Output Resistance Research Articles

Higher Doses of Calcium Associated With Survival in Trauma Patients

IntroductionCalcium is required for coagulation, cardiac output, and peripheral vascular resistance. Between 85% and 94% of trauma patients treated with massive blood transfusion develop hypocalcemia.1 The aim of this study is to evaluate the relationship between increased intravenous calcium administration during massive transfusion and improved survival of trauma patients. MethodsWe performed a retrospective analysis of trauma patients who received massive transfusion over a 2-y period. Doses of elemental calcium administered per unit of blood product transfused were calculated by calcium to blood product ratio (CBR). Chi-square test evaluated association between coagulopathy and 30-d mortality. Two-sample t-test evaluated association between CBR and coagulopathy. Bivariate regression analysis evaluated association between CBR and blood products transfused per patient. Multivariable logistic regression analysis, controlling for age, sex, coagulopathy, and Injury Severity Score evaluated the association between CBR and mortality. ResultsThe study included 77 patients. Coagulopathy was associated with increased 30-d mortality (P < 0.05). Patients who survived had higher CBR than those who died (P < 0.05). CBR was associated with a significant reduction in total blood products transfused per patient (P < 0.05). CBR was not associated with coagulopathy (P = 0.24). Multivariable logistic regression analysis demonstrated that Injury Severity Score ≥16, coagulopathy and decreased CBR were significant predictors of mortality (P < 0.05). CBR above 50 mg was a predictor of survival (P < 0.05). ConclusionsHigher doses of calcium given per blood product transfused were associated with improved 30-d survival and decreased blood product transfusions.

Optoelectronic Transimpedance Converter Based on MOS Photovaricap for High Resistive Gas Sensors

The gas detectors consist of two parts: metal-oxides gas sensor and transducer. The sensing material is made of a thin semiconductor layer. The transducer is responsible for converting the change in the several physical parameters of the thin sensitive layer into a measurable signal. Due to the high output resistance of high resistive gas sensors and the low input currents of amplifiers, electrometric cascades are employed, followed by the conversion of the gas sensors small direct current into an active current signal using a mechanical modulator (dynamic capacitor) to enhance sensitivity and stability. The aim of this research is to analyze the main characteristics of a novel type of dynamic capacitor that utilizes a surface metal-oxide-semiconductor (MOS) photovaricap (PV) as the regulating element when detecting signals from high resistive gas sensors. For the creation of surface MOS PVs, samples of p-Si with varying resistivity were chosen. A thin layer of SiO2 was deposited on these samples, onto which a translucent metallic electrode was applied. Modulation of the PV capacitance was achieved by illuminating it with a gallium arsenide LED. As a result, the capacitance of the PV is changed, producing a variable voltage across the load resistor, which was then amplified and recorded. It was observed that the settling time of the useful signal is determined by two factors. The first is the RC chain composed of the load resistance of the gas sensor and the input capacitance of the PV, and the second is slow relaxation phenomena in the structure of the MOS PV that lead to the screening of the induced charge. Characteristics of the MOS PV as a dynamic capacitor and the features of the photo capacitance as a semiconductor element, in turn, determine the transimpedance conversion coefficient. The conducted research showed that MOS PVs can be applied to register small DC currents and voltages from high resistive gas sensors. In this case, ordinary narrowband or wideband amplifiers with relatively low input resistance can be used instead of electrometric amplifiers with mechanical dynamic capacitors. The considered circuit has been experimentally tested with commercial resistors.

Use of the USCOM® noninvasive cardiac output measurement system to predict the development of pre-eclampsia in hypertensive pregnancies

ABSTRACT Objectives To assess the ability of the USCOM® (USCOM), using measurements of cardiac output (CO) and systemic vascular resistance (SVR), to predict the development of pre-eclampsia (PE) and severe PE in hypertensive pregnancies. Study design Prospective cohort study of women in the second or third trimester recruited at a tertiary center in Sydney, Australia. Demographic data and hemodynamic measurements using the USCOM were taken for all study participants at recruitment. Pregnancy outcome, including development of PE and severe PE, was tracked. Data were analyzed using ANOVA testing, pair-wise comparison testing, and Student’s t-testing. Results Recruitment included 65 normotensive controls, 34 women with chronic hypertension (CH), 51 with gestational hypertension (GH), and 21 with PE. Significantly higher weight, body surface area, and blood pressure measurements were found in the hypertensive, compared with the normotensive control and pregnancies. There were no observed differences in USCOM-measured CO, cardiac index, SVR, or systemic vascular resistance index between hypertensive women who did versus did not develop PE or severe PE in later pregnancy. Analysis of the CH and GH subgroups, as well as only unmedicated hypertensive women (n = 24), also showed no significant difference in hemodynamic parameters between those who did or did not develop PE or severe PE. Conclusions Our group was unable to successfully predict the onset of PE or severe PE based on hemodynamic parameters measured with the USCOM. It is possible this relates to the high proportion of women on antihypertensive medication at recruitment.

