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203 Threads found on edaboard.com: Isolation And Resistor
HI, Like I remember the resistor (in theory) suppose to be 100 omh, and you need it for improve isolation and return loss of the ports. if you need a formula tell me!! David
This is a simple well resistor under STI (Field), the cross section shows an NWell resistor. For better isolation the resistor could sit in another well (for a triple well process). It could also be surrounded by an isolation ring and could have a metal field plate over the top of the (...)
hi in our design we've used a parallel RC circuit for Chassis ground and Digital ground isolation the resistor value is 1M ohm and the capacitor is 1000pf_2KV i was told that it's basically for "EMI ,EMC and ESD protection":?: i would like to know why exactly it is used and how (...)
BUT in real live take and perform measurements (before and after removing the resistor) with network and u will see that RL at output side will be practically the same , with small degradation Interesting. Maybe your measurement ignores physics and math basics? For the power divider that I developed (...)
Dear Basil, The datasheet you uploaded describes: "Splitters are used extensively in wireless signal distribution networks, to split the base station transmitted signal, Tx, into many different paths to reach multiple antennas, ...." It is clear that what is being regarded in the datasheet is a power splitter to be used to feed power to an ante
I have saw a 6-finger mutiple line design ,it use a little cap shunt with the isolation term resistor to compensate.another problem:when I use ADS2002 to design such a coupler,the EM simulate results sames have much difference with schematic results ,so I think the 6-finger lange passive model ADS2002 use maybe not so exact.but how to do a calibrat
If you need only to make a fact: is ringing voltage or not, use opto isolation and a capacitor to block dc voltage. If you need to know what exactly voltage is, use AD on line side (powered from the line), then opto isolation use between AD and uC.
Hi, You could try a Wilkinson type divider, and use coaxial cable for the 2 transmission lines. This is basically composed by 2 quarter wavelength 70.7 ohm transmission lines, which transform the impedance of 50 ohm at the terminations to 100 ohm.The 100 ohm resistor across improves the isolation and the output match. (...)
Hi, trail. A PUN Diode switch is just a current controlled resistor. A simple design can be a shunt diode (one end to the ground) connected to a TX line. When forward biased, the switch acts as a short circuit, reflecting any RF signals entering either ends of the TX line. It seems that you have poor isolation ( as you say you apply the s
anyone know how a series 18ohm resistor comes up for the isolation between VDD and the power supply? why not other value?
Hi, There are several drawbacks of having long(er than needed) lines. 1. Losses will increase 2. Exact phasing of the divider network is difficult in practice. As Flatulent poined, your bandwidth will narrow even in theory when you add extra multiples of quarter wavelength. However, in practice things are going to be even worse as exact elec
The cbe structure will have a larger collector-substrate capacitance than the cbe structure. In addition, dependent on the design rules, the cbe structure will have slightly higher collector-base capacitance (Cbc) due to the collector and base electrode being minimum space from each other. In some double poly bipolar technologies, you will also g
I used Wilkinson 2-way splitter/combiner to combine PA power. The frequency is 900MHz. The port 2 power is 20W, and port 3 is also 20W, so port 1 is 40W. Normaly, the balance resistor (100Ω) is lossless and can provide good isolation between port 2 and port 3. But how to choose the power rating for the (...)
In this case you will need to use a resistor of,say 100kΩ, to provide a reference between 0Vdc of the HV output and the housing (I assume that the MCU GND is identical with the potential of the housing). Using resistors as a voltage divider divide the output voltage of 230Vdc to something that can be measured, say 5Vdc. If the (...)
Hi friends, I have build a water tank controlling system, Using normal metallic probes as sensor. As for power supply i'm using normal Stepdown transformer 230v ac to 6-0-6 v and diodes and regulator with capacitors. Now what i'm afraid is, in INDIA due to voltage fluctuations the transformer burners out and there is current leakage (...)
If you dont worry about isolation, and you may consider 10:1 or similar isolation transformer, here is a simple circuit that will convert +230 to -230 to 5V-0V .. You may feed the output directly to ADC pin or you may use a unity gain buffer (opamp) .. Just add a 5.1V zener diode .. This circuit has a small drawback: at 0V input the (...)
