Homework Assignment #2

EE 477 Fall 2012 Professor Parker

Hardcopies due in the course boxes on the third floor of EEB 5 PM 9/24/12

Ecopies due 11:59 PM 9/24/12 using the "Assignment" Function on DEN

To ensure academic privacy, please use a cover page on your homework hard copies that does not contain any work.

1. (35%) Design a new type of binary counter that continuously counts up to 55, 5 at a time. So the sequence should be 0,5,10,...55, and then repeat itself. The current number will change when the clock falls. If reset is asserted asynchronously, the current number will become 0 and should stay zero until the next negative clock edge, even if reset is subsequently unasserted. Reset is an asynchronous signal. Each bit of storage should be a positive edge-triggered flip flop. Each flip flop should contain two latches, as described in class. The data loaded into the flip flop will depend on the data currently in the flip flop along with data in the other flip flops.

Your counter should be designed at the gate level. Use NOR gates (and inverters if necessary) to build the multiplexer at the input to each latch.

Show your solution for the counter as a gate-level diagram.

2. (15%) Draw a transistor (circuit) level diagram for a compound gate that implements the following Boolean function

H = /[X(Y+W)Z + P(QR+ST)U + N(M+LOK)]

without simplifying the Boolean function.

You can assume that all inputs as well as their complementary inputs are available. Label the sources and drains of all the transistors.

3. (10%) What is a "wired or" connection? What has to be true for the connection to work properly?

Answer the rest of these after the Wed. lecture

4. (10%) Sketch the side view (slice down into the silicon) of a stacked contact that connects poly to metal3 using colored pens or pencils.

5. (5%) In a negative photolithographic process, what material is initially stripped, the exposed or unexposed material?

6. (5%) Show where a parasistic MOS transistor can form.

7. (10%) In the figure below for an N-well process, show the cross-section along the vertical red line.

8. (10 %) Sketch the steps in the photolithographic process necessary to create and pattern a contact between n+ and M1.