What is the best treatment for hypotension in healthy dogs during anaesthesia maintained with isoflurane?

Hypotension is a common and potentially life-threatening complication of general anaesthesia in dogs. Due to the combination of cardiovascular side effects of many anaesthetic, sedative and analgesic drugs used peri-operatively hypotension is frequently reported even in healthy dogs undergoing elective procedures. Several treatment options for hypotension have been advocated. Potential treatments include rapid administration of either crystalloid or colloid fluids; pharmacological treatments to increase cardiac output and/or systemic vascular resistance; or reduction in the delivery of the volatile anaesthetic agents. This critical appraisal considers the current evidence for which treatment is the best option for treating hypotension in healthy euvolemic dogs undergoing general anaesthesia maintained with isoflurane. Fourteen relevant studies were appraised, including 12 laboratory studies and two small clinical trials. One study demonstrated that reduction in the delivery of isoflurane may correct hypotension, but this treatment may not always be feasible. In general, rapid administration of fluids did not increase blood pressure and failed to correct hypotension. Synthetic colloids demonstrated some efficacy, but results were inconsistent between studies and large volumes may be required. Infusion of dopamine appears to be the most reliable pharmacological option consistently increasing blood pressure, cardiac output and correcting hypotension.

LC Tank Oscillator Based on New Negative Resistor in FDSOI Technology

Although Moore’s Law reaches its limits, it has never applied to analog and RF circuits. For example, due to the short channel effect (SCE), drain-induced barrier lowering (DIBL), and sub-threshold slope (SS)…, longer transistors are required to implement analog cells. From 22 nm CMOS technology and beyond, for reasons of variability, the channel of the transistors has no longer been doped. Two technologies then emerged: FinFET transistors for digital applications and UTBB FDSOI transistors, suitable for analog and mixed applications. In a previous paper, a new topology was proposed utilizing some advantages of the FDSOI technology. Thanks to this technology, a novel cross-coupled back-gate (BG) technique was implemented to improve analog and mixed signal cells in order to reduce the surface of the integrated circuit. This technique was applied to a current mirror to reduce the small channel effect and to provide high-output impedance. It was demonstrated that it is possible to overcompensate the SCE and DIBL effects and to create a negative output resistor. This paper presents a new LC tank oscillator based on this current mirror functioning as a negative resistor.

Highly Efficient Differential Frequency Doubler With Output Resistance Boosting Feedback

Highly Efficient Differential Frequency Doubler With Output Resistance Boosting Feedback

Harmonic distortion calibrator: additional uncertainty due to distortion in the measurement cable

The role of measuring instruments of the reference level (working standards of the 1st and 2nd digits) in ensuring the uniformity of measurements of the harmonic coefficient is considered, namely, the transfer of a unit of the harmonic coefficient from the primary standard to all measuring instruments from a huge fleet of working measuring instruments. A continuous search for ways to reduce the error of these measuring instruments is required. The methods of reducing one of the components of the measurement error of the reference level – an additional error caused by distortions in the measuring cable due to a mismatch of the resistances at the output of the calibrator and the input of the meter – are investigated. Until recently, the influence of measuring cable parameters on the results of harmonic coefficient measurements was considered negligible, because harmonic coefficient measuring instruments operate at sufficiently low frequencies (less than 1 MHz). However, for modern reference-level measuring instruments, such an influence has become noticeable, and it needs to be investigated. It has been shown that for calibrators with a large (600 Ohm) output impedance, significantly exceeding the characteristic impedance of the measuring cable, this error can be significant. An analytical dependence of the indicated error on the parameters of the measuring cable and the calibrator signal, as well as the output resistance of the calibrator, is derived. Conditions have been established under which this additional error is absent or can be neglected due to its smallness. When checking harmonic coefficient measuring instruments, a measuring cable 1 m long with a characteristic impedance of 50 Ohms is most often used. For a cable with such parameters and different values of the output resistance of the calibrator, the indicated additional error was theoretically calculated and experimentally evaluated. For a signal with a fundamental frequency of 200 kHz and a uniformly decreasing distribution of harmonic levels with a calibrator output impedance of 600 Ohms, the additional absolute error in generating a harmonic distortion equal to 100 % is 3 %. The use of factory correction for the total error in the formation of the harmonic distortion coefficient of the manufactured calibrator allows us to reduce the additional error only partially. To significantly minimize the additional error of the calibrator used, it is necessary to use the measuring cable supplied with the calibrator or a cable with identical parameters. The experimental estimate of the additional error is in good agreement with the results of its calculations. It is recommended to take into account the additional absolute error in the formation of the harmonic coefficient when developing and testing instruments for measuring the harmonic coefficient.

