Sensitivity of singly and doubly terminated prototype circuits

It is well known that a doubly terminated lossless ladder network has zero sensitivity to each element at every frequency of maximum power transfer. The author shows that a singly terminated ladder network, with the same frequency response as a doubly terminated ladder network, has the same points of zero sensitivity to simultaneous changes in the values of the elements of the same type by an equal relative amount. This result has been extended to cover FDNR-based filters