Document Outline
- DESCRIPTION
- FEATURES
- APPLICATIONS
- PIN CONFIGURATION
- ORDERING INFORMATION
- ABSOLUTE MAXIMUM RATINGS
- RECOMMENDED OPERATING CONDITIONS
- DC ELECTRICAL CHARACTERISTICS
- AC ELECTRICAL CHARACTERISTICS
- TEST CIRCUITS
- TYPICAL PERFORMANCE CHARACTERISTICS
- THEORY OF OPERATION
- BANDWIDTH CALCULATIONS
- NOISE
- DYNAMIC RANGE
- APPLICATION INFORMATION
- BASIC CONFIGURATION
- VARIABLE GAIN
- 16MHZ CRYSTAL OSCILLATOR DIGITAL FIBER OPTIC RECEIVER
- DIGITAL FIBER OPTIC RECEIVER
- Die Sales Disclaimer
- PACKAGE OUTLINES
- Data sheet status
- Definitions
- Disclaimers
Philips
Semiconductors
SA5212A
Transimpedance amplifier (140MHz)
Product specification
Replaces datasheet NE/SA/SE5212A of 1995 Apr 26
IC19 Data Handbook
1998 Oct 07
INTEGRATED CIRCUITS
Philips Semiconductors
Product specification
SA5212A
Transimpedance amplifier (140MHz)
2
1998 Oct 07
853-1266 20142
DESCRIPTION
The SA5212A is a 14k
transimpedance, wideband, low noise
differential output amplifier, particularly suitable for signal recovery in
fiber optic receivers and in any other applications where very low
signal levels obtained from high-impedance sources need to be
amplified.
FEATURES
Extremely low noise: 2.5pA/
Hz
Single 5V supply
Large bandwidth: 140MHz
Differential outputs
Low input/output impedances
14k
differential transresistance
ESD hardened
APPLICATIONS
Fiber-optic receivers, analog and digital
Current-to-voltage converters
PIN CONFIGURATION
GND2
IIN
VCC
GND1
GND1
GND2
OUT ()
OUT (+)
N, FE, D Packages
1
2
3
4
5
6
7
8
SD00336
Figure 1. Pin Configuration
Wideband gain block
Medical and scientific instrumentation
Sensor preamplifiers
Single-ended to differential conversion
Low noise RF amplifiers
RF signal processing
ORDERING INFORMATION
DESCRIPTION
TEMPERATURE RANGE
ORDER CODE
DWG #
8-Pin Plastic Small Outline (SO) Package
-40
C to +85
C
SA5212AD
SOT96-1
8-Pin Plastic Dual In-Line Package (DIP)
-40
C to +85
C
SA5212AN
SOT97-1
8-Pin Ceramic Dual In-Line Package (DIP)
-40
C to +85
C
SA5212AFE
0580A
ABSOLUTE MAXIMUM RATINGS
SYMBOL
PARAMETER
SA5212A
UNIT
V
CC
Power Supply
6
V
Power dissipation, T
A
=25
C (still air)
1
P
8-Pin Plastic DIP
1100
mW
P
D MAX
8-Pin Plastic SO
750
mW
8-Pin Cerdip
750
mw
I
IN MAX
Maximum input current
2
5
mA
T
A
Operating ambient temperature range
-40 to 85
C
T
J
Operating junction
-55 to 150
C
T
STG
Storage temperature range
-65 to 150
C
NOTES:
1. Maximum dissipation is determined by the operating ambient temperature and the thermal resistance:
8-Pin Plastic DIP: 110
C/W
8-Pin Plastic SO: 160
C/W
8-Pin Cerdip: 165
C/W
2. The use of a pull-up resistor to V
CC
, for the PIN diode, is recommended
Philips Semiconductors
Product specification
SA5212A
Transimpedance amplifier (140MHz)
1998 Oct 07
3
RECOMMENDED OPERATING CONDITIONS
SYMBOL
PARAMETER
RATING
UNIT
V
CC
Supply voltage range
4.5 to 5.5
V
T
A
Ambient temperature ranges
-40 to +85
C
T
J
Junction temperature ranges
-40 to +105
C
DC ELECTRICAL CHARACTERISTICS
Minimum and Maximum limits apply over operating temperature range at V
CC
=5V, unless otherwise specified. Typical data applies at V
CC
=5V
and T
A
=25
C
1
.
SYMBOL
PARAMETER
TEST CONDITIONS
Min
Typ
Max
UNIT
V
IN
Input bias voltage
0.55
0.8
1.05
V
V
O
Output bias voltage
2.5
3.3
3.8
V
V
OS
Output offset voltage
120
mV
I
CC
Supply current
20
26
33
mA
I
OMAX
Output sink/source current
3
4
mA
I
IN
Maximum input current (2% linearity)
Test Circuit 6, Procedure 2
40
80
A
I
N MAX
Maximum input current overload threshold
Test Circuit 6, Procedure 4
60
120
A
NOTES:
1. As in all high frequency circuits, a supply bypass capacitor should be located as close to the part as possible.
Philips Semiconductors
Product specification
SA5212A
Transimpedance amplifier (140MHz)
1998 Oct 07
4
AC ELECTRICAL CHARACTERISTICS
Minimum and Maximum limits apply over operating temperature range at V
CC
=5V, unless otherwise specified. Typical data applies at V
CC
=5V
and T
A
=25
C
5
.
