For the MOSFET current source of Fig. Q1(b), the circuit values are VDD = +12 Volts, VSS = 0, and IREF = 100 μA. The transistors are matched and their parameters are VT = 1.8 Volts, kn = 250 μA/V2 and λ = 0.01 V−1. Calculate ILOAD for (i) VDS2 = 2.5 Volts, (ii) VDS2 = 4 Volts and (iii) VDS2 = 10 Volts. Calculate the value of for which transistor T2 enters the linear region and hence determine the range of RLOAD values that can be used for this current source. Fig. Q1(b)
Figure 3 shows an amplifier with a current mirror as an active load. The MOSFETs have the following parameters: Vtn = −Vtp = 0.6 V, kn′ = 200 μA/V2, kp′ = 65 μA/V2, VA(NMOS) = 20 V, VA(PMOS) = 10 V, VT = 26 mV, R1 = 7 kΩ, R2 = 10 kΩ, L = 0.4 μm and W = 4 μm. The base-emitter forward voltage, VBE, of transistor Q4 is 0.7 V. The forward voltage drop for both D1 and D2 is 0.7 V. The supply voltage, VDD = 3 V. Assume the base current of Q4 is negligible compared to the emitter and collector currents of Q4, with all the transistors biased in the active region. (a) Identify the transistors forming the current mirror. (b) Calculate the value of IREF . (c) Calculate the output resistances of transistors Q1 and Q2.
In the circuit shown in Fig. 2 below, Rth = 1 kΩ, RL = 20 kΩ, VDD = VSS = 2 V and IS = 1 mA. The n-channel MOS transistor has VTN = 0.5 V, Kn = 500 μV/A2 and λ → 0. (a) Identify this circuit as a common-source, common-drain, or common-gate amplifier. (b) Draw a DC equivalent circuit of the amplifier. (c) Calculate the gm of the transistor. (d) Draw an AC equivalent of the circuit. Replace the transistor with its small-signal equivalent. (e) Find the overall small-signal voltage gain (vo/vi) of the amplifier. (f) Will the gain (vo/vi) of this amplifier be affected by Rth of the signal source? Why? (g) Find the output resistance of the amplifier seen from RL.
4.26. In the circuit of Fig. 4.39, assume that M5 and M6 have a small threshold voltage mismatch of ΔV and ISS has an output impedance RSS. Calculate the CMRR.
Q3. Assuming gm1 = gm2 = gm, VSB = 0, and ro1 = ro2 = R for the transistors, find out output impedance (Rout) and small signal voltage Gain (Av). (10pts)
Consider the active-loaded MOS differential amplifier of Fig. 1 operates with a bias current I of 100uA. The NMOS transistors are operated at Vov = 0.2 V and the PMOS devices at |Vov| = 0.3 V. The Early voltages are 20 V for the NMOS and 12 V for the PMOS transistors. Find Gm, RO, and Ad. For what value of load resistance is the gain reduced by a factor of 2? Figure. 1