TABLE OF CONTENTS This chapter covers how logic design is converted to a transistor implementation. The chapter describes the behavior of MOSFETs and how to use them to create logic gates and sequentials as well as the electrical checks of circuit timing, noise, and power.
Upon completion of this chapter the reader will be able to:
Describe the regions of operation of a MOSFET.
Describe the differences between NMOS and PMOS devices.
Draw circuit diagrams for CMOS logic gates.
Understand fanout and how it affects circuit timing.
Understand P-to-N ratio and how it affects noise immunity.
Draw circuit diagrams for a latch and a flip-flop and understand their operation.
Describe different sources of circuit noise and ways of reducing them.
Describe different types of power consumption and ways of reducing them.
Circuit design is the task of creating electrical circuits that implement the functionality determined by logic design. Logic design and the steps before largely ignore the details of the behavior of the transistors that will ultimately make up the microprocessor, but in the end the processor is primarily just a collection of transistors connected by wires. No matter how sophisticated or complicated the microarchitecture or logic design of the processor, its functions must be built using transistors and wires.
Although bipolar junction transistors (BJTs) were invented first, today all microprocessors use metal oxide semiconductor field effect transistors ( MOSFETs). Modern microprocessors contain many large arrays of memory elements and MOSFETs are ideal for memory storage as...