SYMBOL
PARAMETER
TEST CONDITIONS
Min
Typ
Max
UNIT
R
T
Transresistance (differential output)
DC tested, R
L
=
Test Circuit 6, Procedure 1
9.0
14
19
k
R
O
Output resistance (differential output)
DC tested
14
30
46
R
T
Transresistance (single-ended output)
DC tested, R
L
=
4.5
7
9.5
k
R
O
Output resistance (single-ended output)
DC tested
7
15
23
Test Circuit 1
D package,
f
3dB
Bandwidth (-3dB)
T
A
= 25
C
100
140
MHz
N, FE packages,
T
A
= 25
C
100
120
R
IN
Input resistance
70
110
150
C
IN
Input capacitance
10
18
pF
R/
V
Transresistance power supply sensitivity
V
CC
= 5
0.5V
9.6
%/V
R/
T
Transresistance ambient
temperature sensitivity
D package
T
A
= T
A MAX
-T
A MIN
0.05
%/
C
I
N
RMS noise current spectral density
(referred to input)
Test Circuit 2
f = 10MHz T
A
= 25
C
2.5
pA/
Hz
Integrated RMS noise current over the band-
T
A
= 25
C Test Circuit 2
f = 50MHz
20
g
width (referred to input) C
S
= 0
1
f = 100MHz
27
I
T
f = 200MHz
40
nA
T
f = 50MHz
22
C
S
= 1pF
f = 100MHz
32
f = 200MHz
52
PSRR
Power supply rejection ratio
2
Any package
DC tested
V
CC
= 0.1V
Equivalent AC
Test Circuit 3
20
33
dB
PSRR
Power supply rejection ratio
2
(ECL configuration)
Any package
f = 0.1MHz
1
Test Circuit 4
23
dB
V
O MAX
Maximum differential output voltage swing
R
L
=
Test Circuit 6, Procedure 3
1.7
3.2
V
P-P
V
IN MAX
Maximum input amplitude for output duty
cycle of 50
5%
3
Test Circuit 5
325
mV
P-P
t
R
Rise time for 50mV output signal
4
Test Circuit 5
2.0
ns
NOTES:
1. Package parasitic capacitance amounts to about 0.2pF.
2. PSRR is output referenced and is circuit board layout dependent at higher frequencies. For best performance use RF filter in V
CC
line.
3. Guaranteed by linearity and over load tests.
4. t
R
defined as 20-80% rise time. It is guaranteed by -3dB bandwidth test.
5. As in all high frequency circuits, a supply bypass capacitor should be located as close to the part as possible.
Philips Semiconductors
Product specification
SA5212A
Transimpedance amplifier (140MHz)
1998 Oct 07
5
TEST CIRCUITS
Test Circuit 1
Rt +
VOUT
VIN
2
@ S21 @ R
Rt +
VOUT
VIN
4
@ S21 @ R
SINGLE-ENDED
DIFFERENTIAL
RO + ZO
1
) S22
1
* S22 *
33
RO + 2ZO
1
) S22
1
* S22 *
66
NETWORK ANALYZER
S-PARAMETER TEST SET
PORT 1
PORT 2
33
IN
DUT
OUT
OUT
50
33
GND1
GND2
VCC
ZO = 50
1
F
RL = 50
R = 1k
1
F
0.1
F
Test Circuit 2
SPECTRUM ANALYZER
33
IN
DUT
OUT
OUT
33
GND1
GND2
VCC
1
F
RL = 50
1
F
AV = 60DB
NC
SD00337
Figure 2. Test Circuits 1 and 2
Test Circuit 3
NETWORK ANALYZER
S-PARAMETER TEST SET
PORT 1
PORT 2
VCC
GND1
GND2
NC
CURRENT PROBE
1mV/mA
CAL
TEST
TRANSFORMER
NH0300HB
100
33
33
16
OUT
OUT
BAL.
10
F
0.1
F
10
F
1
F
1
F
50
UNBAL.
5V +
V
10
F
DUT
IN
SD00338
Figure 3. Test Circuit 3
Philips Semiconductors
Product specification
SA5212A
Transimpedance amplifier (140MHz)
1998 Oct 07
6
TEST CIRCUITS
(Continued)
Test Circuit 4
NETWORK ANALYZER
S-PARAMETER TEST SET
PORT 1
PORT 2
CURRENT PROBE
1mV/mA
CAL
TEST
TRANSFORMER
NH0300HB
100
33
33
16
OUT
OUT
BAL.
50
UNBAL.
VCC
GND1
GND2
NC
0.1
F
1
F
1
F
0.1
F
10
F
5.2V +
V
10
F
IN
SD00339
Figure 4. Test Circuit 4
Test Circuit 5
OSCILLOSCOPE
33
33
1k
OUT
OUT
GND2
GND1
5V
IN
1
F
1
F
PULSE GEN.
