The two resistors in the dashed box below, R+Ar and R-Ar, represent the sensing elements of...

 

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The two resistors in the dashed box below, R+Ar and R-Ar, represent the sensing elements of a pressure sensor. They form one branch of a Wheatstone Bridge. In the absence of pressure (Ar=0), the variable resistance Rx is adjusted to balance the bridge (VA - VB = 0). a) Derive expressions for VA and VB as functions of the bridge resistances and Vs b) What should the value of Rx be to ensure a balanced bridge when Ar is zero? c) The output of the ideal Op Amp circuit can be written as: Vo= VA GA - VB GB. Under what condition will the Op Amp circuit behave as a true difference amplifier with gain GA = gain GB? d) The maximum value that Ar can reach is Armax = 4 Q2. What should the value of R₂ be in order for Vo to equal 6V at Armax? Assume that R=4kQ, RA= Rx = 2 k2, and R3 = R₁ = 1kQ Problem 1 Part B V₁ = 12V H₁ A RA 2k Rx R+Ar R-Ar VB R₁ 1k R3 lin R₂ Vo R₁2k Low Pass Filter (for questions f & g) RF CF VOF e) What is the gain (V/V and dB) of the difference amplifier for the resistance values in d)? f) What is the value of current in into the negative input of the Op Amp? g) The output Vo is contaminated with high frequency noise. Design a passive low pass filter (in the right hand box) with resistance RF and capacitance CF, and derive an expression for VOF/Vo h) What should the value of the corner frequency ooo of the filter be if the filter is to achieve -40dB signal reduction at a frequency... 10,000 rad/sec? The two resistors in the dashed box below, R+Ar and R-Ar, represent the sensing elements of a pressure sensor. They form one branch of a Wheatstone Bridge. In the absence of pressure (Ar=0), the variable resistance Rx is adjusted to balance the bridge (VA - VB = 0). a) Derive expressions for VA and VB as functions of the bridge resistances and Vs b) What should the value of Rx be to ensure a balanced bridge when Ar is zero? c) The output of the ideal Op Amp circuit can be written as: Vo= VA GA - VB GB. Under what condition will the Op Amp circuit behave as a true difference amplifier with gain GA = gain GB? d) The maximum value that Ar can reach is Armax = 4 Q2. What should the value of R₂ be in order for Vo to equal 6V at Armax? Assume that R=4kQ, RA= Rx = 2 k2, and R3 = R₁ = 1kQ Problem 1 Part B V₁ = 12V H₁ A RA 2k Rx R+Ar R-Ar VB R₁ 1k R3 lin R₂ Vo R₁2k Low Pass Filter (for questions f & g) RF CF VOF e) What is the gain (V/V and dB) of the difference amplifier for the resistance values in d)? f) What is the value of current in into the negative input of the Op Amp? g) The output Vo is contaminated with high frequency noise. Design a passive low pass filter (in the right hand box) with resistance RF and capacitance CF, and derive an expression for VOF/Vo h) What should the value of the corner frequency ooo of the filter be if the filter is to achieve -40dB signal reduction at a frequency... 10,000 rad/sec?

Answer rating: 100% (QA)

a VA and VB can be expressed as functions of the bridge resistances and Vs as follows VA RArRArRArVs ... View the full answer