Homework Assignment #5

E477 Spring 2014 Professor Parker

Hardcopies due in the course boxes on the third floor of EEB 5 PM 4/14/14

Ecopies due 5 PM 4/14/14 using the "Assignment" Function on DEN

Assume lambda is .1 microns. Assume Vdd is 1.8 V, V_tp0 is -.7 V. and V_tn0 is .7 V. V_tpbodyeffect is -.9 V. and V_tnbodyeffect is .9 V. Tox = 57 angstroms for thinox, and 5000 angstroms for thick oxide. Metal thickness is .5 microns. You can use these values for transistor betas: βn (beta)= 219.4 W/L μ A(microamps)/V² and βp (beta)= 51 W/L μ A/V² .

ε₀ (epsilon) = 8.85 X 10 ^-14 F/cm and ε_oxide(epsilon) = 3.9.

C_jbsn = 9.725 x 10^-4 pF/ μm² and C_jbswn = 2.27 x 10^-4 pF/ μm (micrometer). Assume drain is the same.

C_jbsp = 11.57 x 10^-4 pF/ μm² and C_jbswp = 1.8 x 10^-4 pF/ μm (micrometer). Assume drain is the same.

x_j (diffusion depth) = 0.1 microns.

1) (10%) For the network of gates given in Lecture 20-1-14, rework the example, assuming rise and fall times are equal, and kn/kp = 4.

2)a) (10%) Connect an output of a 2-input NOR through a long wire to the input of a second 2-input NOR. For the NORs, assume Rchn=Rchp = 1000 ohms, Cgn=Ggp/4=Cdn=Cdp/4=10 ff. For the wire assume Rw= 100 ohms and Cw =200ff. Compare the rise and fall times at the input to the second NOR using lumped wire model. Compute using lumped delay model and recompute using the Elmore delay model.

b) (10%) Insert an inverter at 1/3 and 2/3 of the way along the wire. For the inverters, assume Rchn=Rchp = 1000 ohms, Cgn=Ggp/4=Cdn=Cdp/4=10 ff. Compare the rise time at the input of the second NOR to the rise time found in part (a) using lumped wire model. Compute using lumped delay model and Recompute using the Elmore delay model.

3) (10%) For the example given in lecture note 19-6-14, rework the steps given in the lecture notes with Rchn=Rchp and Wp=4Wn.

4) (15%) For the XOR gate from Weste and Harris (lecture 20) - What is the combination of inputs that first discharges all capacitors then charges them all? What is the rise time RC time constant at the output using elmore delay model?

5) (10%). Assume a wire is 150 microns long. Assume R/micron = .4 ohms, and C/micron = 40 ff. Compute the wire delay using the distributed model.

6) (10%) Compute the gate capacitance for an NMOS transistor in linear and saturation region. The NMOS transistor dimensions are: W=16 lambda, L= 2 lambda.

7) (10%) Compute the source diffusion capacitance of an unit size NMOS transistor with minimum diffusion length.

8) (15%) Use the fringing field figure on p. 247 of the text. Assume w/l = 0.4, and w/h = .25. Estimate the fringing field factor if t/h = 1.