Design of Low Power Analog/RF Signal Processing Circuits Using 22 nm Silicon-on-Insulator Schottky Barrier Nano-Wire MOSFET

The gate-all-around (GAA) silicon-on-insulator (SOI) Schottky barrier (SB) nano-wire (NW) MOSFET was recently proposed for low-power and high-frequency analog and radio frequency (RF) circuits. But their use in low-power and high-frequency analog/RF circuits is still under investigation. In this work, basic analog signal processing circuits using gate-all-around SOI-SB-NW MOSFETs are designed for low-power and high-frequency applications. These basic and necessary analog processing circuits are designed for ± 0.3 V and ± 0.25 V power supplies to work on frequencies up to 10 GHz. The analog/RF characteristics of the GAA SOI-SB MOSFET are compared with those of the GAA SB NW MOSFET. The SOI-SB NW MOSFET shows improvements in early voltage, output resistance, and transconductance generation factor. The Silvaco TCAD simulator is used to obtain the results and perform numerical simulations. Simulation results show good analog/RF performance of the analog processing circuits.

Design of carbon allotrope FET-based folded cascode operational transconductance amplifiers (FC-OTA)

ABSTRACT Throughout this study, a high-gain, low-energy folded cascode operational transconductance amplifier (FC-OTA) was modelled utilising HSPICE software. The FC-OTA designs included implementations availing CNFETs, GNRFETs, and mixed involving a combination of CNFETs with CMOS. Comparison with traditional CMOS-based FC-OTAs revealed that CNFET-based FC-OTAs exhibited considerable enhancements, displaying significant escalation in DC amplification, output resistance, average power dissipation, and CMRR. The phase margin in CNT-based FC-OTAs indicated stability. Moreover, CNT-based devices showed substantial rise in direct current amplification over GNRFET-FC-OTAs. The study further explored the operational effectiveness of proposed FC-OTAs by varying parameters such as CNT diameter, CNT pitch, and the number of CNTs, identifying optimal values that significantly enhance the FC-OTA’s performance. Comprehensive parametric and Monte Carlo analyses demonstrated OTA’s resilience to changes in supply voltage, temperature, capacitance, and mismatches. In summary, the folded cascode approach was found to enhance gain and reduce average power in CNFET-based FC-OTAs in comparison to other structural configurations.

A 0.5 V Nanowatt Biquadratic Low-Pass Filter with Tunable Quality Factor for Electronic Cochlea Applications

A novel implementation of an analogue low-power, second-order, low-pass filter with tunable quality factor (Q) is presented and discussed. The filter feature is a relatively simple, buffer-based, circuit network consisting of eleven transistors operating in a subthreshold region. Q tuning is accomplished by injecting direct current into a network node, which changes the output resistance of the transistors and, as a result, modifies the filter network’s loss, and thus its Q. Q tuning is independent of a filter cut-off frequency (ω0). The filter, with a nominal ω0 of 1 kHz, was fabricated using a 0.18 µm CMOS technology, and features a Q range of 2–11, power consumption of up to 52 nW, and a 59 dB dynamic range when using a 0.5 V supply. The ω0 can be tuned from 0.5 to 2.5 kHz using a traditional method by changing the transistor transconductances, but this process partially affects the quality factor.

High-Fidelity, Low-Hysteresis Bionic Flexible Strain Sensors for Soft Machines.

