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PRELIMINARY DATA SHEET - Rev 1.6 FEATURES
* * * * * * * * Single +5 Volt Supply Automatic Gain Control -38 dBm Sensitivity 0 dBm Optical Overload 175 MHz Bandwidth SONET OC-3/SDH STM-1 (155mb/s) receiver FDDI Ethernet Fiber LAN Low Noise RF Amplifier
AGC Transimpedance Amplifier SONET OC-3
ATA01501
VDD2
VDD1
GND GND
1992
APPLICATIONS
19 I IIN GND GND GND GND CBY CBY GND CAGC
VOUT 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 + 4pF IIN
GND or neg.supply
CAGC
- 45
VGA
+ 0.8
VOUT GND
US PATENT
CBY Photodector cathode must be connected to Iin for proper AGC operation IIN
Figure 1: Equivalent Circuit
08/2001
2-1
ATA01501
VDD2
VDD1
12
11
10
GND GND
1992
1 2
9
8 7
19 I 925 um IIN GND GND GND GND CBY 1250 um CBY GND CAGC
3
VOUT GND
4
5
6
Figure 2: Die Bonding Pads
Figure 3: Pin Layout
Table 3: Pad Description
PAD V DD1 V DD2 IIN VOUT C AGC C BY
D escription V DD1 V DD2 TIA Input C urrent TIA Output Voltage External AGC C apaci tor
C omment Posi ti ve supply for i nput gai n stage Posi ti ve supply for second gai n stage 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
PIN 1 2 3 4 5 6 D ESC R IPTION NC GND IIN C BY GND C AGC PIN 7 8 9 10 11 12 D ESC R IPTION VOUT GND NC VDD GND NC
2
PRELIMINARY DATA SHEET - Rev 1.6 08/2001
ATA01501
ELECTRICAL CHARACTERISTICS
Table 3: Absolute Maximum Ratings
V DD1 V DD2 IIN TA TS 7.0 V 7.0 V 5 mA Operati ng Temp. - 400 C to 1250 C 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= 25C, VDD=+5.0V + 10%, CDIODE+CSTRAY = 0.5 pF, Det. Cathode to IIN)
PAR AMETER Transresi stance (RL=,Idc<500nA) Transresi stance (RL=50W ) (1) Bandwi dth -3dB (D 1C ) Bandwi dth -3dB (S2C ) Input Resi stance Supply C urrent Input Offset Voltage Output Offset Voltage AGC Threshold (IIN) Opti cal Overload
(4) (3) (2)
MIN 5.5 150 130 30 1.4 15 -3
TYP 17 8 175 175 500 50 30 1.6 1.8 30 0 14 16 1 -38 -37
MAX 10
U N IT KW KW MHz MHz
W
60 45 1.9
Output Resi stance
W
mA Volts Volts
mA
dB m 20 nA
Input Noi se C urrent (5) AGC Ti me C onstant (6) Offset Voltage D ri ft Opti cal Sensi ti vi ty -(D 1C ) (7) Opti cal Sensi ti vi ty - (S2C ) Operati ng Voltage Range Operati ng Temperature Range
(7)
m se c
mV/ C dB m dB m + 6.0 85 Volts C
+ 4.5 - 40
+ 5.0
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
56pF
VDD
GND
VDD
56pF
NC 12
0.1F
V DD2 GND GND 1992 VOUT GND GND
11
10
PIN
19 I IIN
GND GND
NC
1 2
9
8 7
NC
OUT
IIN
3
0.1F Vout
CBY CBY
GND CAGC GND
56pF
56pF
GND or Neg.Supply
4
5
6
56 pF
56 pF
Figure 4: ATA01501D1C Die Typical Bonding
Figure 5: ATA01501DS2C Typical SQFP Connection Package
Power Supplies and General Layout
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.
CT = 0.5 pF
0.17
Bandwidth (GHz)
0.15 0.13 V DD = 5.0 V 0.11 0.90
VDD = 5.5 V
VDD = 4.5 V
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).
-40
10
60
85
Temperature (O C)
Figure 6: Bandwidth vs. Temperature
PRELIMINARY DATA SHEET - Rev 1.6 08/2001
5
ATA01501
210 Bandwith (MHz) 200 190 180 170 160 150
1.44
VDD = 5.5 V VDD = 5.0 V
VDD = 5.5 V
1.04 .84 .64
VDD = 4.5 V
Rf
.44 .24
VDD = 4.5 V
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
- 2.1 - 1.6
IIN
- 1.1 - 0.6
50
.04
- 0.1
CT(pF)
Figure 7: Bandwidth vs. CT
Note: All performance curves are typical @ TA =25 oC unless otherwise noted.
IIN (mA DC)
Figure 9: Bandwidth vs. IIN
(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.
IIN Connection
VOUT Connection
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 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.
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
25 22 19 16 13 10 7 4
VDD = 4.5 V
IIN VDD = 5.5 V
50
Transimpedance (K Ohm)
Output Collapse
Heavy AGC
VDD = 5.5 V
Linear Region
1
Rf IIN vOUT VDD = 4.5 V
-4 -3 -2 -1
-2.1
-1.6
-1.1
-0.6
-0.1
IIN (mA DC)
Figure 8: Transimpedance vs. IIN
IIN (mA DC)
Figure 10: VOUT vs. IIN
6
PRELIMINARY DATA SHEET - Rev 1.6 08/2001
BANDWIDTH (GHz)
B(3dB) A / 2 Rf (Cin +Ct)
1.24
VOUT (Volts)
ATA01501
1.9 1.85 1.8 1.75 1.7 1.65 1.6 1.55 1.5
Indirect Measurement of Optical Overload
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.
Input Offset Voltage
VDD = 5.5 V V = 5.0V DD
VDD = 4.5V
10 Temperature oC 60
- 40
Figure 11: Input Offset Voltage vs. Temperature
CBY Connection
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.
Measurement of Input Referred Noise Current
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
14
Hz
Rf
CT
10
pA/
50
6 2
CT=1.0pF
CT =0.5pF 1 10 100 1000
- 0.1
Frequency (MHz)
Sensitivity and Bandwidth
Figure 12: Input Referred Noise Spectral Density
Input Referred Noise in (nA RMS)
Input Referred Noise Test Circuit 16
25dB
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.
VDD = 4.5 V
100 MHz LPF
15 14 13 12 11
0.5pF
TIA
VDD =5.5V (dBm) = 10 LOG 6500in
R
80
- 40
0
40
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.
180
Degrees
200 220 240 VOUT
00501
IIN
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) 0.165 (4.19) 0.152 (3.86) 0.047 (1.19) 0.032 (0.81)
0.065 (1.65) 0.055 (1.40)
7 o 0
0.035 (.89) 0.020 (.51)
12
11
10
0.018 (.460) 0.012 (.300)
1 2 3
9 8 7
0.021X45 4 Sides
0.000 (0.00) 0.020 (.51)
4
5
6 0.024 (.61) 0.018 (.46) 4X 0.023X45 0.011 (.28) 0.007 (.18)
0.015 (.38) 0.000 (0.00)
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 ATA01501D 1C ATA01501S2C
PAC K AGE OPTION D 1C S 2C
PAC K AGE D ESC R IPTION Die 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: Mktg@anadigics.com 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 products 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.
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.
WARNING
12
PRELIMINARY DATA SHEET - Rev 1.6 08/2001

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