LT6230 Ver la hoja de datos (PDF) - Linear Technology

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Fabricante

LT6230

215MHz, Rail-to-Rail Output, 1.1nV/√Hz, 3.5mA Op Amp Family

Linear Technology 

LT6230/LT6230-10

LT6231/LT6232

Typical Applications

The LT6230 is applied as a transimpedance amplifier with

an I-to-V conversion gain of 1.5kΩ set by R1. The LT6230

is ideally suited to this application because of its low

input offset voltage and current, and its low noise. This is

because the 1.5k resistor has an inherent thermal noise

of 5nV/√Hz or 3.4pA/√Hz at room temperature, while the

LT6230 contributes only 1.1nV and 2.4pA /√Hz. So, with

respect to both voltage and current noises, the LT6230 is

actually quieter than the gain resistor.

The circuit uses an avalanche photodiode with the cathode

biased to approximately 200V. When light is incident on

the photodiode, it induces a current IPD which flows into

the amplifier circuit. The amplifier output falls negative

to maintain balance at its inputs. The transfer function

is therefore VOUT = –IPD • 1.5k. C1 ensures stability and

good settling characteristics.  Output offset was measured

at 280µV, so low in part because R2 serves to cancel the

DC effects of bias current. Output noise was measured

at 1.1mVP-P on a 100MHz measurement bandwidth, with

C2 shunting R2’s thermal noise. As shown in the scope

photo, the rise time is 17ns, indicating a signal bandwidth

of 20MHz.

Low Power Avalanche Photodiode Transimpedance Amplifier

IS = 3.3mA

≈200V BIAS

ADVANCED PHOTONIX

012-70-62-541

C1

4.7pF

WWW.ADVANCEDPHOTONIX.COM

R2

1.5k

C2

0.1µF

R1

1.5k

–

5V

LT6230

+

–5V

ENABLE

623012 TA02a

OUTPUT OFFSET = 500µV TYPICAL

BANDWIDTH = 20MHz

OUTPUT NOISE = 1.1mVP-P (100MHz MEASUREMENT BW)

Photodiode Amplifier Time Domain Response

50ns/DIV

623012 TA02b

Related Parts

PART NUMBER

LT1028

LT1677

LT1806/LT1807

LT6200/LT6201

LT6202/LT6203/LT6204

DESCRIPTION

Single, Ultralow Noise 50MHz Op Amp

Single, Low Noise Rail-to-Rail Amplifier

Single/Dual, Low Noise 325MHz Rail-to-Rail Amplifier

Single/Dual, Low Noise 165MHz

Single/Dual/Quad, Low Noise, Rail-to-Rail Amplifier

COMMENTS

0.85nV/√Hz

3V Operation, 2.5mA, 4.5nV/√Hz, 60µV Max VOS

2.5V Operation, 550µV Max VOS, 3.5nV/√Hz

0.95nV√Hz, Rail-to-Rail Input and Output

1.9nV/√Hz, 3mA Max, 100MHz Gain Bandwidth

24 Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com

623012fc

LT 0111 REV C • PRINTED IN USA

 LINEAR TECHNOLOGY CORPORATION 2003

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