Integrated circuits with improved register circuitry

Abstract

Integrated circuits such as programmable integrated circuits may include programmable logic regions that can be configured to perform custom user functions. The programmable logic regions include register circuitry that may be controlled by register control signals. A clock enable feedback loop circuit controlled by a clock enable control signal may couple the register output to the register input. The clock enable feedback loop circuit may facilitate adjustment of register locations within a design while ensuring correct clock enable functionality. A group of programmable logic regions may have shared input selection circuitry that selects register control signals and produces delayed versions of the signals that are shared by the group. If desired, each programmable logic region may be provided with adjustable delay circuitry that individually adjusts control signal delay for registers of that programmable logic region.