Abstract: A signal-seeking tuning system for a television receiver scans the VHF and UHF signal bands until a present TV channel signal is detected. Tuning voltage is developed by a digital-to-analog converter in response to a binary word stored in an up-down counter. The value of the binary word increases when a scan-up signal is applied and decreases when a scan-down signal is applied. Scanning is stopped by inhibiting changing of the binary word when a valid sequence of AFT signals is detected.Thereafter, the tuning voltage is compensated for drifts by incrementing or decrementing the binary word whenever the AFT signal departs from a predetermined condition. This correction is inhibited, however, when the RF carrier signal is lost so that the desired tuning is not also lost, whereby the selected channel is still tuned when the RF carrier signal reappears.

Abstract: First and second transistors of first and second types that can exhibit respective first and second potentials of first and second opposite polarities between their respective input and common electrodes when respective currents flow in conduction paths between their respective output and common electrodes. The transistors are connected in cascade with the input electrode of the first transistor connected to an input point, the common electrode of the first transistor connected to the input electrode of the second, and the conduction path of the second transistor coupled to a load. A circuit for operating the first transistor at the first potential to compensate, at least in part, for the second potential comprises a third transistor of the first type to which is applied a potential of the first polarity between its input and common electrodes to establish a current in its conduction path.

Abstract: A television tuning system includes UHF and VHF signal paths each tuned by a tuning voltage and coupled to a common signal path by a diplexer. So that UHF signals will be attenuated so to not cause interference with a VHF channel signal which is selected to be viewed, the UHF filter is detuned when a VHF channel is selected. Detuning the UHF filter is accomplished by modifying the tuning voltage for the UHF filter responsive to the VHF band-switching voltage.

Abstract: A television tuning system includes UHF and VHF signal paths each tuned by a tuning voltage and coupled to a common signal path by a diplexer. So that UHF signals will be attenuated so to not cause interferences with a VHF channel signal which is selected to be viewed, the UHF filter is detuned when a VHF channel is selected. Detuning the UHF filter is accomplished by modifying the tuning voltage for the UHF filter responsive to the VHF band-switching voltage.

Abstract: A digital filter arrangement is provided which both demodulates and filters the color mixture signals in a television receiver. Samples of a digital chrominance signal are clocked into first and second registers such that the first register is loaded with samples of a first color mixture signal and the second register contains samples of a second color mixture signal. Output taps are connected between various ones of the stages of the first and second registers and weighting function circuits. The weighting function circuits associated with each register are in turn coupled to respective ladder networks of adders, which combine the weighted signals samples so as to exhibit, at an output stage adder, a lowpass response characteristic which is appropriate for the respective color mixture signal. The two digital registers are aligned in time in accordance with their respective peak impulse response characteristic to product filtered color mixture signals in a proper timed relationship.

Abstract: An amplifying circuit comprises a differential amplifier receiving input signals and having first and second output connections to which the input and output connections of a current amplifier respectively connect. A transistor receives signals at its gate from the second output connection of the differential amplifier and has a capacitor connected between its input and output electrodes. A feed-forward circuit, responsive to signals at the first output connection of the differential amplifier, develops a feed-forward signal which is applied to the output electrode of the transistor and poled so as to reinforce the signals thereat. The feed-forward signals tend to cancel signals conducted through the capacitor at high frequencies where the transistor exhibits reduced gain.

Abstract: In television (TV) receivers, the VHF-TV band including channel 2-13 is perceived by most viewers as being a single TV band even though it is in fact partitioned into lower and upper frequency portions, including channels 2-6 and 7-13, respectively, which are separated by a gap. Voltage controlled tuning systems for such TV receivers employ a tuning voltage which varies over substantially the same range of magnitudes from a lower voltage to a higher voltage for each of the frequency portions of the VHF band. Accordingly, conventional channel indicators responsive to the magnitude of the tuning voltage partition the bands to avoid ambiguity in the channel indication. In the present arrangement, a tuning indicator produces an on-screen bar display having a position which is indicative of the selected channel for all VHF channels as if the VHF frequency band was continuous and not partitioned thereby being consistent with the perception of most viewers.

Abstract: A multiband tuning system produces an IF signal from RF signals residing in, in the order named, a first broadcast band, a first cable band, a second broadcast band and a second cable band. A control device generates a tuning signal having a magnitude determined by the frequency of a selected channel. A first filter selects RF signals corresponding to channels selected in a first tuning band including the first broadcast band and a lower frequency portion of the first cable band in response to the tuning signal. A second filter selects RF signals corresponding to channels selected in a second tuning band including an upper frequency portion of the first cable band, the second broadcast and the second cable bands in response to the tuning signal. A selection device enables operation of the first filter when the selected channel is within the first tuning band and enables operation of the second filter when the selected channel is in the second tuning band.

Abstract: In a signal converting apparatus such as one including demodulation and remodulation apparatus for converting RF cable carriers to RF carriers having frequencies corresponding to broadcast frequencies, a character generator is coupled to the tuning selector to generate characters representative of the channel number of the selected cable carrier. The character representative signals are combined with the demodulated base-band signals before remodulation. As a result, the television receiver coupled to the cable converter will produce an on-screen display of the channel number of the selected cable channel. Similar apparatus may be employed to identify a video cassette recorder or video disc player as the source of television signals on the screen of a television receiver.

Abstract: A television (TV) receiver tuning system for selecting one of a plurality of receivable TV channels comprises a frequency selective radio frequency device including trimming elements for receiving TV signals, a local oscillator controlled by a first control signal and a mixer in which the TV signals and the local oscillator signal are heterodyned to develop an intermediate frequency signal. A first control device develops the first control signal in response to the selection of a TV channel to control the local oscillator frequency so that the mixer shifts the selected TV channel signal to the IF frequency. A second control device including a PROM trims the frequency selectivity of the RF device using its trimming elements unaffected by selection of the TV channel whereby mechanical alignment of the TV tuning system can be avoided.

