This circuit illustrates some possible buffer combinations. Tbese include a differential input stage, a voltage follower as well as both noninverting and inverting stages. The allowable resistor ratios and recommended device types are also included. One restriction applies to this type of mixernetwork in which Rg is greater than 2.4 KO.
This limits the worst case output current for each of the input buffers to less than 10 mA.