SNLU314 June 2022 OPA818
The DEM-OPA-DTK-EVM is equipped with footprints for SMA connectors for connection of signal generators and analysis equipment. For best results, the input and output to the EVM should be terminated to 50-Ω impedances and signals must be routed to and from the EVM with cables having 50-Ω characteristic impedance. IN+ (J5) includes termination resistor R9 for non-inverting configurations. For inverting configurations an resistor network (R4, R6, and R10) is included to match the input impedance while maintaining a desired gain resistor value. VOUT (J4) is the output connectors for the amplifier. A resistor network (R5, R7, and R11) at the output of the amplifier can be used to convert the signal to 50-Ω single-ended source while providing a larger total load to the amplifier when terminated with 50-Ω load at J4.
Figure 6-1 shows the inputs and output configured in a typical unity-gain amplifier configuration with a single series output load resistor of 49.9-Ω to directly match 50-Ω test equipment.