ANADIGICS ATA01501

ATA01501
AGC Transimpedance Amplifier
SONET OC-3
PRELIMINARY DATA SHEET - Rev 1.6
FEATURES
·
·
·
·
·
Single +5 Volt Supply
Automatic Gain Control
-38 dBm Sensitivity
0 dBm Optical Overload
175 MHz Bandwidth
VDD2
VDD1
APPLICATIONS
·
·
·
GND
GND
19 I
IIN
SONET OC-3/SDH STM-1 (155mb/s) receiver
FDDI Ethernet Fiber LAN
Low Noise RF Amplifier
1992
VOUT
GND
GND
GND GND
CBY
CBY
GND CAGC
GND
D1
Die Package
PRODUCT DESCRIPTION
The ANADIGICS ATA01501 is a 5V low noise
transimpedance amplifier with AGC designed to be
used in OC-3/STM-1 fiber optic links. The device is
used in conjunction with a photodetector (PIN diode
or avalanche photodiode) to convert an optical signal
S2
12 Pin 4 Sided
SQFP Package
into an output voltage. The ATA01501 offers a wide
bandwidth of 175MHz and a dynamic range of 38dB.
It is manufactured in a GaAs MESFET process and
available in bare die form or a 12 pin SQFP package.
VDD1
VDD2
AGC
19 K
70K
CAGC
+
4pF
IIN
GND
or
neg.supply
+ 0.8
- 45
VGA
US PATENT
VOUT
GND
CBY
Photodector cathode must be connected
to Iin
IIN for proper AGC operation
Figure 1: Equivalent Circuit
08/2001
2-1
ATA01501
VDD2
VDD1
12
10
GND
GND
19 I
925 um
IIN
1
9
2
8
3
7
1992
VOUT
GND
GND
11
CBY
CBY
GND GND
GND CAGC
GND
4
5
6
1250 um
Figure 3: Pin Layout
Figure 2: Die Bonding Pads
Table 3: Pad Description
PAD
D escription
V DD1
V DD1
Posi ti ve supply for i nput gai n stage
V DD2
V DD2
Posi ti ve supply for second gai n stage
IIN
TIA Input C urrent
VOUT
TIA Output Voltage
C AGC
External AGC C apaci tor
C BY
C omment
C onnect detector cathode for proper operati on
Requi res external D C block
70K * C AGC = AGC ti me constant
Input gai n stage bypass capaci tor >56 pF
Table 2: Pin Description
2
PIN
D ESC R IPTION
PIN
D ESC R IPTION
1
NC
7
VOUT
2
GND
8
GND
3
IIN
9
NC
4
C BY
10
VDD
5
GND
11
GND
6
C AGC
12
NC
PRELIMINARY DATA SHEET - Rev 1.6
08/2001
ATA01501
ELECTRICAL CHARACTERISTICS
Table 3: Absolute Maximum Ratings
V DD1
7.0 V
V DD2
7.0 V
IIN
5 mA
TA
Operati ng Temp. - 400 C to 1250 C
TS
Storage Temp. - 650 C to 1500 C
Stresses in excess of the absolute ratings may cause
permanent damage. Functional operation is not implied
under these conditions. Exposure to absolute ratings for
extended periods of time may adversely affect reliability.
