An Electronically Tunable Delay Line With Continuous Control of Slope and Peak Delay

This article presents a continuously tunable dispersive delay line (DDL). The slope as well as peak value of delay can be controlled electronically. The basic unit consists of a stepped-impedance section and two variable resistors in the form of p-i-n diodes. The slope and peak delay are controlled by changing the bias current of the p-i-n diodes. A transmission line model is used for theoretical analysis. Design equations are derived. Three prototypes with variable delay profiles are fabricated to validate the proposed technique. In all the cases, good agreement is obtained among the predicted and measured results. The implementation provides fast tuning over a given frequency band. Furthermore, a comparison with other reported techniques shows that the design is simple, occupies less area, and provides lower insertion loss. The DDLs operate as a linear device at least up to 23 dBm.