JAJSLI5J January 2011 – March 2021 OPA2835 , OPA835
PRODUCTION DATA
A 10-Ω series resistor can be inserted between the capacitor and the noninverting pin to isolate the capacitance.
Figure 9-12 shows the THD+N performance with 100-kΩ and 300-Ω loads, and with no weighting and A-weighting. With no weighting, the THD+N performance is dominated by the noise for both loads. A-weighting provides filtering that improves the noise so a larger difference can be seen between the loads due to more distortion with RL = 300 Ω.
Figure 9-13 and Figure 9-14 show FFT output 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 OPA835 device in-line between generator output and analyzer input, and the other channel is in “Gen Mon” loopback mode, which internally connects the signal generator to the analyzer input. With 100-kΩ load (see Figure 9-13), the curves are indistinguishable from each other except for noise, which means the OPA835 device cannot be directly measured. With a 300-Ω load as shown in Figure 9-14, the main difference between the curves is the OPA835 device due to the higher even-order harmonics. The test-set performance masks the odd-order harmonics.