19-2969; Rev 0, 8/03
MAX3744/MAX3745 Evaluation Kit
______________
General Description
The MAX3744/MAX3745 evaluation kit (EV kit) allows
complete evaluation of both versions of 2.7Gbps
transimpedance amplifiers.
The EV kit includes a circuit that emulates the high speed,
zero-to-peak current input signal that would be produced
by a photodiode. The kit also includes a calibration circuit
that allows accurate bandwidth measurement.
The MAX3744/MAX3745 EV kit is fully assembled and
tested.
________________________
Features
Fully Assembled and Tested
Includes Photodiode Emulation Circuit
Calibration Circuit for Accurate Bandwidth
Measurement
Evaluates: MAX3744/MAX3745
_______________Ordering Information
PART
MAX3744EVKIT
MAX3745EVKIT
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
IC-PACKAGE
Die
Die
________________________________________Electrical Evaluation Component List
DESIGNATION
C3, C5, C6
C4, C7, C8,
C10, C11
C2
C1
R3, R4, R11,
R12
R5, R8
R6, R7
R9, R10
QTY
3
5
1
1
4
2
2
2
DESCRIPTION
0.01µF
±10%
ceramic
capacitors (0201)
0.1µF
±10%
ceramic
capacitors (0402)
10µF
±10%
10V min
ceramic capacitor
33µF
±5%
10V min
tantalum capacitor
499Ω
±1%
resistor (0402)
4.99kΩ
±1%
resistor (0402)
53.6Ω
±1%
resistor (0402)
49.9Ω
±1%
resistor (0402)
MAX3744 EV board
Not installed
MAX3745 EV board
24.9Ω
±1%
resistor (0402)
MAX3744 EV board
0Ω shunt resistor (0402)
MAX3745 EV board
10kΩ
±1%
resis tor (0402)
Outside Vendor
Supply
Outside Vendor
Supply
None
None
0
0
1
1
DESIGNATION
L1
JU1
J3-J7
TP1-TP4
U1
QTY
1
1
5
4
1
DESCRIPTION
56nH inductor
Coilcraft 1008CS-560XKBC
2-pin header, 0.1in centers
SMA connectors, round,
Johnson 142-0701-801
Test Points
MAX3744E/D
MAX3744 EV board
MAX3745E/D
MAX3745 EV board
1mil Au wire (8 bonds)
Epoxy, Ablefilm 84-1 LMI
Shunt
MAX3744 EV board
MAX3745 EV board
None
1
MAX3744/MAX3745
Data Sheet
R13, R14
R15, R16
2
2
__________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct!
at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
MAX3744/MAX3745 Evaluation Kit
_____________Component Suppliers
SUPPLIER
AVX
PHONE
803-946-0690
847-639-6400
814-237-1431
FAX
803-626-3123
847-639-1469
814-238-0490
the transimpedance amplifier is not altered. Surface-
mount resistors have parasitic capacitance that may
reduce their impedance at frequencies above 1GHz.
____________Photodiode Emulation
The following procedure can be used to emulate the
high-speed current signal generated by a photodiode:
1)
2)
Select the desired optical power (P
AVE
, dBm) and
extinction ratio (r
e
).
Calculate the average current (I
AVE
, A). Set the DC
current at TP1 to I
AVE
.
Evaluates: MAX3744/MAX3745
Coilcraft
Murata
Note:
Please indicate that you are using the
MAX3744/MAX3745 when contacting thes e component
suppliers.
________________________Quick Start
1)
Connect a signal source to IN at J3. Set the signal
amplitude to 100mVp-p (this may require some
attenuation between the source and the
MAX3744/MAX3745 EV kit.) The signal should
have a data rate of 2.5Gbps.
Connect OUT+ and OUT- to the 50O inputs of a
high-speed oscilloscope at J6 and J7.
Remove the shunt from jumper JU1.
Connect a +3.3V supply to the VCC terminal and
ground to the GND terminal.
The differential signal at the oscilloscope should
be greater than 280mVp-p (140mVp-p on
MAX3744 EV Kit).
I
AVE
10
( P
AVE
/10)
=
⋅ρ
1000
(?= photodiode responsivity in A/W)
3)
Calculate the AC signal current and adjust the
signal generator to obtain it.
2)
3)
4)
5)
I
AC
=
2
⋅
I
AVE
⋅
r
e
−
1
r
e
+
1
For example: To emulate a photodiode with an average
power of –16dBm and an extinction ratio of 10;
1)
–16dBm optical power will produce 25µA of
average input current (assume photodiode
responsivity of 1A/W). Set the DC current input to
25µA at TP1.
The signal amplitude is 2 I
AVE
(r
e
-1)/(r
e
+1)=41µA.
To generate this current through the 1000O input
resistors, set the signal source to produce an
output level of
41µA*1000 O = 41mVp-p.
______________Detailed Description
The MAX3744/MAX3745 EV kit allows characterisation
without a photodiode. The kit is designed to emulate a
DC-coupled photodiode input. Diode currents may
have 6uA
pp
to 2mA
pp
AC-current with a DC component
from 10uA to 1mA. The high-speed current source of
the photodiode is emulated on the EV kit using
separate AC and DC paths. The AC signal is supplied
from a standard 50O lab source that delivers power to
an on board termination resistor. A current is then
generated from the voltage signal by a resistor with low
stray capacitance. The effect of the DC photodiode
current may be emulated by a current source at TP1.
An isolation resistor prevents the DC source from
loading the AC path.
The values of the series resistive element, R3 and R4,
have been carefully selected so that the bandwidth of
2)
______________Noise Measurement
Remove R3 and R4 before attempting noise
measurements to minimize input capacitance. With R3
and R4 removed the total capacitance at the IN pin is
approximately 0.85pF.
__________________RSSI (MAX3744)
The Average Power at the MAX3744 input is indicated
by the common mode output measured at TP2 and
TP3. Refer to the MAX3744 data sheet for details.
_____________________________________Adjustments and Control Descriptions
COMPONENT
JU1
TP1
TP2, TP3
NAME
OFFSET CORRECTION
DC CURRENT INPUT
OUTPUT COMMON MODE
FUNCTION
Instal JU1 to disable offset correction.
Apply DC current for photodiode simulation.
MAX3744 RSSI Signal
2
_________________________________________________________________________________________
MAX3744/MAX3745 Evaluation Kit
Evaluates: MAX3744/MAX3745
Figure 3. MAX3744/MAX3745 EV Kit
PC Board Layout—Component Side
Figure 5. MAX3744/MAX3745 EV Kit
PC Board Layout—Power Plane
Figure 4. MAX3744/MAX3745 EV Kit
PC Board Layout—Ground Plane
Figure 6. MAX3744/MAX3745 EV Kit
PC Board Layout—Solder Side
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600___________________
4
©
2003 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products
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