Common base configuration impedence
consider a bipolar operating at 1mA, and Vearly of 20 volts. We know the CommonBase config has 'rin' of 0.026 / Ie = 0.026 / 0.001 = 26 ohms. The Vearly does not provide useful 'rout' for CommonBase, because Vearly is related to 'hre', not 'hrb'. However the 'rout' of Common Emitter is Vearly/Ie = 20v/0.001 = 20,000 ohms slop of the I-V output plot for the Common Emitter. 

Usually the CommonBase is much flatter, that is, 'rout_common_base' is much higher than 20,000 ohms. This compares to 'rin' of 26 ohms.