Abstract: A technique provides a clock source that meets accuracy requirements, allows the use of a low cost resonator, provides a wide range of output frequencies, and provides suitable phase noise performance. The technique generates a clock signal having a target output frequency using a controllable oscillator having at least one continuous frequency range of operation. The technique dynamically adjusts a reference control value based on a voltage for adjusting a frequency of the clock signal around a frequency determined by the reference control value. The reference control value is adjusted to be approximately within the center of an actual pull range corresponding to the controllable oscillator and a voltage control input of the controllable oscillator. The effective pull range of the controllable oscillator is continuous across the at least one continuous frequency range of operation.

Abstract: A frequency setting circuit includes a table storing, in an address corresponding to a channel number, a quotient and a remainder calculated by subtracting 1 from the channel number to calculate a difference and dividing the difference by 3 are stored in bits b7 to b3 and bits b1 to b0, respectively. When the channel number is designated by a channel setting unit, a value of the bits b1 to b0 is decoded and given to a selector as a selection signal. A frequency set value of twelve bits of lower-order four digits is selected and output from the selector.

Abstract: A voltage-controlled oscillator (VCO) for a multi-band receiver, and a radio-frequency (RF) communication apparatus having the same. The VCO includes at least two fine tune branches, that is, a main fine tune branch and an auxiliary fine tune branch. The main fine tune branch includes at least one variable capacitor whose capacitance varies according to a tuning voltage. The auxiliary fine tune branch includes at least one varactor that operates either as a variable capacitor whose capacitance varies according to the tuning voltage or a fixed capacitor regardless of the tuning voltage, based on an operating frequency band. Accordingly, it is possible to prevent phase noise from increasing by varying the gain of the VCO according to the frequency band of an oscillation signal from the VCO.

Abstract: A digitally controlled oscillator circuit is provided that comprises a ring oscillator including multiple inverters; multiple digitally controlled capacitors (DCCs), each coupled to apply a digitally controllable amount of capacitance to an output of a different one of the inverters; and control circuitry operable to change an amount of capacitance applied to each inverter during operation of the ring oscillator and to cause the multiple DCCs to apply substantially the same amounts of capacitance to each of the inverter throughout operation of the ring oscillator.

Abstract: The invention comprises a phase locked loop that has an input adapted to receive a reference frequency. A phase detector is connected directly to the input, a charge pump is connected directly to the phase detector, and a loop filter is connected directly to the charge pump. Also, a voltage controlled oscillator is connected directly to the loop filter, and is adapted to perform frequency band selection. A band selection circuit is connected to the voltage controlled oscillator.

Abstract: A voltage-controlled oscillator having an inductor circuit, n pieces (n is two or more) of variable capacitance circuit having variable capacitance elements, negative resistance circuits, and reference voltage generation means of generating a reference voltage from a power supply voltage, and wherein a predetermined reference voltage is inputted to some terminals of the variable capacitance elements of the n pieces of variable capacitance circuit, a control voltage is inputted to the other terminals thereof, and of the variable capacitance elements of the n pieces of variable capacitance circuits, the predetermined reference voltage inputted to some terminals of the variable capacitance elements of at least two pieces of the variable capacitance circuit is different.

Abstract: An oscillator includes a first resonator circuit, a second resonator circuit coupled to the first resonator circuit and a reconfigurable network having a transconductance and coupled to at least one of the resonator circuits. Reconfiguration of the reconfigurable network with respect to the transconductance allows selection of one of multiple oscillation modes of the oscillator.

Abstract: A frequency synthesizer capable of high speed, low power, wideband operation including a method of gain compensation, and a method of fast voltage controlled oscillator (VCO) band calibration. In addition, the frequency synthesizer may include two or more switchable independent loop filters to facilitate wideband operation. Such a frequency synthesizer may be used in many applications, and in one example, may be particularly suitable for use in a multi-band, multi-standard transmitter or radio transceiver.

