Length matching and phase matching between circuit paths of differing lengths is disclosed. Two signals are specified to arrive at respective path destinations at a predetermined time and with a predetermined phase. An IC provides a first electronic signal over a first conductive path to a first destination and a second electronic signal over a second conductive path to a second destination. A first slow wave structure comprises the first conductive path and a second slow wave structure comprises the second conductive path. The effective relative permittivity of the first slow wave structure is tuned such that the first electronic signal arrives at its destination at a first time and at a first phase, and the effective relative permittivity of the second slow wave structure is tuned such that the second electronic signal arrives at its destination at a second time and at a second phase.