JAJSF33B August 2017 – July 2018 THS3491
The THS3491 is a 900-MHz current-feedback operational amplifier that is designed to operate from a power supply of ±7 V to ±16 V.
Figure 61 shows the THS3491 in a noninverting gain configuration of 5 V/V which is used to generate the majority of the performance curves. Most of the curves are characterized using signal sources with a 50-Ω source impedance and measurement equipment presenting a 50-Ω load impedance.
Current-feedback amplifiers are highly dependent on the RF feedback resistor for maximum performance and stability. Table 2 shows the optimal resistor values for RF and RG at different gains to achieve maximum bandwidth with minimal peaking in the frequency response. Use lower RF values for higher bandwidth. Note that this can cause additional peaking and a reduction in phase margin. Conversely, increasing RF decreases the bandwidth but phase margin increases and stability improves. To gain further insight on the feedback and stability analysis of current-feedback amplifiers like the THS3491, see the Current-feedback Amplifiers section of TI Precision Labs.
|GAIN (V/V)||RGT PACKAGE||DDA PACKAGE|
|RG (Ω)||RF (Ω)||RG (Ω)||RF (Ω)|