A phase-lock loop (PLL) has an oscillator having a plurality of operating curves. During PLL auto-trim operations, the oscillator is automatically trimmed to an appropriate oscillator operating curve for use during normal PLL operations. In particular embodiments, the PLL is a charge-pump PLL having a phase/frequency detector (PFD) that generates error signals based on comparing an input signal and a PLL feedback signal; a charge pump that generates amounts of charge corresponding to the error signals; a loop filter that accumulates the amounts of charge to generate a loop-filter voltage; and a voltage-controlled oscillator (VCO), where the VCO output signal is used to generate the PLL feedback signal. During normal PLL operations, the loop-filter voltage is applied to the voltage input of the VCO. During the PLL auto-trim operations, a state machine applies a sequence of digital control input values to the VCO to select different VCO operating curves until an appropriate operating curve for the present PLL application is found. In different embodiments, the state machine uses different signals to determine whether the center frequency of each operating curve in the sequence is above or below the desired nominal operating frequency for the VCO, and select one such operating curve for use in normal operations.

Self-calibrating phase-lock loop with auto-trim operations for selecting an appropriate oscillator operating curve

A frequency synthesizer includes an oscillator which may be coarse-tuned by a first input receiving a digital signal for selecting one of a plurality of frequency ranges, and fine-tuned by a second input receiving an analog signal for selecting the desired frequency within the selected frequency range. The synthesizer further includes a computer storing the oscillator's characteristics in the form of a digital table of the input signals corresponding to a plurality of frequency values, each identified by digital data. The computer receives input data representing the desired oscillator frequency and generates from the stored digital table, a digital signal indicating the frequency range of the desired oscillator frequency, and an analog signal indicating the specific oscillator frequency desired, and applies both signals to the oscillator. A frequency measuring circuit measures the actual output frequency of the oscillator and outputs a signal corresponding thereto. This signal is fed back to the computer for controlling, in response thereto, the digital and analog signals generated by the computer.

Frequency synthesizer having microcomputer supplying analog and digital control signals to VCO

A circuit, such as a phase-lock loop (PLL), has an oscillator having a plurality of operating curves. During circuit auto-trim operations, the oscillator is automatically trimmed to an appropriate oscillator operating curve for use during normal circuit operations. In particular PLL embodiments, the PLL is a charge-pump PLL having a phase/frequency detector (PFD) that generates error signals based on comparing an input signal and a PLL feedback signal; a charge pump that generates amounts of charge corresponding to the error signals; a loop filter that accumulates the amounts of charge to generate a loop-filter voltage; and a voltage-controlled oscillator (VCO), where the VCO output signal is used to generate the PLL feedback signal. During normal PLL operations, the loop-filter voltage is applied to the voltage input of the VCO. During the PLL auto-trim operations, a state machine applies a sequence of digital control input values to the VCO to select different VCO operating curves until an appropriate operating curve for the present PLL application is found. In different embodiments, the state machine uses different signals to determine whether the center frequency of each operating curve in the sequence is above or below the desired nominal operating frequency for the VCO, and select one such operating curve for use in normal operations. The present invention can also be implemented in circuits having self-calibrating oscillators, other than PLLs.

Self-calibrating voltage-controlled oscillator for asynchronous phase applications

A frequency synthesiser comprises a voltage controlled oscillator, VCO, having means for fine tuning the oscillator frequency and switchable capacitive elements for coarse tuning the oscillator frequency. First comparison means are provided for comparing the frequency and phase of the output of the VCO or a signal derived therefrom with that of a reference frequency signal to provide an error signal, the error signal being provided to said means for fine tuning the oscillator frequency. Second comparison means are provided for comparing the error signal against one or more reference values and a control means receives the result of the comparison from the second comparison means and switches said switchable capacitive elements on and off in dependence upon the result so as to coarse tune the oscillator frequency.

Voltage controlled oscillators

An apparatus for conducting measurements of electrochemiluminescent (ECL) phenomena includes a cell unit having an electrode configuration for inducing the emission of ECL light by the application of a selected voltage waveform to a sample fluid including an ECL moiety. The sample fluid is transported to and from the cell unit by a flow-through pump/tubing system. A photomultiplier tube detects the intensity of light emitted by the sample fluid during the ECL measurement process. A computer control unit both analyzes the detected data and provides digital control signals to the cell unit to generate effective voltage waveforms. The digital control signals are supplied to a novel pulse width modulated digital to analog converter which outputs a ramp voltage waveform having the desired slope.

