AD500-8-1.3G-TO5 APD-TIA 850nm高速探测器

OPTICAL DATA RECEIVER USING AN AVALANCHE PHOTODIODE

AND A 1.3 GHz AMPLIFIER

SCHEMATIC DIAGRAM

AD500-1.3G-TO5 is a high frequency optical data

receiver com bining an Avalanche Silicon Photodiode with a transimpedance amplifier in a hermetically sealed TO-5 package.

APD CHIP

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AVALANCHE PHOTODIODE DATA

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TRANSIMPEDANCE AMPLIFIER DATA

Symbols: V BR - Breakdown Voltage C T - Capacitance I d - Dark Current

Resp. - Responsivity (no avalanche effect)T R - Rise Time

NEP - Noise Equivalent Power

(V CC = +3.0V to + 5.5V, T A = 0°C to 70°C, 100? load between OUT+ and OUT–. Typical values are at T A = +25°C, V CC = 3.3V).

Note 1: Source capacitance for AD500-1.3G-TO5 is the capacitance of APD.

Note 2: Input Referred Noise is calculated as RMS Output Noise/ (Gain at f = 10 Mhz)Noise Density is (Input Referred Noise)/÷bandwidth

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FIG. 1: APD GAIN VS BIAS VOLTAGE

FIG. 2: APD SPECTRAL RESPONSE

(NO AVALANCHE EFFECT)

FIG. 3: DIFFERENTIAL OUTPUT VS TEMPERATURE

FIG. 4: APD CAPACITANCE VS VOLTAGE

FIG. 5: AMPLIFIER TRANSFER FUNCTION FIG. 6: TOTAL FREQUENCY RESPONSE

200

0.70.60.50.4A /W

0.30.20.1

0.0G A I N

100010010

1300400

500600WAVELENGTH, nm

70080090010001100

130

135140

145150APPLIED VOLTAGE

155160165170

D I F F

E R E N T I A L O U T P U T A M P L I T U D E , m V p -p

460440420400

380360340320300

-0

-20

020406080

100

AMBIENT TEMPERATURE, ∞C

D I F F

E R E N T I A L O U T P U T V O L T A G E , m V p -p

150

200100500-50-100-150-200-100

-75

-50

INPUT CURRENT, μA

-2502550

75

100

C J , p F

4035302520151050

020********

6070U R , V

FREQUENCY , Hz

8090100

T R A N S I M P E D A N C E , d b

75

7065

60

55

501M

10M

100M

1G

10G

HIGH SPEED OPTICAL DATA RECEIVER

5700 Corsa Avenue, #105 ? Westlake Village, CA 91362

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APPLICATIONS NOTE

TRANSFER CHARACTERISTICS

The circuit used is an avalanche photodiode directly coupled to a high speed data handling transimpedance amplifier. The output of the APD (light generated current) is applied to the input of the amplifier. The amplifier output is in the form of a differential voltage pulsed signal.

The APD responsivity curve is provided in Fig. 2. The term Amps/Watt involves the area of the APD and can be expressed as Amps/mm2/Watts/mm2, where the numerator applies to the current generated divided by the area of the detector, the denominator refers to the power of the radiant energy present per unit area. As an example assume a radiant input of 1 microwatt at 850 nm. The APD’s corresponding responsivity is 0.4 A/W.

If energy in = 1 μW, then the current from the APD = (0.4 A/W) x (1 x 10–6 W) = 0.4 μA.

We can then factor in the typical gain of the APD of 100, making the input current to the amplifier

40 μA.

From Fig. 5 we can see the amplifier output will be approximately 40 mV p-p.

The AD500-1.3G-TO5 is a high speed optical data receiver. It incorporates an internal transimpedance amplifier with an avalanche photodiode.

This detector requires +3.5V to +5.0V voltage supply for the amplifier and a high voltage supply (100-200V) for the APD. The internal APD follows the gain curve published for the AD500-1.3G-TO5 avalanche photodiode. The transimpedance amplifier provides differential output signals in the range of 200 millivolts differential.

In order to achieve highest gain, the avalanche photodiode needs a positive bias voltage (Fig. 1). However, a current limiting resistor must be placed in series with the photodiode bias voltage to limit the current into the transimpedance amplifier. Failure to limit this current may result in permanent failure of the device. The suggested initial value for this limiting resistor is 390 k OHM.

When using this receiver, good high frequency placement and routing techniques should be followed in order to achieve maximum frequency response. This includes the use of bypass capacitors, short leads and careful attention to impedance matching. The large gain bandwidth values of this device also demand that good shielding practices be used to avoid parasitic oscillations and reduce output noise.

Caution: These parts are extremely static sensitive. Standard ESD precautions must be followed.