Abstract: Methods and apparatuses for testing a calibrated VCO to determine whether the VCO has adequate fine frequency tuning capability. A range of coarse frequency tuning calibration settings are determined from coarse frequency tuning calibration settings obtained during a coarse frequency tuning calibration process. A determination is then made as to whether a fine frequency tuning capability of the VCO is adequate based on the determined range of coarse frequency tuning calibration settings.

Abstract: The voltage controlled oscillator comprises an oscillating system wherein two variable capacitors are alternately connected. The capacitances of these two capacitors vary respectively in the same direction as the voltage that is applied thereto and in the opposite direction. Replacing one variable capacitor by the other is performed automatically when the output frequency of the oscillator reaches a predetermined switching value. It is thus possible to divide an operating frequency band of the oscillator into at least two parts in which the frequency varies alternately in the same direction as the control voltage of the oscillator and in the opposite direction. Switchable fixed capacitors can be connected in the oscillating system, either when one variable capacitor is replaced by the other or by means of a command, to make the oscillator switch from one frequency band to a lower band.

Abstract: A method for automatic frequency tuning in a phase lock loop suitable for use in multi-band VCO wireless systems having very limited initial frequency lock times is disclosed. A predetermined subset of VCOs out of a larger bank of VCOs is selected to serve as interpolation points. The interpolation point VCOs are pre-calibrated with a predetermined voltage and the resultingly generated frequency for each of the interpolation point VCOs is stored into memory as a (frequency, VCO) pair, one pair for each interpolation point VCO. When a desired frequency then is given to the system, an appropriate VCO is selected by interpolation using the (frequency, VCO) pairs of the two most adjacent interpolation points for tracking and locking.

Abstract: A voltage comparing circuit activates a first voltage comparison signal when a control voltage is lower than a first reference voltage and a second voltage comparison signal when the control voltage is higher than a second reference voltage. In synchronization with a count clock, a counter decrements a counter value during activation of the first voltage comparison signal and increments the counter value during activation of the second voltage comparison signal. An oscillating circuit selects one of oscillation frequency bands by the counter value and regulates an oscillation frequency according to the control voltage within the selected oscillation frequency band to output an output clock. This makes it possible to secure a wide oscillation frequency range in response to variance in operating conditions or a reduction in a range of the control voltage and to regulate the oscillation frequency of the voltage controlled oscillator by the control voltage alone.

Abstract: An integrated circuit package comprises an integrated circuit that comprises a temperature sensor that senses a temperature of the integrated circuit. A memory module stores data relating to oscillator calibrations and selects one of the oscillator calibrations as a function of the sensed temperature. An oscillator module generates a reference signal having a frequency that is based on the selected one of the oscillator calibrations. A packaging material encases at least part of the integrated circuit and has a low dielectric loss.

Abstract: A VCO circuit (20) has a coil (21) and, in parallel therewith, a constant capacitance (24) and adjustable capacitance elements (22, 23). A first capacitance element (22) is formed by one or more varactors whose capacitance can be adjusted by an analogue adjusting voltage (Vtune), while a second capacitance element (23) is formed by an arrangement comprising a plurality of capacitors which can be actuated by a digital bit word VCWD[N:1]. Digital calibration for the VCO (20) is performed by determining whether the present adjusting voltage is within a particular voltage range and, if this is not the case, the digital bit word being incremented or decremented by a bit value.

Abstract: A semiconductor integrated circuit with a PLL (Phase Locked Loop) built therein is used in a semiconductor integrated circuit for wireless communication. The PLL circuit generates an oscillation signal having a predetermined frequency, which is combined with a receive signal or a transmit signal for wireless communication. The PLL circuit includes a VCO capable of switching an oscillation frequency band, a variable divider, a loop filter and a phase comparator. An oscillation frequency of the VCO is controlled according to the difference in phase between a signal obtained by dividing the output of the VCO and a reference signal, and a discrimination circuit makes a decision as to a lead or delay of the phase of an output of the variable divider with respect to a reference signal having a predetermined frequency. An auto band selection circuit generates a signal for selecting a frequency band for the VCO.