Stretchable flexible strain sensors based on conductive elastomers are rapidly emerging as a highly promising candidate for popular wearable flexible electronic and soft-mechanical sensing devices. However, due to the intrinsic limitations of low fidelity and high hysteresis, existing flexible strain sensors are unable to exploit their full application potential. Herein, a design strategy for a successive three-dimensional crack conductive network is proposed to cope with the uncoordinated variation of the output resistance signal arising from the conductive elastomer. The electrical characteristics of the sensor are dominated by the successive crack conductive network through a greater resistance variation and a concise sensing mechanism. As a result, the developed elastomer bionic strain sensors exhibit excellent sensing performance in terms of a smaller overshoot response, a lower hysteresis (∼2.9%), and an ultralow detection limit (0.00179%). What's more, the proposed strategy is universal and applicable to many conductive elastomers with different conductive fillers (including 0-D, 1-D, and 2-D conductive fillers). This approach improves the sensing signal accuracy and reliability of conductive elastomer strain sensors and holds promising potential for various applications in the fields of e-skin and soft robotic systems.

Dynamic Estimation of Cardiovascular State From Arterial Blood Pressure Recordings.

Real-time estimation of patient cardiovascular states, including cardiac output and systemic vascular resistance, is necessary for personalized hemodynamic monitoring and management. Highly invasive measurements enable reliable estimation of these states but increase patient risk. Prior methods using minimally invasive measurements reduce patient risk but have produced unreliable estimates limited due to trade-offs in accuracy and time resolution. Our objective was to develop an approach to estimate cardiac output and systemic vascular resistance with both a high time resolution and high accuracy from minimally invasive measurements. Using the two-element Windkessel model, we formulated a state-space method to estimate a dynamic time constant - the product of systemic vascular resistance and compliance - from arterial blood pressure measurements. From this time constant, we derived proportional estimates of systemic vascular resistance and cardiac output. We then validated our method with a swine cardiovascular dataset. Our estimates produced using arterial blood pressure measurements not only closely align with those using highly invasive measurements, but also closely align when derived from three separate locations on the arterial tree. Moreover, our estimates predictably change in response to standard cardiovascular drugs. Overall, our approach produces reliable, real-time estimates of cardiovascular states crucial for monitoring and control of the cardiovascular system.

Maternal posture-physiology interactions in human pregnancy: a narrative review.

There are several well-known medical conditions in which posture and gravity interact with natural history, including pregnancy. In this review, we provide a comprehensive overview of interactions between maternal posture and maternal physiology and pathophysiology at rest during pregnancy. We conducted a systematic literature search of the MEDLINE database and identified 644 studies from 1991 through 2021, inclusive, that met our inclusion criteria. We present a narrative review of the resulting literature and highlight discrepancies, research gaps, and potential clinical implications. We organize the results by organ system and, commencing with the neurological system, proceed in our synthesis generally in the craniocaudal direction, concluding with the skin. The circulatory system warranted our greatest and closest consideration-literature concerning the dynamic interplay between physiology (heart rate, stroke volume, cardiac output, blood pressure, and systemic vascular resistance), pathophysiology (e.g., hypertension in pregnancy), and postural changes provide an intricate and fascinating example of the importance of the subject of this review. Other organ systems discussed include respiratory, renal, genitourinary, gastrointestinal, abdominal, and endocrine. In addition to summarizing the existing literature on maternal posture-physiology interactions, we also point out gaps and opportunities for further research and clinical developments in this area. Overall, our review provides both insight into and relevance of maternal posture-physiology interactions vis à vis healthcare's mission to improve health and wellness during pregnancy and beyond.

Frequency and severity of autonomic dysfunction assessed by objective hemodynamic responses and patient-reported symptoms in individuals with myasthenia gravis.

