The non-inverting op amp configuration is most common for low noise applications so we’ll make that the focus. Modeling the input source as a voltage source with a series resistance (figure 1), we ...

The circuit is based upon a design from the 1990s which as far as we can see is a pretty conventional non-inverting amplifier.

2. The high-speed summing amplifier can sum as many as four input voltages without the need for an inverter to change the sign of the output. Figure 3 is the performance photo at 1 MHz.