[introduction] become more and more complex as the addition of working frequency and electronic system and smaller and smaller, design personnel must pay close attention to capacitor ESR closely, because it can affect power,be used and efficiency.

Become more and more complex as the addition of working frequency and electric subsystem and smaller and smaller, design personnel must pay close attention to capacitor ESR closely, because it can affect power,be used and efficiency.

The ESR cost that understanding expects to working requirement falls can help affirmatory and specific capacitor whether suit to carry out greatly give a function.

A few manufacturer appoint the ESR below specific frequency and working requirement, a few define dissipation factor, and other manufacturer both neither offers ESR to also do not offer dissipation factor.

Resistor of equivalent series connection (one of blame ideal character that ESR) is capacitor, may bring about electronic circuit to appear all sorts of performance issues. Because loss of I 2 R, noise is mixed taller pressure fall, tall ESR value can reduce performance.

In certain applying, the quantity of heat that ESR produces is very small, the likelihood is not a problem. However, in certain circuitry, especially in application of big electric current, the quantity of heat that send out may cause apparent temperature rise, those who affect circuit move, make capacitor function drops. In addition, resistor two end can appear a large number of voltage drop, the one part in reducing application thereby is useful energy.

Accordingly, collect for radio frequency, energy, when the application such as filter wave circuit and other and sensitive circuit chooses capacitor, need considers the other character beyond capacitance and voltage value.

ESR collects the influence of circuit to radio frequency and energy

Although the ESR of capacitor of pottery and porcelain is very small (fine long hair Europe class) , this resistor also can show the circuit such as influence radio frequency and low power circuit.

In hand-held RF emitter, amplifier leaks extremely coupling or source extremely as a result of,the tall ESR capacitor in bypass class is met loss of higher I 2 ESR and use up and waste more batteries n. This meeting lowers output of efficiency, power and battery life.

In addition, great majority has low-down to input impedance with the RF semiconductor device at matching level. Accordingly, a distribution container that has tall ESR (for example multilayer capacitor of contented ceramics type (MLCC) ) showing those who occupy whole network impedance percentage. For example, if the input impedance of equipment is 1 ohm, about 40% what ESR is 0.8 ohm, reduce output power and circuit efficiency thereby.

Energy collects the capacitor in application to producing mainer effect, can accumulate charge from inside low-pressure the sources of energy, the energy that releases memory effectively quickly is laden power supply. Accordingly, energy collects the capacitor in circuit and other component to should consume very little power during move.

Tall ESR capacitor can have losses of more I 2 ESR, such a few captured energy can be wasted with caloric form eventually, what reduce capacitor thereby is energy out-put. However, design personnel may prefer super capacitor (although they have taller ESR and leak) , because they offer higher energy density.

Use ESR plan affirmatory ESR

ESR expresses the instrument that is moderate of a kind of precision, price moderate and use convenient, measuring especially still be when the many capacitor in circuit. In configuration of voltage divider network, alternating voltage is brought to bear on capacitor. The frequency that uses alternating current is the value that capacitor reactance can ignor normally.

Graph 1.  The simple die that ESR measures. The picture is offerred by Kerry Wong.

During use ESR watch has a test, the time that electric current passes capacitor is very short, because this capacitor won’t be complete,charge. Electric current in capacitor two end produce tension. The small charge that this voltage increases the ESR that is electric current and capacitor and but the product of the voltage of oversight.

Because electric current is foregone, ESR value is come with electric current through dividing metrical voltage calculative. Show as a result next go up in appearance reading.

ESR test can be in capacitor in circuit or outside circuit when undertake. To shunt-wound connective capacitor, measure give out total resistor. If want to decide the individual ESR of specific capacitor, must move except specific capacitor. However, if have hundreds capacitor, criterion of every capacitor disassemble very trival, and disassembling attaint capacitor can increase in the process or the risk of circuit board.

Typical ESR watch uses the 250 MV of peace treaty of high frequency electric current that makes an appointment with 100 KHz or lower low pressure. Low voltage can’t slant the circuit is medium semiconductor device all round buy and activation, ensure the impedance of around component won’t affect ESR reading.