Abstract: A Phase-Locked Loop (PPL) circuit includes a voltage controlled oscillator (VCO), a reference signal oscillator, first and second frequency dividers, a phase comparator, a charge pump and a loop filter. The VCO has a plural number of oscillation frequency boards and oscillates according to a control voltage in a selected band. The first frequency divider frequency divides the output signal of the VCO. The second frequency divider frequency divides the reference signal outputted from the reference signal oscillator. The phase comparator detects the phase difference between the output signal of the first and second frequency dividers and outputs a phase difference signal. The charge pump inputs and outputs a current generated by a gain that was set depending on the selected band based on the phase difference signal. The loop filter increases or decreases the voltage with a specified low pass filter.

Abstract: For use in a multi-band wireless communication system, a local oscillator includes a voltage-controlled oscillator that generates an oscillating signal in response to a control signal. A local oscillating signal generator includes buffers and frequency dividers for generating from the oscillating signal a plurality of frequency signals having different frequencies. A switching circuit selects one of the frequency signals, and a phase locked loop generates the control signal from the selected frequency signal.

Abstract: Improved voltage controlled oscillator (VCO) circuits are disclosed. A symmetrical voltage controlled oscillator (VCO) system according to the embodiments of the present invention comprises a frequency tuning circuit containing one or more varactors for receiving a predetermined tuning signal and a frequency tuning bias signal for altering capacitances of the varactors, a modulation circuit coupled in parallel with the frequency tuning circuit containing one or more varactors for modulating one or more outputs, and a core circuit coupled in a parallel with the tuning circuit and the modulation circuit for providing an oscillation mechanism, wherein the core circuit has an inductance module coupled in a parallel fashion with the frequency tuning circuit and the modulation circuit, wherein circuit elements of the VCO system are symmetrically arranged for increasing oscillation efficiency thereof and the varactors are tuned to deliver the output at an output frequency.

Abstract: A tuning circuit uses a VCO with a trimming capacitor bank. The trimming capacitor bank is calibrated by logic to accommodate a desired frequency, fwanted. A search renders an initial control word that is accurate within one LSB. In a first embodiment, comparisons between the desired frequency and the upper and lower frequency bounds of the VCO with the trimming capacitor bank configured by the initial control word. The control word may be increased or decreased based on the comparisons. In a second embodiment, differences between the desired frequency and the actual frequency of the VCO, with the trimming capacitor bank configured by the initial control word, are compared to a threshold. The control word may be increased or decreased based on the comparison.

Abstract: The phase locked loop frequency synthesizer, includes: an LC-tank circuit which includes an inductor and a variable capacitor in which the capacity changes depending on the input voltage; a group of fixed-value capacitors which is connected to the LC-tank circuit in parallel; a voltage control oscillating unit which outputs a signal with a frequency determined by the LC-tank circuit and the group of fixed-value capacitors; a phase control unit which generates an output current based on an error operator between a first signal with a divided frequency of a reference frequency and a second signal with a divided frequency of the frequency output from the voltage control oscillating unit; a fixed-value capacitor controlling unit which outputs a selection signal which determines the combination of the fixed-value capacitors to be connected to the LC-tank circuit in parallel based on a frequency dividing ratio setting signal including information about dividing ratio of the second signal, and controls the connectio

Abstract: A phase lock loop and the control method thereof. The phase lock loop adjusts operating states automatically to generate a feedback clock for tracing a reference clock. The control method generates the first and second clocks corresponding to the highest and lowest frequency oscillating clocks respectively generated by the phase lock loop when operating in one of select states. The frequencies of the first and second clocks are compared to the frequency of the reference clock respectively, thereby holding the select state of the phase lock loop when the first, second, and reference clocks are in a first predetermined condition or changing the select state of the phase lock loop when in a second predetermined condition.

Abstract: A resonance circuit is interposed between a base and a collector of an oscillating transistor and is configured such that a resonance frequency is switched in correspondence with two different frequency bands. A first feedback unit is interposed between the base and an emitter of the oscillating transistor and a second feedback unit is interposed between the emitter and the collector of the oscillating transistor. One of the first feedback unit and the second feedback unit is configured by series-parallel connection of three reactive elements so as to exhibit one of inductive and capacitance characteristics in the two different frequency bands, and the other feedback unit is configured so as to exhibit the same characteristic as that of one feedback unit. As a result, oscillation is performed in the two frequency bands.

