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Philips Semiconductors

SA5211

Transimpedance amplifier (180 MHz)

Product specification

Rev. 03 — 07 October 1998

13 of 28

9397 750 07427

© Philips Electronics N.V. 2001. All rights reserved.

11. Theory of operation

Transimpedance amplifiers have been widely used as the preamplifier in fiber-optic
receivers. The SA5211 is a wide bandwidth (typically 180 MHz) 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 50

µ

A. The SA5211 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 11

.

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

= 14.4 k

. 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

(1)

The single-ended transresistance of the amplifier is typically 14.4 k

.

The simplified schematic in

Figure 12

 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

Fig 10. Typical performance characteristics. (cont.)

0

2

4

6

8

10

12

14

16

18

20

(ns)

V

CC

= 5V

T

A

= 25°C

20mV/Div

Output Step Response

R

T

V

OUT

diff

(

)

I

IN

-----------------------------

R

F

2 14.4 K

(

)

28.8 k

=

=

=

=

Summary of Contents for SA5211

Page 1: ...er RF applications as a general purpose gain block 2 Features Extremely low noise 1 8 pA Hz Single 5 V supply Large bandwidth 180 MHz Differential outputs Low input output impedances High power supply rejection ratio 28 kΩ differential transresistance 3 Applications Fiber optic receivers analog and digital Current to voltage converters Wide band gain block Medical and scientific Instrumentation Se...

Page 2: ...2 11 10 9 GND2 GND2 NC IIN NC VCC1 VCC2 GND1 GND1 GND1 GND1 GND2 OUT OUT D Package TOP VIEW SD00318 Table 1 Ordering information Type number Package Name Description Version Temperature range C SA5211D SO14 plastic small outline package 14 leads body width 3 9 mm SOT108 1 40 to 85 Table 2 Limiting values In accordance with the Absolute Maximum Rating System IEC 60134 Symbol Parameter Conditions Mi...

Page 3: ...t 20 26 31 mA IOMAX output sink source current 1 3 4 mA IIN input current 2 linearity Test Circuit 8 Procedure 2 20 40 µA IIN MAX maximum input current overload threshold Test Circuit 8 Procedure 4 30 60 µA Table 5 AC electrical characteristics Typical data and Min and Max limits apply at VCC 5 V and Tamb 25 C Symbol Parameter Test conditions Min Typ Max Unit RT transresistance differential output...

Page 4: ... PSRR power supply rejection ratio 2 VCC1 VCC2 DC tested VCC 0 1V Equivalent AC Test Circuit 3 23 32 dB PSRR power supply rejection ratio 2 VCC1 DC tested VCC 0 1V Equivalent AC Test Circuit 4 23 32 dB PSRR power supply rejection ratio 2 VCC2 DC tested VCC 0 1V Equivalent AC Test Circuit 5 45 65 dB PSRR power supply rejection ratio ECL configuration 2 f 0 1 MHz Test Circuit 6 23 dB VOMAX maximum d...

Page 5: ...t circuits 1 and 2 Test Circuit 2 Test Circuit 1 SINGLE ENDED DIFFERENTIAL NETWORK ANALYZER S PARAMETER TEST SET PORT 1 PORT 2 5V 33 IN DUT OUT OUT 50 33 GND1 GND2 VCC1 VCC2 ZO 50 0 1µF RL 50 R 1k 0 1µF 0 1µF SPECTRUM ANALYZER 5V 33 IN DUT OUT OUT 33 GND1 GND2 VCC1 VCC2 0 1µF RL 50 0 1µF AV 60DB NC ZO 50 ZO 50 SD00319 RT VOUT VIN R 2 S21 R RT VOUT VIN R 4 S21 R RO ZO 1 S22 1 S22 33 RO 2ZO 1 S22 1 ...

Page 6: ...t Circuit 3 NETWORK ANALYZER S PARAMETER TEST SET PORT 1 PORT 2 VCC2 VCC1 GND1 GND2 IN CURRENT PROBE 1mV mA CAL TEST TRANSFORMER NH0300HB 100 33 33 16 5V OUT OUT BAL 0 1µF 0 1µF 10µF 0 1µF 0 1µF 50 UNBAL NETWORK ANALYZER S PARAMETER TEST SET PORT 1 PORT 2 CURRENT PROBE 1mV mA CAL TEST TRANSFORMER NH0300HB 100 33 33 16 5V OUT OUT BAL 50 UNBAL VCC1 VCC2 IN 0 1µF 0 1µF 10µF 0 1µF 0 1µF 0 1µF 10µF 5V ...

