Voltage Controlled Oscillator for Small-Signal Capacitance Sensing

Enache, Andrei; Draghici, Florin; Pristavu, Gheorghe; Brezeanu, Gheorghe

doi:10.1109/smicnd.2019.8923728

Cited by 2 publications

(16 citation statements)

References 3 publications

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“…The characteristic of interest for the MOS capacitor sensor was the small-sig pacitance, denoted by Cg, versus the DC bias voltage, VG (C-V characteristic), meas a frequency of 1 MHz. Two theoretical C-V curves (in an inert gas and in the pres H2) are given in Figure 2 [22,33]. It can be seen that the presence of H2 leads to a le of the C-V characteristic [22].…”

Section: Hydrogen Detection Principlementioning

confidence: 98%

“…This behavior is most obvious in the region where pacitance is strongly dependent on the bias voltage. As a result, two hydrogen de principles may be used, illustrated in Figure 2 [33]. The supplementary contact pad shown in Figure 1 is a "dummy" structure used for parasitic capacitance evaluation [20].…”

Section: Hydrogen Detection Principlementioning

confidence: 99%

“…The sensing element is a SiC-MOS capacitor. The innovative readout circuit is essentially a phase locked loop (PLL) [31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

“…As the sensor was exposed to hydrogen, its C-V characteristic shifted [22] and the PLL varied the bias to maintain a constant capacitance, thus generating a voltage value proportional to the H 2 concentration. Moreover, the PLL topology allowed for selecting the initial sensor bias voltage (i.e., at 0 ppm H 2 ) to achieve optimal sensitivity [33]. Unlike conventional readout circuit architectures [30] it does not require dedicated bias and amplification blocks.…”

Section: Introductionmentioning

confidence: 99%

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PLL-Based Readout Circuit for SiC-MOS Capacitor Hydrogen Sensors in Industrial Environments

Enache

Draghici

Mitu

et al. 2022

Sensors

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For proper operation in real industrial conditions, gas sensors require readout circuits which offer accuracy, noise robustness, energy efficiency and portability. We present an innovative, dedicated readout circuit with a phase locked loop (PLL) architecture for SiC-MOS capacitor sensors. A hydrogen detection system using this circuit is designed, simulated, implemented and tested. The PLL converts the MOS nonlinear small-signal capacitance (affected by hydrogen) into an output voltage proportional to the detected gas concentration. Thus, the MOS sensing element is part of the PLL’s voltage-controlled oscillator. This block effectively provides a small AC signal (around 70 mV at 1 MHz) for the sensor and acquires its response. The correct operation of the proposed readout circuit is validated by simulations and experiments. Hydrogen measurements are performed for concentrations up to 1600 ppm. The PLL output exhibited voltage variations close to those discernable from experimental C-V curves, acquired with a semiconductor characterization system, for all investigated MOS sensor samples.

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Section: Hydrogen Detection Principlementioning

confidence: 98%

Section: Hydrogen Detection Principlementioning

confidence: 99%

“…The sensing element is a SiC-MOS capacitor. The innovative readout circuit is essentially a phase locked loop (PLL) [31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

PLL-Based Readout Circuit for SiC-MOS Capacitor Hydrogen Sensors in Industrial Environments

Enache

Draghici

Mitu

et al. 2022

Sensors

Self Cite

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“…A voltage-controlled oscillator (VCO) is a key component in a frequency synthesizer that generates local oscillator (LO) signals for frequency conversion in a radio-frequency (RF) transceiver [ 1 , 2 , 3 ]. A VCO-based readout circuit, which is that the output voltage of the sensing core is applied to the node of the VCO tuning voltage, has merit to achieve a low sensitivity level and a high signal-to-noise ratio compared to the amplifier-based readout circuit [ 4 , 5 ]. In addition, high integration and low power consumption of the VCO-based readout circuit are advantageous for implementing a large-scale sensor array [ 6 , 7 ].…”

Section: Introductionmentioning

confidence: 99%

Switched-Biasing Techniques for CMOS Voltage-Controlled Oscillator

Kang

Moon

Yang

2021

Sensors

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A voltage-controlled oscillator (VCO) is a key component to generate high-speed clock of mixed-mode circuits and local oscillation signals of the frequency conversion in wired and wireless application systems. In particular, the recent evolution of new high-speed wireless systems in the millimeter-wave frequency band calls for the implementation of the VCO with high oscillation frequency and low close-in phase noise. The effect of the flicker noise on the phase noise of the VCO should be minimized because the flicker noise dramatically increases as the deep-submicron complementary metal-oxide-semiconductor (CMOS) process is scaled down, and the flicker corner frequency also increases, up to several MHz, in the up-to-date CMOS process. The flicker noise induced by the current source is a major factor affecting the phase noise of the VCO. Switched-biasing techniques have been proposed to minimize the effect of the flicker noise at the output of the VCO with biasing AC-coupled signals at the current source of the VCO. Reviewing the advantages and disadvantages reported in the previous studies, it is analyzed which topology to implement the switched-biasing technique is advantageous for improving the performance of the CMOS VCOs.

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Voltage Controlled Oscillator for Small-Signal Capacitance Sensing

Cited by 2 publications

References 3 publications

PLL-Based Readout Circuit for SiC-MOS Capacitor Hydrogen Sensors in Industrial Environments

PLL-Based Readout Circuit for SiC-MOS Capacitor Hydrogen Sensors in Industrial Environments

Switched-Biasing Techniques for CMOS Voltage-Controlled Oscillator

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