1. Saturday, March 21, 2015IEEE @ UCSB0 ECE 92 Projects in Electrical and Computer Engineering Lecture 2

2. Transistor Saturday, March 21, 2015IEEE @ UCSB1 The transistor is a three-terminal semiconductor device. Can control electric current or voltage between two of the terminals. Used as amplifier or as switch. Field-Effect Transistors JFET, MESFET Depletion-mode (normally on) n-chp-ch MOSFET Depletion-mode (normally on) Enhancement-mode (normally off) n-chp-chn-chp-ch

3. JFETs Saturday, March 21, 2015IEEE @ UCSB2 V gs Gate Source Drain I ds (V gs,V ds ) V ds Gate Source Drain N-ch JFET Saturation region I D V gs ≤ V t (cutoff) Ohmic or Triode region V ds V gs = V t + 0.5 V gs = V t + 1.0 V gs = V t + 1.5 V gs = 0 I dss Increasing V gs

4. MOSFETs Saturday, March 21, 2015IEEE @ UCSB3 V gs Gate Source Drain I ds (V gs,V ds ) V ds Gate Source Drain NMOS Saturation region I D V gs ≤ V t (cutoff) Ohmic or Triode region V ds V gs = V t + 0.5 V gs = V t + 1.0 V gs = V t + 1.5 V gs = V t + 2.0 Increasing V gs

5. BJTs Saturday, March 21, 2015IEEE @ UCSB4 Base Emitter Collector NPN BJT IbIb Ic=βIBIc=βIB B C E I c,, mA Forward active region V CE 70 μA Increasing I b 60 μA 50 μA 40 μA 30 μA 20 μA 10 μA 0 μA V ce,sat 2 4 6 8

6. NMOS and PMOS Saturday, March 21, 2015IEEE @ UCSB5

7. Example Saturday, March 21, 2015IEEE @ UCSB6 Find W/L and R for the circuit below assuming k n = 100 μA/V 2 (transconductance), V t = 1 V (threshold voltage), and r DS = 40 Ω (drain-to-source resistance).

8. Op-Amps Saturday, March 21, 2015IEEE @ UCSB7 Active circuit element designed to perform mathematica operations of addition, subtraction, multiplication, division, differentiation and integration. Useful term: gain=amount of amplification produced by an op-amp. Defined as:

9. Op-Amps Saturday, March 21, 2015IEEE @ UCSB8

10. Op-Amps Saturday, March 21, 2015IEEE @ UCSB9

11. Example Saturday, March 21, 2015IEEE @ UCSB10 + - VoVo 30 kΩ60 kΩ 30 kΩ V s1 V s2 The switch in the following figure is open. Find v 0 in term of the inputs v s1 and v s2. Repeat with the switch closed.