This paper describes a method of measuring the unsymmetric voltage of conducted noise using a floating measurement system. Here, floating means that there is no physical connection to the reference ground. The method works by correcting the measured voltage to the desired unsymmetric voltage using the capacitance between the measurement instrument and the reference ground plane acting as the return path of the conducted electromagnetic noise. The existing capacitance measurement instrument needs a probe in contact with the ground, so it is difficult to use for on-site measurement of stray capacitance to ground at troubleshooting sites where the ground plane is not exposed or no ground connection point is available. The authors have developed a method of measuring stray capacitance to ground that does not require physical connection of the probe to the ground plane. The developed method can be used to estimate the capacitance between the measurement instrument and ground plane even if the distance and relative permittivity of the space are unknown. And a method is proposed for correcting the voltage measured with the floating measurement system to obtain the unsymmetric voltage of the noise by using the measured capacitance to ground. In the experiment, the unsymmetric voltage of a sinusoidal wave transmitting on a co-axial cable was measured with a floating oscilloscope in a shield room and the measured voltage was corrected to within 2dB of expected voltage by using the capacitance measured with the developed method. In addition, the voltage of a rectangular wave measured with the floating oscilloscope, which displays sag caused by the stray capacitance to ground, was corrected to a rectangular wave without sag. This means that the phase of the unsymmetric voltage can also be corrected by the measured stray capacitance. From these results, the effectiveness of the proposed methods is shown.

In IoT (Internet-of-Things) era, the number and variety of hardware devices becomes continuously increasing. Several IoT devices are utilized at infrastructure equipments. How to maintain such IoT devices is a serious concern. Capacitance measurement is one of the powerful ways to detect anomalous states in the structure of the hardware devices. Particularly, measuring capacitance while the hardware device is running is a major challenge but no such researches proposed so far. This paper proposes a capacitance measuring device which measures device capacitance in operation. We firstly combine the AC (alternating current) voltage signal with the DC (direct current) supply voltage signal and generates the fluctuating signal. We supply the fluctuating signal to the target device instead of supplying the DC supply voltage. By effectively filtering the observed current in the target device, the filtered current can be proportional to the capacitance value and thus we can measure the target device capacitance even when it is running. We have implemented the proposed capacitance measuring device on the printed wiring board with the size of 95mm × 70mm and evaluated power consumption and accuracy of the capacitance measurement. The experimental results demonstrate that power consumption of the proposed capacitance measuring device is reduced by 65% in low-power mode from measuring mode and proposed device successfully measured capacitance in 0.002μF resolution.

In this paper, the measurement of capacitance variation, of an on-chip power distribution network (PDN) due to the change of internal states of a CMOS logic circuit, is studied. A state-dependent PDN-capacitance model that explains measurement results will be also proposed. The model is composed of capacitance elements related to MOS transistors, signal and power supply wires, and substrate. Reflecting the changes of electrode potentials, the capacitance elements become state-dependent. The capacitive elements are then all connected in parallel between power supply and ground to form the proposed model. By using the proposed model, state-dependence of PDN-capacitances for different logic circuits are studied in detail. The change of PDN-capacitance exceeds 12% of its total capacitance in some cases, which corresponds to 6% shift of anti-resonance frequency. Consideration of the state-dependence is important for modeling the PDN-capacitance.

For analog applications, the Metal-Insulator-Metal (MIM) capacitance has to be measured at a much higher resolution than using the conventional methods, i.e. to a sub-femto level. A new robust mismatch measurement technique is proposed, which is more accurate and robust compared to the conventional Floating Gate Capacitance Measurement (FGCM) methods. A capacitance mismatching measurement methodology based on Vs is more stable than that based on Vf because the influence of pre-existing charge in the floating-gate can be cancelled in the slope of ΔVs/ΔVf based on Vs. The accuracy of this method is evaluated through silicon measurement in a 0.13 µm technology. It shows that, compared to the ideal value, the average of the new method are within 0.12% compared to 49.23% in conventional method while the standard deviation is within 0.15%.

To improve measurement accuracy and speed, a switched-capacitor capacitance measurement circuit with the vernier scale is developed. Its process consists of a coarse measurement by charge-balancing A-D conversion and a fine measurement by single-slope A-D conversion. a prototype using discrete components confirms the principles of operation.