Abstract: A balun converts a single-ended radio-frequency signal into differential signals. A differential matching circuit outputs a maximum-level positive-phase output signal at a lower or higher frequency than the center frequency and outputs a maximum-level reverse-phase output signal at a higher or lower frequency than the center frequency. An amplification circuit amplifies a positive-phase output signal and a reverse-phase output signal of the differential matching circuit. A mixing circuit converts the positive-phase output signal and the reverse-phase output signal that are output from the amplification circuit into intermediate-frequency signals using locally generated signals.

Abstract: Methods, systems, and apparatuses are provided for resolution-independent dither sample insertion for audio transmissions. Audio transmitters transmit audio data streams to audio receivers. Data inactivity in the data stream triggers the audio receivers to enter power-saving/sleep modes in which synchronization with the audio transmitters is lost thus requiring time consuming resynchronization. Inactivity such as silence or zero-value data is detected in a data stream. Upon detection, a dither sample is inserted into the data stream and transmitted to the audio receiver to prevent the loss of synchronization. The dither sample may have a negative value and be formatted for resolution-independence with respect to the audio receiver.

Abstract: 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.

Abstract: A tunable capacitor device may be provided in accordance with example embodiments of the invention. The tunable capacitor device may include a first capacitor; a second capacitor; a third capacitor, where the first, second, and third capacitors are connected in series, wherein the second capacitor is positioned between the first capacitor and the second capacitor; and at least one switch transistor, where the at least one switch transistor is connected in parallel with the second capacitor.

Abstract: A system and method of improving the power efficiency of a receiver for low duty cycle applications. In one aspect, the receiver includes a low noise amplifier (LNA) that is capable of being enabled in a relatively quick fashion so as to amplify an incoming signal when needed, and then being disabled to set the LNA in a low power consumption mode. In particular, the LNA includes a pair of complimentary devices, and an enable circuit adapted to quickly cause the complimentary devices to conduct substantially the same current. In another aspect, a bias voltage generating apparatus is provided that uses a residual voltage from a prior operation to establish the current bias voltage for the LNA. In particular, the apparatus includes a controller adapted to tune an adjustable capacitor to a capacitance based on a residual voltage applied to a fixed capacitor, and couple the capacitors together to establish the bias voltage.

Abstract: A receiver comprises two tuners and a DC-to-DC converter (DCC) for generating an increased supply voltage (VH) on the basis of a main supply voltage. Each tuner comprises a tunable circuit (TUC1), which can be tuned by means of a tuning voltage (VT1). Each tuner further comprises a tuning control circuit (TCC1) that is coupled to the DC-to-DC converter (DCC) via a load circuit (LD1) for generating the tuning voltage (VT1). The load circuit (LD1) of at least one of the two tuners comprises a branch (D1) coupled to receive the main supply voltage (VCC). The branch (D1) is conductive when the tuning voltage (VT1) is within a voltage range substantially comprised between 0 and the main supply voltage (VCC).

Abstract: A digitally adjustable inductive element which can be implemented in an integrated circuit. The digitally adjustable inductive element can include a first inductor, and a digital inductance controller operatively coupled to the first inductor which can be utilized to vary the effective inductance of the first inductor. The digitally adjustable inductive element can include a second inductor operatively coupled to the first inductor, and a digital current controller operatively coupled to the second inductor. The digital current controller can include a number of transistors operatively coupled to the second inductor. The digitally adjustable inductive element can be utilized to create a tunable oscillator.

Abstract: The invention provides an improved variable capacitance circuit which is substantially linearly controlled using voltage or current control. The circuit comprises two emitter connector transistors and a constant current source or drain forming a current steering circuit. A fixed capacitor is connected to the emitters of the transistors forming a port into the circuit. AC current into the port flows through the fixed capacitor and is fed back through the transistors in a proportion depending on the voltage at their bases. The effective capacitance of the circuit is varied using this variable AC feedback arrangement. Other embodiments use current control to vary the circuit capacitance by varying the effective constant current source level.