Before measuring, should discharge capacitor. Watch of a few ESR is had inside buy discharge mechanism. But, it is very important to capacitor discharge that the hand is moved, especially if it is high-pressured capacitor, its charge can damage ESR plan.

Although ESR watch can check online capacitor easily, but it has frequency limitation and OK and accurate metrical resistance level.

Use at high frequency the coaxial and syntonic canal that exceeds low resistance is measured

As a result of ESR the value depends on working frequency, because this is when watch of use tradition ESR, measure below very tall frequency exceed low ESR value to make a challenge.

To capacitor of pottery and porcelain, affirmatory and high frequency (100 MHz comes 1.3 GHz) the accurate method of ESR is law of coaxial and syntonic line. This technology is based on standard of Boonton model 34A, use together with RF signal generator and RF volmeter.

Graph 2. Coaxial resonance runs block diagram. Picture by Knowles Capacitors (PDF) is offerred.

Coaxial resonator the line is made by copper pipe, it is central conductor with sincere copper club. Series connection of the capacitor that be measured is placed between central conductor and ground connection conductor.

Before undertaking to capacitor ESR is measured, the sky that must fix resonator line above all holds character. The RF drive of coaxial to short circuit line conduces to affirmatory λ / 4 with 3 λ / 4 bandwidth, and λ / 2 with λ bandwidth be build when circuit open a way (what λ points to is wavelengh; About pertinent information, consult please article) .  This data token the sky of syntonic frequency, syntonic line carries Q and clamping apparatus resistor.

The capacitor that will check next is placed in DUT (the equipment that be measured) part, be aimed at signal generator of tuning of voltage of peak value resonance. Capacitor can bring about syntonic frequency and Q factor to produce change, its value differs with the cost that holds coaxial line for nothing now. Use transmission line calculation, the relation between the frequency that carries a condition to fall according to new frequency and Q value and initiative sky and Q value decides ESR is worth.

Graph 3. To load and the bandwidth that uninstall transmission line. Picture by American Technical Ceramics (PDF) is offerred.

Nowadays, normally the practice is to use vector network analyzer to replace signal generator and radio frequency volmeter. Use VNA, can read from indication screen take syntonic frequency. Certain VNA model can derive the result computational program shows directly eventually ESR value.

Work of tubal long design is in about 100 MHz arrives inside the frequency limits of 1.5 GHz; But, can think the frequency that exceeds this range is custom-built length.

Affect the factor that ESR measures

ESR measures an error may be caused.

The resistance that must consider to measure instrument and its down-lead, from feeling and capacitance, be in especially tall measure frequency to fall.

Check down-lead resistor and inductance

The resistor that checks down-lead is the error source that low resistance measures middling to see. This resistor increased DUT resistance.

In addition, should avoid to use shrink oneself type helix twines test lead, because their inductance may be error source.

Come from the interference of around equipment

Measure should be in be far from or screen is showing EMI (electromagnetism is disturbed) the area of the source undertakes. Otherwise, test lead may be disturbed, this may affect reading.

Conclusion

ESR because capacitor type and working requirement (be like frequency and temperature) and different. A few manufacturer appoint the ESR below specific frequency and specific work requirement, other manufacturer offers dissipation factor only, and other manufacturer both neither offers ESR to also do not offer dissipation factor. However, the ESR cost that understanding expects to working requirement falls can help affirmatory and specific capacitor whether suit to carry out greatly give a function.

The methodological type that is used at deciding ESR depends on frequency of capacitor type, job and place require the element such as precision. Although ESR plan and other DIY measure enough,contented frequency is as high as a lot of application of 100 KHz left and right sides, but they cannot fall in extremely high frequency rate accurate and extremely affirmatory low ESR cost. When low ESR exceeds to be worth certainly below the frequency between 100 MHz and 1.3 GHz about, coaxial is normally syntonic line means.

Become as the addition of working frequency and electric subsystem more and more Xiaohe is more and more complex, must pay close attention to the parameter such as ESR closely, it affects circuit function and power source efficiency directly.

Avoid duty statement: The article is reprint an article, reprint this article purpose to depend on passing more information, the person that copyright puts in original work ‘s charge is all. If involve work copyright issue,article place uses video, picture, written language, contact please small make up undertake handling.