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US 6,642,701 B2Granted
Device and method for testing phase-locked loops
AssigneeFujitsu Limited
InventorKwame Osei Boateng
Life of this patent
Estimating the term…
Abstract
A phase-locked loop (PLL) is tested based on a divide-and-conquer strategy. First, digital components in the PLL are isolated from analog components and tested. Next, the digital components are connected to the analog components and the PLL is exercised by causing it to undergo a series of frequency transitions.
Claims4
A testing device for a phase-locked loop including a phase comparator, a charge pump, a loop filter and a voltage-controlled oscillator, comprising:
- a reset circuit resetting the phase-locked loop by disconnecting the charge pump from the loop filter and providing an alternative discharge path for the loop filter;
- an input circuit receiving a feedback signal from an output of the phase-locked loop and a control signal, producing a combination signal from the received signals and inputting the combination signal to the phase-locked loop, the combination signal, together with a reference signal, causing the phase-locked loop to perform one of charging up the loop filter, discharging the loop filter and a normal operation;
- an output circuit outputting a signal with a frequency corresponding to an output of the voltage-controlled oscillator in cases that the phase-locked loop charges up the loop filter, that the phase-locked loop discharges the loop filter and that the phase-locked loop performs the normal operation;
- and
- a connection control circuit controlling connection between a digital circuit and an analog circuit of the phase-locked loop.
2 more elements
A testing device for a phase-locked loop including a phase comparator, a charge pump, a loop filter and a voltage-controlled oscillator, comprising:
- reset means for resetting the phase-locked loop by disconnecting the charge pump from the loop filter and providing an alternative discharge path for the loop filter;
- input means for receiving a feedback signal from an output of the phase-locked loop and a control signal, producing a combination signal from the received signals and inputting the combination signal to the phase-locked loop, the combination signal, together with a reference signal, causing the phase-locked loop to perform one of charging up the loop filter, discharging the loop filter and a normal operation;
- output means for outputting a signal with a frequency corresponding to an output of the voltage-controlled oscillator in cases that the phase-locked loop charges up the loop filter, that the phase-locked loop discharges the loop filter and that the phase-locked loop performs the normal operation;
- and
- connection control means for controlling connection between a digital circuit and an analog circuit of the phase-locked loop.
2 more elements
Dependencies are inferred from the claim text.