Measurement done using
differential wave forms
0.1
F
50
ZO = 50
A
B
ZO = 50
DUT
SD00545
Figure 5. Test Circuit 5
Philips Semiconductors
Product specification
SA5212A
Transimpedance amplifier (140MHz)
1998 Oct 07
7
TEST CIRCUITS
(Continued)
GND2
Test Circuit 8
OUT +
OUT
GND1
IN
DUT
IIN (
A)
5V
VOUT (V)
+
Typical Differential Output Voltage
vs Current Input
2.00
1.60
1.20
0.80
0.40
0.00
0.40
0.80
1.20
1.60
2.00
200
160
120
80
40
0
40
80
120
160
200
DIFFERENTIAL
OUTPUT VOL
T
AGE
(V)
CURRENT INPUT (
A)
NE5212A TEST CONDITIONS
Procedure 1
RT measured at 30
A
RT = (VO1 VO2)/(+30
A (30
A))
Where: VO1 Measured at IIN = +30
A
VO2 Measured at IIN = 30
A
Procedure 2
Linearity = 1 ABS((VOA VOB) / (VO3 VO4))
Where: VO3 Measured at IIN = +60
A
VO4 Measured at IIN = 60
A
V
OA
+
R
T
@
(
)
60
m
A)
)
V
OB
V
OB
+
R
T
@
(
*
60
m
A)
)
V
OB
Procedure 3
VOMAX = VO7 VO8
Where: VO7 Measured at IIN = +130
A
VO8 Measured at IIN = 130
A
Procedure 4
IIN Test Pass Conditions:
VO7 VO5 > 20mV and V06 VO5 > 20mV
Where: VO5 Measured at IIN = +800
A
VO6 Measured at IIN = 80
A
VO7 Measured at IIN = +130
A
VO8 Measured at IIN = 130
A
SD00340
Figure 6. Test Circuit 8
Philips Semiconductors
Product specification
SA5212A
Transimpedance amplifier (140MHz)
1998 Oct 07
8
TYPICAL PERFORMANCE CHARACTERISTICS
POPULA
TION (%)
NE5212A Typical
Bandwidth Distribution
(75 Parts from 3 Wafer Lots)
50
40
30
20
10
0
112.5
122.5
132.5
142.5
152.5
162.5
FREQUENCY (MHz)
PIN 5
SINGLE-ENDED
RL = 50
VCC = 5.0V
TA = 25
C
N, F PKG
17
60
20
0
20 40
60 80 100 120
40
OUTPUT
RESIST
ANCE ( )
AMBIENT TEMPERATURE (
C)
PIN 5
DC TESTED
PIN 7
16
15
14
13
12
11
10
9
140
VCC = 5.0V
NE5212A Output Resistance
vs Temperature
NE5212A Power Supply Rejection Ratio
vs Temperature
40
39
38
37
36
35
34
33
60 40 20
0
20 40
100
60
120
80
POWER
SUPPL
Y
REJECTION RA
TIO
(dB)
AMBIENT TEMPERATURE (
C)
VCC = 5.0V
VCC =
0.1V
DC TESTED
OUTPUT REFERRED
140
NE5212A Differential Transresistance
vs Temperature
17.0
60 40 20
0
20 40
100
60
120
80
DIFFERENTIAL
TRANSRESIST
ANCE (k )
140
AMBIENT TEMPERATURE (
C)
VCC = 5.0V
DC TESTED
RL =
16.5
16.0
15.5
15.0
14.5
14.0
60 40 20
0
20 40
100
60
120
80
140
AMBIENT TEMPERATURE (
C)
80
60
40
20
0
20
40
60
VCC = 5.0V
VOS = VOUT5 VOUT7
OUTPUT OFFSET VOL
T
AGE
(mV)
NE5212A Output Offset Voltage
vs Temperature
NE5212A Differential Output Swing
vs Temperature
VCC = 5.0V
DC TESTED
RL =
60 40 20
0
20 40
100
60
120
80
140
AMBIENT TEMPERATURE (
C)
3.8
DIFFERENTIAL
OUTPUT SWING (V)
3.6
3.4
3.2
3.0
2.8
2.6
2.4
60 40 20
0
20 40
100
60
120
80
140
AMBIENT TEMPERATURE (
C)
VCC = 5.0V
30
SUPPL
Y
CURRENT (mA)
29
28
27
26
25
NE5212A Output Bias Voltage
vs Temperature
NE5212A Input Bias Voltage
vs Temperature
NE5212A Supply Current
vs Temperature
VCC = 5.0V
60 40 20
0
20 40
100
60
120
80
140
AMBIENT TEMPERATURE (
C)
950
INPUT BIAS VOL
T
AGE
(mV)
900
850
800
750
700
650
600
60 40 20
0
20 40
100
60
120
80
140
AMBIENT TEMPERATURE (
C)
3.50
OUTPUT BIAS VOL
T
AGE
(V) 3.45
3.40
3.35
3.30
3.25
PIN 5
PIN 7
VCC = 5.0V
SD00341
Figure 7. Typical Performance Characteristics
Philips Semiconductors
Product specification
SA5212A
Transimpedance amplifier (140MHz)
1998 Oct 07
9
TYPICAL PERFORMANCE CHARACTERISTICS
(Continued)
Gain vs Frequency
Gain vs Frequency
Output Resistance
vs Frequency
Gain vs Frequency
Gain and Phase Shift
vs Frequency
12
11
10
9
8
7
6
5
4
3
0.1
1
10
100
GAIN (dB)
FREQUENCY (MHz)
11
10
9
8
7
6
5
4
3
0.1
1
10
100
GAIN (dB)
FREQUENCY (MHz)
0.1
1
10
100
FREQUENCY (MHz)
80
OUTPUT
RESIST
ANCE ( )
70
60
50
40
30
20
10
Gain vs Frequency
Output Resistance
vs Frequency
Gain and Phase Shift
vs Frequency
