Phase limitations of generalised OZF multipliers: further results

We present phase limitations for multipliers that preserve the positivity of nonlinearities with memoryless and monotone bounds. The phase limitations are tighter than those previously reported. For discrete-time multipliers specific phase limitaions can be found at each frequency that is a rational multiple of π. For continuous-time multipliers phase limitations can be found at pairs of frequencies that are rational multiples of each other. Both cases lead to insightful graphical interpretation.