392results about "Angle modulation by variable impedence" patented technology

A method and apparatus for fully integrating a Voltage Controlled Oscillator (VCO) on an integrated circuit. The VCO is implemented using a differential-mode circuit design. The differential-mode implementation of the VCO preferably comprises a differential mode LC-resonator circuit, a digital capacitor, a differential pair amplifier, and a current source. The LC-resonator circuit includes at least one tuning varactor and two high Q inductors. The tuning varactor preferably has a wide tuning capacitance range. The tuning varactor is only used to "fine-tune" the center output frequency f0 of the VCO. The center output frequency f0 is coarsely tuned by the digital capacitor. The VCO high Q inductors comprise high gain, high self-resonance, and low loss IC inductors. The IC VCO is fabricated on a high resistivity substrate material using a trench isolated guard ring. The guard ring isolates the fully integrated VCO, and each of its component parts, from RF signals that may be introduced into the IC substrate by other devices. By virtue of the improved performance characteristics provided by the digital capacitor, the analog tuning varactor, the high Q inductor, and the trench isolated guard ring techniques, the inventive VCO is fully integrated despite process variations in IC fabrication.

The LC VCO includes an LC oscillator module with first and second tank nodes and a control module with positive and negative input voltage terminals. The control module includes four voltage dependent capacitive elements which are configured to be biased for operation as voltage dependent variable capacitances. The voltage dependent capacitive elements are interconnected such that the effect of a common mode input voltage is to increase the capacitance of two of the voltage dependent capacitive elements, while simultaneously decreasing the capacitance of two of the other voltage dependent capacitive elements by a substantially similar amount, such that a differential voltage applied across the positive and negative input voltage terminals is operable to change the capacitance of the voltage dependent capacitive elements, and thereby the frequency of the LC oscillator module, while effects on the output frequency of the oscillator caused by a common mode voltage tend to cancel. Accordingly, a fully differential signal path in phase locked loops employing LC oscillators, with improved noise rejection, substantial suppression of common mode noise, and a minimal increase in complexity over a single-ended control design can be achieved. Additional supply voltages need not be employed.

A voltage controlled LC resonance oscillation circuit has a plurality of capacitive elements connected to an output node. These capacitive elements are applied with voltages at opposing terminals for selecting an oscillating frequency band, so that the oscillating frequency band can be changed step by step in accordance with the selection voltage. The capacitive elements include at least one variable capacitive element such as a MOS capacitor, the capacitance of which is varied in accordance with a voltage applied thereto. The MOS capacitor is similar in structure to a MOS transistor. The variable capacitive element can be supplied at a terminal opposite to the output node with a voltage from a variable voltage source, for example, in place of the selection voltage. The voltage controlled LC resonance oscillation circuit can measure the output amplitude and oscillating frequency without affecting the characteristics thereof, and reduce the parasitic capacitance.

MEMS-based, computer system, clock generation and oscillator circuits and LC-tank apparatus for use therein are provided and which are fabricated using a CMOS-compatible process. A micromachined inductor (L) and a pair of varactors (C) are developed in metal layers on a silicon substrate to realize the high quality factor LC-tank apparatus. This micromachined LC-tank apparatus is incorporated with CMOS transistor circuitry in order to realize a digital, tunable, low phase jitter, and low power clock, or time base, for synchronous integrated circuits. The synthesized clock signal can be divided down with digital circuitry from several GHz to tens of MHz—a systemic approach that substantially improves stability as compared to the state of the art. Advanced circuit design techniques have been utilized to minimize power consumption and mitigate transistor flicker noise upconversion, thus enhancing clock stability.

A fully integrated, programmable mixed-signal radio transceiver comprising a radio frequency integrated circuit (RFIC) which is frequency and protocol agnostic with digital inputs and outputs, the radio transceiver being programmable and configurable for multiple radio frequency bands and standards and being capable of connecting to many networks and service providers. The RFIC includes a tunable resonant circuit that includes a transmission line having an inductance, a plurality of switchable capacitors configured to be switched into and out of the tunable resonant circuit in response to a first control signal, and at least one variable capacitor that can be varied in response to a second control signal, wherein a center resonant frequency of the resonant circuit is electronically tunable responsive to the first and second control signals that control a first capacitance value of the plurality of switchable capacitors and a second capacitance value of the at least one variable capacitor.

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.

Exemplary embodiments of the invention provide a system, method and apparatus for spread spectrum functionality for a free-running, reference harmonic oscillator. In an exemplary embodiment, an apparatus comprises a reference oscillator adapted to provide a reference signal having a reference frequency; and a spread spectrum controller adapted to control the reference oscillator to generate a spread-spectrum reference signal at a plurality of different reference frequencies during a predetermined or selected time period. An exemplary apparatus may also include a coefficient register adapted to store a plurality of coefficients and a plurality of controlled reactance modules responsive to a corresponding coefficient of the plurality of coefficients to modify an amount of reactance effectively coupled to the reference oscillator. An exemplary spread spectrum controller is further adapted to sequentially modify the plurality of coefficients during the predetermined time period to provide the spread spectrum reference signal.

