View ATA12001_225136.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

AGC Transimpedance Amplifier SONET OC-24
FEATURES
* * * * * Single +5 Volt Supply Automatic Gain Control -31 dBm Sensitivity 0 dBm Optical Overload 1100 MHz Bandwidth
925 um
VDD1
ATA12001
PRELIMINARY DATA SHEET-Rev 4
VDD2
GND GND
1992
4E IIN
APPLICATIONS
* * * * SONET OC-24 (1 Gb/s) Receiver Low Noise RF Amplifier
GND GND GND GND CBY CBY GND CAGC
VOUT GND
BISDN
HIPPI
1250 um
D1C
PRODUCT DESCRIPTION
The ANADIGICS ATA12001 is a 5V low noise transimpedance amplifier with AGC designed to be used in 1Gb/s fiber optic links. The device is used in conjunction with a photodetector (PIN diode or avalanche photodiode) to convert an optical signal into an output voltage. The ATA12001 offers a bandwidth of 1100MHz and a dynamic range of 31dB. It is manufactured in a GaAs MESFET process and is available in bare die form.
VDD1
AGC
4K 70K
VDD2
CAGC
GND or neg. Supply
IIN
- 35
VGA
4pF + 0.8
VOUT
GND
PATENT PENDING
BY Photodetector Cathode must be connected to IIN for proper AGC operation
C
Figure 1: Equivalent Circuit
08/2001
ATA12001
VDD2
VDD1
GND GND
1992
925 um
4E IIN GND GND GND GND CBY CBY
VOUT GND CAGC GND
1250 um
Figure 2: Bonding Pad Layout Table 1: ATA12001 Pad Description
PAD V DD1 V DD2 IIN VOUT C AGC C BY D ESC R IPTION V DD1 V DD2 TIA Input C urrent TIA Output Voltage External AGC C apaci tor Input Gai n Stage Bypass C apaci tor C OMMEN T 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 RC Ti me C onstant >56 pF
ELECTRICAL CHARACTERISTICS
Table 2: Absolute Maximum Ratings
V DD1 V DD2 IIN TA TS
7.0 V 7.0 V 5 mA Operati ng Temp. - 40 C to 125 C Storage Temp. - 65 C to 150 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.
2
PRELIMINARY DATA SHEET - Rev 4 08/2001
ATA12001 Table 3: 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=50 W ) (1) Bandwi dth -3dB Input Resi stance Supply C urrent Input Offset Voltage Output Offset Voltage AGC Threshold (IIN) (3) Opti cal Overload
(4) (5) (6) (2)
MIN 1.2 900 30 15 1.4 100 -3
TYP 3.5 1.4 1100 100 50 30 1.6 1.8 150 0 120 16 1
MAX
U N IT KW KW MHz
W
Output Resi stance
60 45 1.9
W
mA Volts Volts
mA
dB m 170 nA
m se c
Input Noi se C urrent Offset Voltage D ri ft
AGC Ti me C onstant Opti cal Sensi ti vi ty (7)
mV/ C dB m + 6.0 85 Volts C
-29 + 4.5 - 40
-31 + 5.0
Operati ng Voltage Range Operati ng Temperature Range
Notes: 1. f = 50MHz 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 @ 1.2 Gb/s, assuming dectector responsivity of 0.9.
VDD
56pF GND
56pF
VDD2
VDD1
GND GND
1992
P IN
4E IIN GND GND GND GND CBY CBY GND CAGC
OUT
VOUT GND
56pF
56pF
Figure 3: ATA 12001 Typical Bonding Diagram
PRELIMINARY DATA SHEET - Rev 4 08/2001
3
ATA12001 APPLICATION INFORMATION
VDD CAGC
0.1 F
0.1 f
VDD
AGC RF CDET
0.4pF
4pf
700 MHz NOISE FILTER
4K I-IN DET-BYP AV=-35
18pF 20pF
50
0.1 F
20 nH
R
5pF CBY .01 f
GND
50
Figure 4: Typical Application HIPPI 1 Gb/s Power Supplies and General Layout Considerations The ATA12001D1C 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. General Layout Considerations Since the gain stages of the transimpedance amplifier have an open loop bandwidth in excess of 1.5 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).
CT = 0.5 pF
1.3
Bandwidth (GHz)
1.2 1.1 1.0 0.9
VDD = 5.5 V VDD = 5.0 V
VDD=4.5 V
10 60 85
-40
Temperature (OC)
Figure 4: Bandwidth vs. Temperature
4
