Achieving optimal power transfer in RF PCBs hinges on meticulously routed traces that meet specific impedance requirements. Impedance matching is essential to ensure that traces have the same impedance to prevent signal reflection and inefficient pow...(read more)

Dear Community,

I have created a PCB board and let's say I have found some parts of the PCB board where there are impedance issues, then how to resolve that impedance issue using the OrCAD X Professional.

Regards,

Rohit Rohan

The proton-conducting material (NH4)4H2(SeO4)3 is examined to check whether its conductivity spectra are sensitive to subtle changes in the crystal structure and proton dynamics caused by external pressure. The AC conductivity was measured using impedance spectroscopy, in the frequency range from 100 Hz to 1 MHz, at temperatures 260 K < T < 400 K and pressures 0.1 MPa < p < 500 MPa. On the basis of the impedance spectra, carefully analyzed at different thermodynamic conditions, the p–T phase diagram of the crystal is constructed. It is found to be linear in the pressure range of the experiment, with the pressure coefficient value dTs/dp = −0.023 K MPa−1. The hydrostatic pressure effect on proton conductivity is also presented and discussed. Measurements of the electrical conductivity versus time were performed at a selected temperature T = 352.3 K and at pressures 0.1 MPa < p < 360 MPa. At fixed thermodynamic conditions (p = 302 MPa, T = 352.3 K), the sluggish solid–solid transformation from low conducting to superionic phase was induced. It is established that the kinetics of this transformation can be described by the Avrami model with an effective Avrami index value of about 4, which corresponds to the classical value associated with the homogeneous nucleation and three-dimensional growth of a new phase.

The proton-conducting crystal (NH4)4H2(SeO4)3 is examined to check whether its conductivity spectra and the phase transition to the superprotonic phase are sensitive to subtle changes in the crystal structure and proton dynamics caused by various thermodynamic conditions. It is established that the kinetics of this transformation can be described using the Avrami model with an effective Avrami index value associated with homogeneous nucleation and three-dimensional growth of a new phase.

Diagnosis of high impedance fault (HIF) is a challenge for nowadays distribution network protections. The fault current of a HIF is much lower than that of a normal load, and fault feature is significantly affected by fault scenarios. A detection and feeder identification algorithm for HIFs is proposed in this paper, based on the high-resolution and synchronous waveform data. In the algorithm, an interval slope is defined to describe the waveform distortions, which guarantees a uniform feature description under various HIF nonlinearities and noise interferences. For three typical types of network neutrals, i.e.,isolated neutral, resonant neutral, and low-resistor-earthed neutral, differences of the distorted components between the zero-sequence currents of healthy and faulty feeders are mathematically deduced, respectively. As a result, the proposed criterion, which is based on the distortion relationships between zero-sequence currents of feeders and the zero-sequence voltage at the substation, is theoretically supported. 28 HIFs grounded to various materials are tested in a 10kV distribution networkwith three neutral types, and are utilized to verify the effectiveness of the proposed algorithm.

A device for electroimpedance tomography with an electrode belt (2), which has electrodes (E1 . . . E16), wherein at least two groups (5, 6) of electrodes located next to each other are formed and the electrodes of one group are contacted with at least one, multiwire feed cable (7, 8). For a reduced noise level during data acquisition, provisions are made for at least one electrode (E9) of two mutually adjacently located electrodes (E8, E9) of two different groups (5, 6) to have an additional electrode feed line (15), which is led over the feed cable (7) of the adjacent group (5).

A device and method for accurately characterizing tissue impedance employs multiple electrodes at a plurality of separation distances to cancel the effects of front end loading leakage currents and electrode polarization to improve the accuracy of sensitive impedance measurements used to identify cancerous tissues. These measurements may be automated over a range of frequencies.

A device is described for measuring electrical characteristics of biological tissues with one or a plurality of electrodes and a processor controlling the stimulation and measurement in order to detect the presence of abnormal tissue masses in the breast and determine probability of tumors containing malignant cancer cells being present in a breast. The device has the capability of providing the location of the abnormality, at least to the quadrant. Either single or multiple source electrodes can be used. Either palpable lumps can be evaluated or screening or breasts, whether with palpable masses or not, can be accomplished. The method for measuring electrical characteristics includes placing electrodes and applying a voltage waveform in conjunction with a current detector. A mathematical analysis method is then applied to the collected data, which computes spectrum of frequencies and correlates magnitudes and phases with given algebraic conditions to determine mass presence and type.

The systems and methods of the present disclosure calibrate impedance loss model parameters associated with an electrosurgical system having no external cabling or having external cabling with a fixed or known reactance, and obtain accurate electrical measurements of a tissue site by compensating for impedance losses associated with the transmission line of an electrosurgical device using the calibrated impedance loss model parameters. A computer system stores voltage and current sensor data for a range of different test loads and calculates sensed impedance values for each test load. The computer system then predicts a phase value for each load using each respective load impedance value. The computer system back calculates impedance loss model parameters including a source impedance parameter and a leakage impedance parameter based upon the voltage and current sensor data, the predicted phase values, and the impedance values of the test loads.

