OPA827AI datasheet(16/24 Pages) TI

16 / 24 page

TRANSIMPEDANCE AMPLIFIER

-3dB =

UGBW

2 R (C

)

TOT

(2)

Key Transimpedance Points

1MW

(1)

<1pF

-V

=I R

OUT

TOT

(1)C isoptionaltopreventgainpeaking.

(2)C

isthestraycapacitanceofR

STRAY

(typically,2pFforasurface-mountresistor).

STRAY

(2)

NOTES:

OPA827

4 R UGBW

(

)

(8 C

TOTR UGBW

(

)

1+ 1+

(1)

IN-

IN+

OUT

V+

V-

OPA827

SBOS376E – NOVEMBER 2006 – REVISED SEPTEMBER 2008 ..................................................................................................................................... www.ti.com

Bandwidth (f–3dB) calculated by Equation 2:

The gain bandwidth, low voltage noise, and current

noise of the OPA827 series make them ideal wide

bandwidth

transimpedance

amplifiers

These equations result in maximum transimpedance

photo-conductive application. High transimpedance

bandwidth.

For

additional

information,

refer

gains with feedback resistors greater than 100k

Ω

Application

Bulletin

SBOA055,

Compensate

benefit from the low input current noise (2.2fA/Hz) of

Transimpedance Amplifiers Intuitively, available for

the JFET input. Low voltage noise is important

download at www.ti.com.

because photodiode capacitance causes the effective

noise

gain

the

circuit

increase

high

frequencies. Total input capacitance of the circuit

limits the overall gain bandwidth of the amplifier and

is addressed below. Figure 46 shows a photodiode

transimpedance application.

• The total input capacitance (C

TOT) consists of the

photodiode junction capacitance, and both the

common-mode and differential input capacitance

of the operational amplifier.

• The desired transimpedance gain, V

OUT = IDRF.

• The Unity Gain Bandwidth Product (UGBW)

(22MHz for the OPA827).

With these three variables set, the feedback capacitor

value (CF) can be calculated to ensure stability.

CSTRAY is the parasitic capacitance of the PCB and

passive components, which is approximately 0.5pF.

To ensure 45° phase margin, the minimal amount of

feedback

capacitance

can

calculated

using

Figure 46. Transimpedance Amplifier

Equation 1:

Figure 47. Equivalent Schematic (Single Channel)

Submit Documentation Feedback

Product Folder Link(s): OPA827

OPA827AI Datasheet(PDF) 16 Page - Texas Instruments

OPA827AI Datasheet(HTML) 16 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Datasheet Download

Link URL