Abstract: A variable capacitance circuit capable of switching on and off a variable capacitance function, includes variable capacitance means formed such that variable capacitance elements whose capacitance values change according to a voltage value of a supplied capacitance control voltage are connected so as to be paired and a plurality pairs of variable capacitance elements are connected in parallel forming multiple stages; bias voltage generation means for generating bias voltages of different voltage values based on a constant voltage from a constant voltage source; and an on-off switch for the variable capacitance function, in which the variable capacitance function of the variable capacitance means is turned on by supplying the bias voltage to the variable capacitance element of each stage of the variable capacitance means and turned off by grounding the bias voltage of each voltage value.

Abstract: In one embodiment, the present invention includes a capacitor array that may provide a selected capacitance to a digitally controlled crystal oscillator (DCXO). The array may include multiple sections each having at least one array portion, where each section is to receive different significant portions of a digital control value. The different sections may have different coding schemes. Other embodiments are described and claimed.

Abstract: A gain compensator compensates for the gain variation of a varactor-tuned voltage tuned oscillator (VCO) in a phase lock loop (PLL). The VCO includes a parallel LC circuit having multiple fixed capacitors that can be switched-in or switched-out of the LC circuit according to a capacitor control signal to perform band-select tuning of the VCO. The gain compensator compensates for the variable VCO gain by generating a charge pump reference current that is based on the same capacitor control signal that controls the fixed capacitors in the LC circuit. The gain compensator generates the charge pump reference current by replicating a reference scale current using unit current sources. The number of times the reference scale current is replicated is based on the fixed capacitance that is switched-in to the LC circuit and therefore the frequency band of the PLL.

Abstract: A VCO include a resonance tank circuit(A) and an amplification circuit(B) which oscillates and is amplified at a resonance frequency of the resonance tank circuit(A). The resonance tank circuit(A) is provided with a capacity band switching circuit(D) for varying an oscillation frequency band, and a current band switching circuit(E) for feeding an appropriate current, corresponding to each oscillation frequency band, to the amplification circuit(B). This allows expansion of the oscillation frequency variable range as well as realization of a favorable phase noise characteristic in a broad band by optimization of a current in each frequency band.

Abstract: The invention is directed to a phase locked loop. The phase locked loop comprises a variable frequency divider for performing a fraction frequency division by switching a dividing value having an integer portion and a fraction portion; a memory for storing the fraction portion; and a data converter for adding the integer portion to the fraction portion from the memory based on a clock signal from the variable frequency divider to determine the dividing value to be supplied to the variable frequency divider.

Abstract: Exemplary embodiments of the invention provide a system, method and apparatus for frequency calibration of a free-running, harmonic oscillator. A reference oscillator provides a reference frequency. An exemplary system comprises the harmonic oscillator, a frequency divider, a comparator, and a reactance modulator. The oscillator comprises a plurality of switchable reactance modules and a coefficient register, and provides an oscillation signal having an oscillation frequency. The frequency divider provides an output frequency as a fraction of the oscillation frequency. The comparator compares the output and reference frequencies and provides a comparison signal when the output frequency is not substantially equal to the reference frequency.

Abstract: A PLL circuit provides a self-selecting divide ratio, which is varied as necessary to lock the circuit to a reference clock which may have several possible frequencies, thereby enabling the VCO to employ a type of oscillator having a superior jitter characteristic. The PLL circuit includes a variable divider which divides the VCO output by a divide ratio value provided by a frequency band select circuit, which provides the divide ratio needed to drive the phase difference between the reference and divided clocks toward zero while the VCO clock output operates within a predetermined frequency range. The self-selecting variable divide ratio allows the VCO's oscillator to have a narrow output frequency range, thereby allowing the use of an oscillator type with a jitter characteristic which may be low enough to meet the requirements of JEDEC, for example.

