OPA325IDBVR datasheet(23/42 Pages) TI1

23 / 42 page

GND

2.5 V

-2.5 V

VOUT

4-VPP

Sine Wave

Typical CMOS

rail-to-rail amplifiers

GND

+2.5 V

-2.5 V

VOUT

4 VPP

Sine Wave

OPAx325

±150

±125

±100

±75

±50

±25

100

125

150

±3

±2

±1

CM (V)

C003

CM = ±2.85 V

CM = 2.85 V

OPA325, OPA2325, OPA4325

www.ti.com

SBOS637D – OCTOBER 2016 – REVISED JUNE 2019

Product Folder Links: OPA325 OPA2325 OPA4325

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Typical Application (continued)

The unique zero-crossover topology shown in Table 1 eliminates the input offset transition region, typical of most

rail-to-rail input operational amplifiers. This topology allows the OPAx325 to provide superior CMRR across the

entire common-mode input range that extends 100 mV beyond both power-supply rails. Figure 50 shows the

input offset voltage versus input common-mode voltage plot for the OPAx325.

Figure 50. Offset Voltage vs Common-Mode Voltage (OPAx325, Zero-Crossover Amplifier)

The OPAx325 and a typical CMOS amplifier were used in identical circuits where these amplifiers were

configured as a unity-gain buffer amplifier; see Figure 51 and Figure 52. A pure sine wave with an amplitude of

2 V (4 VPP) was given as input to the two identical circuits of Figure 51 and Figure 52. The outputs of these

circuits were captured on a spectrum analyzer. Figure 53 and Figure 54 illustrate the output voltage spectrum for

the OPAx325 and a typical CMOS rail-to-rail amplifier, respectively. The output of the OPAx325 has very few

spurs and harmonics when compared to the typical rail-to-rail CMOS amplifier, as illustrated in Figure 55.

Figure 51. OPAx325 as a Unity-Gain Buffer

Figure 52. Typical CMOS Rail-to-Rail Amplifier as a Unity-Gain Buffer

OPA325IDBVR Datasheet(PDF) 23 Page - Texas Instruments

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