1. L25 April 171 Semiconductor Device Modeling & Characterization Lecture 25 Professor Ronald L. Carter ronc@uta.edu Spring 2001

2. L25 April 172 Based on figure 12.18* n-type channel L 0 Junction Field-Effect Transistor (JFET) Active channel height, a Ch to Substr D.R.

3. L25 April 173 Pinch-off Voltage Note: In depl mode devices, V p0 > V bi

4. L25 April 174 Channel conductance and drain current

5. L25 April 175 N-channel drain current solution

6. L25 April 176 Saturation drain current,

7. L25 April 177 Ideal JFET drain characteristics IDID V DS V DS,sat I D,sat Ohmic, I D1 Non-physical analytic extension of I D1 Saturated: I D,sat ~I D1,sat

8. L25 April 178 n-channel JFET gate characteristic IDID V GS VpVp I DSS Saturated: I D,sat, approx. Saturated: I D1,sat

9. L25 April 179 Small-signal para- meters: g ds and g d

10. L25 April 1710 Graphical interpre- tation of g ds and g d IDID V DS V DS,sat I D,sat Slope = g ds Slope = g d

11. L25 April 1711 Small-signal gain params: g mL and g ms