Myasthenia gravis (MG), a rare autoimmune disorder, poses diagnostic and management challenges, with increasing incidence in Europe and significant impact on patient quality of life. Despite prevalent autonomic symptoms, comprehensive assessments integrating subjective and objective measures are lacking. We aimed to investigate the prevalence and severity of autonomic dysfunction in patients with MG and healthy controls (HCs). We used beat-to-beat hemodynamic responses during standardized autonomic function tests (AFTs) and the Composite Autonomic Symptom Score 31 (COMPASS-31) questionnaire. Study participants including, 53 patients with MG and 30 age- and sex matched HCs underwent standardized cardiovascular AFTs and completed the COMPASS-31 questionnaire. Patients were categorized into Non-CAN and CAN groups based on their Cardiovascular Autonomic Neuropathy (CAN) status, as evaluated using the Composite Autonomic Scoring Scale (CASS). During the AFTs, cardiovascular parameters including heart rate, systolic blood pressure (BP), diastolic BP, mean BP, stroke volume (SV), cardiac output (CO), and total peripheral resistance (TPR) were measured. Twenty patients with MG (38%) exhibited mild CAN (CASS ≥2) with a median total CASS score of 1.00 and CASS 0.00 in HCs. Adrenergic impairment was observed in 27 patients (52%), with 13 patients (24.5%) exhibiting longer pressure recovery time after Valsalva maneuver (VM). Cardiovagal impairment was evident in 71% of patients, with abnormal results observed in 39.6% for the deep breathing test and 56.6% for the VM. CAN MG showed worse scores than HCs for the total COMPASS-31 (p < 0.001), orthostatic (OI) (p < 0.001), secretomotor (p = 0.004), and pupillomotor domains (p = 0.004). Total COMPASS-31 and OI scores were correlated with worse disease outcomes (disease duration, severity), hemodynamic parameter changes (SV, CO, TPR) during phase II late of VM, and with changes (Δtilt-supine) in Δsystolic BP, Δdiastolic BP, Δmean BP, ΔTPR during head-up-tilt test, but not with CASS score. Our findings demonstrate mild cardiovascular autonomic impairment in adrenergic and cardiovagal domains in patients with MG. Additionally, patient-reported autonomic symptoms correlated with hemodynamic changes during AFTs and worse disease outcomes and not with the grade of autonomic abnormalities. Incorporating beat-to-beat hemodynamics during AFTs may offer further insights for characterizing orthostatic intolerance symptoms in MG group.

Development of thermoelectric exhaust energy recovery system of a hydrogen internal combustion engine in a city bus using a Three-Dimensional multiphysics model

In this study, individual thermoelectric generator (TEG) module was developed and validated through comprehensive analyses and experiments. A model of the TEG module was constructed and subsequently verified through a coherent alignment with experimental results, ensuring its viability and accuracy within the application of interest. A thermoelectric exhaust energy recovery (TEER) system designed with a robust rectangular structure was also developed for an urban mass transit bus, which operates using a hydrogen internal combustion engine. By accommodating 40 TEG modules, each complemented with cooling fins, and placing cooling channels at the top and bottom of the exhaust channel, it was demonstrated that a proportionality between the power output and load resistance of the TEER system through a dimensionless analysis. The system’s three-dimensional multiphysics model constructed concurrently with the actual system facilitated both optimization and validation, predicting an energy recovery of 1.0–1.1% from the hydrogen engine exhaust and an optimal load resistance of 3.2 Ω under various operating conditions.

Magnetorheological Damper with Variable Displacement Permanent Magnet for Assisting the Transfer of Load in Lower Limb Exoskeleton.

Magnetorheological (MR) fluid exhibits the ability to modulate its shear state through variations in magnetic field intensity, and is widely used for applications requiring damping. Traditional MR dampers use the current in the coil to adjust the magnetic field strength, but the accumulated heat can cause the magnetic field strength to decay if it works for a long time. In order to deal with this shortcoming, a novel MR damper is proposed in this paper, which is based on a variable displacement permanent magnet to adjust the output resistance torque and applied to an exoskeleton joint for human load transfer assistance. A finite element model is used to determine the size parameters of the magnet and separator, so that the maximum output torque is optimal and the torque is uniformly distributed with the magnet displacement. The MR damper was characterized and calibrated on the experimental bench to make it controllable. The novel design enables the torque mass density of the MR damper to reach 8.83Nmm/g, the torque volume density to reach 48.7N/mm2, and has stability for long-term operation. Based on the torque control method proposed, a preliminary human experiment is conducted. The ground reaction force (GRF) data of the subjects is analyzed here, which represents the effect of load transfer to the exoskeleton. Compared with no exoskeleton, the GRF with exoskeleton is significantly reduced: the peak GRF in early stance phase is reduced by 24.14%, and in late stance phase is reduced by 19.77%. Based on our net load benefit (NLB) and net force benefit (NFB) evaluation indicators, the effectiveness of the proposed MR damper exoskeleton for human weight bearing assistance is established.

