Figure 5-1 Delay-Pulse Cycle; Pulse Concepts - Keithley 2520 User Manual

5-2 Source-Measure Concepts

Pulse concepts

Overview
The Model 2520 laser diode current source can output either DC or pulse waveforms.
Maximum current is as follows:
•
•
In addition, the current source can be operated in either the fixed or sweep mode. In the
fixed mode, the source simply outputs the programmed DC level (DC mode), or pulses at
a fixed amplitude (pulse mode). In the sweep mode, the source DC or pulse amplitude can
be swept across a series of steps at given increments. In addition, you can design your own
sweep waveforms by using the custom (list) sweep mode. See
5-8, for more sweep information.
Delay-pulse cycle
Model 2520 laser diode current source and voltage measurements consist of a series of
delay-pulse cycles
1.
2.
3.
4.
5.
Figure 5-1
Delay-pulse cycle
Trigger
DC: 1A
Pulse mode: 5A
(Figure 5-1). During each cycle, the following occurs:
Wait for the programmed delay period.
Output the programmed current pulse.
During the current pulse, the 10MHz A/D converter processes a number of raw
voltage and current samples.
After the pulse, the raw samples are processed by a DSP (Digital Signal Processor)
into one set of laser diode voltage and detector current readings.
Repeat the cycle.
Delay
Pulse
10MHz A/D
Conversions
Model 2520 User's Manual
"Sweep waveforms," page