1. Transient Signals of pn Junction Diodes

2. Transient Signals of pn Junction Diodes
Transient signals caused by buildup of minority carrier charge
Must build up charge to turn on pn diode
Must remove charge to turn off diode
Can test transient response by using resistor in series with pn diode
Circuit diagram for pn diode time delay measurement.

3. Transient Signals of pn Junction Diodes
Turn on transient: Must build up charge more quickly during transient to turn on diode before voltage relaxes to steady state. 3

4. Transient Signals of pn Junction Diodes
Turn off transient: Must drop voltage across resistor to discharge current from pn diode. 4

5. Transient Signals of pn Junction Diodes
Turn on measurements:
IF = (VCh2,ss – VCh1,ss)/R
Vpk - Vss
tfr
Turn off measurements:
Vss – Voff
trd
Measured data for the turn on and turn off transients for square wave at 20 kHz
Plot data for one representative data point for both turn on and turn off transients 5

6. Transient Signals of pn Junction Diodes
Turn on and turn off transients generated from a 1 V to 0 V voltage transition taken on both Channel 1 and Channel 2. 6

7. Transient Signals of pn Junction Diodes
Turn on and turn off transients for both Channels 1 and 2 for 1 V transition (top) and turn on (bottom left) and turn off (bottom right) transients for Channel 1. 7

8. Transient Signals of pn Junction Diodes
Positive to negative transient: First reverse biases resistor to rapidly discharge current from pn diode during tsd before diode begins to approach reverse saturation current causing a rapid drop in voltage towards end of trr. 8

9. Transient Signals of pn Junction Diodes
Measurements: VF
IF = VCh1/R VR
IR = VCh1/R
tsd
trr
Measured data for positive to negative transient for square wave at 20 kHz
Plot data for one representative data point for positive to negative transient 9

10. Transient Signals of pn Junction Diodes
Reverse recovery transient generated from a 0.9 V to 0 V transition taken on Channel 1. 10

11. Switching transient generated from a 0.9 V to 0 V transition.
Transient Signals of pn Junction Diodes
Switching transient generated from a 0.9 V to 0 V transition. 11