AK2572 Datasheet, PDF (18/50 Pages) Asahi Kasei Microsystems – APC for Burst Mode Applicable Direct Modulation Laser Diode

ASAHI KASEI
[AK2572]
Table 4-6 APC Operation Setting Examples
RE_APC RE_APC BIAS MOD
_FF_SET _FB_SET Current Current
Note
Figure
Set MOD (Modulation) for FF (Feed Forward) setting.
01
(1)
10
(2)
FB
Degraded LD characteristic is compensated by BIAS
FF only. Initial value of BIAS FB (FeedBack) can be 4-5
programmed in response to a start-up temperature
(Set by RE_APC_INIT_SET).
Set BIAS for FF setting.
10
(2)
01
(1)
FF
FB
Degraded LD is compensated by MOD only. Initial
value of MOD FB can be programmed in response to
4-6
a start-up temperature (Set by RE_APC_INIT_SET).
11
(3)
00
(0)
FF
FF
Set both BIAS and MOD for FF setting. No
compensation of degraded LD is made.
4-7
11
(3)
01
(1)
FF
FF+FB
Set both BIAS and MOD for FF setting.
Compensation of degraded LD is made by the MOD.
4-8
11
(3)
10
(2)
FF+FB
FF
Set both BIAS and MOD for FF setting.
Compensation of degraded LD is made by BIAS.
4-9
Compensation of degraded LD is made in accordance
00
(0)
11
(3)
FB
FB
with the dividing coefficient for BIAS and MOD initial
value of FB can be programmed in response to a
4-10
start-up temperature (Set by RE_APC_INIT_SET).
MOD outputs a current that is sum of the divided FB
current and the FF setting current.
01
(1)
11
(3)
FB
FF+FB
BIAS outputs a current that is proportional to the
divided FB current. Initial value of BIAS FB can be
4-11
programmed in response to a start-up temperature
(Set be RE_APC_INIT_SET).
BIAS outputs a current that is sum of the divided FB
10
(2)
11
(3)
current and the FF setting current.
FF+FB FB MOD outputs a current that is proportional to the 4-12
divided FB current. APC_FB initial value setting is
prohibited in this setting [*].
Both in BIAS and MOD, a current that is
11
(3)
11
(3)
FF+FB
FF+FB
proportional to the divided FB is added to the FF
setting current and compensation of degraded LD is
4-13
made by the FB current.
[*] RE_APC_INIT_SET＝“1” setting is prohibited when RE_APC_FF_SET＝”10 (2)” and RE_APC_FB_SET
＝”11 (3)” (BIAS＝FF＋FB / MOD＝FB)
Fig.4-5 Setting Example 1 (BIAS＝FB,MOD＝FF)
R_APC_FB
0
R_MOD_FF
R_MOD_FB
=0
R_MOD
RE_DAC1_GAIN
(RE_DAC3_GAIN)
I-DAC1(V-DAC3)
10/255
(2.2/255)
G_DAC1
(G_DAC3)
Imod
(Vmod)
R_BIAS_FB
=R_APC_FB
1
R_BIAS
I-DAC2
85/255
G_DAC2
Ibias
Fig.4-6 Setting Example 2 (BIAS＝FF,MOD＝FB)
R_APC_FB
R_MOD_FF=0
RE_DAC1_GAIN
(RE_DAC3_GAIN)
R_MOD_FB
=R_APC_FB
1
R_MOD
I-DAC1(V-DAC3)
10/255
(2.2/255)
G_DAC1
(G_DAC3)
Imod
(Vmod)
R_BIAS_FB
=0
I-DAC2
R_BIAS
0
85/255
G_DAC2
Ibias
R_BIAS_FF=0
R_MOD=R_MOD_FF
R_BIAS=R_BIAS_FB=R_APC_FB
RE_DAC2_GAIN
G_DAC1= 1 or 0.1
G_DAC2= 1 or 0.5
G_DAC3= 1 or 1.2/2.2
R_BIAS_FF
R_MOD=R_MOD_FB=R_APC_FB
R_BIAS=R_BIAS_FF
RE_DAC2_GAIN
G_DAC1= 1 or 0.1
G_DAC2= 1 or 0.5
G_DAC3= 1 or 1.2/2.2
-18-
<MS0290-E-01>
2004/8