Gain and Phase Shift
vs Frequency
5.5V
4.5V
5.0V
PIN 5
TA = 25
C
N PKG
PIN 7
TA = 25
C
N PKG
5.5V
5.0V
4.5V
VCC = 5V
TA = 25
C
N PKG
PIN 7
PIN 5
11
0.1
1
10
100
GAIN (dB)
FREQUENCY (MHz)
10
9
8
7
6
5
4
3
PIN 5
VCC = 5V
N PKG
25
C
55
C
125
C
85
C
55
C
125
C
11
0.1
1
10
100
GAIN (dB)
10
9
8
7
6
5
4
3
PIN 7
VCC = 5V
N PKG
FREQUENCY (MHz)
55
C
125
C
55
C
125
C
100
OUTPUT
RESIST
ANCE ( )
0.1
1
10
100
FREQUENCY (MHz)
90
80
70
60
50
40
30
20
10
TA = 25
C
VCC = 5V
D PKG
11
0.1
1
10
100
GAIN (dB)
10
9
8
7
6
5
4
3
FREQUENCY (MHz)
PIN 5
VCC = 5V
N PKG
TA = 25
C
45
135
225
PHASE ( )
o
11
0.1
1
10
100
GAIN (dB)
10
9
8
7
6
5
4
3
180
270
360
PHASE ( )
o
FREQUENCY (MHz)
PIN 7
VCC = 5V
D PKG
TA = 25
C
11
0.1
1
10
100
GAIN (dB)
10
9
8
7
6
5
4
3
180
270
360
PHASE ( )
o
PIN 7
VCC = 5V
N PKG
TA = 25
C
FREQUENCY (MHz)
SD00342
Figure 8. Typical Performance Characteristics (cont.)
Philips Semiconductors
Product specification
SA5212A
Transimpedance amplifier (140MHz)
1998 Oct 07
10
TYPICAL PERFORMANCE CHARACTERISTICS
(Continued)
FREQUENCY (MHz)
Gain and Phase Shift
vs Frequency
Output Voltage
vs Input Current
Differential Output Voltage
vs Input Current
Differential Output Voltage
vs Input Current
Group Delay
vs Frequency
Output Step Response
0
2
4
6
8
10
12
14
16
18
20
(ns)
VCC = 5V
TA = 25
C
20mV/Div
10
8
6
4
2
0
0.1
20
40
60
80
100
120 140
160
DELA
Y
(ns)
2.000
0
2.000
OUTPUT VOL
T
AGE
(V)
150.0
150.0
INPUT CURRENT (
A)
25
C
55
C
125
C
85
C
55
C
25
C
85
C
125
C
11
10
9
8
7
6
5
4
3
0.1
1
10
100
FREQUENCY (MHz)
0
90
180
GAIN (dB)
PHASE ( )
o
4.5
DIFFERENTIAL
OUTPUT VOL
T
AGE
(V)
2.0
150.0
150.0
0
125
C
85
C
25
C
55
C
INPUT CURRENT (
A)
85
C
125
C
25
C
55
C
2.0
DIFFERENTIAL
OUTPUT VOL
T
AGE
(V)
0
2.0
150.0
150.0
0
INPUT CURRENT (
A)
5.5V
4.5V
5.0V
5.5V
4.5V
5.0V
PIN 5
VCC = 5V
D PKG
TA = 25
C
SD00343
Figure 9. Typical Performance Characteristics (cont.)
Philips Semiconductors
Product specification
SA5212A
Transimpedance amplifier (140MHz)
1998 Oct 07
11
THEORY OF OPERATION
Transimpedance amplifiers have been widely used as the
preamplifier in fiber-optic receivers. The SA5212A is a wide
bandwidth (typically 140MHz) transimpedance amplifier designed
primarily for input currents requiring a large dynamic range, such as
those produced by a laser diode. The maximum input current before
output stage clipping occurs at typically 240
A. The SA5212A is a
bipolar transimpedance amplifier which is current driven at the input
and generates a differential voltage signal at the outputs. The
forward transfer function is therefore a ratio of the differential output
voltage to a given input current with the dimensions of ohms. The
main feature of this amplifier is a wideband, low-noise input stage
which is desensitized to photodiode capacitance variations. When
connected to a photodiode of a few picoFarads, the frequency
response will not be degraded significantly. Except for the input
stage, the entire signal path is differential to provide improved
power-supply rejection and ease of interface to ECL type circuitry. A
block diagram of the circuit is shown in Figure 10. The input stage
(A1) employs shunt-series feedback to stabilize the current gain of
the amplifier. The transresistance of the amplifier from the current
source to the emitter of Q
3
is approximately the value of the
feedback resistor, R
F
=7k
. The gain from the second stage (A2)
and emitter followers (A3 and A4) is about two. Therefore, the
differential transresistance of the entire amplifier, R
T
is
R
T
+
V
OUT
(diff)
I
IN
+
2R
F
+
2(7.2K)
+
14.4k
W
The single-ended transresistance of the amplifier is typically 7.2k
.