Abstract: A band switchable double tuned circuit having a balanced secondary is presented. A primary tunable tank circuit with a plurality of first inductances is tuned to a first frequency by a first capacitor coupled in parallel with the first inductances. A secondary tank circuit with a plurality of second inductances inductively coupled to ones of the first inductances has a second capacitor coupled in parallel with the second inductances for tuning the secondary to the first frequency. The DC reference potential for the secondary circuit is coupled to a nodal junction of the plurality of second inductances with the secondary tank circuit providing a balanced signal output. At least one of the plurality of first inductances and the second inductances are switchable for bandswitching the tuning of the primary and secondary tank circuits to a second frequency.

Abstract: Tuning apparatus for a television system, comprising a rotary encoder having a slidable and rotatable channel changing mechanism, the rotary encoder outputting a plurality of signals with a phase difference with respect to one another, corresponding to a channel change in accordance with the rotation of the channel changing mechanism, a microcomputer for calculating a channel number to be changed in accordance with the output signals from the rotary encoder and outputting channel receive data corresponding to the calculated channel number, and a tuner for receiving a television broadcasting signal of a channel corresponding to the channel receive data from the microcomputer.

Abstract: A tuning device has a dial drum rotatably supported in a frame, and a rheostat operatively connected to the dial drum. A knob is disposed in alignment with the dial drum. The dial drum has an outer toothing formed on the periphery thereof. A drive gear is secured to the knob, and a reduction gear train is disposed between the drive gear and the outer toothing for transmitting the rotation of the drive gear to the dial drum.

Abstract: A digital-to-analog converter suitable for use in a television tuning system for converting bits of a digital word to a corresponding tuning voltage includes a first digital-to-duty factor converter responsive to a group of the most significant bits of the digital word for generating a first incrementally variable duty factor pulse signal and a second digital-to-duty factor converter responsive to a group of the next most significant bits of the digital word for generating a second incrementally variable duty factor pulse signal. The amplitude of the first and second pulse signals are differentially weighted, e.g., by standard tolerance resistors (.+-.10%), such that the maximum average DC potential of the second signal is greater than a single increment of the average DC potential of the first signal. The weighted signals are combined and filtered by a lowpass filter which derives the tuning voltage. This deliberately results in non-monotonicity but without a significant reduction in resolution.

Abstract: A touch sensitive variable speed tuning selector is disclosed. A rotary tuning selector knob includes a finger contact coupled to touch sensitive circuitry. Tuning selector rotation causes a shaft encoder to provide a first pulsed output to tuning circuitry for normal frequency change increments. When the touch sensitive circuitry detects the presence of a finger on the contact, a signal is provided to the tuning circuitry causing each pulse from the shaft encoder to change frequency in larger increments for fast, or coarse, tuning. In a preferred embodiment, a change in the capacitance of a touch sensitive capacitive network changes the timing of input pulses provided to a flip-flop which, in turn, changes the flip-flop output to the variable speed tuning circuitry resulting in an increase in frequency change increments.

Abstract: A presettable tuning apparatus includes a digital tuner; a source of digital signals representing radio frequencies to which the tuning apparatus is respectively tuned; an addressable memory having a plurality of sequentially addressable storage locations therein for storing selected ones of the digital signals; write-in circuitry for selectively writing the digital signals from the source into selected ones of the storage locations in the memory; a comparator circuit for comparing the digital signals stored in an adjacent pair of the sequentially addressable storage locations and providing a control signal indicating the relative values of the frequencies represented by such digital signals; and circuitry for replacing the digital signals stored in the pair of storage locations with one another when the control signal indicates that the frequency represented by the digital signal stored in the lower-address one of the pair of storage locations is higher than that represented by the signal stored in the highe

Abstract: Tuning control apparatus is provided for use with a frequency synthesizer tuner of the type having a phase-locked loop including a reference oscillator, a variable frequency oscillator to produce a local oscillating signal, a programmable frequency divider coupled to the variable frequency oscillator for dividing the frequency of the local oscillating signal by a variable dividing ratio to produce a frequency-divided oscillating signal, a phase comparator for comparing the frequency-divided oscillating signal to the output of the reference oscillator to produce an error signal, and a feedback circuit for feeding back the error signal from the phase comparator to the variable frequency oscillator to adjust the frequency of the local oscillating signal and thereby establish a tuning condition of the tuner. The tuning control apparatus includes a counter for counting control pulses supplied thereto, the count of this counter determining the dividing ratio of the programmable frequency divider.