Apparatus for conducting measurements of electrochemiluminescent phenomena

A wideband phase locked loop oscillator (PLLO) for tracking the frequency of an altitude signal in an FM/CW type radio altimeter. The phase locked loop oscillator conventionally includes a voltage controlled oscillator (VCO), a phase comparator for comparing the phase of the altitude signal to be tracked with the phase of the VCO output and an error signal amplifier for applying the output of the phase comparator as control voltage to the VCO. The frequency range of the PLLO is extended by changing the natural frequency of the VCO in steps spanning the useful frequency range of the altitude signal. Selection of the proper value of VCO natural frequency is effected through microprocessor directed digital control.

Wideband phase locked loop tracking oscillator for radio altimeter

A linear sweep frequency modulator for a varactor tuned transistor microwave oscillator used in an FM/CW radio altimeter where the oscillator-frequency v. varactor bias characteristic is non-linear. A linear triangular wave is converted by means of a function generator to the non-linear wave required for varactor bias to cause linear frequency modulation of the oscillator. Linearity of modulation is tested by measuring variations in the period of a calibration signal derived from a delay line. Variations in the period of the calibration signal are measured by determining the difference between the average and the instantaneous calibration period and sampling the difference during each cycle of the triangular wave, once during the upswing thereof when the oscillator is at low frequency and once during the down swing thereof when the oscillator is at high frequency and separately integrating the up swing and down swing samples. By applying both results of integration to the function generator it thereby has its biases controlling the low frequency and the high frequency operation of the oscillator separately adjusted.

Linear sweep frequency modulator for FM/CW radio altimeter

A filter for tracking the ground signal return in an FM/CW radio altimeter. The filter has a variable band pass frequency response which is adjusted as a function of the altitude measured by the altimeter. The control means of the filter respond to altitude measurements in digital format.

Tracking filter for radio altimeter

L'INVENTION CONCERNE UN FILTRE POUR UN RADIO-ALTIMETRE A MODULATION DE FREQUENCE ET A ONDE ENTRETENUE, CE FILTRE AYANT UNE REPONSE EN FREQUENCE VARIABLE EN FONCTION DE L'ALTITUDE. A CETTE FIN, IL COMPORTE UN FILTRE PASSE-BANDE 45-55, 46-55 DONT LA CARACTERISTIQUE D'ATTENUATION EN FONCTION DE LA FREQUENCE EST ETABLIE PAR UN RESEAU DE COMMANDE DE GAIN 47, 48, 51-55, 47, 48, 51-55 SOUS LA COMMANDE D'UN COMMUTATEUR NUMERIQUE 49, 49 EN FONCTION DE L'ALTITUDE MESUREE PAR L'ALTIMETRE DE MANIERE QUE L'ATTENUATION DES HAUTES FREQUENCES SOIT ACCRUE LORSQUE L'ALTITUDE MESUREE DIMINUE.

Filtre d'accord dynamique pour radio-altimetre

L'INVENTION CONCERNE UN MODULATEUR DE FREQUENCE LINEAIRE POUR UN OSCILLATEUR HYPERFREQUENCE ACCORDE AU MOYEN D'UN VARACTOR ET UTILISE DANS UN RADIO-ALTIMETRE A ONDE ENTRETENUE MODULEE EN FREQUENCE. L'ONDE TRIANGULAIRE PRODUITE PAR UN GENERATEUR 19, 22, 23 EST CONVERTIE PAR UN GENERATEUR DE FONCTION NON LINEAIRE 28 EN L'ONDE NON LINEAIRE REQUISE POUR POLARISER LE VARACTOR 24 D'UNE MANIERE QUI ASSURE UNE MODULATION DE FREQUENCE LINEAIRE DE L'OSCILLATEUR. LES VARIATIONS DE LA PERIODE D'UN SIGNAL D'ECHANTILLONNAGE PRODUIT AU MOYEN D'UNE LIGNE A RETARD 29 SONT MESUREES PAR UN PERIODE-METRE 32 A DES TEMPS CORRESPONDANT AU SIGNAL DE SORTIE BASSE FREQUENCE ET HAUTE FREQUENCE DE L'OSCILLATEUR ET LES SIGNAUX D'ERREUR RESULTANTS SONT UTILISES POUR COMMANDER LE GENERATEUR DE FONCTION DE FACON A MODIFIER, EN BOUCLE FERMEE, LE SIGNAL DE POLARISATION DU VARACTOR DANS LES PARTIES DE CE SIGNAL QUI CORRESPONDENT RESPECTIVEMENT AUX PARTIES BASSE ET HAUTE FREQUENCE DU SIGNAL DE SORTIE DE L'OSCILLATEUR.

Constantinos S. Kyriakos

Papers

Wideband phase locked loop tracking oscillator for radio altimeter

Linear sweep frequency modulator for FM/CW radio altimeter

Tracking filter for radio altimeter

Filtre d'accord dynamique pour radio-altimetre

Modulateur de frequence lineaire pour un radio-altimetre a onde entretenue modulee en frequence