9 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification, and TI

does not warrant its accuracy or completeness. TI’s customers are responsible for determining

suitability of components for their purposes. Customers should validate and test their design

implementation to confirm system functionality.

9.1 Application Information

The OPA856 offers over 1 GHz of bandwidth, high slew-rate, low noise, excellent linearity, and is stable for unity

gain applications. The low noise and unity gain stability make the OPA856 a great choice for use as a front-end

buffer in high-speed data acquisition systems. Additionally the wide bandwidth allows the amplifier to perform

excellently in transimpedance applications or in a high-gain active filter configuration.

9.2 Typical Application

The high GBWP of the OPA856 makes the device an excellent choice as a transimpedance amplifier while the

unity gain stability allows for use of feedback clamping or other unity gain circuitry that would not work for a

decompensated amplifier. Figure 9-1 shows the OPA856 configured as a transimpedance amplifier with an

option feedback clamping diode connection.

+

±

R

F

VBIAS

VOFFSET

VOUT

C

F

Figure 9-1. OPA856 transimpedance amplifier with optional diode clamping

9.2.1 Design Requirements

The objective is to design a low noise, wideband optical front-end system using the OPA856

as a transimpedance amplifier. The design requirements are:

• Amplifier supply voltage: ± 2.5 V

• 1 kΩ transimpedance gain

• Transimpedance bandwidth > 100 MHz

• Total input capacitance 4 pF (1.1 pF from amplifier)

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OPA856

SBOS623 – OCTOBER 2020

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