The simplified schematic in Figure 11 shows how an input current is
converted to a differential output voltage. The amplifier has a single
input for current which is referenced to Ground 1. An input current
from a laser diode, for example, will be converted into a voltage by
the feedback resistor R
F
. The transistor Q1 provides most of the
open loop gain of the circuit, A
VOL
70. The emitter follower Q
2
minimizes loading on Q
1
. The transistor Q
4
, resistor R
7
, and V
B1
provide level shifting and interface with the Q
15
Q
16
differential
pair of the second stage which is biased with an internal reference,
V
B2
. The differential outputs are derived from emitter followers Q
11
Q
12
which are biased by constant current sources. The collectors of
Q
11
Q
12
are bonded to an external pin, V
CC2
, in order to reduce
the feedback to the input stage. The output impedance is about 17
single-ended. For ease of performance evaluation, a 33
resistor is
used in series with each output to match to a 50
test system.
BANDWIDTH CALCULATIONS
The input stage, shown in Figure 12, employs shunt-series feedback
to stabilize the current gain of the amplifier. A simplified analysis can
determine the performance of the amplifier. The equivalent input
capacitance, C
IN
, in parallel with the source, I
S
, is approximately
7.5pF, assuming that C
S
=0 where C
S
is the external source
capacitance.
Since the input is driven by a current source the input must have a
low input resistance. The input resistance, R
IN
, is the ratio of the
incremental input voltage, V
IN
, to the corresponding input current, I
IN
and can be calculated as:
R
IN
+
V
IN
I
IN
+
R
F
1
)
A
VOL
+
7.2K
70
+
103
W
More exact calculations would yield a higher value of 110
.
Thus C
IN
and R
IN
will form the dominant pole of the entire amplifier;
f
*
3dB
+
1
2
p
R
IN
C
IN
Assuming typical values for R
F
= 7.2k
, R
IN
= 110
, C
IN
= 10pF
f
*
3dB
+
1
2
p
(110) 10
@
10
*
12
+
145MHz
The operating point of Q1, Figure 2, has been optimized for the
lowest current noise without introducing a second dominant pole in
the pass-band. All poles associated with subsequent stages have
been kept at sufficiently high enough frequencies to yield an overall
single pole response. Although wider bandwidths have been
achieved by using a cascade input stage configuration, the present
solution has the advantage of a very uniform, highly desensitized
frequency response because the Miller effect dominates over the
external photodiode and stray capacitances. For example, assuming
a source capacitance of 1pF, input stage voltage gain of 70, R
IN
=
60
then the total input capacitance, C
IN
= (1+7.5) pF which will
lead to only a 12% bandwidth reduction.
INPUT
OUTPUT +
OUTPUT
A1
A2
A3
A4
RF
SD00327
Figure 10. SA5212A Block Diagram
NOISE
Most of the currently installed fiber-optic systems use non-coherent
transmission and detect incident optical power. Therefore, receiver
noise performance becomes very important. The input stage
achieves a low input referred noise current (spectral density) of
3.5pA/
Hz. The transresistance configuration assures that the
external high value bias resistors often required for photodiode
biasing will not contribute to the total noise system noise. The
equivalent input
RMS
noise current is strongly determined by the
quiescent current of Q
1
, the feedback resistor R
F
, and the
bandwidth; however, it is not dependent upon the internal
Miller-capacitance. The measured wideband noise was 52nA RMS
in a 200MHz bandwidth.
Philips Semiconductors
Product specification
SA5212A
Transimpedance amplifier (140MHz)
1998 Oct 07
12
INPUT
OUT
OUT+
PHOTODIODE
VB2
+
+
R1
R3
R12
R13
R5
R4
R7
R14
R15
Q1
Q3
Q2
Q4
Q15
Q16
Q11
Q12
GND2
GND1
VCC2
VCC1
R2
SD00328
Figure 11. Transimpedance Amplifier
VCC
VEQ3
VIN
IIN
INPUT
IF
IB
Q1
Q2
Q3
R2
R3
R4
RF
R1
IC1
SD00329
Figure 12. Shunt-Series Input Stage
DYNAMIC RANGE
The electrical dynamic range can be defined as the ratio of
maximum input current to the peak noise current:
Electrical dynamic range, D
E
, in a 200MHz bandwidth assuming
I
INMAX
= 120
A and a wideband noise of I
EQ
=52nA
RMS
for an
external source capacitance of C
S
= 1pF.
D
E
+
(Max. input current)
(Peak noise current)
D
E
(dB)
+
20 log
(120
@
10
*
6
)
( 2 52nA)
D
E
(dB)
+
20 log
(120
m
A)
(73nA)
+
64dB
In order to calculate the optical dynamic range the incident optical
power must be considered.
