Advances in Voltage-Controlled-Oscillator-Based ΔΣ ADCs

Li, Shaolan; Sanyal, Arindam; Lee, Kyoungtae; Yoon, Yeonam; Tang, Xiyuan; Zhong, Yi; Ragab, Kareem; Sun, Nan

doi:10.1587/transele.2018cti0001

Cited by 5 publications

(4 citation statements)

References 38 publications

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“…The FDSM is a novel delta-sigma modulation technique using a VCO [ 4 , 5 , 7 ]. Figure 2 shows the configuration of the FDSM together with the conventional one.…”

Section: Frequency Delata-sigma Modulationmentioning

confidence: 99%

“…Recently, another type of the DSM, called Frequency Delta-Sigma Modulator (FDSM), has attracted considerable attention, which uses a voltage controlled oscillator (VCO) [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. The FDSM uses an intermediate frequency modulation (FM) signal that is generated by the VCO, and it has no feedback DAC or integrator.…”

Section: Introductionmentioning

confidence: 99%

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Noise Floor Reduction in Frequency Delta-Sigma Modulation Microphone Sensors

Maezawa

Mori

Andoh

2021

Sensors

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Frequency delta-sigma modulator (FDSM) employing a variable frequency oscillator is a novel replacement of the classical delta-sigma modulators. This is advantageous for application to sensors, because an ADC can be intrinsically integrated with the sensors. We have already proposed to use this technique to various sensors. However, the signal-to-noise ratio was significantly degraded by noise floor, in the previous papers. In this paper, we have investigated the origin of the noise floor in the FDSM microphone sensors as a promising example. It was demonstrated that improving the phase noise of the oscillator can drastically reduce the noise floor. For this reduction we improved the Q-factor of the cavity resonator, and the design of the oscillator circuit. With these improvements, the phase noise, and, hence, the noise floor, were improved by approximately 40 dB. In addition, we obtained an SNR of 57 dB for 114 dBSPL sound input with 96 kHz bandwidth, which corresponds to the dynamic range of 87 dB for maximum 140 dBSPL. A much larger dynamic range of around 120 dB is expected by increasing the sampling rate and decreasing the Al diaphragm thickness. These results also indicate the promise of the FDSM to varieties of physical sensors.

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“…The FDSM is a novel delta-sigma modulation technique using a VCO [ 4 , 5 , 7 ]. Figure 2 shows the configuration of the FDSM together with the conventional one.…”

Section: Frequency Delata-sigma Modulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Noise Floor Reduction in Frequency Delta-Sigma Modulation Microphone Sensors

Maezawa

Mori

Andoh

2021

Sensors

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“…The FDSM is suitable for high frequency operation, because it has no feedback loop and no DAC, which restrict the operation frequency. Consequently, this technique is promising for wide band, high-resolution analog-to-digital converters (ADCs) [5]- [9].…”

Section: Introductionmentioning

confidence: 99%

A Novel Displacement Sensor Based on a Frequency Delta-Sigma Modulator and its Application to a Stylus Surface Profiler

MAEZAWA

Farooq

MORI

2023

IEICE Trans. Electron.

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A novel displacement sensor was proposed based on a frequency delta-sigma modulator (FDSM) employing a microwave oscillator. To demonstrate basic operation, we fabricated a stylus surface profiler using a cylindrical cavity resonator, where one end of the cavity is replaced by a thin metal diaphragm with a stylus probe tip. Good surface profile was successfully obtained with this device. A 10 nm depth trench was clearly observed together with a 10 µm trench in a single scan without gain control. This result clearly demonstrates an extremely wide dynamic range of the FDSM displacement sensors.

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“…Among them, the integrator and feedback DAC limit the sampling rate and, thus, the bandwidth. Recently, frequency DSMs (FDSMs) based on a voltage-controlled oscillator (VCO) have been attracting considerable attention (Høvin et al , 1997; Iwata et al , 1999; Maezawa et al , 2006; Straayer and Perrott, 2008; Li et al , 2019) because they require no integrator or feedback DAC and can be operated at significantly high frequencies.…”

Section: Introductionmentioning

confidence: 99%

Delta-sigma modulation microphone sensors employing a resonant tunneling diode with a suspended microstrip resonator

Maezawa

Itö

Mori

2020

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Purpose This paper aims to propose and demonstrate novel microphone sensors based on the frequency delta-sigma modulation (FDSM) technique, which replaces the conventional delta-sigma modulator in the delta-sigma analog-to digital converters. A key of the FDSM technology is to use a voltage-controlled oscillator (VCO) for converting an input analog signal to a 1-bit pulse-density modulated digital signal. High-performance sensors can be realized if the VCO is replaced by an oscillator whose oscillation frequency depends on an external physical parameter. Design/methodology/approach Microphone sensors are proposed based on FDSM that uses a suspended microstrip disk resonator, where the backside ground plane is replaced by a thin metal diaphragm. A resonant tunneling diode (RTD) oscillator is also used, as the performance of these sensors significantly depends on the oscillation frequency. To demonstrate the basic operation of the proposal, prototype devices were fabricated with an InGaAs/AlAs RTD. Findings A satisfactory noise shaping property, which is a significant nature of delta-sigma modulation, was demonstrated over three decades for the prototype device. A sound-sensing peak was also clearly observed when applying 1 kHz sound from a speaker. Practical implications High-performance ultrasonic microphone sensors can be realized if the sensors are fabricated by using a thin InP substrate with high-frequency oscillator design. Originality/value In this study, the authors proposed and experimentally demonstrated novel microphone sensors, which are promising as future ultrasonic sensors that have high dynamic range with wide bandwidth.

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Advances in Voltage-Controlled-Oscillator-Based ΔΣ ADCs

Cited by 5 publications

References 38 publications

Noise Floor Reduction in Frequency Delta-Sigma Modulation Microphone Sensors

Noise Floor Reduction in Frequency Delta-Sigma Modulation Microphone Sensors

A Novel Displacement Sensor Based on a Frequency Delta-Sigma Modulator and its Application to a Stylus Surface Profiler

Delta-sigma modulation microphone sensors employing a resonant tunneling diode with a suspended microstrip resonator

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