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# Input Impedance Measure

149 Threads found on edaboard.com: Input Impedance Measure

## True Large Signal Differential Input Impedance Evaluation

I want to measure differential mode input impedance of true large signal differential driving. Target frequency is around 1GHz. How can I do this task ? I don't mean conversion from large signal single-ended driving like following. {S11, S12, S21, S22} -> {Sdd, Sdc, Scd, Scc}

## [Moved]: dark and illuminate current of a photo diode in a

Do you measure its output as current, or as voltage? To measure output as current, you need a loop of some kind for the current to flow around. It's likely that photodiode output is easier to measure as a voltage, instead of as a current. Photodiode schematics commonly show one terminal going to a high-impedance (...)

## [ASK] Help me measure this graph

Seeing different return loss numbers only means that the antennas have slightly different input impedance. The image might change completely with small variations of the matching network. The most significant information is that the 4x1 array has larger bandwidth.

## measuring impedance using spectrum analyser

i do not have a network analyzer, but i want to measure the input impedance at one of the sma connectors of my ic(supposed to have seen 50 ohm). i have seen some post which can give a basic idea about the matching but they all require tracking generator but is there any other way by which i can see whether the impedance is (...)

## problem with txline and manufacture of microstrips

S11 of the antenna and the transmission line impedance, they are different things. measure the impedance of the transmission line alone, and later measure the input impedance of the antenna without the feeding transmission line (if is possible). measure the real Er of your (...)

## How can one pracatically measure input/output impedance of a circuit?

The terms input impedance and output impedance are used quite often when it comes to amplifiers or when cascading circuits together to determine how each will load the other. While it all makes sense on paper, how can one measure the input and output impedances of a circuit also seeing that (...)

## measuring energy of incoming pulse

Energy is the integral of U x I. I presume we are dealing with constant load impedance, e.g. 50 ohm. So you get E = ∫V?dt. Means the input signal has to be squared before integrating/averaging, either in the digital domain or by analog means.

## How to Measure Tank Impedance of LC Tank in Cross Coupled CMOS Oscillator

Hello, I am designing a CMOS LC Cross Coupled Oscillator in ADS. How do I measure the Tank impedance in ADS - What testbench and set up would I use - would I just measure the input impedance using Zin. I also want to measure the Q of the tank as well to compare both to my hand (...)

## How to measure the line impedance

What kind of measurement instruments do you have available? You can terminate the transmission line with a resistor in the range of the expected transmission line impedance and measure the input impedance versus frequency. ZL can be determined from the observed minimal and maximal (...)

## Impedance measurement scheme

circa 70's-80's , I used to measure input impedance by using the scope X sweep out on the back to drive an FM input sweep generator then examine the envelope ratio on the scope for a linear frequency response. I got fancier by using X sweep out into Channel 1 then use CH1 Out on back of scope to FM input (...)

## Can we measure floating voltage (of power supply) with reference to chassis ground?

Hi, read below "similar threads" In my eyes measuring this voltage makes no sense, because it is "floating". The voltage ins inpredictable an may change any time. (Caused by airflow, humidity, touching, connections of other floating devices...) Additionally the measurement device usually has a finite input impedance, so the (...)

## Transmission Line Input Impedance by monitoring the voltage over the line

Dear, Is possible calculate the imput impedance of a line (unknow Zo) just using the voltage values over the line (graph V versus position) and knowing the load impedance Zl (in my case pure resistive) ? THANKS !!!!

## how to measure input impedance of gilbert mixer in cadence

LO input impedance has less importance compare to RF/IF input impedance because LO port is driven hardly to commutate the mixer pairs.RF/IF input impedance can be found easily by s-parameter simulation or LSSP simulation.Differential impedances are found by termination (...)

## complex impedance covert to RL OR RC circuit

thanks for your input. i know how to calc them, but i want to use a VNA to measure some small rf compnents, so i need a tool. :) maybe i can built a simple program to calc them.

## How to measure and obtain input impedance by R//C model

Hi all, Maybe you've found one input impedance of some RF or microwave device by the model of R//C,for example, the SAW filter is the most popular device in handset phone system and the input differential impedance of SAW filter is often the R//C or R//L model,such as 150Ω//82nH. My question is that how i can (...)

## [CST MWS] How to Find input impedance of schottky diodes via simulation

Hi everyone, Can someone tell me the best way to simulate and measure the input impedance of a Schottky diode in CST MWS? It's an Avago HSMS-285X and a SkyWorks SMS7630 diode. The frequency range is commercial GSM/WLAN. Thanks,

## Battery voltage divider to get hundreds of ?V levelse to measure ADC offset.

Hello. I'm trying to determine the offset of the ADC in my arduino Due, 3,3V reference 12bit SAR ADC. I can put on a small voltage without any transition from 0 reading but I want to know how little it is, 3300mV/4095=0,80586≈806?V LSB My brain does not literally work always as it should and today I can't figure out the simplest of thi

## Return loss vs Gain level

The measure of good performance is good attenuation on the input reflection or in other words high Return Loss. Since it is loss a positive number is used. RL=15dB is generally considered minimum acceptable for simple circuits. impedance is geometric ratio of conductor width to gap to nearest grounds. Uniformity is key and matching (...)

