Lightwave Communications Local Calibration of the LDX-3232 Current Source, Range, Setpoint

CA LI BRATION AND TR OUBLESHOOTING

Local Calibration of the LDX-3232 Current Source

C H A P T E R 6

9-Pin D-Sub
LD Cathode (5)
LD Anode (9)
PD Cathode + (6)		R4
PD Anode - (7)		1 M
	V	R1	R2	R3
			100
		49
	Voltmeter	U1	TIL117
		6	1
		5
A
	Ipd Current		2
Ammeter		4
			3
	CALIBRATION CIRCUIT

Figure 6.1 IPD Calibration Circuit

Local Calibration of the LDX-3232 Current Source

There are three calibration adjustments required for the LASER current source of the LDX-3232 Current Source. They are calibration of the constant current source for both bandwidths and ranges, calibration of the laser voltage measurement, and calibration of the constant light power (IPD) feedback circuits.

The LDX-3232 Current Source implements a two-point calibration for the Laser current source. Two currents (approximately 80% and 20% of FS) are applied to a test load, and the resulting actual currents are fed back (by the user) to the Current Source. The Laser Current Source calibration program uses the two sets of data to calculate new calibration constants. These calibration constants are used to set the actual current output of the current source.

Current Source Calibration

The following procedure is for calibrating each range of the current source. Calibration must be performed on both bandwidth modes. A total of four calibrations will be performed on the current source. Start with the low range, low bandwidth mode. Configure the Laser Current Source in the following state:

Function	State
MODE	I (constant current low bandwidth)
RANGE	low (lowest per instrument model)
CURRENT LIMIT	90% of FS (full scale of range)
SETPOINT	80% of FS

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