Abstract: A gain compensator compensates for the gain variation of a varactor-tuned voltage tuned oscillator (VCO) in a phase lock loop (PLL). The VCO includes a parallel LC circuit having multiple fixed capacitors that can be switched-in or switched-out of the LC circuit according to a capacitor control signal to perform band-select tuning of the VCO. The gain compensator compensates for the variable VCO gain by generating a charge pump reference current that is based on the same capacitor control signal that controls the fixed capacitors in the LC circuit. The gain compensator generates the charge pump reference current by replicating a reference scale current using unit current sources. The number of times the reference scale current is replicated is based on the fixed capacitance that is switched-in to the LC circuit and therefore the frequency band of the PLL.

Abstract: A frequency synthesizer includes a VCO (1), measures an oscillation frequency of each of multiple bands with a predetermined voltage (V1) applied to the VCO (1), and stores the measurement result to a storage circuit (11). The synthesizer compares a frequency division ratio from a PLL control circuit (14) with the measured oscillation frequency stored to the storage circuit, and selects one band from VCO (1) based on the comparison result. The synthesizer causes the VCO (1) to oscillate on the selected band with a fixed voltage, and determines a frequency band to be used for phase-locked operation in actual based on an error between the oscillation frequency and a reference frequency.

Abstract: An oscillation circuit comprises a SAW resonator having a pair of reflectors disposed on a piezoelectric substrate and a pair of IDTs which are set up in parallel between the pair of reflectors and which are constituted by teeth-of-a-comb electrodes; an inverter to which the pair of IDTs are connected in parallel; and a change-over unit which is provided between each of a pair of the teeth-of-a-comb electrodes constituting either of the IDTs of the pair of IDTs and the inverter and which changes over and connects an input side and an output side of the inverter connected to each of the pair of the teeth-of-a-comb electrodes.

Abstract: A VCO circuit including a VCO, a voltage supply and a control circuit. The VCO has a supply voltage input and a gain that changes with its supply voltage. The voltage supply has an adjust input and an output coupled to the supply voltage input of the VCO. The voltage supply adjusts the voltage level of its output in response to changes of the adjust input. The control circuit has a first adjust output coupled to the adjust input of the voltage supply to adjust the gain of the VCO. The VCO may include a frequency range adjust input controlled by the control circuit so that the gain of the VCO is adjusted when the frequency range is changed. For a multi-band VCO, the gain is adjusted for different frequency bands to maintain a relatively constant gain for each frequency band.

Abstract: The present invention is related with a dual-band LC voltage controlled oscillator, which utilizes a substantial amount of feedback loop paths in the circuit. The circuit is a core of a substantial amount of communication ICs. The voltage controlled oscillator can provide wide-band or dual-band radio frequency generation, and it utilizes a switch controlled circuit to select one of the feedback loops in order to choose the assigned frequency band output. Generic wide-band or dual-band LC voltage controlled oscillations are obtained by switching parallel-connected capacitors or switching inductor array, in contrast, the present invention is used for switching several parallel connected feedback loops, each of which associated with an LC tank forms an oscillation frequency output. Utilizing the switch to control the feedback loop and integrating different band oscillator circuit is capable of saving chip's size and power consumption.

Abstract: In various embodiments, the invention provides a clock generator and/or a timing and frequency reference, with multiple operating modes, such power conservation, clock, reference, and pulsed modes. The various apparatus embodiments include a resonator adapted to provide a first signal having a resonant frequency; an amplifier; a temperature compensator adapted to modify the resonant frequency in response to temperature; and a process variation compensator adapted to modify the resonant frequency in response to fabrication process variation. In addition, the various embodiments may also include a frequency divider adapted to divide the first signal having the resonant frequency into a plurality of second signals having a corresponding plurality of frequencies substantially equal to or lower than the resonant frequency; and a frequency selector adapted to provide an output signal from the plurality of second signals.