Sometimes putting a capacitor in parallel with the resistor greatly improves isolation. Try using a 120ohm resistor so that the parallel cap brings it down closer to 100ohms. The cap basically reduces the inductance of the resistor and reduces the phase delay through the resistor. (...)
It can serve as an isolation for high frequency noise since this O ohms are inductive in nature!
I don't understand why you installed the transorbs from each line to the chassis. I think you should have installed one from each line to ground. After all, you need protection from overvoltages between these lines. Then you can install something else from ground to chassis, like a single transorb that would give you the required isolation. Or
Hello I'm now designing a 5 stages 'cascade' Wilkinson power divider (bandwidth 0.5GHz -6.5 GHz) on RF-60A (Er=6.15, H=1.542mm)according to "A general design formula of multi-section power divider based on singly terminated filter design theory". With the value I calculated according to the specifications in my case, I can have exactly the
Hi If you for example have a two way wilkinson power splitter, and one output is disconnected. Half of the power is transmitted to one port and the other half is dissipated in the isolation resistor. Regards
Hi, Is someone able to solve any doubt I have about the circuitry which must be set between the LAN PHY chip and the RJ45 connector? I know it is necessary to set a transformer, and I guess it works as an isolation protector against voltage peak coming from the RJ45 connector, but actually I cannot explain some physical aspects of its (...)
Hi, One can apply even-odd mode analysis to understand the operation of Willkinson divider. Even mode: the middle point of resistor is open circuit and resistor is not contained in the circuit, so the even part is indeed losless. Odd mode: the middle point of resistor is short circuited so the (...)
OD stands for the thin oxide region or active area. STI stands for shallow trench isolation (opposite of OD) In an OD NWELL resistor the resistor is formed in an active area. In the case of an STI NWELL resistor it is formed under the STI oxide. The models for these two (...)
Total isolation and in the same time dc leakage detection is not possible .. Unfortunatelly, you need a common reference to monitor any leakages or shortcircuits .. One method is to introduce a dc offset (say 10Vdc - now your 0V is 10V and 12V becomes 22V) through a high-ohm resistor (something like 10MΩ) (...)
I am facing one problem in ADS momentum, i am designing Wilkinson power divider. i have done the lay out. and trying to tune it in 1 Ghz. but the problem is coming due the isolation reistor 100Ω, connected b/n the two o/p. i am confused abt the choosing the resistor. what kind of resistor should i choose ? thats why o/p (...)
I have a optocoupler input with a resistor and reverse voltage protection diode. See basic circuit attached. The opto is a ACPL-217-500E device from Avago and is rated for 3000Vrms isolation and 10kV/us (CMR). My questions are as follows: 1: How does the CMR rating actually relate to ESD? (ESD (...)
I have used resistive dividers @ 3 GHz with no problem. Of course you get a losses compared to conventional wilkinson divider. But in case you do not mind burning half of the power in the divider resistors and you don't mind that the isolation between output ports is only 6 dBs, then resistive power divider is most simple solution (...)
Can anybody tell me how to choose the Power Rating of isolation resisters while designing Power Divider?
Its easy, Use transformer for best isolation and conversion of voltages to low rang and use ADC to measure your voltage. but you need to make a lookup table for translating ADC values to voltages scaled from 240 to 5-10 volts by transformer.
Seriously, the question for best method can't be answered without a full specification. An AC only measurement generally suggests a current transformer or di/dt sensing (Rogowski) coil. Both provide high bandwidth, isolation and low interference susceptibility, the latter also insensitiveness to DC currents and (...)
Hi, To Measure voltage :- Just drop the voltage by using step down transformer. After that check whether isolation is needed. If yes than use Opto coupler for isolation. To measure current :- For Current there is three different technology 1. With Sense resistor 2. Current Transformer 3. Hall Effect Sensor. Use any one & after (...)
Hi Simply use 1:1 isolation transformer to isolate the 220V from main and then use the 1:20 resistor divider Also you can use measurement IC like ADE7753 from analog and optocupler to measure voltage and current from 220V rail Please remember to act with caution when using high voltage All (...)
