128results about "Discontinuous tuning with variable tuning element" patented technology

The present invention provides a system for a moving body which enables a user to know a receivable broadcast station at the current position in real time and to select smoothly a desired broadcast station in a receiver even in an unfamiliar area. This system includes a broadcast station data memory that stores the channel data of a receivable broadcast station for each area, and a main processing circuit which is responsive to the vehicle's current position sensed by a coordinate computing unit for referring to the channel data and for showing the channel data of a receivable broadcast station at the current position on a display.

A method and apparatus for use in a digitally tuning a capacitor in an integrated circuit device is described. A Digitally Tuned Capacitor DTC is described which facilitates digitally controlling capacitance applied between a first and second terminal. In some embodiments, the first terminal comprises an RF+ terminal and the second terminal comprises an RF− terminal. In accordance with some embodiments, the DTCs comprise a plurality of sub-circuits ordered in significance from least significant bit (LSB) to most significant bit (MSB) sub-circuits, wherein the plurality of significant bit sub-circuits are coupled together in parallel, and wherein each sub-circuit has a first node coupled to the first RF terminal, and a second node coupled to the second RF terminal. The DTCs further include an input means for receiving a digital control word, wherein the digital control word comprises bits that are similarly ordered in significance from an LSB to an MSB.

In an antenna unit, the generation of capacitances between each of the open ends of first and second microstrip antennas and a control electrode is controlled by turning a switch on and off, both antenna frequencies being simultaneously changed. The antenna unit has a basic body having first and second main surfaces and at least one end surface extending between the main surfaces; a grounding electrode provided on the first main surface of the basic body; a first radiation electrode forming a first antenna, having an open end at one end thereof, and provided on the second main surface of the basic body; a second radiation electrode forming a second antenna, having an open end at one end thereof, and provided on the second main surface of the basic body; a first connecting electrode for connecting the first radiation electrode to the grounding electrode, and provided on an end surface of the basic body; a second connecting electrode for connecting the second radiation electrode to the grounding electrode, and provided on an end surface of the basic body; a feeding electrode for transmitting a signal to at least one of the first radiation electrode and the second radiation electrode, and provided on the basic body; and a control electrode on the basic body for providing coupling capacitances between the open end of the first radiation electrode and the control electrode and between the open end of the second radiation electrode and the control electrode, and provided so as to be close to each of the open ends.

An automatic tuning system for a magnetic field generating tuned circuit includes a processor configured to maintain the resonant frequency of a tuned circuit equal to a reference frequency. The tuned circuit is driven by a power amplifier whose output provides an amplified signal at the reference frequency. The tuned circuit includes a magnetic field generating inductor and a bank of individually switchable capacitors controlled by the processor capable of adding and removing the respective capacitances to and from the tuned circuit. The inductor includes a Faraday shield to shield the tuned circuit from the influence of electric fields. In an embodiment of the invention, the variable capacitor is in the form of a diode variable capacitor (varicap) in parallel circuit relationship with the tuned circuit capacitor and the inductor. In an alternate embodiment the inductor and a fixed capacitor are in series circuit relationship with the varicap in parallel circuit relationship with the fixed capacitor and the tuning sequence relies on a phase locked loop using the phase of a reference frequency signal and the phase of the inductor voltage as control parameters.

A single chip superhetrodyne AM receiver including a local oscillator which sweeps through a frequency range at a rate higher than a modulation frequency of the incoming RF signal. The local oscillator frequency is mixed with the incoming RF signal. An IF filter passes a selected frequency band from the mixer to a demodulator. The demodulator is tuned to demodulate any signal within a band of frequencies determined by the sweeping of the local oscillator. This increases the signal to noise ratio of the receiver since it allows for variations in the transmitter output frequency. The frequency responses of the various filters are tied to the reference frequency and allows the user to set the tuning and alignment of the receiver. To compensate for process variations in the implementation of the IC, bias currents setting the operating conditions for various amplifiers and other components in the system are adjusted based on frequency control signals in a PLL circuit in the local oscillator.

A multiport RF switch assembly with integrated impedance tuning capability is described that provides a single RFIC solution to switch between transmit and receive paths in a communication system. Dynamic tuning is integrated into each switch sub-assembly to provide the capability to impedance match antennas or other components connected to the multiport switch. The tuning function at the switch can be used to shape the antenna response to provide better filtering at the switch / RF front-end (RFFE) interface to allow for reduced filtering requirements in the RFFE. Memory is designed into the multiport switch assembly, allowing for a look-up table or other data to reside with the switch and tuning circuit. The resident memory will result in easier integration of the tunable switch assembly into communication systems.

