[introduction] although can use special device to carry out frequency,answer an analysis, but also can use newer oscillograph to measure power source operating ring of the road answer. Source of use oscillograph, signal and automation software, can undertake metrical quickly and appear with familiar Bodetu. This makes evaluate abundant to measure and have circuit function and model comparative becoming easy. The frequency that Bodetutong passes system of two graphs scale is answered — amplitude graph and phasic graph (the phase shift that is an unit in order to spend) . From inside these graphs abundant of OK and affirmatory gain is spent and phasic abundant is spent in order to measure power source stability.

Although can use special device to carry out frequency to answer an analysis, but also can use newer oscillograph to measure power source operating ring of the road answer. Source of use oscillograph, signal and automation software, can undertake metrical quickly and appear with familiar Bodetu. This makes evaluate abundant to measure and have circuit function and model comparative becoming easy. The frequency that Bodetutong passes system of two graphs scale is answered — amplitude graph and phasic graph (the phase shift that is an unit in order to spend) . From inside these graphs abundant of OK and affirmatory gain is spent and phasic abundant is spent in order to measure power source stability.

Frequency answers analytic brief introduction

Systematic frequency is answered is a function related to frequency, state the system is inputted (incentive) the referenced signal that is in specific frequency (it is sine weaveform normally) how to transmit through the system.

Graph 1 showed a broad sense dominates return circuit, apply sine wave A(t) at having the system of transfer function G(s) among them. The twinkling that causes in initiative condition changes after attenuation, output B(t) becomes the sine wave that has distinct range B and relatively phasic ω . The extent that outputs B(t) and phasic actually with frequency of input sine wave (the transfer function G(s) that Ω Rad/s) is in is concerned. Feedback coefficient ” K ” the load that decided to input signal how to be carried according to output undertakes modulatory.

Graph 1: The broad sense that has transfer function G(s) dominates return circuit

Input sine signal has swept a series of frequency with distinct range, in order to understand systematic act. This conduces to it is certain to state annulus road is in the gain inside frequency limits and phase shift, provide the valuable information about rate of operating ring region and power source stability. The gain that leaves through measuring different frequency orderly and phasic, can scale gain and phasic pursue with the relation of frequency. Through using logarithm frequency scale, plot can cover very wide frequency range. These graphs are called normally Bodetu, because they are used at the control that Hendrik Wade Bode initiates,the system devises a method. The article that rich him heart published at periodical of technology of shellfish Er system 1940 in him ” the attenuation in feedback amplifier design and phasic the relation between ” in say.

In power source design, operating ring road is measured conduce to token power source how answering the change such as change of voltage of output load condition, input, temperature change. Good power supply must be answered quickly and keep constant output, and won’t appear excessive ringing or oscillation. This is mixed through control power source normally between load component (it is MOSFET normally) sudden switch will come true. With shut time photograph to compare, the time that switch opens is longer, the power that provides load is higher.

Not steady power supply or manostat may oscillation, bring about operating ring road thereby very big apparent ripple appears on bandwidth. This kind of oscillation causes EMI problem possibly also.

Use automatic frequency to answer analytic oscillograph to measure

The real gain that surveys circuit through be inside certain frequency limits and phasic, the confidence that we can gain pair of design stability — this is emulated than be being relied on only be close friends more.

Executive control loop answers the feedback way that measures need user to will stimulate infuse to dominate return circuit inside certain frequency limits. Source of use oscillograph, signal and automation software, can undertake metrical quickly and appear with familiar Bodetu. This makes evaluate abundant to measure and have circuit function and model comparative becoming easy.

If the graph is shown 2 times,operating ring road answers metrical test plant. It includes to measure generator of software, function (inside in park oscillograph) , infuse / resistor of segregation transformer, infuse and probe of passive of two low attenuation.

Graph 2: With the is based on oscillograph system that answers at measuring control return

Contemporary oscillograph can be deployed power is measured and analyse software. This application software includes a variety of frequency to answer measure, include:

Control loop is answered
Power source is restrained than (PSRR)
Impedance
To decide control loop is measured, analytic software executes the following and main function:
Control function generator
Input computation and scale gain according to two voltage (20 Log V OUT /V IN) , among them V IN is the incentive voltage that comes from function generator
According to two voltage the input is calculated and the phase shift between scale V IN and V OUT

Computational gain and phasic abundant are spent

Two probe that step application of resistor of low cost infuse provide all information that analytic software place wants. It is measured stimulate and answer extent to be mixed with computational gain stimulation and answer the phasic defer between.

Want to measure the response of power system, must feedback foregone signal infuse loop. Oscillograph of gram of a few kinds of peaceful is offerred inside believe number source, can use at passing segregation transformer to feedback road of signal infuse annulus. To this give typical examples, random is undee / function generator makes sine wave inside designation frequency limits. DC-DC converter or LDO must configure in road of its feedback annulus small (Ω of 5 – 10) infuse resistor / terminal resistor, with violating those who come from function generator way of signal infuse annulus. The amplitude of infuse signal must keep inferior, in order to avoid excessive drive operating ring road.

An infuse transformer link that has evenness to answer on wide bandwidth is in infuse resistor two end, source of ground connection signal and power source segregation. The choice of infuse transformer depends on interested frequency.

Proposal general small electric capacity and probe of low attenuation passive (for example TPP0502) use at voltage to measure. Low probe attenuation can realize good sensitivity. Attenuation supports the 2X of TPP0502 to go up to undertake metrical with the perpendicular sensitivity of V/div of 500 μ in 6 series MSO, in 4 or undertake metrical with the perpendicular sensitivity of 1 MV/div on 5 series MSO. The small electric capacity of 12.7 PF but limit ground reduces probe load effect.

Graph 3 indication wave heart pursue (right on) , sweep range comes for 10 Hz 20 MHz, and spectrum view window (left) . These measurement undertake on 5 series MSO.

Graph 3: Bodetu (right go up) with spectrum view window (left)

Conclusion

Most power source and manostat are the amplifier that contains closed circuit feedback substantially. Operating ring road is measured conduce to the change that ensures power source design can answer output load condition, and won’t appear excessive ringing or oscillation.

Source of use oscillograph, signal and automation software, can undertake metrical quickly and appear with familiar Bodetu, evaluate abundant easily to spend thereby and have circuit function and model comparative.

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