In contrast to theory, practical realizations of micro-strip-to-slotline and CPW-to-slotline baluns do not demonstrate characteristics of an all-pass network
1] is an all-pass network
with a delay equal to the delay of [H.
Under some circumstances, the performance of the lossy impedance match can be improved by including a capacitor from the input to the node between the inductor and the resistor that forms an all-pass network
A quadrature filter using active all-pass networks
is an attractive solution since the filter poles can be adjusted independently and each adjustment requires a change in only one component.
It is important that all four blocks be designed completely symmetrical except for two variable GaAs MESFETs used as variable resistors in the two all-pass networks
of the quadrature power splitter.