page_title: Topology (electrical circuits)
section_title: Bridge topology
hierarchical_section_title: Topology (electrical circuits) / Bridge topology
context_page_description: The topology of an electronic circuit is the form taken by the network of interconnections of the circuit components. Different specific values or ratings of the components are regarded as being the same topology. Topology is not concerned with the physical layout of components in a circuit, nor with their positions on a circuit diagram; similarly to the mathematic concept of topology, it is only concerned with what connections exist between the components. There may be numerous physical layouts and circuit diagrams that all amount to the same topology.
  Strictly speaking, replacing a component with one of an entirely different type is still the same topology. In some contexts, however, these can loosely be described as different topologies. For instance, interchanging inductors and capacitors in a low-pass filter results in a high-pass filter. These might be described as high-pass and low-pass topologies even though the network topology is identical. A more correct term for these classes of object is prototype network.
context_section_description: Bridge topology is an important topology with many uses in both linear and non-linear applications, including, amongst many others, the bridge rectifier, the Wheatstone bridge and the lattice phase equaliser.  There are several ways that bridge topology is rendered in circuit diagrams.  The first rendering in figure 1.8 is the traditional depiction of a bridge circuit.  The second rendering clearly shows the equivalence between the bridge topology and a topology derived by series and parallel combinations.  The third rendering is more commonly known as lattice topology.  It is not so obvious that this is topologically equivalent.  It can be seen that this is indeed so by visualising the top left node moved to the right of the top right node.
  It is normal to call a network bridge topology only if it is being used as a two-port network with the input and output ports each consisting of a pair of diagonally opposite nodes.  The box topology in figure 1.7 can be seen to be identical to bridge topology but in the case of the filter the input and output ports are each a pair of adjacent nodes.  Sometimes the loading (or null indication) component on the output port of the bridge will be included in the bridge topology as shown in figure 1.9.
caption: Figure 1.9.  Bridge circuit with bridging output load shown