An electrode assembly that includes an electrically conductive layer, a first impedance reduction system, and a second impedance reduction system. The electrically conductive layer forms an electrode portion of the electrode assembly and a first surface to be placed adjacent a person's skin. The first impedance reduction system is configured to dispense a first amount of an electrically conductive gel onto the first surface of the electrically conductive layer in response to a first activation signal. The second impedance reduction system is configured to dispense a second amount of the electrically conductive gel onto the first surface of the electrically conductive layer in response to a second activation signal.

An impedance tuning circuit includes a calibration unit and a post-processing unit. The calibration unit generates an initial pull-up code and an initial pull-down code by performing a calibration operation using an external resistor during an initial impedance tuning operation. The post-processing unit outputs the initial pull-up code and the initial pull-down code as a final pull-up code and a final pull-down code during the initial impedance tuning operation, and generates the final pull-up code and the final pull-down code by using the initial pull-up code and the initial pull-down code during a subsequent impedance tuning operation.

Systems and methods for switching impedance are provided. In some aspects, a system includes first and second impedance elements and an impedance switch module, which includes a third impedance element coupled between the first and second impedance elements and a switch parallel to the third impedance element. The switch is coupled between the first and second impedance elements, and is configured to switch between an open configuration and a closed configuration. An electrical path is completed between the first impedance element and the second impedance element via the first switch in the closed configuration. The electrical path is not completed in the open configuration. A total impedance of the first impedance element, the second impedance element, and the impedance switch module is varied based on the switching between the open configuration and the closed configuration.

An improved grounding technique for mechanically adjustable rotary capacitors uses a directly grounded bronze sliding contact to effectively and continuously ground the rotating comb-like blades of the capacitor. RF measurements of the continuity and repeatability of the capacitance settings prove the suitability of the modified capacitors for using in pre-calibrated multi-capacitor MHz range impedance tuners.

A transceiver includes an antenna, an impedance adjustment device, an RF (Radio Frequency) front-end circuit, a storage device, and a processor. The antenna receives an RF signal. The impedance adjustment device is coupled to the antenna, and includes a plurality of branch circuit with different impedance values and a switch module. The processor is coupled to the RF front-end circuit and controls the switch modules. In a comparison mode, the switch module selects to connect to the branch circuits individually, and the processor detects each RSSI (Received Signal Strength Indications) value corresponding to the branch circuit and records all of the RSSI values to the storage device respectively. In the comparison mode, the processor further compares the RSSI values to for highest one. Finally, the switch module selects the branch circuit corresponding to the highest RSSI value as a transmission branch.

The present invention is directed to an impedance transformation device for use in a system having a characteristic system impedance, the device being characterized by a predetermined bandwidth having a center frequency. The device housing size is one-eighth wavelength of the center frequency. A first coupler is characterized by an even mode impedance and an odd mode impedance. The bandwidth is a function of the even mode impedance and the odd mode impedance substantially corresponds to the component port impedance. At least one second coupler is disposed in parallel with the first coupler and is characterized by the even mode impedance and the odd mode impedance.

A direct feeding apparatus for impedance matching of a wireless power transmission device includes a helical type resonator, and a feeding unit configured to directly feed power to a region having a relatively small current value as compared to a center of a conductive line of the resonator.

A TIA circuit and method are provided that merge the automatic gain control function with the bandwidth adjustment function to allow the TIA circuit to operate over a wide dynamic range at multiple data rates. The TIA circuit has an effective resistance that is adjustable for adjusting the gain and the bandwidth of the TIA circuit. The mechanism of the TIA circuit that is used to adjust the effective resistance, and hence the gain and bandwidth of the TIA circuit, is temperature independent, and as such, the performance of the TIA circuit is not affected by temperature variations.

High impedance, high frequency nanoscale device electronics configured to interface with low impedance loads include an impedance transforming stage constructed of multiple nanoscale devices, such as carbon nanotube field-effect transistors. In an embodiment of the present invention, an impedance transforming output stage of a multistage amplifier is configured to drive a 50 ohm transmission line with unity voltage gain using multiple carbon nanotube field-effect transistors in parallel. In a further embodiment, a receiver provided for an electronically steered receive array is a monolithic, lumped-element system formed from nanoscale devices and configured to interface with the external electrical systems via a single transmission line.

An amplifier circuit amplifies a signal for wireless transmission. A feedback circuit, including a capacitor, is coupled to the amplifier circuit. Components of the feedback circuit are selected based on a feedback factor such that an input impedance to the amplifier circuit has a same impedance characteristic as a feedback circuit impedance of the feedback circuit.