Abstract: A bandgap reference voltage generating circuit develops a predetermined reference potential between first and second terminals. A pair of transistors are operated at different emitter current densities to develop a difference between their base-emitter potentials. That difference is applied across a first resistance and is increased and applied across a second resistance. The reference potential comprises the sum of at least the scaled-up potential and the conduction potential of a semiconductor junction. A regulating transistor completes a degenerative feedback connection and controls the current flowing between the first and second terminals responsive to the reference potential departing from the predetermined value. A regenerative feedback connection responds to the current in the regulating transistor to decrease the potential across the second resistance when the controlled current increases.

Abstract: A signal-seeking tuning system for a television receiver scans the VHF and UHF signal bands until a present TV channel signal is detected. Tuning voltage is developed by a digital-to-analog converter in response to a binary word stored in an up/down counter. The value of the binary word increases when a scan-up signal is applied and decreases when a scan-down signal is applied. Band signals are automatically sequenced to the next higher frequency band when the binary word "rolls-over" from a maximum to a minimum value, or to the next lower frequency band when the binary word rolls-over from its minimum to its maximum value. Scanning is stopped by inhibiting changing of the binary word when a valid sequence of AFT signals is detected.Thereafter, the tuning voltage is compensated for drifts by incrementing or decrementing the binary word whenever the AFT signal departs from a predetermined condition.

Abstract: A diplexer comprises a first frequency selective filter coupled between its first input terminal and a circuit point, a second frequency selective filter coupled between the circuit point and its output terminal, and third frequency selective filter coupled between its second input terminal and the circuit point. The first filter selects frequencies higher than a first frequency and the second filter selects frequencies lower than a second frequency which is higher than the first frequency. The third filter selects frequencies lower than a third frequency which is lower than the first frequency. In a television receiver, the first and second filters serve as a bandpass filter for the UHF band, and the third filter passes the VHF and CATV bands.

Abstract: A television (TV) receiver which receives TV signals in a plurality of TV frequency bands includes apparatus for developing an accentuated and uncontaminated on-screen tuning indication. Specifically, a blanking device is responsive to a tuning signal for eliminating the display of a portion of the TV picture for the duration of a pulse signal. The pulse signal is delayed in time relative to a deflection signal by a time related to the tuning signal so that a blanked bar is generated in the TV picture. A tuning indicator device causes a predetermined display unaffected by the TV picture during the blanked portion of the TV picture.

Abstract: A current amplifier comprises four like-conductivity transistors on a substrate of an integrated circuit with a first pair connected in current mirror amplifier configuration. The third and fourth transistors have their respective bases cross-coupled to the other's collector, and their respective collector-emitter paths interposed serially between the respective emitters of the first and third transistors and a common terminal. Adjustable resistances external to the substrate are serially interposed between the emitters of the third and fourth transistors and the common terminal for adjusting the current gain of the current amplifier.

Abstract: In a wired remote control for use with a television receiver, audio signals are coupled to a loudspeaker by a transformer providing electrical isolation. The remote control device comprises an oscillator applying a signal at a frequency above the audio range to the transformer and a rectifier at the transformer secondary converting the oscillator signal to a DC signal. That DC signal is selectively applied by a switch to an optocoupler which couples to a control device for controlling the audio source. A filter blocks the oscillator signal from the speaker. Additionally, the control device controls TV channel selection.

Abstract: In one embodiment of the present invention, photocurrents induced in the collector-base junction of a transistor by ionizing radiation incident thereon are compensated by the photocurrent generated by a plurality of series-connected diodes. One feature of the invention includes the selection of the junction areas of the diodes relative to that of the transistor to obtain a predetermined potential at an electrode of the transistor during the incidence of the ionizing radiation.

Abstract: An operational amplifier employing complementary MOSFET transistors includes first and second differential amplifiers respectively employing complementary conductivity type transistors. The input connections of the first and second differential amplifiers connect in parallel to receive the same input signal, the common-mode voltage of which may vary to and include first and second supply potentials. First and second current mirror amplifiers, respectively employing complementary conductivity type transistors, have input connections to which first and second output connections of the first differential amplifier respectively connect, and have output connections connected to an output terminal. Third and fourth current mirror amplifiers, respectively employing complementary conductivity type transistors, have input connections to which first and second output connections of the second differential amplifier respectively connect, and have output connections connected to the output terminal.

Abstract: In a television receiver having an in-cabinet receiving antenna that has a plurality of electrically controllable states having different radiation reception pattern conditions, an automatic antenna steering apparatus selects one of the controllable patterns. In response to the selection of a channel to be received, the apparatus sequences through each of the plurality of states and determines the relative amplitude of the received signal in each. When the amplitude of received signals in all of the states has been determined, the apparatus selects the state wherein the received signal is of a predetermined amplitude condition. One convenient measure of signal amplitude is an internal AGC signal of the receiver. In one embodiment of the present invention a microcomputer is employed to control the various operations to establish the antenna in the state producing the predetermined amplitude condition.

Abstract: A complementary field-effect transistor amplifier includes first, second, and third FET inverter amplifiers. Input signals are applied to input connections of the first and third inverter amplifiers and the output connections thereof respectively connect to first and second nodes. The first node connects to the input connection of the second inverter amplifier, the output connection of which amplifier connects to the second node where the input signals are combined. A fourth inverter amplifier includes a degenerative feedback connection and has its output connected for providing a load at the first node. Signals responsive to the combination of the first and second input signals can be further amplified by a fifth inverter amplifier and supplied therefrom to an output terminal.