Question

Notify Me Bookmark

An instrumentation amplifier is used to provide a differential amplifier for highly sensitive sensors. A designer would like to have an instrumentation amplifier with a differential gain of 9 V/V, i. e. vo = 9∗(v2−v1), and has selected R3 = R4 = 10 kΩ, and R1 = 1 kΩ. What should the resistance of R2 be, in kΩ?

An instrumentation amplifier is used to provide a differential amplifier for highly sensitive sensors. A designer would like to have an instrumentation amplifier with a differential gain of 9 V/V, i. e. vo = 9∗(v2−v1), and has selected R3 = R4 = 10 kΩ, and R1 = 1 kΩ. What should the resistance of R2 be, in kΩ?

Image text
An instrumentation amplifier is used to provide a differential amplifier for highly sensitive sensors. A designer would like to have an instrumentation amplifier with a differential gain of 9 V / V , i.e. vo = 9 ∗ ( v 2 − v 1 ) , and has selected R 3 = R 4 = 10 k Ω , and R 1 = 1 k Ω . What should the resistance of R 2 be, in k Ω ?

Detailed Answer

0 0

Please enter your email here. You will get email when this question is answered by our tutor.

Doubtrix Logo

Problem is not yet solved!

Click on Notify me to get email when question is answered.

Join Doubtrix with 7-days free trial

  • Icon Correct & Verified Answers
  • Icon No AI-Generated Answers
  • Icon Video Solution for Difficult Questions
  • Icon Work With Experts to Reach at Correct Answers
Notify me Login Sign Up

Similar/Related Questions

For the following circuit, n-MOSFET Q1 works as a common source (CS) amplifier while Q2 and Q3 work as a current mirror. These transistors are identical with Vt = 2 V, kn = μnC0 x(W/L) = 2 mA/V2, VA = 100 V, and VDD = VSS = 5 V. (5%) (a) To make sure the resistance of the current mirror is large enough, we would like to have the output resistance (for Q3)r0 = VA/ID = 100 kΩ. Please find the corresponding Rref . (15%) (b) Followed by (a), if the open-circuit gain ( Aw without Rt ) of the CS amplifier is designed to be Avo = −10. What is RD ? What are the corresponding VD and VS for Q1? (5%) (c) Followed by (b), if now the load RL is connected at the drain with a capacitor CL = 100 nF, what is the minimal RL to operate this circuit at low frequency f(L(dB) < 500 Hz. Figure 3
Solution
0 0

Current Mirrors (35 points) This problem introduces current mirrors, which will be covered in more details in future lectures. Consider the circuit shown below (Figure 2). (W/L)1 = 1, (W/L)2 = 5, Rref = 50 kΩ, ignore channel length modulation unless otherwise stated. Assume L1 = L2 = 1 μm. Figure 2 a) (5 points) Assume RL = 10 kΩ. Calculate IL, the current flowing through RL. What is the current mirroring ratio ( IL over Iref , where Iref is the current through Rref )? We want the current mirror to provide a load-independent current as much as possible, so check that M2 is in saturation. b) (5 points) Determine the maximum RL and minimum VOut such that the current mirror still functions with the same current mirroring ratio you calculated in part a). Hint: for the current mirror to function as desired, transistor saturation should be maintained. c) (5 points) Channel length modulation introduces load-dependent errors in the mirroring ratio. Using λ = 0.1 V−1 for L = 1 μm, estimate the percentage error in the mirroring ratio. Here, set RL to its maximum value you got in part b ), and assume that we want the same IL as in parts a) and b). Hint: what should be the new VX and Iref ? d) (4 points) Compute the output resistance, Rout, , looking into the drain of M2. Use λ = 0.1 V−1 and assume the same IL as in parts a) through c). e) (5 points) Now consider redesigning the previous current mirror with source-degenerated transistors as shown in Figure 3. Ignore channel length modulation and body effect ( Assume bulk is tied to source). Transistor sizes remain the same, (WL)1 = 1 and (WL)2 = 5. This circuit has been designed to have the same Iref as in part a). What should the value of Rs2 be if we want the same current mirroring ratio as in a)? f) (5 points) Similarly to part b, determine the maximum RL and minimum VOut such that the current mirror still functions with the same current mirroring ratio as in part e). g) (4 points) Now compute the output resistance, Rout , looking into the drain of M2 (using λ = 0.1 V−1 ). Assume IL as used in parts e) and f ). h) (2 points) Comparing the minimum output voltage and the output resistance of these two current mirrors, comment on the advantages and disadvantages of using source degeneration in a current mirror. Figure 3 Current Mirrors (35 points) This problem introduces current mirrors, which will be covered in more details in future lectures. Consider the circuit shown below (Figure 2). (W/L)1 = 1, (W/L)2 = 5, Rref = 50 kΩ, ignore channel length modulation unless otherwise stated. Assume L1 = L2 = 1 μm. Figure 2 a) (5 points) Assume RL = 10 kΩ. Calculate IL, the current flowing through RL. What is the current mirroring ratio ( IL over Iref , where Iref is the current through Rref )? We want the current mirror to provide a load-independent current as much as possible, so check that M2 is in saturation. b) (5 points) Determine the maximum RL and minimum VOut such that the current mirror still functions with the same current mirroring ratio you calculated in part a). Hint: for the current mirror to function as desired, transistor saturation should be maintained. c) (5 points) Channel length modulation introduces load-dependent errors in the mirroring ratio. Using λ = 0.1 V−1 for L = 1 μm, estimate the percentage error in the mirroring ratio. Here, set RL to its maximum value you got in part b ), and assume that we want the same IL as in parts a) and b). Hint: what should be the new VX and Iref ? d) (4 points) Compute the output resistance, Rout, , looking into the drain of M2. Use λ = 0.1 V−1 and assume the same IL as in parts a) through c). e) (5 points) Now consider redesigning the previous current mirror with source-degenerated transistors as shown in Figure 3. Ignore channel length modulation and body effect ( Assume bulk is tied to source). Transistor sizes remain the same, (WL)1 = 1 and (WL)2 = 5. This circuit has been designed to have the same Iref as in part a). What should the value of Rs2 be if we want the same current mirroring ratio as in a)? f) (5 points) Similarly to part b, determine the maximum RL and minimum VOut such that the current mirror still functions with the same current mirroring ratio as in part e). g) (4 points) Now compute the output resistance, Rout , looking into the drain of M2 (using λ = 0.1 V−1 ). Assume IL as used in parts e) and f ). h) (2 points) Comparing the minimum output voltage and the output resistance of these two current mirrors, comment on the advantages and disadvantages of using source degeneration in a current mirror. Figure 3

Solution
0 0

A differential amplifier with a single-ended output is shown below along with the MOSFET parameters. The amplifier is to be designed for a differential mode gain of 10 and a CMRR of 200 . The current source I must have a voltage drop VCS ≥ 1 volt. The voltage V0 = 0 when the MOSFET gates are at ground potential (Va = Vb = 0). Assume the current source I must have a voltage drop of at least Vcs, min = 1 V. MOSFET Parameters kn = 2×10−4 A/V2 Vt = 1 V;VA = 30 V a. Show that the single-ended differential gain can be expressed as Ad = gmro||RD/2 = Ad = kn I VDD(1 + VDD/VA). Hint: Express gm, RD, and ro as functions of the drain current 1 /2. b. Use the result of step #1 to find the required bias current I. c. What should be the value of RD ? d Find the required value of Rss. e. What is the maximum differential input voltage Vid for linear operation. f. What is the common mode input voltage range?
Solution
0 0