OPA855 datasheet(16/33 Pages) TI

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8.3.3 Wide Gain-Bandwidth Product

Figure 7-7 shows the open-loop magnitude and phase response of the OPA856. Calculate the gain bandwidth

product of any op amp by determining the frequency at which the AOL is 40 dB and multiplying that frequency by

a factor of 100. The open-loop response shows the OPA856 to have approximately 57° of phase-margin when

configured as a unity-gain buffer.

Figure 8-5 shows the open-loop magnitude (AOL) of the OPA856 as a function of temperature. The results show

minimal variation over the entire temperature range. Semiconductor process variation is the naturally occurring

variation in the attributes of a transistor (Early-voltage, β, channel-length and width) and other passive elements

(resistors and capacitors) when fabricated into an integrated circuit. The process variation can occur across

devices on a single wafer or across devices over multiple wafer lots over time. Typically the variation across a

single wafer is tightly controlled. Figure 8-6 shows the AOL magnitude of the OPA856 as a function of process

variation over time. The results show the AOL curve for the nominal process corner and the variation one

standard deviation from the nominal. The simulated results show less than 5° of phase-margin difference within

a standard deviation of process variation when the amplifier is configured as a unity-gain bufffer.

Frequency (Hz)

-15

10k

100k

10M

100M

AOL at 125qC

AOL at 25qC

AOL at 40qC

Figure 8-5. Open-Loop Gain vs Temperature

Frequency (Hz)

-15

10k

100k

10M

100M

AOL ( V)

AOL (Typ.)

AOL ( V)

Figure 8-6. Open-Loop Gain vs Process Variation

OPA856

SBOS623 – OCTOBER 2020

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OPA855 Datasheet(PDF) 16 Page - Texas Instruments