For a given wavelength
;
Energy of one Photon = hc
l
watt sec (Joule)
Where h=Planck's Constant = 6.6
10
-34
Joule sec.
c = speed of light = 3
10
8
m/sec
c /
= optical frequency
No. of incident photons/sec= where P=optical incident power
No. of incident photons/sec =
P
hc
l
where P = optical incident power
No. of generated electrons/sec =
h @
P
hc
l
where
= quantum efficiency
+
no. of generated electron hole paris
no. of incident photons
N
I
+ h @
P
hc
l @
e Amps (Coulombs sec.)
where e = electron charge = 1.6
10
-19
Coulombs
Responsivity R =
h@
e
hc
l
Amp/watt
I
+
P
@
R
Assuming a data rate of 400 Mbaud (Bandwidth, B=200MHz), the
noise parameter Z may be calculated as:
1
Z
+
I
EQ
qB
+
52
@
10
*
9
(1.6
@
10
*
19
)(200
@
10
6
)
+
1625
Amp
Amp
where Z is the ratio of
RMS
noise output to the peak response to a
single hole-electron pair. Assuming 100% photodetector quantum
efficiency, half mark/half space digital transmission, 850nm
lightwave and using Gaussian approximation, the minimum required
optical power to achieve 10
-9
BER is:
P
avMIN
+
12
hc
l
B Z
+
12 (2.3
@
10
*
19
)
200
@
10
6
1625
+
897nW
+ *
30.5dBm,
where h is Planck's Constant, c is the speed of light,
is the
wavelength. The minimum input current to the SA5212A, at this
input power is:
I
avMIN
+
qP
avMIN
l
hc
+
897
@
10
*
9
@
1.6
@
10
*
19
2.3
@
10
*
19
= 624nA
Philips Semiconductors
Product specification
SA5212A
Transimpedance amplifier (140MHz)
1998 Oct 07
13
Choosing the maximum peak overload current of I
avMAX
=120
A, the
maximum mean optical power is:
OUT+
OUT
IN
VIN
NE5212A
R = 560
a. Non-inverting 20dB Amplifier
OUT
OUT+
IN
NE5212A
R = 560
VIN
b. Inverting 20dB Amplifier
OUT
OUT+
IN
NE5212A
R = 560
VIN
c. Differential 20dB Amplifier
SD00344
Figure 13. Variable Gain Circuit
P
avMAX
+
hcI
avMAX
l
q
+
2.3
@
10
*
19
(120
@
10
*
6
)
1.6
@
10
*
19
= 172
W or 7.6dBm
Thus the optical dynamic range, D
O
is:
D
O
= P
avMAX
- P
avMIN
= -30.5 -(-7.6) = 22.8dB.
This represents the maximum limit attainable with the SA5212A
operating at 200MHz bandwidth, with a half mark/half space digital
transmission at 820nm wavelength.
APPLICATION INFORMATION
Package parasitics, particularly ground lead inductances and
parasitic capacitances, can significantly degrade the frequency
response. Since the SA5212A has differential outputs which can
feed back signals to the input by parasitic package or board layout
capacitances, both peaking and attenuating type frequency
response shaping is possible. Constructing the board layout so that
Ground 1 and Ground 2 have very low impedance paths has
produced the best results. This was accomplished by adding a
ground-plane stripe underneath the device connecting Ground 1,
Pins 811, and Ground 2, Pins 1 and 2 on opposite ends of the
SO14 package. This ground-plane stripe also provides isolation
between the output return currents flowing to either V
CC2
or Ground
2 and the input photodiode currents to flowing to Ground 1. Without
this ground-plane stripe and with large lead inductances on the
board, the part may be unstable and oscillate near 800MHz. The
easiest way to realize that the part is not functioning normally is to
measure the DC voltages at the outputs. If they are not close to their
quiescent values of 3.3V (for a 5V supply), then the circuit may be
oscillating. Input pin layout necessitates that the photodiode be
physically very close to the input and Ground 1. Connecting Pins 3
and 5 to Ground 1 will tend to shield the input but it will also tend to
increase the capacitance on the input and slightly reduce the
bandwidth.
As with any high-frequency device, some precautions must be
observed in order to enjoy reliable performance. The first of these is
the use of a well-regulated power supply. The supply must be
capable of providing varying amounts of current without significantly
changing the voltage level. Proper supply bypassing requires that a
good quality 0.1
F high-frequency capacitor be inserted between
V
CC1
and V
CC2
, preferably a chip capacitor, as close to the package
pins as possible. Also, the parallel combination of 0.1
F capacitors
with 10
F tantalum capacitors from each supply, V
CC1
and V
CC2
, to
the ground plane should provide adequate decoupling. Some
applications may require an RF choke in series with the power
supply line. Separate analog and digital ground leads must be
maintained and printed circuit board ground plane should be
employed whenever possible.
BASIC CONFIGURATION
A trans resistance amplifier is a current-to-voltage converter. The
forward transfer function then is defined as voltage out divided by
current in, and is stated in ohms. The lower the source resistance,
the higher the gain. The SA5212A has a differential transresistance
of 14k
typically and a single-ended transresistance of 7k
typically. The device has two outputs: inverting and non-inverting.
