SBOSA14A April 2023 – November 2023 OPA814
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
Figure 7-4 shows the open-loop gain and phase response of the OPA814. The GBWP of an op amp is measured in the 20‑dB/decade constant slope region of the AOL magnitude plot. The open-loop gain of 60 dB for the OPA814 is along this 20‑dB/decade slope, and the corresponding frequency intercept is at 250 kHz. Converting 60 dB to linear units (1000 V/V) and multiplying the open-loop gain with the 250-kHz frequency intercept gives the GBWP of OPA814 as 250 MHz. As is inferred from the AOL Bode plot, the second pole in the AOL response occurs after AOL magnitude drops to less than 0 dB (1 V/V). This occurrence results in a phase change of less than 180° at 0‑dB AOL, indicating that the amplifier is stable in a gain of 1 V/V. Amplifiers such as the OPA814 that are JFET input, low noise, and unity-gain stable can be used as high input-impedance buffers and gain stages with minimal degradation in SNR. The OPA814 has 600 MHz of SSBW in gain of 1‑V/V configuration with approximately 65° of phase margin.
The low input offset voltage and offset voltage drift of the OPA814 make the device an excellent amplifier for high-precision, high input-impedance, wideband data-acquisition-system front-ends. Figure 8-2 shows that the system benefits from the low-noise JFET input stage with picoamperes of input bias current to achieve higher precision at the 1-MΩ input impedance setting, and higher SNR at the 50-Ω input impedance setting simultaneously in a typical data-acquisition front-end circuit.
RL = 100 Ω |
RL = 100 Ω |