OPA320AIDBVT datasheet(22/58 Pages) TI2

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3dB =

2 R C

GBW

(Hz)

2 R C

4 R C

GBW

OPA320

OUT

V+

V-

10MW

< 1pF

(1)

OPA320, OPA2320, OPA320S, OPA2320S

SBOS513F – AUGUST 2010 – REVISED DECEMBER 2016

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Product Folder Links: OPA320 OPA2320 OPA320S OPA2320S

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8 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.

8.1 Application Information

The OPA320 family offers outstanding DC and AC performance. These devices operate up to a 5.5-V power

supply and offer ultra-low input bias current and 20-MHz bandwidth. These features make the OPA320 family a

robust operational amplifier for both battery-powered and industrial applications.

8.1.1 Transimpedance Amplifier

Wide gain bandwidth, low-input bias current, low input voltage, and current noise make the OPA320 an ideal

wideband photodiode transimpedance amplifier. Low-voltage noise is important because photodiode capacitance

causes the effective noise gain of the circuit to increase at high frequency.

The key elements to a transimpedance design, as shown in Figure 40, are the expected diode capacitance (CD),

which should include the parasitic input common mode and differential-mode input capacitance (4 pF + 5 pF for

the OPA320); the desired transimpedance gain (RF); and the gain-bandwidth (GBW) for the OPA320 (20 MHz).

With these three variables set, the feedback capacitor value (CF) can be set to control the frequency response.

CF includes the stray capacitance of RF, which is 0.2 pF for a typical surface-mount resistor.

(1)

CF is optional to prevent gain peaking. It includes the stray capacitance of RF.

Figure 40. Dual-Supply Transimpedance Amplifier

To achieve a maximally-flat, second-order Butterworth frequency response, the feedback pole should be set as

shown in Equation 2.

(2)

Bandwidth is calculated by Equation 3.

(3)

For even higher transimpedance bandwidth, consider the high-speed CMOS OPA380 (90-MHz GBW), OPA354

(100-MHz GBW), OPA300 (180-MHz GBW), OPA355 (200-MHz GBW), or OPA656/57 (400-MHz GBW).

OPA320AIDBVT Datasheet(PDF) 22 Page - Texas Instruments

OPA320AIDBVT Datasheet(HTML) 22 Page - Texas Instruments

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