Abstract:
A semiconductor integrated circuit device having a function to perform oscillation in combination with a crystal oscillator, includes: a first impedance element including a first external terminal coupled to one terminal of the crystal oscillator, a second external terminal coupled to the other terminal of the crystal oscillator, and first and second terminals coupled to the first and second external terminals when the oscillation is performed; a first variable capacitance circuit coupled to the first terminal of the feedback impedance element, and a configuration circuit for setting a capacitance value of the first variable capacitance circuit. A measurement signal is supplied to the second terminal of the feedback impedance element, and in response to this, the capacitance value of the first variable capacitance circuit is set by the configuration circuit based on the delay time of an observation signal generated at the first terminal with respect to the measurement signal.
Abstract:
It is intended to provide a VCO apparatus having: a local oscillation signal generation circuit for outputting a local oscillation signal corresponding to a frequency signal of a tuned channel to be received, the frequency signal being included in high frequency signals received by an input terminal, and a mixing circuit for outputting a baseband signal by mixing the high frequency signal and the local oscillation signal, wherein the local oscillation signal generation circuit has an oscillator for oscillating the local oscillation signal and a frequency reduction unit for outputting a frequency of the local oscillation signal oscillated by the oscillator to the mixing circuit at a ratio of ×1/N, and the local oscillation signal frequency is set to a frequency different from a communication wireless frequency used by a mobile phone by adjusting the ratio of ×1/N.
Abstract:
In a phase-lock-loop circuit a frequency detector measures a frequency error between an oscillatory signal and a synchronizing signal in alternate horizontal line periods for generating a frequency error indicative signal. The frequency error indicative signal is applied to an oscillator for correcting the frequency error in other alternate horizontal line periods in a manner to prevent frequency error measurement and correction from occurring in the same horizontal line period.
Abstract:
A phase-locked-loop circuit includes an oscillator having switched capacitors that are selectively coupled to a positive feedback path of the oscillator in a coarse frequency error correction mode of operation. When the frequency error is small, the circuit operates in a fine error correction mode without varying the selection of the switched reactive elements.
Abstract:
A capacitor array provides a variable capacitance, having FET's as respective switching elements (10, 11, 12) for switching each capacitor (20, 21, 22) in the array on and off, and means (8) for controlling switching of the switching elements to switch selected ones of the capacitors on, characterised in that the control means are arranged to co-operate with voltage generation means (7) so as to supply to a control electrode of each switching element for switching on a selected said capacitor a voltage which causes the impedance provided by said switching element to change between multiple levels.
Abstract:
The invention relates to a radio frequency oscillator (100), the radio frequency oscillator (100) comprising a resonator circuit (101) being resonant at an excitation of the resonator circuit (101) in a differential mode and at an excitation of the resonator circuit (101) in a common mode, wherein the resonator circuit (101) has a differential mode resonance frequency at the excitation in the differential mode, and wherein the resonator circuit (101) has a common mode resonance frequency at the excitation in the common mode, a first excitation circuit (103) being configured to excite the resonator circuit (101) in the differential mode to obtain a differential mode oscillator signal oscillating at the differential mode resonance frequency, and a second excitation circuit (105) being configured to excite the resonator circuit (101) in the common mode to obtain a common mode oscillator signal oscillating at the common mode resonance frequency.
Abstract:
A method and apparatus for digitally controlling the capacitance of an integrated circuit device using MOS-FET devices. In accordance with one aspect of the present invention, a one-bit or "binary" varactor is presented wherein the gate-to-bulk capacitance of the MOS-FET device exhibits dependency to a D.C. voltage applied between its gate and well implant regions. The capacitance of the binary capacitor can be changed from simply by changing the polarity of the applied D.C. voltage from a positive to a negative value. A plurality of binary capacitors are configured in a parallel arrangement to produce a digitally controlled capacitor. The digitally controlled capacitor can be used in any integrated circuit requiring a tightly controlled tuned network. One application is a voltage-controlled oscillator (VCO) wherein the center output frequency of the VCO is calibrated by digitally modifying the capacitance of the VCO's digitally controlled capacitor.
Abstract:
A variable frequency oscillator comprising: an oscillatory circuit for generating a periodic output dependant on the capacitance between a first node and a second node of the circuit, and having a capacitative element connected between the first node and the second node; the capacitative element comprising: a variable capacitance unit, the capacitance of which is variable for varying the frequency of the output; and a plurality of trimming capacitances each being selectively connectable in parallel with the variable capacitance unit between the first node and the second node to trim the frequency of the output.
Abstract:
An IF VGA utilizes distorsion cancellation achieved with cross coupled differential pair amplifiers having their VDs dynamically modified in conjunction with current steering of the differential pairs sources.
Abstract:
A transmitter system comprises an oscillator and having an adjustable monolithic capacitor circuit used for frequency stabilization. The oscillator signal is modulated and transmitted. A data generating chip is coupled to the transmitter. The data generating chip is used for adjusting and controlling the transmitter oscillator frequency signal. The adjustable capacitor circuit is located internal to the data generating chip and is coupled to a ground pin and one of a plurality of function pins on the data generating chip. The adjustable capacitor circuit is used for adjusting and setting the centerpoint of the transmitter oscillator frequency signal.