Many audio opamps are wideband and therefore oscillate at a high frequency if they drive the fairly high capacitance of a shielded audio cable. A 100 ohm resistor from the output of the opamp circuit isolates the cable capacitance and prevents oscillation. Inside a receiver there might not be shielded cable or its length is (...)
using a transformer or a gate driver are better solutions ,since it provide isolation, and reduce the stress for some components.
Hi, Have looked at your design, but not your code. The circuit is really wrong, R3 is at 10k so it will never turn on the optos led. Your AC circuit is connected to the 0v of the Pic - so you do not have any isolation ! If you search on this string, as I have just done, you will find similar circuits in this forum that should show you h
Hi guys, I want to isolate two voltage supplies that I have in spice, I mean I do not want to connect their negative side together( In experiment, easily I do not connect) but what about in spice? I want to use one of the voltage supplies as a floating volatage supply. any idea will be appreciated, Thanks, Ela
There is the problem with isolation. Enough power could leak from one transmitter to the other to damage the other receiver. I would suggest not doing this.
Hi, I am using 8051 for serial communication. It talks with another microcontroller at TTL level. So I think there is no need for MAX232. Am I correct ?. Is it enough if I connect tx of miconA to rx of moconB and rx miconA to tx of miconB. Is it like this or I need to connect some other way?. If I want to isolate this path, how can I do that?. Re
can i use an optocoupler which will provide a better isolation also.
FIRST and FOREMOST - the circuit is connected directly to AC mains and is therefore potentially lethal to touch - make sure you respect that before going any further. There are several ways to do what you want although most use a different method to fire the triac. In your case, you absolutely MUST isolate the control circuit (0 - 5V circuit) fro
I've done this a couple of times. The line is normally 50vdc, either polarity and when the phone rings there is 75v ac on the line. If you feed the line to a bridge rectifier and then to a voltage detector, when the voltage exceeds say 60v you can turn on the led in a opto isolator via a zener diode circuit to give you a ringing signal. T o off
Hello, Do you know where I can source high-voltage , low-power 1 MegOhm resistors for paralleling with Y caps, which bridge the primary ? to ? secondary isolation barrier in an offline SMPS? These resistors must withstand the 3500VAC HiPot isolation tester. -Though I cannot find (...)
Hello everyone, its my first post here. I have two separate issues in which I require your input, thanking you in advance. Low powered design is not a priority in this prototype. 1. I have a relay JQC-3F, 12V relay which has an internal resistance of 400 ohms at 12V meaning the drive current required to run the relay is 30mA. I selected a singl
Yes you can do it this way, but in order to avoid any additional current dividers, why not to use a 40-50A sensor? See for example: Allegro | Products | ACS756 Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 3 kVRMS Voltage isolation and a Low-Resistance Cu
Hello everyone I have a RS485 based relay control hardware. I need to transfer a ground signal to a remote component. Once the component is on (by receiving my ground signal), it sends a back indication in form of ground signal which is received at AT89C51. I have isolated the ground sent/received to/from the component using optocouplers. I need
1:what is the output of the pin7 of the hcpl-7840? how about the pin6? is it sinusoidal waveform? Yes, if apply some sinusoidal waveform on the shunt resistor. The HCPL-7840 consists of a sigma-delta analog-to-digital converter optically coupled to a digital-to-analog converter. 2:what is the output of the mc34082a whi
Rogers 4350 material should work fine at least up to 10GHz. To get good isolation at high frequencies must have the right terminating impedance at the other port (where you placed a 51 ohms resistor). The 50 ohms load resistor should have minimum parasitic inductance (preferable is to place 3 x 150 ohms SMD resistors in (...)
Hello, As you may know there is lots of info on the SEPIC topology on the web. I think best is to try to figure out how it functions (what are the voltages and currents in each component for your output requirements). When done, you have some idea of the components you require. the inductors will be the hardest ones. If you have specific proble
The resistor / capacitor circuits are simply voltage dividing ; and can only be use (with a lot of care as there is no isolation) for low load current applications. Isolated opamps are used for signal only (no power transfer) and use magnetic or optical isolation techniques