Page 7: ...RAMETER TEST SET PORT 1 PORT 2 CURRENT PROBE 1mV mA CAL TEST TRANSFORMER NH0300HB 100 33 33 16 5V OUT OUT BAL 50 UNBAL VCC2 VCC1 IN 0 1µF 0 1µF 10µF 0 1µF 0 1µF 0 1µF 10µF 5V Test Circuit 6 Test Circuit 5 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 GND2 GND1 VCC1 VCC2 IN 0 1µF 0 1µF 0 1µF 10µF GND 0 1µF 10...

Page 8: ...v 03 07 October 1998 8 of 28 9397 750 07427 Philips Electronics N V 2001 All rights reserved Fig 5 Test circuit 7 Test Circuit 7 OSCILLOSCOPE 33 33 1k OUT OUT GND2 GND1 VCC1 VCC2 IN 0 1µF 0 1µF PULSE GEN Measurement done using differential wave forms 0 1µF 50 ZO 50Ω A B ZO 50Ω DUT SD00322 ...

Page 9: ... 40 60 80 100 DIFFERENTIAL OUTPUT VOLTAGE V CURRENT INPUT µA NE5211 TEST CONDITIONS Procedure 1 RT measured at 15µA RT VO1 VO2 15µA 15µA Where VO1 Measured at IIN 15µA VO2 Measured at IIN 15µA Procedure 2 Linearity 1 ABS VOA VOB VO3 VO4 Where VO3 Measured at IIN 30µA VO4 Measured at IIN 30µA Procedure 3 VOMAX VO7 VO8 Where VO7 Measured at IIN 65µA VO8 Measured at IIN 65µA Procedure 4 IIN Test Pass...

Page 10: ...40 TOTAL SUPPLY CURRENT mA I I CC1 CC2 3 50 3 45 3 40 3 35 3 30 3 25 OUTPUT BIAS VOLTAGE V VCC 5 0V PIN 14 PIN 12 950 INPUT BIAS VOLTAGE mV 5 5V 4 5V 40 OUTPUT OFFSET VOLTAGE mV 5 5V 5 0V 4 5V VOS VOUT12 VOUT14 4 1 3 9 3 7 3 5 3 3 3 1 2 9 2 7 PIN 14 5 5V 5 0V 4 5V DIFFERENTIAL OUTPUT SWING V 4 0 3 8 3 6 3 4 3 2 3 0 2 8 2 6 5 5V 5 0V 4 5V 2 4 2 2 DC TESTED RL 4 5 2 5 100 0 0 100 0 INPUT CURRENT mA ...

Page 11: ...15 14 13 12 11 10 9 8 PIN 14 RL 50W TA 25 C 17 0 1 1 10 100 FREQUENCY MHz GAIN dB 16 15 14 13 12 11 10 9 8 PIN 12 VCC 5V 17 0 1 1 10 100 FREQUENCY MHz GAIN dB 16 15 14 13 12 11 10 9 8 PIN 14 VCC 5V 17 0 1 1 10 100 FREQUENCY MHz GAIN dB 16 15 14 13 12 11 10 9 8 33 60 40 20 0 20 40 100 60 120 80 DIFFERENTIAL TRANSRESISTANCE k 140 AMBIENT TEMPERATURE C DC TESTED RL W 32 31 30 29 28 27 220 60 40 20 0 ...

Page 12: ... 15 14 13 PIN 14 PIN 12 DC TESTED VCC 5 0V W 18 60 40 20 0 20 40 100 60 120 80 OUTPUT RESISTANCE 140 17 16 15 14 13 DC TESTED W AMBIENT TEMPERATURE C PIN 12 4 5V 5 0V 5 5V 19 60 40 20 0 20 40 100 60 120 80 OUTPUT RESISTANCE 140 18 17 16 15 14 DC TESTED W PIN 14 4 5V 5 0V 5 5V AMBIENT TEMPERATURE C 40 60 40 20 0 20 40 100 60 120 80 POWER SUPPLY REJECTION RATIO dB 140 DC TESTED VCC1 VCC2 5 0V AMBIEN...

Page 13: ...tion and ease of interface to ECL type circuitry A block diagram of the circuit is shown in Figure 11 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 Q3 is approximately the value of the feedback resistor RF 14 4 kΩ The gain from the second stage A2 and emitter followers A...

Page 14: ...ming typical values for RF 14 4 kΩ RIN 200 Ω CIN 4 pF 4 The operating point of Q1 Figure 12 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 casc...

Page 15: ...eak noise current Electrical dynamic range DE in a 200 MHz bandwidth assuming IINMAX 60 µA and a wideband noise of IEQ 41 nARMS for an external source capacitance of CS 1 pF 5 6 7 In order to calculate the optical dynamic range the incident optical power must be considered For a given wavelength λ Energy of one Photon watt sec Joule Where h Planck s Constant 6 6 10 34 Joule sec c speed of light 3 ...

