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The differential amplifier of Figure 2 uses BJTs with β = 100. Identify and sketch the differential and common-mode equivalent half circuits. Determine the differential and common-mode input resistances. Assuming the output is taken single-endedly (as shown), determine the differential and common-mode voltage gains and the CMRR. Figure 2

The differential amplifier of Figure 2 uses BJTs with β = 100. Identify and sketch the differential and common-mode equivalent half circuits. Determine the differential and common-mode input resistances. Assuming the output is taken single-endedly (as shown), determine the differential and common-mode voltage gains and the CMRR. Figure 2

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The differential amplifier of Figure 2 uses BJTs with β = 100 . Identify and sketch the differential and common-mode equivalent half circuits. Determine the differential and common-mode input resistances. Assuming the output is taken single-endedly (as shown), determine the differential and common-mode voltage gains and the CMRR. Figure 2

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Consider a BJT differential amplifier biased with a Widlar current source, as shown in Figure 4. The transistor parameters are: β = 200, VBE(ON) = 0.7 V (except for Q3 and Q4), VA = ∞ for Q1 and Q2, and VA = 100 V for Q3 and Q4. Reverse saturation current, Is for transistor Q3 and Q4 is given as 1×10−15 A. From analysis, it is determined that I1 = 0.5 mA, la = 400 μA, v1 = v2 = 0 V, VCE2 = 2.7 V and CMRR (dB) = 80 dB Figure 4 a) Calculate the value of resistors R1, R2 and RC. b) Find the amplifier's differential-mode voltage gain (Ad), common-mode voltage gain (ACM) and common-mode output resistance ( Ricm ). [Ricm ≈ (1+β)Rocs where Rocs is the output resistance of the current source ] c) Draw the pnp version for the differential amplifier of Figure 4. Clearly label all resistors and currents.

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The differential amplifier above has the following parameters: βo = 150, VCC = 5 V, VEE = 5 V, VBE−on = 0.7 V, REE = 20 kΩ, R1 = 3 kΩ, and RC = 20 kΩ. v1 and v2 are purely AC signals with 0 DC voltage. Determine the following: (a) The DC Q-points for Q1 and Q2. [4 pt. (b) Draw the differential-mode and common-mode AC equivalent half-circuits for the differential amplifier. [ 6 pt. ] (c) What is the differential-mode gain (Add) ? [4 pt. ] (d) What is the common-mode gain (Acm)? [4 pt.] (e) What is the CMRR? [4 pt.] (f) What is the differential-mode input resistance? [4 pt.] (g) What is the common-mode input resistance? [4 pt.]

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Nonideal (i.e., real) operational amplifiers respond to both the differential and common-mode components of their input signals (refer to Fig. 2.4 for signal representation). Thus the output voltage of the op amp can be expressed as vO = AdvId +AcmvIcm where Ad is the differential gain (referred to simply as A in the text) and Acm is the common-mode gain (assumed to be zero in the text). The op amp’s effectiveness in rejecting common-mode signals is measured by its CMRR, defined as CMRR = 20 log|Ad/Acm| Consider an op amp whose internal structure is of the type shown in Fig. E2.3 except for a mismatch ∆Gm between the transconductances of the two channels; that is, Gm1 = Gm – 1/2∆Gm Gm2 = Gm + 1/2∆Gm Find expressions for Ad , Acm, and CMRR. What is the maximum permitted percentage mismatch between the two Gm values if a minimum CMRR of 60 dB is required?

Nonideal (i.e., real) operational amplifiers respond to both the differential and common-mode components of their input signals (refer to Fig. 2.4 for signal representation). Thus the output voltage of the op amp can be expressed as vO = AdvId +AcmvIcm where Ad is the differential gain (referred to simply as A in the text) and Acm is the common-mode gain (assumed to be zero in the text). The op amp’s effectiveness in rejecting common-mode signals is measured by its CMRR, defined as CMRR = 20 log|Ad/Acm| Consider an op amp whose internal structure is of the type shown in Fig. E2.3 except for a mismatch ∆Gm between the transconductances of the two channels; that is, Gm1 = Gm – 1/2∆Gm Gm2 = Gm + 1/2∆Gm Find expressions for Ad , Acm, and CMRR. What is the maximum permitted percentage mismatch between the two Gm values if a minimum CMRR of 60 dB is required?
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