PRELIMINARY DATA SHEET - Rev 4 08/2001
ATA12001
BANDWIDTH vs. CT
1800
1.7
Bandwith (MHz)
1600 1400 1200 1000 800 600
VDD=5.5 V
1.5 1.4
VDD = 5.5 V VDD = 5.0 V
VDD=4.5 V
RF
I
1.3 1.2
VDD = 4.5 V
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
Figure 5: Bandwidth vs. CT
- 2.2 - 1.7
IIN
5 1.1
1.0
- 1.2
- 0.7
- 0.2
CT(pF)
IIN (mA DC)
Figure 7: Bandwidth vs. IIN
Note: All performance curves are typical @ TA =25C unless otherwise noted.
IIN Connection (refer to the equivalent circuit diagram) Bonding the detector cathode to IIN (and thus drawing current from the ATA12001) 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.
2.0 1.8 1.6 1.4
I
IIN
12001 50
1.2 1.0 0.8 0.6 0.4
Transimpedance (K Ohm)
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.
heavy AGC
Output Collapse
3.4 3.2 3.0 2.9 2.7 2.5 2.4 2.2 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
VDD = 5.5 V
VDD = 4.5 V
VDD =5.5 V
Linear Region
Rf IIN
12001
-2.2
-1.7
-1.2 IIN (mA DC)
-0.7
-0.2
VOUT
Figure 6: Transimpedance vs. IIN
-4
VDD=4.5 V
-3 -2 -1
IIN(mA DC)
Figure 8: VOUT vs. IIN
PRELIMINARY DATA SHEET - Rev 4 08/2001
VOUT(Volts)
BANDWIDTH (GHz)
5
B(3dB) A / 2 RF (CN + CT)
1.6
ATA12001
Input Offset Voltage DC
1.9 1.85 1.8 1.75 1.7 1.65 1.6 1.55 1.5 - 40 10 60 85
VDD = 5.5 V VDD = 5.0V
(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. 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 1 GHz lowpass filter at the output of the TIA) divided by the AC transresistance.
10
VDD = 4.5V
Temperature (C)
Figure 9: Input Offset Voltage vs. Temperature CBY Connection The CBY pad must be connected via a low inductance path to a surface mount capacitor of at least 56 pF (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 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. ndirect 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 ATA12001D1C 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 6
9 8
Hz
7 6 5 4 3 -0.1 1 10
CT
RF
50
pA/
CT = 1.0pF CT = 0.5pF
100
1000
Figure 10: Input Referred Noise Spectral Density
Input Referred Noise in (nA RMS)
Input referred noise test circuit 16
25dB
VDD = 4.5 V
100 MHz LPF
15 14 13 12 11 10 -40 0
0.5pF
TIA
VDD = 5.5V (dBm) = 10 LOG 6500in
R
40
80
Temperature (OC)
FIgure 11: Input Referred Noise vs Temperature
PRELIMINARY DATA SHEET - Rev 4 08/2001
ATA12001 AGC Capacitor It is important to select an external AGC capacitor of high quality and appropriate size. The ATA12001D1C has an on-chip 70 KW resistor with a shunt 4.5 pF capacitor to ground. Without external capacitance the chip will provide an AGC time constant of 315 nS. For the best performance in a typical OC-24 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 1200 MHz.
Phase (IIN to VOUT)
180 Degrees 200
RF
220 240
IIN
0.5pF
VOUT
50
50
100
150
Frequency (MHz)
Figure 12: Phase (IIN to VOUT)
PRELIMINARY DATA SHEET - Rev 4 08/2001
7
ATA12001
ORDERING INFORMATION
PAR T N U MB ER ATA12001D 1C PAC K AGE OPTION D 1C PAC K AGE D ESC R IPTION Die
ANADIGICS, Inc. 141 Mount Bethel Road Warren, New Jersey 07059, U.S.A Tel: +1 (908) 668-5000 Fax: +1 (908) 668-5132 http://www.anadigics.com 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. 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. PRELIMINARY DATA SHEET - Rev 4 08/2001
8

▲Up To Search▲

Price & Availability of ATA12001

	To Download ATA12001 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .