A CMOS-input instrumentation amplifier's datasheet quotes and at .

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

Electronics for Measurement, Ch Sensors, transducers and the measurement front end

Problem

A CMOS-input instrumentation amplifier's datasheet quotes

e_n = 20\,\mathrm{nV}/\sqrt{\mathrm{Hz}}

and

i_n = 10\,\mathrm{fA}/\sqrt{\mathrm{Hz}}

1\,\mathrm{kHz}

. ((a)) Estimate the crossover source resistance

e_n/i_n

at which this amplifier's own voltage-noise and current-noise contributions are equal. ((b)) A

350\,\Omega

strain-gauge bridge has a Johnson-noise voltage density of about

2.4\,\mathrm{nV}/\sqrt{\mathrm{Hz}}

at room temperature. State, with a reason, whether this amplifier is a good match for that bridge, or would suit a much higher-impedance source better.

Browse the problem library