SFT-0100 Sirenza Microdevices, SFT-0100 Datasheet - Page 4

• Manufacturer Part Number: SFT-0100
• Description: Transimpedance Amplifier
• Manufacturer: Sirenza Microdevices

Application Circuit
303 South Technology Court
Broomfield, CO 80021
Imon: When tied to the supply voltage through an amme-
ter, the current through the ammeter “Imon” reflects the
average photo diode current. The Imon current will be
approximately the value of the average photo diode cur-
rent and will be directly proportional to this quantity. Imon
can be used for loss of signal detection or photodiode/fiber
alignment in manufacturing. A third function this monitor
can provide is the manual adjustment of the DCDR thresh-
old. With no input photocurrent applied to the TIA, the
Imon will give a finite quiescent current (uA). The finite cur-
rent indicates that the automatic circuit has already started
to turn on. By employing a shunt resistor (1K-50K) on the
C
rent can be reduced to a few uA) setting the automatic cir-
cuit for maximum sensitivity and dynamic range.
DCDR (Duty Cycle Distortion Reduction): This patented
feature compensates for the duty cycle distortion as a
result of high input current seen by the amplifier. As the
optical input power and induced photo current is
increased, an automatic circuit is invoked to prevent dis-
torted operation in the transistors of the TIA. The threshold
input current where the circuit turns on can be adjusted by
employing a shunt resistor to ground at the DCDR pin. The
value of the shunt resistor can be set between 1K and
50K. The lower the value, the higher the input current
Description of External Connections and How They Operate
IN
DCDR
Vcc (5V)
Vcc (5V)
port to ground, this threshold can be reduced (cur-
Zo = 50 Ω
0.1uF
0.1uF
1000pF
1000pF
GND
GND
GND
GND
IN
100pF
100pF
IMON
VCC
Imon
DCDR
CEXT
100pF
100pF
OUTN
OUTP
GND
GND
GND
1000pF 0.1uF
1000pF 0.1uF
Zo = 50 Ω
Phone: (800) SMI-MMIC
Zo = 50 Ω
R
(1K-50KΩ, optional)
DCDR
4
OUTN
OUTP
threshold in which the circuit turns on. In order to optimize
for maximum sensitivity and dynamic range, the Imon cur-
rent can be monitored while tuning this shunt resistor.
Optimum sensitivity and dynamic range can be obtained
by tuning the resistor value until only a few uA of Imon cur-
rent is observed when there is no optical input power
applied.
C
grate and produce the automatic circuit control voltage.
C
operation for the amplifier. For 30KHz operation and
below, a 0.1uF capacitor is required. Wirebond length is
critical and should be minimized.
C
length is critical and should be minimized.
Ground Wirebonds: The SFT-0100 has backside vias
and backside metal. The bottom of the die must be electri-
cally connected to ground using eutectic or conductive
epoxy die attach methods. It is not recommended to attach
any wirebonds to the top GND pads.
DCDR
EXT
VCC
SFT-0100 Transimpedance Amplifier
: An off chip capacitor sets the lower frequency of
: An off chip bypass capacitor is required. Wirebond
: An off chip capacitor is required in order to inte-
Preliminary Data Sheet
http://www.sirenza.com
EDS-102714 Rev. D