OPA1612-Q1 Datasheet, PDF (21/31 Pages) Texas Instruments – SoundPlus High-Performance, Bipolar-Input Audio Operational Amplifier

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OPA1612-Q1
SLOS931A – NOVEMBER 2015 – REVISED NOVEMBER 2015
Typical Application (continued)
Validity of this technique can be verified by duplicating measurements at high gain and/or high frequency where
the distortion is within the measurement capability of the test equipment. Measurements for this data sheet were
made with an audio precision system two distortion and noise analyzer, which greatly simplifies such repetitive
measurements. The measurement technique can, however, be performed with manual distortion measurement
instruments.
R₁
R₂
Signal Gain = 1+ ^R2
R₁
Distortion Gain = 1+ ^R2
R₁ || R₃
R₃
Device
V_O = 3 V_RMS
Generator
Output
Analyzer
Input
Audio Precision
System Two⁽¹⁾
with PC Controller
Load
(1) For measurement bandwidth, see Figure 7 through Figure 12.
SIGNAL
GAIN
1
–1
10
DISTORTION
GAIN
101
101
110
R₁
∞
4.99 kΩ
549 Ω
R₂
1 kΩ
4.99 kΩ
4.99 kΩ
R₃
10 Ω
49.9 kΩ
49.9 kΩ
Figure 39. Distortion Test Circuit
9.2.2.3 Capacitive Loads
The dynamic characteristics of the OPA1612-Q1 device is optimized for commonly encountered gains, loads,
and operating conditions. The combination of low closed-loop gain and high capacitive loads decreases the
phase margin of the amplifier and can lead to gain peaking or oscillations. As a result, heavier capacitive loads
must be isolated from the output. The simplest way to achieve this isolation is to add a small resistor (R_S equal to
50 Ω, for example) in series with the output.
This small series resistor also prevents excess power dissipation if the output of the device becomes shorted.
Figure 19 and Figure 20 illustrate graphs of Small-Signal Overshoot vs Capacitive Load for several values of R_S.
For details of analysis techniques and application circuits, refer to Applications Bulletin AB-028, Feedback Plots
Define Op Amp AC Performance (SBOA015).
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