An automatic antenna impedance matching method for a radiofrequency transmission circuit. An impedance matching network is inserted between an amplifier and an antenna. The output current and voltage of the amplifier and their phase difference are measured by a variable measurement impedance, and the complex load impedance of the amplifier is deduced from this; the impedance of the antenna is calculated as a function of this complex impedance and as a function of the known current values of the impedances of the matching network. Starting from the value found for the impedance of the antenna, new values of the matching network are calculated that allow the load to be matched to the nominal impedance of the amplifier. The measurement impedance has a value controllable by the calculation processor according to the application and notably as a function of the operating frequency and of the nominal impedance of the amplifier.

An antenna system including: a metal base plate; an antenna element arranged on and extending away from the front side of the base plate; a circuit board including a ground plane, adjacent to, and in thermal contact with the base plate; a plurality of electrical components on the circuit board including a power amplifier and an I/O connector; a metal support plate separated from, parallel to, and facing the base plate, with the circuit board located between the base and support plates; a plurality of thermally conductive standoffs thermally connecting the base plate to the support plate; and a master board including an I/O connector mating with the I/O connector on the circuit board and electrically connecting the circuit board to the master board, the master board located between the circuit board and the support plate and including signal paths for routing signals to the circuit board.

Have you ever manufactured a printed circuit board (PCB) without analyzing all the routed signal traces? Most designers will say “yes, all the time.” Trace widths and spacing are set by constraints,...

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Have you ever manufactured a printed circuit board (PCB) without analyzing all the routed signal traces? Most designers will say “yes, all the time.” Trace widths and spacing are set by constraints, and many designers simply don’t h...(read more)

Hi,
I am new to the circuit design and troubleshooting. My project is to design a trans-impedance amplifier using Cadence that can amplify a signal coming from a photodiode. I started out with the regulated cascode configuration as shown in the circuit below. I look at the frequency response using AC simulation and it looks like a high pass (/net 5). The results doesn ot show any gain (transient response), or expected low-pass roll-off in the AC response.

First thing, I looked into the operating regions of the MOSFETs and adjusted the input dc voltage of the Vsin to 0.5 to make sure that the T0, T1 mosfets are in saturation(checked this with the print->dc operating points). Beyond this point, I am not sure on how to proceed and interpret the results to make changes. Any help would be greatly appreciated.

Thanks,

-Rakesh.

BACKGROUND:Electrical impedance tomography (EIT) is a noninvasive, portable lung imaging technique that provides functional distribution of ventilation. We aimed to describe the relationship between the distribution of ventilation by mode of ventilation and level of oxygenation impairment in children who are critically ill. We also aimed to describe the safety of EIT application.METHODS:A prospective observational study of EIT images obtained from subjects in the pediatric ICU. Images were categorized by whether the subjects were on intermittent mandatory ventilation (IMV), continuous spontaneous ventilation, or no positive-pressure ventilation. Images were categorized by the level of oxygenation impairment when using SpO2/FIO2. Distribution of ventilation is described by the center of ventilation.RESULTS:Sixty-four images were obtained from 25 subjects. Forty-two images obtained during IMV with a mean ± SD center of ventilation of 55 ± 6%, 14 images during continuous spontaneous ventilation with a mean ± SD center of ventilation of 48.1 ± 11%, and 8 images during no positive-pressure ventilation with a mean ± SD center of ventilation of 47.5 ± 10%. Seventeen images obtained from subjects with moderate oxygenation impairment with a mean ± SD center of ventilation of 59.3 ± 1.9%, 12 with mild oxygenation impairment with a mean ± SD center of ventilation of 52.6 ± 2.3%, and 4 without oxygenation impairment with a mean ± SD center of ventilation of 48.3 ± 4%. There was more ventral distribution of ventilation with IMV versus continuous spontaneous ventilation (P = .009), with IMV versus no positive-pressure ventilation (P = .01) cohorts, and with moderate oxygenation impairment versus cohorts without oxygenation impairment (P = .009). There were no adverse events related to the placement and use of EIT in our study.CONCLUSIONS:Children who had worse oxygen impairment or who received controlled modes of ventilation had more ventral distribution of ventilation than those without oxygen impairment or the subjects who were spontaneously breathing. The ability of EIT to detect changes in the distribution of ventilation in real time may allow for distribution-targeted mechanical ventilation strategies to be deployed proactively; however, future studies are needed to determine the effectiveness of such a strategy.

Background and objectives

Bioelectrical impedance analysis (BIA) devices can help assess volume overload in patients receiving maintenance peritoneal dialysis. However, the effects of BIA on the short-term hard end points of peritoneal dialysis lack consistency. This study aimed to test whether BIA-guided fluid management could improve short-term outcomes in patients on peritoneal dialysis.

RF port impedance verification

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