A voltage controlled oscillator including a first oscillator circuit portion with at least one first inductor, and a second oscillator circuit portion with at least one second inductor, wherein the at least one first inductor and the at least one second inductor are electromagnetically coupled to each other.

Voltage controlled oscillator circuits are provided in which variable capacitance degeneration is employed to provide increased tuning ranges and output amplitudes for VCO circuits for millimeter wave applications

A voltage-controlled oscillator including an active oscillator circuit, an inductor, and capacitive circuits is disclosed. The capacitive circuits are selectively turned on and off to control the frequency of the voltage-controlled oscillator. Particularly, the inductor and the capacitors in the capacitive circuits form LC circuits that provide feedback to the active oscillator circuit. To avoid damage to the switches in the capacitive circuits, the capacitive circuits further comprise resistors. The resistors can be configured in several different ways so that the voltage-controlled oscillator can have a high degree of reliability, and a wide tuning range with constant phase noise performance.

Embodiments of the invention provide techniques for calibrating voltage-controlled oscillators (VCOs). Multiple VCOs may be disposed on a chip with the VCOs having different frequency ranges. The VCOs may be selected and tested to determine a desired VCO to use to tune to a selected channel frequency. Each of the VCOs has multiple possible varactor configurations. The varactor configurations of the desired VCO determined to be used to tune to the selected channel frequency can be selected and tested to determine a desired varactor configuration for the desired VCO. The desired VCO with the desired varactor configuration will preferably be able to produce a full range of desired frequencies corresponding to all channel frequencies desired.

A wide-band voltage controlled oscillator includes a cross-connected transistors for providing a stable oscillating signal, an inductor unit for providing an inductance for determining a resonance frequency, a varactor bank including a plurality of switchable variable-capacitance elements parallely connected to the inductor unit and having a varactor capacitance varying with the first switching signal and a tuning voltage, a subsection capacitor bank including a plurality of switchable capacitor elements parallely connected to the inductor unit and having predetermined capacitances for grouping frequency sections, and a binary-weighted capacitor bank including a plurality of binary-weighted capacitor arrays parallely connected to the inductor unit and a bank selector for selecting one of the binary-weighted capacitor arrays, wherein each binary-weighted capacitor arrays includes a plurality of parallely connected switchable capacitor elements selectively switched on by a third switching signal to determine a variable weighted capacitance of the tunable binary-weighted capacitor bank.

In the case of a trimming method for a PLL circuit operating based on the principle of a two-point modulation, the PLL circuit is locked without any modulation being impressed and then an analog and a digital modulation signal are impressed into the locked PLL circuit. A signal that is characteristic of the PLL control error is tapped from the PLL circuit, and the modulation swing in the analog modulation signal is changed such that the characteristic signal has the same value as before the analog and digital modulation signals were impressed.

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.

A voltage-controlled oscillator operates at high frequency without high gain by dividing the frequency range into a plurality of subranges, which preferably are substantially equal in size. Within any subrange, the full extent of variation in the control signal changes the frequency only by the extent of the subrange. The gain is thus substantially equal to the gain one would expect for the full frequency range, divided by the number of subranges. The subrange may be selected manually, or by an initial calibration process. In one embodiment, the oscillator includes a voltage-to-current converter and a current-controlled oscillator, with a current mirror arrangement. In that embodiment, selection of the subrange may be controlled by turning on the correct number of current legs.

A system for generating in-phase and quadrature phase signals is provided. The system includes a first and a second differential output, such as from a sinusoidal oscillator. A first injection-locked frequency divider, such as one that uses an LC oscillator in conjunction with cross-coupled transistors, receives the first differential output and generates a in-phase or in-phase output. A second injection-locked frequency divider receives the second differential output and generates a quadrature phase output.

A tunable oscillator includes an input for receiving an input signal from a source of precision frequency such as a CMOS quartz crystal oscillator. The tunable oscillator converts the frequency of the input signal to a first current using a frequency to current converter. The current produced is proportional to a first capacitor, C1. The first current is replicated to produce a subsequent current using a current mirror structure. The subsequent current is then used to generate a periodic signal using a current to frequency converter. The output frequency of the current to frequency converter is inversely proportional to a second capacitor, C2. As such the output frequency of the tunable oscillator is tunable by changing the value of the capacitance ratio C1/C2. The invention is suitable for applications that require a precision tunable source of frequency such as automated test equipment (ATE) and electrical instrumentation.

Exemplary embodiments of the invention provide a reference signal generator, system and method. An exemplary apparatus to generate a harmonic reference signal includes a reference resonator, such as an LC-tank, and a frequency controller. The reference resonator generates a first reference signal having a resonant frequency, and the frequency controller maintains substantially constant a magnitude of a peak amplitude of the first reference signal and maintains substantially constant a common mode voltage level of the reference resonator. A temperature-dependent control voltage is also generated and utilized to maintain the resonant frequency substantially constant or within a predetermined variance of a calibrated or selected frequency.