## HSPICE Software/Current Conveyor

I want to measure the input and output impedance (parasitics resistane at X, Y, Z port)of a current conveyor (CC-II) using HSPICE. Please tell me the method.

## IC op amp input resistance or impedance measurement

Troubleshooting boards that are inoperative To test each stages IC inputs and output incircuit I tried using my Digital meter and set it to ohm to measure the IC op amps input The IC op amps input pins should be in the meg ohms from the the datasheets say for a 741 op amp out of circuit input (...)

## Microcontroller ESD level 4 pin protection

I have been looking for a level 4 ESD pin protection on microcontroller pin( pic16f1503). The micro digital input pin is used to measure pulses between 50us to 200us. Do you think a circuit like this would work? R=500 ohms and C=0.01uF VESD=V0=15kv ( Level 4) Vc=V0(1-e^(-t/RC)) Ic=(V0/R)*e^(-t/RC) the RC filter will take 1.67uS t

## Resistance/impedance measurement

Another possible solution.. If you know the components' values and part numbers, you can build the same circuit on a seperate PCB and measure it standalone. Then measure the input impedance of the circuit at the antenna input after that extract the s-parameters of the first copied circuit from these second (...)

## Input imp. of diff. input stage using Port, RFlib balun and AnalogLib ideal_balun

I tried to measure the input impedance of differential input stage of mixer using s2p analysis in Cadence Spectre RF, I got same Z11 in following cases 1) When the Port connected deferentially 2) Using AnalogLib ideal_balun 3) Using RFlib balun (with Balanced output impedance set to 25 Ohms), (...)

## Analog circuit design to measure pH value from sensor.

That link tells you every thing but the things you need to know. Normally PH probes have to operate into an impedance of greater then 500 M ohms and only provide a few mV output. So you need an input amp with an extremely high input impedance which should be protected against static followed by a gain of 1000 or more before (...)

## How to set the termination resistance of a GPS LNA power supply?

Hi, Bigboss, good idea. I will try later. But does anyone can provide a typical value for simulation? At VDD input of the IC, there is probably an internal regulator,a ESD protection diodes, some PAD-nitride capacitances,bonding wire inductances, intrinsic regulator capacitances etc. So, input impedance can be consi

## Measuring Input or Output Capacitance of a buffer

Hi i am trying to measure the input and output capacitance of a buffer stage (for example) as i need to measure several other stages i set up the following circuit 104476 and i set the input voltage to 1.2 with AC Magnitude and Amplitude to 1.2 , also vdd is set to 1.2 then i calculated Zin = I/1.2 * f howe

## Gain changes in Low Voltage Amplifier over the time

I built up simple inverting-Amplifier with LM358 which Gain is R2/R1 = 26. input voltage is 20mV fixed and hence output voltage should be approximately 520mV. the problem is that the output voltage changes over time while the temperature(25°C) and other circumstances are stable. for instance, if output is 520mV today, next week it changes to 530mV

## need help on OVP and OCP circuit

Hi Everyone, I am design a OVP and OCP circuit, and the input voltage is 3.7V~4.2V, max current is 3A. Here are some requirements: 1. The total impedance of the trace should be less than 0.1ohm. 2. OVP threshold is 6V and OCP threshold is 3A. 3. the OVP and OCP circuit can not draw current from the input rail since I will (...)

## measure Zin of an cascode LNA from S parameters

Just s-parameters are enough. Zin\neqZ11 Z11 is "input impedance while the other ports are open".. In order to see the right input impedance, put you marker on the smith chart as " S11impedance" that's it..

## convert frequency counter to Rf frequency counter

At 300mW you won't need any further amplification to measure the frequency. What is the input impedance of your frequency counter? It's probably a safe bet - and especially given its low working frequency - to assume it's high (...perhaps of order ~1Mohm?) The most important thing to be done for the measurement is to (...)

## How to measure input impedence of an opamp?

You have OP common mode and differential input impedance and the input impedance of a specific amplifier circuit. What are you looking for?

## How do you measure the output impedance of an OTA in Cadence?

As a suggestion, should I place a voltage source at the output and inject a current back into the OTA, can I calculate Rout by vsrc / iinput? Or something like that? Yes - that is the classical method. Use a small-signal ac source and provide the proper biasing (operating point). The signal input must be grounded

## Input to ADC from a voltage divider

You did read the ADuCM360 absolute input voltage specification? It's 100 mV in buffered mode, so your measurement probably won't work in this mode. I can generally confirm that the ADuC analog front end works as specified. Without knowing your exact circuit and ADC configuration, it's hard to say what's wrong in your application.

