Consider the following signal condition circuit which provides adjustable gain a

Question

Consider the following signal condition circuit which provides adjustable gain and offset.

Examine the schematic carefully and answer/solve the following questions/problems:

What are the configurations of each op-amp (U1, U2, U3, and U4)?

Is there any interference between the gain adjustment and offset adjustment?

Determine the adjustable range of the gain G.

Determine the adjustable range of the offset Voffset.

Sketch a block diagram which relates input Vs to output Vo.

Determine the expression for Vo in terms of input Vs

Consider the following signal condition circuit which provides adjustable gain and offset. Exam the schematic carefully and answer/solve the following questions/problems (1) What are the configurations of each op-amp (Ul, U2, U3, and U4)? (2) Is there any interference between the gain adjustment and offset adjustment? (3) Determine the adjustable range of the gain G (4) Determine the adjustable range of the offset Voffiet. (5) Sketch a block diagram which relates input Vs to output Vo. (6) Determine the expression for Vo in terms of input Vs OPAMP 3T VIRTUA 30kOhm Kays Kay9 R1 OPAMP 3T VIRTUAL OPAMP 3T VIRTUAL Vs RS RJ GAIN U1 R6 U2 30kOhm Kaya R14 R11 R10 OFFSET U3 5% Course ffset Key- OPAMP 3T VIRTUAL 55 % FineOffset Kay-h

Explanation / Answer

1ans )

u1 - input applied to Non inverting input and non-inverting input and output are shoted it is a voltage fallower circuit.

u2 - Non inverting input is grounded so it is a inverting Amplifier.

u3 - this also same as u2, a inverting Amplifier.

u4 - Non inverting input is grounded and two inputs applied at inverting teminal through resistors so it is an inverting Adder circuits.

2 ans) Opamp circuit U3 is used for offcet adjustment, whare as U2 is used for gain adjustment. so these two circuits are operating independently so thare will be no interference between gain adjustment and offcet adjustments.

3ans ) it can be observed from u2 circuit Rf min = 0 (if two pots at minimum position), Rf max = 50k +500 = 50.5k

so gain of a inverting amplifier is = Rf / Ri ,   whare Ri = 2 Kohms

so Gain min = 0/ 2Kohm = 0 similarly Gainmax = 50.5Kohm/2Kohm = 25.25

so gain range 0 to 25.25

4 ans ) adjustble offcet range minimum = 0 if ground the inverting terminals of u3 through avilable adjustble POTs

if pots ooering max resistance then total pot resistance at u3 inverting terminal = 50K+500 = 50.5Kohms

these pots conncetd to 12v supply through 100 K ohm resistor

so votage at inverting terminal if pots offer 50.5k will be 12* (50.5K/(50.5+ 100)K) = 4.026V

so offcet range will be 0 to 4.026v

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