The output
voltage in the differential output mode is twice that of the output
voltage in the single-ended mode. Although the device can be used
without coupling capacitors, more care is required to avoid upsetting
the internal bias nodes of the device. Figure 13 shows some basic
configurations.
VARIABLE GAIN
Figure 14 shows a variable gain circuit using the SA5212A and the
SA5230 low voltage op amp. This op amp is configured in a
non-inverting gain of five. The output drives the gate of the SD210
DMOS FET. The series resistance of the FET changes with this
output voltage which in turn changes the gain of the SA5212A. This
circuit has a distortion of less than 1% and a 25dB range, from
-42.2dBm to -15.9dBm at 50MHz, and a 45dB range, from -60dBm
to -14.9dBm at 10MHz with 0 to 1V of control voltage at V
CC
.
SD210
OUT+
OUT
05V
IN
+5V
10k
2.4k
01V
51
NE5212A
VCC
RFOUT
RFIN
0.1
F
SD00345
Figure 14. Variable Gain Circuit
Philips Semiconductors
Product specification
SA5212A
Transimpedance amplifier (140MHz)
1998 Oct 07
14
16MHZ CRYSTAL OSCILLATOR
Figure 15 shows a 16MHz crystal oscillator operating in the series
resonant mode using the SA5212A. The non-inverting input is fed
back to the input of the SA5212A in series with a 2pF capacitor. The
output is taken from the inverting output.
+5V
OUT+
OUT
IN
NE5212A
SD00346
Figure 15. 16MHz Crystal Oscillator
DIGITAL FIBER OPTIC RECEIVER
Figures 16 and 17 show a fiber optic receiver using off-the-shelf
components.
The receiver shown in Figure 16 uses the SA5212A, the Philips
Semiconductors 10116 ECL line receiver, and Philips/Amperex
BPF31 PIN diode. The circuit is a capacitor-coupled receiver and
utilizes positive feedback in the last stage to provide the hysteresis.
The amount of hysteresis can be tailored to the individual application
by changing the values of the feedback resistors to maintain the
desired balance between noise immunity and sensitivity. At room
temperature, the circuit operates at 50Mbaud with a BER of 10E-10
and over the automotive temperature range at 40Mbaud with a BER
of 10E-9. Higher speed experimental diodes have been used to
operate this circuit at 220Mbaud with a BER of 10E-10.
Figure 17 depicts a TTL receiver using the SA5212A and the
SA5214 fast amplifier system along with the Philips/Amperex PIN
diode. The system shown is optimized for 50 Mb/s Non Return to
Zero (NRZ) data. A link status indication is provided along with a
jamming function when the input level is below a
user-programmable threshold level.
4.7
+5.0
1k
1
2
3
4 6
8
5
7
BPF31
15V
5.2V
1k
9
10
11 6
7
16
1
1/3
10116
NE5212A
510
510
5
4
8
3
2
510
510
100pF
100pF
1k
1k
1k
1k
13
12
14
15
510
510
ECL
ECL
0.01
F
0.01
F
0.01
F
0.01
F
0.1
F
0.1
F
0.1
F
1.0
F
2.7
H
4.7
F
4.7
F
0.1
F
VEE
VEE
VBB
1
VBB
1
VBB
1
VBB
1
1/3
10116
1/3
10116
VEE
VCC
NOTE:
1. Tie all VBB points together.
SD00347
Figure 16. ECL Fiber Optic Receiver
Philips Semiconductors
Product specification
SA5212A
Transimpedance amplifier (140MHz)
1998 Oct 07
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
1
2
3
4
5
6
7
8
LED
C
PKDET
THRESH
GND
A
FLAG
JAM
V
CCD
V
CCA
GND
D
TTL
OUT
IN
1B
IN
1A
C
AZP
C
AZN
OUT
2B
IN
8B
OUT
2A
IN
8A
R
HYST
R
PKDET
NE5214
OUT+
GND
2
OUT
GND
2
GND
1
GND
1
V
CC
I
IN
NE5212A
R2
220
D1
LED
C9
100pF
100pF
C7
.01
F
47
F
C1
C2
GND
+V
CC
0.1
F
R4
5.1k
R3
47k
V
OUT
(TTL)
L3
10
H
L2
10
H
C11
C10
.01
F
.01
F
C13
C12
10
F
10
F
C8
L1
10
H
BPF31
OPTICAL
INPUT
R1
100
C5
1.0
F
C6
.01
F
.01
F
C4
10
F
C3
SD00348
Figure 17. A 50Mb/s TTL Digital Fiber Optic Receiver
Philips Semiconductors
Product specification
SA5212A
Transimpedance amplifier (140MHz)
1998 Oct 07
16
1
2
3
4
5
6
7
8
GND1
GND1
OUT+
GND2
OUT
GND2
IIN
VCC
ECN No.: 99918
1990 Jul 5
SD00489
Figure 18. SA5212A Bonding Diagram
Die Sales Disclaimer
Due to the limitations in testing high frequency and other parameters
at the die level, and the fact that die electrical characteristics may
shift after packaging, die electrical parameters are not specified and
die are not guaranteed to meet electrical characteristics (including
temperature range) as noted in this data sheet which is intended
only to specify electrical characteristics for a packaged device.