## ac vs dc analysis of a BJT

Thanks Frank. Every parameter in the sense , input impedance , output impedances can be measured ??? Also what is meant by Ft. that you mentioned in your reply Praneeth No - of course, impedances cannot be measured using dc analysis. With dc analyses you can only (...)

## impedance matching for saw sensors ()

If this capacitor is series you should add an inductor in parallel.If it's parallel, you should add an inductor in series. Depends on capacitance configuration. But I'm not sure that the input impedance becomes purely capacitive.Because SAW filters generally have an input impedance with a real part by their nature. There (...)

## Matching fet multiplier question.

yes I would match the input at F0 to get power into the fet. But I would also do something about presenting the right impedance to the gate at 2F0, 3F0..nF0 Similarly I would match S22 at NF0, but the question is: what impedance is optimal for that. it is NOT the S22 you would measure at small signal at nF0. Also, as (...)

The most plausible explanation is that your multimeter has about 10 MOhm input impedance, and you switched it between input and output. You need to connect an equivalent load instead of the multimeter to get the same input voltage when the multimeter is disconnected... To suggest a measurement trick: If (...)

## How to calculate the input impedance?

In my opinion, it doesn't matter so much how you calculate or measure the input impedance as long as you tell how you did calculate/measure it: real circuits never are like an (ideal) VCVS nor VCCS - mostly something in between, and they mostly have defined loads. In a real circuit I'd want to know the (...)

## high input range amplifier

hi guys i wanna build a volt meter from range 500 micro volt to 5 volt i need a front end amplifier or op amp which support this range as its input any suggestion?:-o

## opamp feedback calculation

I would look on the "floating battery" point from the other side. A differential amplifier with finite common mode input impedance has no problems to measure a floating voltage. A floating voltage will be "pulled" to the amplifier ground by the input impedance. But the battery is unlikely to be floating (...)

Neither one.. When you do s-parameter simulation, you should terminate each port with PORT element to able to measure input and output impedances and the Gain.

## Calculation of PULLING resistance for PULL-UP and PULL-DOWN Bidirectional I/O PAD cel

bidirectional pull-up(PDU02DGZ from tsmc) and pull-down(PDD02DGZ from tsmc) cells. Help me how to simulate for pulling resistance. I/O pad cells' output always can be disabled (OEN=1 , input state is irrelevant). Run a DC analysis and measure the output impedance.

## how to measure input impedance of a power detector (diode detector) circuit

Hi all, I got zero bias shottky diode based power detector. It gives DC output upto -30 dBm power input. I want to measure input impedance of this circuit. I just connected the input of the circuit to VNA port 1; it shows about -3 dB in magnitude plot. 1. Is the method I used to (...)

## Impedance measurement using I/Q demodulation

Hello! I want to measure an unknown impedance using an I/Q demodulator. Setup: I was thinking of using a DDS (Direct Digital Synthesizer) as the sine wave signal generator. Splitting this signal to a reference signal and an excitation signal. The reference signal will go directly to the LO input while the excitation signal will go (...)

## HS1101 humidity sensor

We've already established that the ADC input is not high impedance. Maybe another approach would be to apply a square wave to the RC, and measure the peak output voltage, since it would essentially be a low pass filter.

Using high resistor values will give you wrong results due to the slow charge rate of the S&H capacitor but if the signal you measure is not a rapidly changing one you can use a capacitor at the ADC input that can act as a reserve and present a low impedance to the ADC input It is also a good idea to use Schottky diodes (...)

## 50 ohm antenna matching

To be able to measure various impedances, there is a general concensus to use 50 Ohms for signal sources, transmission lines and loads. In your case the receiver input may be matched (i.e. having the impedance of ) 50 Ohms as well as the antenna. Antenna impedance often differs (due to conductive objects in (...)

## S-parameter measurements

The RF input power for the transistor (or the output from network analyser) is indeed 0dBm. Do I need any higher value for S-parameter measurement? 0 dBm is 0.77 V into a 50 Ohm load, and up to 1.54 V into a high impedance load. You should measure with less power.

## Accurately measure voltages across loop antennas

I would measure using the usual instruments (network analyzer or signal generator + spectrum analyzer/power meter) with some high impedance (kOhm) voltage divider at the loop antenna. This gives you (relatively) high impedance to measure the voltage. Calculating the attenuation caused by the voltage divider to the 50 ohm (...)

## how to determine RF receiver input impedance

Hello, I'm making a very low bandwidth 40MHz receiver. The receiver is fairly simple: an LC input filter and two FET gain stages go into an ADC. I'm using an "electrically small" strip-line antenna which of course has a tiny input impedance: ~1.96 -j1758. Do I need to add a matching network even though it's at such low frequency? The (...)