PRELIMINARY DATA SHEET - Rev 1.6
08/2001
3
ATA01501
Table 4: Electrical Specifications (1)
(TA= 25°C, VDD=+5.0V + 10%, CDIODE+CSTRAY = 0.5 pF, Det. Cathode to IIN)
PAR AMETER
MIN
Transresi stance (RL=¥,Idc<500nA)
TYP
MAX
U N IT
KW
17
Transresi stance (RL=50W ) (1)
5.5
8
Bandwi dth -3dB (D 1C )
150
175
MHz
Bandwi dth -3dB (S2C )
130
175
MHz
500
W
Input Resi stance
(2)
Output Resi stance
30
Supply C urrent
Input Offset Voltage
1.4
Output Offset Voltage
AGC Threshold (IIN)
Opti cal Overload
(3)
(4)
10
KW
50
60
W
30
45
mA
1.6
1.9
Volts
1.8
Volts
15
30
mA
-3
0
dB m
Input Noi se C urrent (5)
14
AGC Ti me C onstant (6)
16
m se c
1
mV/ º C
Opti cal Sensi ti vi ty -(D 1C ) (7)
-38
dB m
Opti cal Sensi ti vi ty - (S2C )
-37
dB m
Offset Voltage D ri ft
(7)
Operati ng Voltage Range
+ 4.5
Operati ng Temperature Range
- 40
+ 5.0
20
nA
+ 6.0
Volts
85
ºC
Notes:
1. f = 50 MHz
2. Measured with IIN below
AGC Threshold. During AGC, input impedance will decrease proportionally to IIN
3. Defined as the IIN where Transresistance has decreased by 50%.
4. See note on “Indirect Measurement of Optical Overload”.
5. See note on “Measurement of Input Referred Noise Current”.
6. CAGC = 220 pF
7.
Parameter is guaranteed (not tested) by design and characterization data
@155Mb assuming detector responsivity of 0.9
4
PRELIMINARY DATA SHEET - Rev 1.6
08/2001
ATA01501
VDD
VDD
56pF
GND
56pF
12
V DD2
VDD
PIN
11
10
GND
19 I
IIN
GND
GND
VOUT
GND
0.1µF
NC
NC
1992
GND GND
CBY CBY
GND CAGC GND
56pF
56pF
OUT
IIN
1
9
2
8
3
7
GND
or
Neg.Supply
4
5
General Layout Considerations
Since the gain stages of the transimpedance
amplifier have an open loop bandwidth in excess
of 1.0 GHz, it is essential to maintain good high
frequency layout practices. To prevent oscillations,
a low inductance RF ground plane should be made
available for power supply bypassing. Traces that
can be made short should be made short, and
the utmost care should be taken to maintain very
low capacitance at the photodiode-TIA interface
(IIN), as excess capacitance at this node will
cause a degradation in bandwidth and sensitivity
(see Bandwidth vs. CT curves).
56 pF
Figure 5: ATA01501DS2C Typical SQFP
Connection Package
Power Supplies and General Layout
CT = 0.5 pF
0.17
Bandwidth (GHz)
The ATA00501D1C may be operated from a positive
supply as low as +4.5 V and as high as +6.0 V. Below
+4.5 V, bandwidth, overload and sensitivity will
degrade, while at +6.0 V, bandwidth, overload and
sensitivity improve (see “Bandwidth vs. Temperature”
curves). Use of surface mount (preferably MIM type
capacitors), low inductance power supply bypass
capacitors (>=56pF) are essential for good high
frequency and low noise performance. The power
supply bypass capacitors should be mounted on or
connected to a good low inductance ground plane.
0.1µF
Vout
6
56 pF
Figure 4: ATA01501D1C Die Typical Bonding
NC
VDD = 5.5 V
0.15
0.13 V
DD = 5.0 V
0.11
0.90
-40
VDD = 4.5 V
10
60
85
Temperature (O C)
Figure 6: Bandwidth vs. Temperature
PRELIMINARY DATA SHEET - Rev 1.6
08/2001
5
ATA01501
1.44
B(3dB) A
≈ / 2 π Rf (Cin +Ct)
Bandwith (MHz)
200
1.24
.84
VDD = 5.0 V
180
.64
170
160
1.04
VDD = 5.5 V
VDD = 5.5 V
190
BANDWIDTH (GHz)
210
Rf
VDD = 4.5 V
VDD = 4.5 V
.44
.24
IIN
50
.04
150
0 0.2 0.4 0.6 0.8
1
1.2
1.4 1.6
- 2.1
- 1.6
CT(pF)
- 1.1
- 0.6
- 0.1
IIN (mA DC)
Figure 7: Bandwidth vs. CT
Figure 9: Bandwidth vs. IIN
Note: All performance curves are typical @ TA =25 oC
unless otherwise noted.
