Optilab, LLC
600 E. Camelback Road, Phoenix, AZ 85012
Phone: 1-888-553-3888, Fax: (602) 343-1489, Email: [email protected]
1.2
Bandwidth Adjustment
BPR offers a bandwidth adjustment feature that allows users to optimize optical receiver
performance for different applications. BPR bandwidth can be adjusted as needed. The
table below gives the bandwidth based on BWM and BWA settings when both PDs are
reversed biased at 3.3V.
Table 2. Bandwidth Setting Lookup Table
Setting
BWM
BWA
Min. Bandwidth (GHz)
1
GND
Vcc
13
2
GND
FLT
15
3
GND
GND
16
4
FLT
FLT
18
5
Vcc
GND
20
6
Vcc
FLT
20.5
7
Vcc
Vcc
21
In default setting on the evaluation board, both BWM and BWA are preset to Vcc to
achieve the largest bandwidth. If a bandwidth smaller than 13 GHz is desired, the user
can lower VPD1 and VPD2 to further reduce the overall bandwidth of BPR.
1.3
Operation Mode
BPR integrates a single, differential linear trans-impedance / variable-gain amplifier
(TIA/VGA). The TIA offers two gain control modes: manual gain control and automatic
gain control. In manual mode, MC pin should be connected to GND. The gain is
adjustable from 50 Ω to 5000 Ω differential by adjusting the GC level. When MC is
floating, BPR is operated in automatic gain control (AGC) mode. In AGC mode, the gain
is automatically adjusted to deliver a constant output voltage. The output amplitude is
adjustable over 20 dB dynamic range by adjusting the level of OA.
Table 3. Operation Mode Selection
Operation Mode
MC Setting (Pin 12)
Amplitude / Gain Adjustment
Manual Gain Control
GND
GC (Pin 11), 0 ~ 3.3V
Auto Gain Control
Floating
OA (Pin 4), 0 ~ 3.3 V
Shut Down
Vcc
N.A.
The default setting on the evaluation board is MGC. GC is preset to Vcc to maximize the
TIA gain.