An acoustic-emission sensor's conditioning amplifier uses an equal-component…

PHYSICS · Multi-part · Fermi University Physics · Electronics, Instrumentation & Communication · Feedback, operational amplifiers and analogue signal processing · Feedback, operational amplifiers and analogue signal processing

Electronics for Measurement, Ch Active filters, oscillators and timers

Problem

An acoustic-emission sensor's conditioning amplifier uses an equal-component Sallen-Key low-pass with frequency-setting resistors

R_1=R_2=15\,\mathrm{k}\Omega

and capacitors

C_1=C_2=10\,\mathrm{nF}

, all four parts five percent tolerance. The passband gain is set by two feedback resistors

R_f

and

R_g

, each also five percent tolerance, with nominal ratio

R_f/R_g = 1.1667

, giving nominal gain

K=1+R_f/R_g=2.1667

and design

Q = 1/(3-K) = 1.20

. ((a)) Find the nominal (design) corner frequency

f_0 = 1/(2\pi\sqrt{R_1R_2C_1C_2})

. ((b)) Find the worst-case range of

f_0

R_1

R_2

C_1

and

C_2

are all simultaneously at the extreme of their five percent tolerance, in the direction that gives the largest deviation. ((c)) Find the worst-case range of

Q

R_f

and

R_g

are simultaneously at the extreme of their five percent tolerance, in the direction that gives the largest deviation in

K

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