Page 16: ...nimum required optical power to achieve 10 9 BER is 9 where h is Planck s Constant c is the speed of light λ is the wavelength The minimum input current to the SA5211 at this input power is 10 Choosing the maximum peak overload current of IavMAX 60 µA the maximum mean optical power is 11 Thus the optical dynamic range DO is 12 1 S D Personick Optical Fiber Transmission Systems Plenum Press NY 1981...

Page 17: ...h the SA5211 operating at 200 MHz bandwidth with a half mark half space digital transmission at 850nm wavelength Fig 11 SA5211 Block diagram INPUT OUTPUT OUTPUT A1 A2 A3 A4 RF SD00327 Fig 12 Transimpedance amplifier 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 Fig 13 Shunt series input stage VCC VEQ3 VIN IIN INPUT IF IB Q1 Q...

Page 18: ...ormally is to measure the DC voltages at the outputs If they are not close to their quiescent values of 3 3 V for a 5 V 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 sli...

Page 19: ... create extra high frequency noise on the NE5210 VCC pin s Fig 14 A 50Mb s fiber optic receiver 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 9 10 11 12 13 14 LED CPKDET THRESH GNDA FLAG JAM VCCD VCCA GNDD TTLOUT IN1B IN1A CAZP CAZN OUT1B IN8B OUT1A IN8A RHYST RPKDET NE5214 GND GND GND OUT GND GND OUT VCC VCC NC IIN NC GND GND NE5210 R2 220 D1 LED C9 100pF 100pF C7 01µF 47µF C...

Page 20: ...d 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...

Page 21: ...ffle 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 car...

Page 22: ...19 8 75 8 55 4 0 3 8 1 27 6 2 5 8 0 7 0 6 0 7 0 3 8 0 o o 0 25 0 1 DIMENSIONS inch dimensions are derived from the original mm dimensions Note 1 Plastic or metal protrusions of 0 15 mm maximum per side are not included 1 0 0 4 SOT108 1 X w M θ A A1 A2 bp D HE Lp Q detail X E Z e c L v M A A 3 A 7 8 1 14 y 076E06 MS 012 pin 1 index 0 069 0 010 0 004 0 057 0 049 0 01 0 019 0 014 0 0100 0 0075 0 35 0...

Page 23: ...on heating method Typical reflow peak temperatures range from 215 to 250 C The top surface temperature of the packages should preferable be kept below 220 C for thick large packages and below 235 C small thin packages 17 3 Wave soldering Conventional single wave soldering is not recommended for surface mount devices SMDs or printed circuit boards with a high component density as solder bridging an...

Page 24: ... may occur due to vaporization of the moisture in them the so called popcorn effect For details refer to the Drypack information in the Data Handbook IC26 Integrated Circuit Packages Section Packing Methods 2 These packages are not suitable for wave soldering as a solder joint between the printed circuit board and heatsink at bottom version can not be achieved and as solder may stick to the heatsi...

Page 25: ...20142 Product specification third version supersedes second version SA5211_2 of 1998 Oct 07 9397 750 04624 Modifications The format of this specification has been redesigned to comply with Philips Semiconductors new presentation and information standard 02 19981007 853 1799 20142 Product specification second version supersedes first version SA5211_1 of 1995 Apr 26 Modifications Changed prefix from...

Page 26: ...ystems 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 wit...

Page 27: ...2 27 09 1415 Malaysia Tel 60 37 50 5214 Fax 60 37 57 4880 Mexico Tel 9 5 800 234 7381 Middle East see Italy Netherlands Tel 31 40 278 2785 Fax 31 40 278 8399 New Zealand Tel 64 98 49 4160 Fax 64 98 49 7811 Norway Tel 47 22 74 8000 Fax 47 22 74 8341 Philippines Tel 63 28 16 6380 Fax 63 28 17 3474 Poland Tel 48 22 5710 000 Fax 48 22 5710 001 Portugal see Spain Romania see Italy Russia Tel 7 095 755 ...

Page 28: ...number 9397 750 07427 Contents Philips Semiconductors SA5211 Transimpedance amplifier 180 MHz 1 Description 1 2 Features 1 3 Applications 1 4 Pinning information 2 4 1 Pinning 2 5 Ordering information 2 6 Limiting values 2 7 Static characteristics 3 8 Dynamic characteristics 3 9 Test circuits 5 10 Typical performance characteristics 10 11 Theory of operation 13 12 Bandwidth calculations 14 13 Nois...

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