Advanced Micro Devices Corporation

Ati Technologies Ulc

Naeem Ibrahim Ally

Stephen Victor Kosonocky

Joyce Cheuk Wai Wong

Kaushik Mazumdar

Jonathan David Hauke

A apparatus includes a reference signal generator, a droop detection circuit, a digital frequency-locked loop (DFLL), and a DFLL control circuit. The reference signal generator that receives a digital value and produces a pulse-density modulated signal based on the digital value. The droop detection circuit converts the pulse-density modulated signal to an analog signal, compares the analog signal to a monitored supply voltage, and responsive to detecting a droop of the monitored supply voltage below a designated value relative to the analog signal, produces a droop detection signal. The DFLL provides a clock signal for synchronizing circuitry within a domain of the monitored supply voltage. The DFLL control circuit, responsive to receiving the droop detection signal, causes the DFLL to slow the clock signal.

Droop detection and control of digital frequency-locked loop

An oscillator circuit includes a first oscillator, a second oscillator, and a calibration circuit to calibrate the first and second oscillators. The first oscillator is supplied with a first supply voltage, and the second oscillator is supplied with a second supply voltage. The calibration includes setting a frequency control of the second oscillator at a target frequency. Then, a voltage control of the second supply voltage is adjusted incrementally until a first control value is identified at which a second oscillator output frequency matches the target frequency. Then, a voltage control of the first supply voltage is set to the first control value. Then, the voltage control for the first supply voltage is adjusted incrementally until a second control value is identified at which a first oscillator output frequency is as close to the second oscillator output frequency as is achievable, but does not exceed it.

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Mississauga, Canada

Naeem Ibrahim Ally