VOUT Connection
IIN Connection
(Refer to the equivalent circuit diagram.) Bonding
the detector cathode to IIN (and thus drawing current
from the ATA00501) improves the dynamic range.
Although the detector may be used in the reverse
direction for input currents not exceeding 25 mA, the
specifications for optical overload will not be met.
22
19
16
IIN
13
50
10
4
VDD = 4.5 V
-2.1
-1.6
-1.1
-0.6
1
to a high input impedance decision circuit (>500
ohms), then a coupling capacitor may not be
required, although caution should be exercised since
DC offsets of the photo detector/TIA combination may
cause clipping of subsequent gain or decision
circuits.
Heavy AGC
Output Collapse
VDD = 5.5 V
Linear Region
Rf
IIN
-0.1
vOUT
VDD = 4.5 V
IIN (mA DC)
Figure 8: Transimpedance vs. IIN
-4
-3
-2
-1
IIN (mA DC)
Figure 10: VOUT vs. IIN
6
PRELIMINARY DATA SHEET - Rev 1.6
08/2001
3.4
3.2
3.0
2.9
2.7
2.5 (
2.4
2.2 o
2.0
1.9
1.7
1.5
1.4
1.2
1.0
0.8
0.7
0.5
0.3
0.2
0.0
VOUT (Volts)
7
VDD = 5.5 V
Transimpedance (K Ohm)
25
The output pad should be connected via a coupling
capacitor to the next stage of the receiver channel
(filter or decision circuits), as the output buffers are
not designed to drive a DC coupled 50 ohm load
(this would require an output bias current of
approximately 36 mA to maintain a quiescent 1.8
Volts across the output load). If VOUT is connected
VDD = 4.5V
10
Temperature oC
60
Figure 11: Input Offset Voltage vs. Temperature
CBY Connection
The C BY pad must be connected via a low
inductance path to a surface mount capacitor of at
least 56pF (additional capacitance can be added in
parallel with the 56 pF or 220 pF capacitors to
improve low frequency response and noise
performance). Referring to the equivalent circuit
diagram and the typical bonding diagram, it is critical
that the connection from CBY to the bypass capacitor
use two bond wires for low inductance, since any
high frequency impedance at this node will be fed
back to the open loop amplifier with a resulting loss
of transimpedance bandwidth. Two pads are
provided for this purpose
Sensitivity and Bandwidth
Measurement of Input Referred Noise
Current
The “Input Noise Current” is directly related to
sensitivity . It can be defined as the output noise
voltage (Vout), with no input signal, (including a 30
MHz lowpass filter at the output of the TIA) divided by
the AC transresistance.
14
Rf
Hz
- 40
VDD = 5.5 V V = 5.0V
DD
Optical overload can be defined as the maximum
optical power above which the BER (bit error rate)
increases beyond 1 error in 10 10 bits. The
ATA00501D1C is 100% tested at die sort by a DC
measurement which has excellent correlation with
an PRBS optical overload measurement. The measurement consists of sinking a negative current
(see VOUT vs IIN figure) from the TIA and determining the point of output voltage collapse. Also the
input node virtual ground during “heavy AGC” is
checked to verify that the linearity (i.e. pulse width
distortion) of the amplifier has not been compromised.
10
CT
pA/
1.9
1.85
1.8
1.75
1.7
1.65
1.6
1.55
1.5
50
CT=1.0pF
6
2
CT =0.5pF
- 0.1
1
10
100
1000
Frequency (MHz)
Figure 12: Input Referred Noise Spectral Density
In order to guarantee sensitivity and bandwidth
performance, the TIA is subjected to a
comprehensive series of tests at the die sort level
(100% testing at 25 oC) to verify the DC parametric
performance and the high frequency performance
(i.e. adequate |S21|) of the amplifier. Acceptably high
|S21| of the internal gain stages will ensure low
amplifier input capacitance and hence low input
referred noise current. Transimpedance sensitivity
and bandwidth are then guaranteed by design and
correlation with RF and DC die sort test results.