An automatic tuning system for a magnetic field generating tuned circuit includes a processor configured to maintain the resonant frequency of a tuned circuit equal to a reference frequency. The tuned circuit is driven by a power amplifier whose output provides an amplified signal at the reference frequency. The tuned circuit includes a magnetic field generating inductor and a bank of individually switchable capacitors controlled by the processor capable of adding and removing the respective capacitances to and from the tuned circuit. The inductor includes a Faraday shield to shield the tuned circuit from the influence of electric fields. In an embodiment of the invention, the variable capacitor is in the form of a diode variable capacitor (varicap) in parallel circuit relationship with the tuned circuit capacitor and the inductor. In an alternate embodiment the inductor and a fixed capacitor are in series circuit relationship with the varicap in parallel circuit relationship with the fixed capacitor and the tuning sequence relies on a phase locked loop using the phase of a reference frequency signal and the phase of the inductor voltage as control parameters.

A superheterodyne receiver apparatus comprises: a tuning circuit for selecting and receiving a high frequency signal, said circuit being composed of a voltage-variable capacitance element and an inductance element; and a frequency converting unit for frequency converting the high frequency signal to an intermediate frequency signal. The superheterodyne receiver apparatus further comprises: an electrically rewritable read only memory; a calculation unit for calculating tuning voltage setting data, which used to set the tuning circuit to a tuning voltage corresponding to a desired reception frequency, in accordance with a mathematical expression that uses the data stored in the memory as coefficients; and a D / A conversion unit for D / A converting the tuning voltage setting data to the tuning voltage.

A resonator of a VCO includes a fine tuning main varactor circuit, an auxiliary varactor circuit, and a coarse tuning capacitor bank circuit coupled in parallel with an inductance. The main varactor circuit includes a plurality of circuit portions that can be separately disabled. Within each circuit portion is a multiplexing circuit that supplies a selectable one of either a fine tuning control signal (FTAVCS) or a temperature compensation control signal (TCAVCS) onto a varactor control node within the circuit portion. If the circuit portion is enabled then the FTAVCS is supplied onto the control node so that the circuit portion is used for fine tuning. If the circuit portion is disabled then the TCAVCS is supplied onto the control node so that the circuit portion is used to combat VCO frequency drift as a function of temperature. How the voltage of the TCAVCS varies with temperature is digitally programmable.

An in-vehicle system comprises a location unit, a frequency selection unit, and a receiving unit. Frequency tuning data is loaded into the selection unit. The frequency tuning data includes a radio signal reception area for each unique frequency in the tuning data. The location unit determines the system location and passes the location information to the frequency selection unit. The selection unit selects tuning data for a particular frequency having a signal reception area that encompasses the present vehicle location, and passes the selected data to the receiving unit. The receiving unit uses the selected tuning data to tune the radio signal.

A circuit arrangement includes a first phase locked loop to generate a first oscillator frequency, a second phase locked loop to generate a second oscillator frequency, a reference frequency emitter connected to a reference frequency input of both phase locked loops, and a signal attenuator and optionally a switch connected between a master signal output of the first (master) loop and an input of the second (slave) loop. In a method, a common reference frequency is provided to both loops, the first loop generates a first oscillator frequency, and the second loop generates a second oscillator frequency that matches the first oscillator frequency in at least one operating mode and optionally differs from the first oscillator frequency in another operating mode. The frequency matching in one of the modes involves feeding an attenuated signal from the first loop operating as a master into the second loop operating as a slave.

In a broadcast receiver, determination is made, as channel search, whether a broadcast wave is valid for reception for all reception directions by a variable directional antenna with respect to only the frequency having the information stored as being invalid for reception in a storage unit.

A single chip superhetrodyne AM receiver is disclosed herein. To compensate for process variations in the implementation of the IC, bias currents setting the operating conditions for various amplifiers and other components in the system are adjusted based on frequency control signals in a PLL circuit in the local oscillator. Since the magnitude of the control signal reflects the process variations, the bias currents are adjusted based on the control signal to offset these variations in other portions of the receiver. To further improve the signal to noise ratio of the receiver, the IF filter is tuned within a range so as not to include any integer multiple or integer divisor of the timing reference frequency. Various techniques are described for enabling a complete superhetrodyne AM receiver to be implemented on a single chip which receives an antenna input signal and outputs a digital data signal.

In a broadcast receiver, determination is made, as channel search, whether a broadcast wave is valid for reception for all reception directions by a variable directional antenna with respect to only the frequency having the information stored as being invalid for reception in a storage unit.

A circuit may be tuned to resonate at a driving frequency. The circuit includes a source that provides an output at a drive frequency and a resonant circuit having an input coupled to the source, an output, and first and second selectable resonant frequencies. The first resonant frequency is below the drive frequency and the second resonant frequency is above the drive frequency. A control coupled to the resonant circuit output selects the first and second resonant frequencies to cause the resonant circuit to provide an output at an apparent resonant frequency equal to the drive frequency.