1. Lecture 8 Transistors Topics Review: Combinational Circuits Decoders Multiplexers Breadboards, LEDs Components on integrated circuit (ICs) Transistors CMOS Readings 5.4, 5.7 September 29, 2014 CSCE 211 Digital Design

2. – 2 – CSCE 211H Fall 2014 Hot Batteries You should regularly check your batteries “slightly warm” is OK but hot indicates that your circuit has a short circuit. Unplug quickly and check.  Look for direct lines Vcc to GND.  Remember you need 330 ohm resistors in series with LEDs and that includes segments of the seven segment display.  Recheck sections of the breadboard.

3. – 3 – CSCE 211H Fall 2014 Transistor: Water Flow Model Water flow in B raises the plunger so that water can flow from C to E. Small flow turns on and off bigger flow. Put signal on B, transfer signal C to E Reference: http://www.satcure-focus.com/tutor/page4.htm

4. – 4 – CSCE 211H Fall 2014 Transistor Terminology Conductor – electrons easily passed from one atom to next (copper every atom has loose electron) Insulator – electrons tightly tied down to atoms, no flow Semiconductor – by adding impurities (doping) can be changed to increase conductivity Silicon wafer – used for IC circuits N-type - silicon doped with boron (excess electrons) P-ype - silicon doped with phosphorous (excess “holes” lack of electrons)

5. – 5 – CSCE 211H Fall 2014 Transistor Reference: http://www.intel.com/education/transworks/

6. – 6 – CSCE 211H Fall 2014 Transistor Reference: http://www.intel.com/education/transworks/

7. – 7 – CSCE 211H Fall 2014 Transistor Reference: http://www.intel.com/education/transworks/ Put Positive charge on gate. This attracts electrons into gap. This allows electrons to pass freely through the gap.

8. – 8 – CSCE 211H Fall 2014 Transistor Reference: http://www.intel.com/education/transworks/

9. – 9 – CSCE 211H Fall 2014 Transistor Reference: http://www.intel.com/education/transworks/ Take positive charge off Gate This stops attracting electrons. This shuts off the flow.

10. – 10 – CSCE 211H Fall 2014 N channel transitor

11. – 11 – CSCE 211H Fall 2014 P channel Transistor

12. – 12 – CSCE 211H Fall 2014 CMOS Inverter

13. – 13 – CSCE 211H Fall 2014 CMOS NAND

14. – 14 – CSCE 211H Fall 2014 What’s This?

15. – 15 – CSCE 211H Fall 2014

16. – 16 – CSCE 211H Fall 2014 High impedance High impedance is the state of an output terminal which is not currently driven by the circuit; neither high nor low Like an unconnected wire It is also known as hi-Z, tri-stated, or floating http://en.wikipedia.org/wiki/High_impedance

17. – 17 – CSCE 211H Fall 2014 Tri-state Buffer http://en.wikipedia.org/wiki/Three-state_logic In the tri-state buffer the enable input (B) acts as a switch Note if B is enabled then C=A and if B is not enabled then C = High-impedance

18. – 18 – CSCE 211H Fall 2014 Tri-state Buffer Implementation. En ABCD Q1Q2 OUTOUT LL LH HL HH

19. – 19 – CSCE 211H Fall 2014 Transmission Gates (Fig 3.45) EnEn_LAB 010 011 100 101 A is the input; B the output

20. – 20 – CSCE 211H Fall 2014 2-to-1 Mux from transmission gates.

21. – 21 – CSCE 211H Fall 2014