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Frequency dependency of ESR value of capacitor (for LDO)

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pseudockb

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esr for capacitor low frequency

I am currently designing a LDO voltage regulator making use of the ESR value of the external compensating capacitor to make the regulator stable. It is well known that the ESR value helps to create a zero to stabilize the regulating loop. I got the impedance and ESR plot of a capacitor from a vendor, as shown below. Now I am quite puzzle by the plot. Does the ESR value of the capacitor vary so much with frequencies? By extrapolating the ESR curve, I find that the ESR value at very low frequencies can be close to 10KOhm or higher!!! Am I making a fair assumption here? And how do I incoporate the frequency dependency of the ESR value in my simulation? Thanks
 

esr value

I think you don't care more very low frequency,beacuse the ESR just measured from a lot numbers and use a complex formula to culculate the ESR and plot the curve as you shown, we only care the normal operating range( several milliOhm to several Ohm), just for my opinion.if I wrong pls correct me.thanx.
 

Since the zero due to the ESR locates at 100KHz for exmaple, and the zero, as we known, is formed by the load capcacitor and the ESR, so we should only care about the ESR value at 100kHz.
 

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