Efficient controller design for telescopic units

Telescopic units represent an effective and innovative design option for increasing the average throughput of a combinational block. Throughput improvement is obtained at the price of a small reduction in average latency by allowing the unit to run with variable latency. Although this design paradigm has proved to be very effective, there are still some issues that need to be addressed before it can be used in practice: First, the introduction of variable-latency units complicates the control flow, and therefore the design of the controller. Second, the availability of telescopic units affects the way the high-level synthesis algorithms operate; this is because such units provide additional alternatives for realizing maximum-speed designs. This paper focuses on the first aspect, and gives a general criterion for the re-design of a controller when some data-path units are replaced by telescopic units. The viability of the proposed approach is demonstrated through a case study.