Abstract: A television tuning system for generating a tuning voltage for a varactor controlled local oscillator includes a continuous resistive element having first, second, third and fourth points along its resistive path which define first, second and third resistive sections corresponding, respectively, to the low VHF, high VHF and UHF tuning bands and a movable contact. A position detecting arrangement determines the position of the movable contact along the path of the resistive element to determine which band is being tuned and in response selectively couples voltages corresponding to the magnitudes of the tuning voltage corresponding to the beginning and end points of the various bands to respective points along the resistive element. As a result, with continuous motion of the movable contact a tuning voltage for each channel in the television range is developed at the movable contact.

Abstract: A circuit network for the non-linear digital-to-analog conversion of a periodic pulse signal having a linear average value which depends on a digital value into a direct current signal, wherein said network has different charge and discharge time constants for the pulse signals and the smoothing filter, so that a non-linear relation is obtained between the value of the input signal and the amplitude of the output signal of the filter circuit. The input network includes in series a resistor and a capacitor, the resistor of which is shunted at least partially by a diode.

Abstract: An electrically tuned filter arrangement including several tuned filters which may alternatively be coupled to the input and output of the filter arrangement so as to provide the arrangement with different tuning ranges. Each tuned filter has a tuning input to which a capacitive impedance is to be connected for establishing the center tuning frequency of the filter. A capacitor bank is provided including plural individual capacitor elements, and means for coupling any selected combination of the capacitor elements to a capacitive impedance output. This capacitive impedance output is switchably connectable to the tuning inputs of any of the tuned filters.

Abstract: A combination VHF, UHF and superband tuner, the superband and UHF tuners cooperating with the Channel 1 section of the VHF tuner, is provided with a connection network including voltage sensitive switching devices, such as voltage sensitive diodes, so that selectively energizing a particular desired tuner by applying a supply voltage thereto will automatically effect the appropriate interconnections between the tuning units to render the selected tuner operatively effective and the non-selected tuners non-interfering therewith.

Abstract: A receiver tuning circuit in which without operation of extra switches a change-over can be made from tuning by means of a continuously varying tuning voltage to tuning by means of one of a number of adjusted tuning voltages by using a capacitor controlled by an automatic tuning correction current source circuit for obtaining said voltage, and an automatic switch for applying the desired tuning voltages to this capacitor.

Abstract: A tuning apparatus using a voltage-dependent reactance element comprising a tuning circuit including a voltage-dependent reactance element as a tuning element, a voltage sweep circuit for generating a sweep tuning voltage to be applied to the voltage-dependent reactance element, an operational circuit for converting the tuning voltage to a reference voltage which linearly varies in proportion with a tuning frequency and a voltage comparator circuit for comparing an output of the operational circuit with a predetermined standard voltage, an output of the voltage comparator circuit being used to control the sweep of the voltage sweep circuit to produce a predetermined tuning frequency.

Abstract: An automatic oscillator frequency control is provided for operations such as employed in channel selection in radio and television receiver systems. A code is stored representative of a selected frequency band within which a selected channel is located. The frequency of an oscillator is varied monotonically from a reference frequency at one extremity of a selected frequency range successively to traverse a plurality of such frequency bands. A frequency marker is generated at the margin of each band and the markers are counted. The number of counted markers is compared with the stored code to generate a control state. In response to the control state, a pattern control causes it to dither between limits of the selected band until a signal is encountered at the selected frequency within the selected band. At that point, the oscillator is locked to the frequency of the received signal.

Abstract: A tuning device has a dial drum rotatably supported in a frame, and a rheostat operatively connected to the dial drum. A knob is disposed in alignment with the dial drum. The dial drum has an outer toothing formed on the periphery thereof. A drive gear is secured to the knob, and a reduction gear train is disposed between the drive gear and the outer toothing for transmitting the rotation of the drive gear to the dial drum.