Abstract: A circuit includes a phase adjustment circuit and a dead zone detect circuit. The phase adjustment circuit is operable to receive periodic signals and is operable to provide one of the periodic signals as a selected periodic signal based on a phase comparison between a data signal and the selected periodic signal. Each of the periodic signals has a different phase. The dead zone detect circuit is operable to cause the phase adjustment circuit to shift a phase of the selected periodic signal if the dead zone detect circuit determines that the data signal is in a dead zone. The dead zone detect circuit defines the dead zone based on two of the periodic signals. The phase adjustment circuit is operable to adjust a phase range of the dead zone.

Abstract: Voltage regulator circuitry is provided. The voltage regulator circuitry is suitable for powering core logic on a programmable logic device. The voltage regulator circuitry receives an external power supply voltage and reduces the external power supply voltage to a core power supply voltage if needed. If the external power supply voltage is at the same level needed to power the core logic, the voltage regulator circuitry passes the power supply voltage to the core logic. The voltage regulator circuitry monitors the core power supply voltage using a feedback path. Overshoot and undershoot fluctuations are minimized. The external power supply voltage may be supplied to a first bus. The core power supply voltage may be distributed on a second bus. A ring of transistors may be used to convey power from the first bus to the second bus. Control circuitry may control the ring of transistors based on programmable setpoint voltages.