a digital electrical signal. A typical digital biomedical sensor is composed of a transducer for signal energy conversion, an interface circuit to buffer the transducer output, and a digitizer to digitize the signal as shown in Fig. 3.1. The interface circuit and the digitizer circuit forms the sensor readout circuit and can usually be implemented within one integrated circuit using the CMOS technologies.In the biomedical sensor, the transducer first converts the body information signal in one form of energy to another form of energy, namely, an electrical signal. The original energy types include mechanical, chemical, optical, magnetic, thermal, acoustic, electrical, and some other types of energy.

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“…10 (input pair not shown). Current sources and , carrying a current , represent the upper PMOS current sources, and the chopper demodulator is located at the sources of the cascode transistors [15], [16]. In the presence of an offset between the NMOS cascode transistors, a net DC voltage is established at the sources of the cascode transistors and across the chopper.…”

Section: Circuit Designmentioning

confidence: 99%

“…The sum of these two currents is an AC current, -, which is rectified by the chopper itself into an output current -. At a chopping frequency , the DC value of this current is: (16) To minimize , the parasitic capacitances at the high-impedance input nodes of the chopper demodulator should be shielded from the DC voltage across its outputs. As shown in Fig.…”

Section: Circuit Designmentioning

confidence: 99%

A Temperature-to-Digital Converter Based on an Optimized Electrothermal Filter

Kashmiri

Xia

Makinwa

2009

IEEE J. Solid-State Circuits

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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 low noise, low residual offset, chopped amplifier for mixed level applications

Cited by 23 publications

References 4 publications

Interface electronics for a CMOS electrothermal frequency-locked-loop

Interface electronics for a CMOS electrothermal frequency-locked-loop

Biomedical Signal Acquisition Circuits

A Temperature-to-Digital Converter Based on an Optimized Electrothermal Filter

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