All die are 100% functional with various parametrics tested at the
wafer level, at room temperature only (25
C), and are guaranteed to
be 100% functional as a result of electrical testing to the point of
wafer sawing only. Although the most modern processes are
utilized for wafer sawing and die pick and place into waffle pack
carriers, it is impossible to guarantee 100% functionality through this
process. There is no post waffle pack testing performed on
individual die.
Since Philips Semiconductors has no control of third party
procedures in the handling or packaging of die, Philips
Semiconductors assumes no liability for device functionality or
performance of the die or systems on any die sales.
Although Philips Semiconductors typically realizes a yield of 85%
after assembling die into their respective packages, with care
customers should achieve a similar yield. However, for the reasons
stated above, Philips Semiconductors cannot guarantee this or any
other yield on any die sales.
Philips Semiconductors
Product specification
SA5212A
Transimpedance amplifier (140MHz)
1998 Oct 07
17
DIP8:
plastic dual in-line package; 8 leads (300 mil)
SOT97-1
Philips Semiconductors
Product specification
SA5212A
Transimpedance amplifier (140MHz)
1998 Oct 07
18
SO8:
plastic small outline package; 8 leads; body width 3.9mm
SOT96-1
Philips
Semiconductors
Product specification
SA5212A
T
ransimpedance amplifier (140MHz)
1998
Oct 07
19
0580A
8-PIN (300 mils wide) CERAMIC DUAL IN-LINE (F) P
ACKAGE
NOTES:
1. Controlling dimension: Inches. Millimeters are
2. Dimension and tolerancing per ANSI Y14. 5M-1982.
3. "T", "D", and "E" are reference datums on the body
4. These dimensions measured with the leads
5. Pin numbers start with Pin #1 and continue
and include allowance for glass overrun and meniscus
on the seal line, and lid to base mismatch.
constrained to be perpendicular to plane T.
counterclockwise to Pin #8 when viewed
shown in parentheses.
from the top.
0.200 (5.08)
0.010 (0.254)
T
E D
0.023 (0.58)
0.015 (0.38)
0.165 (4.19)
0.125 (3.18)
0.165 (4.19)
0.175 (4.45)
0.145 (3.68)
0.320 (8.13)
0.290 (7.37)
(NOTE 4)
BSC
0.300 (7.62)
0.395 (10.03)
0.300 (7.62)
(NOTE 4)
0.015 (0.38)
0.010 (0.25)
0.035 (0.89)
0.020 (0.51)
D
PIN # 1
E
0.303 (7.70)
0.245 (6.22)
0.100 (2.54) BSC
0.408 (10.36)
0.376 (9.55)
0.055 (1.40)
0.030 (0.76)
T
SEATING
PLANE
0.070 (1.78)
0.050 (1.27)
0.055 (1.40)
0.030 (0.76)
8530580A
006688
Philips Semiconductors
Product specification
SA5212A
Transimpedance amplifier (140MHz)
1998 Oct 07
20
Definitions
Short-form specification -- The data in a short-form specification is extracted from a full data sheet with the same type number and title. For
detailed information see the relevant data sheet or data handbook.
Limiting values definition -- Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one
or more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation of the device at these or
at any other conditions above those given in the Characteristics sections of the specification is not implied. Exposure to limiting values for extended
periods may affect device reliability.
Application information -- Applications that are described herein for any of these products are for illustrative purposes only. Philips
Semiconductors make no representation or warranty that such applications will be suitable for the specified use without further testing or
modification.
Disclaimers
Life support -- These products are not designed for use in life support appliances, devices or systems where malfunction of these products can
reasonably be expected to result in personal injury. Philips Semiconductors customers using or selling these products for use in such applications
do so at their own risk and agree to fully indemnify Philips Semiconductors for any damages resulting from such application.
Right to make changes -- Philips Semiconductors reserves the right to make changes, without notice, in the products, including circuits, standard
cells, and/or software, described or contained herein in order to improve design and/or performance. Philips Semiconductors assumes no
responsibility or liability for the use of any of these products, conveys no license or title under any patent, copyright, or mask work right to these
products, and makes no representations or warranties that these products are free from patent, copyright, or mask work right infringement, unless
otherwise specified.
Philips Semiconductors
811 East Arques Avenue
P.O. Box 3409
Sunnyvale, California 940883409
Telephone 800-234-7381
Copyright Philips Electronics North America Corporation 1998
All rights reserved. Printed in U.S.A.
Date of release: 10-98
Document order number:
9397 750 04625
Philips
Semiconductors
Data sheet
status
Objective
specification
Preliminary
specification
Product
specification
Product
status
Development
Qualification
Production
Definition
[1]
This data sheet contains the design target or goal specifications for product development.
Specification may change in any manner without notice.
This data sheet contains preliminary data, and supplementary data will be published at a later date.
Philips Semiconductors reserves the right to make chages at any time without notice in order to
improve design and supply the best possible product.
This data sheet contains final specifications. Philips Semiconductors reserves the right to make
changes at any time without notice in order to improve design and supply the best possible product.
Data sheet status
[1]
Please consult the most recently issued datasheet before initiating or completing a design.
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