Abstract: In various embodiments, the invention provides a frequency controller and a temperature compensator for frequency control and selection in a clock generator and/or a timing and frequency reference. The various apparatus embodiments include a resonator adapted to provide a first signal having a resonant frequency; an amplifier; a temperature compensator adapted to modify the resonant frequency in response to temperature; and a process variation compensator adapted to modify the resonant frequency in response to fabrication process variation. In addition, the various embodiments may also include a frequency divider adapted to divide the first signal having the resonant frequency into a plurality of second signals having a corresponding plurality of frequencies substantially equal to or lower than the resonant frequency; and a frequency selector adapted to provide an output signal from the plurality of second signals.

Abstract: A method and system for VCO with switchable varactor for low KVCO variation is provided. Aspects of a method for controlling a signal may comprise controlling an oscillating frequency of a time varying signal in a circuit, and controlling a change in the oscillating frequency based on switching of a plurality of varactors. The switching of the varactors may control a change in the oscillating frequency based on a control voltage. The method may further comprise minimizing a change in the rate of change in the oscillating frequency based on the switching of the varactors. Aspects of a system for controlling a signal may comprise circuitry that controls an oscillating frequency of a time varying signal in a circuit, and circuitry that controls a change in the oscillating frequency based on switching of a plurality of varactors. An executable computer program may cause a machine to execute steps as described above.

Abstract: The present invention is directed to a system that enables the simultaneous remote monitoring of a plurality of infants' skin temperatures. The system comprises an electronic circuit that combines the functions of sensoring and multiple-channel transmitting, a pre-deployment temperature bath for calibration of the temperature sensor(s), and a receiving and reporting station for centralized monitoring the infants' skin temperatures. The present invention is further directed to a temperature sensor that measures the temperature and transmits the data in multiple channels to a remote receiver. In one embodiment, the temperature sensor comprises a ring oscillator, having a plurality of odd number of inverters, and the ring oscillator is capable of utilizing less than all of the inverters in the ring to modulate the frequency of the signal. In another embodiment, the temperature sensor comprises one inverter and a plurality of delay elements and sensor transmits phase shifted signals to modulate the signals.

Abstract: A mixed signal method and system for tuning a voltage controlled oscillator is described. The method includes dividing a frequency range of an oscillator circuit into a plurality of regions, digitally selecting and tuning one of the plurality of regions of the divided frequency range of the oscillator circuit, and further tuning the selected region of the frequency range of the oscillator circuit via one or more analog tuning elements.

Abstract: According to one exemplary embodiment, a digitally controlled oscillator includes a capacitive tuning network, where the capacitive tuning network controls a frequency of an output signal of the digitally controlled oscillator. The capacitive tuning network includes a switched capacitor array, where a change of a first capacitance of the switched capacitor array causes the capacitive tuning network to change by a second capacitance, and where the first capacitance is larger than the second capacitance. According to this exemplary embodiment, the capacitive tuning network further includes a first capacitor coupled in parallel with the switched capacitor array. The first capacitor has a third capacitance, which is larger than the first capacitance. The capacitive tuning network further includes a second capacitor coupled in series with the first capacitor and the switched capacitor array. The second capacitor can have a fourth capacitance, where the third capacitance is larger than the fourth capacitance.

Abstract: A system is provided to improve frequency stability and system linearity in voltage controlled oscillators.

Abstract: An apparatus and method of oscillating a wideband frequency are disclosed. The apparatus includes: a frequency oscillating unit for oscillating a predetermined frequency; a phase-locked loop for comparing the oscillated frequency and a reference frequency by feed-backing the oscillated frequency from the frequency oscillating unit and fixing an oscillating frequency of the frequency oscillating unit; and a variable dividing unit for varying a division ratio to approach to a frequency band required by the oscillating frequency and dividing the oscillating frequency.

Abstract: A voltage-controlled oscillator comprising a resonant circuit and MOS transistors which constitute a negative resistance circuit of a differential structure. The resonant circuit consists of an inductance element and a MOS variable capacitance element connected in parallel therewith. The MOS variable capacitance element is divided into plural pairs connected in parallel with each other. A voltage division circuit generates staircase different-step DC bias voltages to be applied respectively to the gates of the plural divided MOS transistors. The divided MOS variable capacitance elements have a common terminal to which a common control voltage is applied. The resonant circuit is capable of reducing a load on the control voltage generator and improving the characteristics of the voltage-controlled oscillator.

