摘要:
Der Phasenregelkreis ist durch die Serienschaltung eines Zählers (ZS), eines Registers (R), einer Arithmetikeinrichtung (AE), eines Tiefpaß- und PI-Filters (TP, PIF) sowie eines spannungsgesteuerten Oszillators (VC0) gebildet. Die vom Oszillator (VCO) erzeugten digitalen, internen Taktsignale (its) werden in einem Zähler gezählt und zu Zeitpunkten, die durch Zeitintervall-Taktsignale (zts) bestimmt sind, als aktueller Zählerstand in das Register (R) übernommen und gespeichert. Die Zeitintervall-Taktsignale (zts) werden beispielsweise mittels einer Dividiereinrichtung (DIV) aus Referenztaktsignalen (nts) gewonnen und weisen eine niedrigere Frequenz als die internen Taktsignale (its) auf. In der Arithmetikeinrichtung (AE) wird mittels des aktuellen Zählerstandes, des Zählerstandes des vorhergehenden Auswerteintervalls und eines Sollwertes ein Ansteuersignal (as) in digitaler Form ermittelt. Dieses Ansteuersignal (as) gelangt über ein digitales Tiefpaß- und PI-Filter (TP, PIF) und einen A/D-Wandler (AD) an den Steuereingang (SE) des Oszillators (VCO) und steuert diesen derart, daß die Referenztaktsignale (nts) hinsichtlich ihrer Phase mit den internen Taktsignalen (its) übereinstimmen.
摘要:
An oscillator produces an output signal which is frequency locked to a reference signal but phased locked to a triggering signal (YTRIG). The oscillator includes a NOR gate (12) having its output fed back to one of its inputs through a programmable delay circuit (14) while the triggering signal is applied to another of its inputs. When enabled by the triggering signal, the output signal of the NOR gate oscillates at a frequency inversely proportional to the delay time of the delay circuit. The delay time is controlled by a control circuit which counts NOR gate output signal cycles occurring during a predetermined number of reference signal cycles and increments the delay time when the count is higher than expected for an oscillator output signal of a desired frequency and decrements the delay time when the count is lower than expected.
摘要:
Oscillator calibration circuits and wireless transmitters including oscillator calibration circuits. An oscillator calibration circuit includes a first frequency locking circuit (FLC) coupled to a first oscillator, wherein the first FLC calibrates the frequency of the first oscillator using an over-the-air reference signal, wherein the first FLC calibrates the first oscillator prior to a data transmission session and remains free running during the data transmission session.
摘要:
Systems and methods related to digital frequency locked looping to synchronize frequencies between the local signal from a local oscillator and a reference clock signal from a remote oscillator. A reference counter increments its count for every pulse in the reference clock signal. The value in the reference counter is compared to a configurable reference value. Whenever a match between the reference counter value and the reference value occurs, a hit signal is generated and the reference counter value is reinitialized. Concurrent with the above, a feedback counter increments for every pulse from the local signal. When the hit signal is generated, the value in the feedback counter is compared to a configurable feedback value (by subtraction) to generate a difference value. The difference value is then converted to a frequency adjust signal for use in either increasing or decreasing the frequency of the local oscillator. The hit signal also reinitializes the feedback counter.
摘要:
A phase lock control system is presented for controlling a voltage controlled oscillator. The system includes a voltage controlled oscillator that produces a frequency signal exhibiting an output frequency that varies dependent upon the value of a control voltage applied thereto. A frequency deviation determining system employs a counter intermittently triggered ON for a fixed time by successive timing pulses received from a reference source and a comparator that determines any frequency deviation of the output frequency relative to a preset frequency. An error filter monitors the comparator for any frequency deviation for a plurality of samples of the frequency deviation determinations. A controller varies the control voltage to vary the output frequency in a direction to eliminate any frequency deviation.
摘要:
A device (D2) is dedicated to the reconstruction of clock signals, for example within communication equipment (EQ2) of an IP network. This device (D2) comprises i) a phase-locked loop (BV) having a cut-off frequency dependent, on the one hand, on a configuration value making it possible to reconstruct clock signals according to a chosen clock frequency, and on the other hand, a chosen sampling frequency, and ii) control means (MC2) responsible for forcing the phase-locked loop (BV) to present a variable cut-off frequency according to a received operating mode indication.