OPA2836-Q1 Datasheet, PDF (35/44 Pages) Texas Instruments – Very-Low Power, Rail-to-Rail Out, Negative-Rail In, Voltage-Feedback Operational Amplifier

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OPA2836-Q1
SBOS794 – DECEMBER 2016
9.2.1.3 Application Curves
A 10-Ω series resistor can be inserted between the capacitor and the noninverting pin to isolate the capacitance.
Figure 72 shows the THD+N performance with 100-kΩ and 300-Ω loads, with A-weighting and with no weighting.
Both loads show similar performance. With no weighting, the THD+N performance is dominated by the noise;
whereas, A-weighting provides filtering that improves the noise.
Figure 73 and Figure 74 show FFT outputs with a 1-kHz tone and 100-kΩ and 300-Ω loads. To show relative
performance of the device versus the test set, one channel has the OPA2836-Q1 in-line between generator
output and analyzer input and the other channel is in Gen Mon loopback mode that internally connects the signal
generator to the analyzer input. With a 100-kΩ load, Figure 73, the curves are basically indistinguishable from
each other except for noise, meaning that the OPA2836-Q1 cannot be directly measured. With a 300-Ω load,
Figure 74, the main difference between the curves is that the OPA2836-Q1 shows slightly higher even-order
harmonics, but odd-order harmonics are masked by the test-set performance.
-90
-95
-100
-105
-110
-115
No weighting
R_L = 300 W,
R_L = 100 kW
A-weighting
R_L = 300 W,
R_L = 100 kW
V_S = 5 V,
V_OUT = 1 V_RMS,
G = 1,
R_F = 0 W,
BW = 80 kHz
-120
10
100
1k
10k
f - Frequency - Hz
100k
Figure 72. OPA2836-Q1 1 V_RMS, 20-Hz to 80-kHz THD+N
0
-10
V_S = 5 V,
-20
V_OUT = 1 V_RMS,
G = 1,
-30
R_F = 0 W
-40
-50
-60
-70
-80
-90
-100
-110
Gen Mon - 100k
-120
-130
R_L = 100k
-140
0
2k 4k 6k 8k 10k 12k 14 16k 18k 20k
f - Frequency - Hz
Figure 73. OPA2836-Q1 and AP Gen Mon 10-kHz FFT Plot;
V_OUT = 1 V_RMS, R_L = 100 kΩ
0
-10
V_S = 5 V,
V_OUT = 1 V_RMS,
-20
G = 1,
-30
R_F = 0 W
-40
-50
-60
-70
-80
-90
-100
Gen Mon - 300
-110
-120
R_L = 300
-130
-140
0
2k 4k 6k 8k 10k 12k 14 16k 18k 20k
f - Frequency - Hz
Figure 74. OPA2836-Q1 and AP Gen Mon 10-kHz FFT Plot;
V_OUT = 1 V_RMS, R_L = 300 Ω
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