Abstract: A method and apparatus for tuning a VCO circuit to provide desired modulations is described. In one embodiment, the method of the present invention uses a controlled voltage from a digital-to-analog converter to obtain VCO voltage/frequency characteristics. The VCO voltage/frequency characteristics are used to determine a VCO capacitance value as well as a charge pump current level for each frequency band of interest. For one embodiment, the VCO circuit includes a bank of switchable capacitors used to set the VCO capacitance value. The charge pump includes a number of switch-controlled current meters to set the charge pump current level. The VCO capacitors and charge pump current meters are controlled by an off-chip CPU.

Abstract: Synthesizer and calibrating method utilizing same. The frequency synthesizer modulates input signals comprising a phase locked loop circuit. The phase locked loop circuit comprises a phase frequency detector for generating a first signal, a low pass filter for outputting a filtered control signal derived from the received first signal, a voltage control oscillator for generating an output signal with a first frequency based on the control signal, a frequency divider dividing the first frequency for output to the input terminal of the phase frequency detector, a modulator coupled to the frequency divider, a pre-emphasis filter receiving and filtering the input signal for output to the modulator, and an auto loop gain calibration circuit, receiving the control signal, and calculating a current gain of the control signal in accordance with the voltage of the control signal to compensate for the frequency response mismatch between the pre-emphasis filter and the frequency synthesizer.

Abstract: A PLL circuit comprises a phase comparator for comparing phases between a reference signal and an internal signal and outputting a phase difference signal according to a phase difference therebetween, a voltage controlled oscillator group composed of a plurality of oscillators which have mutually different frequency variable ranges and whose oscillation frequencies are respectively controlled in accordance with a phase control signal, a selecting means for selecting one of the outputs from the plurality of oscillators based on the phase difference signal or the phase control signal, and a frequency divider for generating the internal signal by dividing an output of an oscillator selected by the selecting means, and when the oscillator selecting state is changed, an output phase of the frequency divider is approximated to the phase of the reference signal. Thereby, a required voltage controlled oscillator can be selected in a short time according to a desirable oscillation frequency.

Abstract: A range controller circuit has a master counter with a recovered clock input. A sampled counter has a reference clock input. A link fault indicator logic is coupled to an output of the master counter and an output the sampled counter.

Abstract: Certain exemplary embodiments provide a method for producing pulsed outputs, comprising: automatically changing a first user-specified pulse frequency to a second pulse frequency; and automatically outputting a plurality of pulses from the programmable logic controller at frequencies varying between the first user-specified pulse frequency and the second pulse frequency according to a user-specified linear-time-rate variation.

Abstract: A voltage controlled oscillator comprises a parallel resonance circuit including an inductor circuit, a variable capacitance circuit, and a high-frequency switch circuit, a negative resistance circuit and a frequency control section, and a frequency tuning sensitivity control section. The frequency control section shifts a band of an oscillation frequency by controlling ON/OFF of a switching element included in the high-frequency switch circuit. The frequency tuning sensitivity control section adjusts a change rate of a total capacitance of the variable capacitance circuit with respect to a control voltage, depending on a band to be used. The frequency tuning sensitivity control section is connected to a virtual ground point of a differential signal.

Abstract: A technique for establishing a tuning signal window for a multi-band VCO involves setting the tuning signal window to an initial size, preferably a relatively small size, and determining whether the VCO is churning. When the VCO is determined to be churning, the tuning signal window is expanded until the VCO stops churning. In an embodiment, the tuning signal window is expanded incrementally until the tuning signal window is large enough to include a solution, where a solution is defined as an operating point along a frequency band that satisfies both the setpoint frequency and tuning window signal requirements. The tuning signal window can be set at an offset relative to the tuning signal zero to compensate for shifts in the frequency bands that may result from changes in operating conditions.