A Taylor Series Approximation Model for Characterizing the Output Resistance of a GFET

A Taylor Series Approximation Model for Characterizing the Output Resistance of a GFET

Evaluating the intraoperative changes in several hemodynamic parameters using uscom method in severe burn patients undergoing burn necrotomy, skin grafting

Objective: To evaluate the intraoperative changes in some hemodynamic parameters by the USCOM method in severe burn patients undergoing burn necrotomy, skin grafting.Subjects and methods: 30 severe burn patients, aged 16-60, treated at the Emergency Department, National Burn Hospital, were scheduled for necrosis and skin grafting from May 2023 to December 2023. Cross-sectional, clinical descriptive study.Results: CO and CI values at all study times were within normal limits (3.5-8 l/min and 2.4-4.2 l/min/m2). CO and CI were highest at the time of pre-medication (6.93 and 4.24) and lowest at the time of skin grafting (5.87 and 3.61). SVR values at all times were within normal limits (800 - 1600 d.s.cm-5). SVR was highest at the time the patient was awake (1278.33) and lowest at the time immediately after induction of anesthesia (976.93). SVRI values at 3 times after induction of anesthesia, before necrotomy, and at the time of necrotomy were lower than normal values (1800-3200 d.s.cm-5.m2). SVI at the remaining time points was within normal limits. SV values at all times were within normal ranges (50-110 cm3). SVI values at most times were smaller than normal values (35 - 65 ml/m2), except for at the time of necrotomy (35.03). SVV values at all times were higher than normal (&lt; 20%).Conclusion: Stroke volume variation (SVV) parameters at all study times were higher than normal values corresponding to the age range. The stroke volume index parameter SVI at most times was lower than the normal value, and SVRI at all times was not higher than the normal value. However, the parameters cardiac output (CO), cardiac index (CI), stroke volume (SV), and systemic vascular resistance (SVR) were all within the range of normal values corresponding to the age range at the research time points.

Challenge or Threat? The Effects of the Standard and a Second-Generation Mindfulness Intervention with Buddhist Practices on Cognitive Appraisals of Stress: Secondary Analysis of a Randomized Controlled Experiment Performed in Switzerland.

Contemplative approaches rooted in Buddhist traditions have been linked to the attenuation of response to social stress. Anticipatory cognitive appraisals of social situations potentially represent a mechanism explaining the stress-reducing effects of contemplative practices. The cognitive appraisal of threat is associated with an anticipated loss of social self-esteem. In contrast, the cognitive appraisal of challenge involves recognizing the potential for gain or growth in stressful situations and is associated with a more adaptive cardiovascular response. In this secondary analysis of a randomized controlled experiment performed in Switzerland, we evaluated the effects of two contemplative interventions on cognitive appraisals of challenge and threat and associated physiological profiles. The interventions were a standard Mindfulness-Based Stress Reduction (MBSR) program and a new program (MBSR-B), which included several elements from Buddhist practices. After an eight-week intervention, participants completed the Trier Social Stress Test (TSST) and underwent the assessment of primary cognitive appraisals and cardiovascular response to stress. The results demonstrated greater challenge appraisal in the MBSR (n = 20) and MBSR-B (n = 21) groups compared to Control (n = 24), and MBSR-B participants scored higher on the challenge than threat appraisal. At the physiological level, the groups did not differ on changes in cardiac output and total peripheral resistance. Still, an exploratory analysis demonstrated that the MBSR-B group's cardiovascular profile best resembled challenge appraisal. The results suggest that contemplative approaches foster challenge appraisal, contributing to a more adaptive response to stress.

Modeling of Cross-Coupled AC–DC Charge Pump Operating in Subthreshold Region

This paper proposes a circuit model of a cross-coupled CMOS AC–DC charge pump (XC–CP) operating in the subthreshold region. The aim is to improve the efficiency of designing XC–CPs with a variety of specifications, e.g., input and output voltages and AC input frequency. First, it is shown that the output resistance (Ro) of XC–CP is much higher than those of CPs with single diodes (SD–CP) and ultra-low-power diodes (ULPD–CP) as charge transfer switches (CTSs). Second, the reason behind the above feature of XC–CP, identified by a simple model, is that the gate-to-source voltages of CTS MOSFETs are independent of the output voltage of the CP. Third, the high but finite Ro of XC–CP is explainable with a more accurate model that includes the dependence of the saturation current of MOSFETs operating in the subthreshold region on the drain-to-source voltage, which is a function of the output voltage of CP. The model is in good agreement with measured and simulated results of XC–, SD–, and ULPD–CPs fabricated in a 250 nm CMOS.