Determine the rise and fall time of Inverter, designed using the following transistor parameters. pMOS Vtp = -0.6 V upCox = 200 uA/V2 (W/L)p = 5 nMOS Vtn = 0.6 V unCox = 500 uA/V2 (W/L)n = 2 VDD = 1.5 V Use the following two cases when calculating average current and determine the difference in the rise and fall time between the following two cases. Case#1: Use 90%, 50%, and 10% Case#2: Use 90% and 10%
(a) Determine the switching threshold (Vth) of Inverter, 2-input NAND (NAND2), 3input NAND (NAND3), 2-input NOR (NOR2), and 3-input NOR (NOR3). Use the transistor parameters given above. (10 Marks) (b) Now, we want to make Vth of the above gates identical to Vth of Inverter. Determine the new transistor sizes of the above logic gates. (10 Marks) (c) Figure 1 is designed using the above device parameters. Determine VIH, VIL, Vth, and the noise margin of the 2-input NOR gate and the inverter using the equivalent device sizes of the best case. Assume VOH is 90% of VDD and VOL is 10% of VDD. (10 Marks) (d) Explain how to make the noise margins of the above NOR2 balanced for logic ' 0 ' and ' 1 '. (10 Marks) The parameters of the pMOS and nMOS transistors are given below: pMOS Vtp = -0.6 V upCox = 200 uA/V2 (W/L)p = 5 nMOS Vtn = 0.6 V unCox = 500 uA/V2 (W/L)n = 2 VDD = 1.5 V
a) Your job is to design the following circuit, using 2 mA of bias current and achieve a gain of at least 3.5 V/V. You realize that you can bias an amplifier using degeneration resistance using the circuit topology shown below. Calculate values for RS to get 2 mA of current, and RL to get the gain you need. For large signal calculations, you may assume lambda = 0. What is the problem with this amplifier? b) You suggest replacing the load resistance RL with a current source that has a very large output impedance, as shown below. The current source requires a headroom of at least 0.5 V. What is the gain of the amplifier? How does this fix the problem from the previous part? 1 Debugging Amplifiers Suppose you are given an NMOS transistor with the following parameters: In addition, VDD = 5 V.
For the circuit below, perform the following calculations: (i) Find I1 when VIN = 1.2 V and R1 = 2 kohm. (ii) If W/L of the transistor is changed to W/L = 80/1, compute the new value of overdrive voltage VOV such the current I1 remains the same as in part (i). (iii) Find the maximum value of R1 which ensures that the transistor remains in saturation. (iv) Determine the minimum value of supply voltage VDD to bias the transistor in saturation.