Input Referred Noise in (nA RMS)
Input Offset Voltage
ATA01501
Indirect Measurement of Optical Overload
Input Referred Noise Test Circuit
16
VDD = 4.5 V
25dB
15
14
0.5pF
TIA
100
MHz
LPF
13
VDD =5.5V
12
11
- 40
η(dBm) = 10 LOG
0
40
6500in
R
80
Temperature (oC)
FIgure 13: Input Referred Noise vs Temperature
PRELIMINARY DATA SHEET - Rev 1.6
08/2001
7
ATA01501
AGC Capacitor
It is important to select an external AGC capacitor of
high quality and appropriate size. The ATA00501D1C
has an on-chip 70 KW resistor with a shunt 4 pF
capacitor to ground. Without external capacitance the
chip will provide an AGC time constant of 280 nS. For
the best performance in a typical 51MB/s SONET
receiver, a minimum AGC capacitor of 56pF is
recommended. This will provide the minimum amount
of protection against pattern sensitivity and pulse
width distortion on repetitive data sequences during
high average optical power conditions. Conservative
design practices should be followed when selecting
an AGC capacitor, since unit to unit variability of the
internal time constant and various data conditions
can lead to data errors if the chosen value is too small.
Phase Response
At frequencies below the 3dB bandwidth of the device,
the transimpedance phase response is characteristic
of a single pole transfer function (as shown in the
Phase vs Frequency curve). The output impedance is
essentially resistive up to 1000 MHz.
Degrees
180
200
220
240
VOUT
IIN
00501
0.5pF
50
100
150
Frequency (MHz)
Figure 14: Phase (IIN to VOUT)
8
PRELIMINARY DATA SHEET - Rev 1.6
08/2001
ATA01501
PACKAGE OUTLINE
0.245 (6.22)
0.230 (5.84)
0.065 (1.65)
0.055 (1.40)
0.165 (4.19)
0.152 (3.86)
7°
o
0
0.047 (1.19)
0.032 (0.81)
12
11
0.035 (.89)
0.020 (.51)
10
0.018 (.460)
0.012 (.300)
1
9
2
8
3
7
0.000 (0.00)
0.020 (.51)
4
5
0.021X45°
4 Sides
0.015 (.38)
0.000 (0.00)
6
0.024 (.61)
0.018 (.46)
4X 0.023X45°
0.011 (.28)
0.007 (.18)
0.032 BSC
(0.81)
Figure 15: SQFP Package Outline
PRELIMINARY DATA SHEET - Rev 1.6
08/2001
9
ATA01501
NOTES
10
PRELIMINARY DATA SHEET - Rev 1.6
08/2001
ATA01501
NOTES
PRELIMINARY DATA SHEET - Rev 1.6
08/2001
11
ATA01501
ORDERING INFORMATION
PAR T N U MB ER
PAC K AGE OPTION
PAC K AGE D ESC R IPTION
ATA01501D 1C
D 1C
Die
ATA01501S2C
S 2C
12 Pi n 4 Si ded SQFP Package
ANADIGICS, Inc.
141 Mount Bethel Road
Warren, New Jersey 07059, U.S.A.
Tel: +1 (908) 668-5000
Fax: +1 (908) 668-5132
URL: http://www.anadigics.com
E-mail: [email protected]
IMPORTANT NOTICE
ANADIGICS, Inc. reserves the right to make changes to its products or to discontinue any product at any time without
notice. The product specifications contained in Advanced Product Information sheets and Preliminary Data Sheets are
subject to change prior to a product’s formal introduction. Information in Data Sheets have been carefully checked and are
assumed to be reliable; however, ANADIGICS assumes no responsibilities for inaccuracies. ANADIGICS strongly urges
customers to verify that the information they are using is current before placing orders.
WARNING
ANADIGICS products are not intended for use in life support appliances, devices or systems. Use of an ANADIGICS
product in any such application without written consent is prohibited.
12
PRELIMINARY DATA SHEET - Rev 1.6
08/2001