US3908172A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit arrangement for influencing frequency response by electronic means, in particular electronic tone control circuit
Assignee: US Philips Corp
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Filing: 1973-11-29
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Granted: 1975-09-23
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Expires: 1993-11-29
Abstract
Abstract The invention describes an electronic tone control circuit in which the tone can be influenced by means of a direct voltage. The tone control circuit includes two cross-connected differential amplifiers which each have a transistor connected in the emitter lead. The output signal is amplified by means of an operational amplifier. The input signal is applied via impedances to the bases of the transistors connected in the emitter leads which in turn are connected via impedances to the output of the operational amplifier. Depending upon the configuration of the impedance network the application of a direct voltage enables the higher frequencies and/or the lower frequencies to be boosted or attenuated.
Inventors
- 👤 Wilfried Aschermann
- 👤 Paul Bockelmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 20:48
CPC Classifications
H; H03; H03G; H03G5/00; H03G5/02; H03G5/04; H03G5/10; H03G1/00; H03G1/0005; H03G1/0017; H03G1/0023
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
121 words
A circuit arrangement comprising first and second amplifiers, each of said amplifiers having an input and an output; a common output terminal cOupled to said amplifier outputs; first and second input impedance networks having different transfer functions, each having an input means for receiving a single input signal and an output coupled to said amplifier inputs respectively; first and second feedback impedance networks for providing negative feedback around said amplifiers respectively, said networks comprising impedance means having different transfer functions, each having an input coupled to said common output terminal an an output coupled to said amplifier inputs respectively; and means coupled to said amplifiers for varying the gain of said amplifiers in opposite senses in accordance with a control signal.
Claim 2
Dependent Claim
121 words
A circuit arrangement comprising first and second amplifiers, each of said amplifiers having an input and an output; a common output terminal cOupled to said amplifier outputs; first and second input impedance networks having different transfer functions, each having an input means for receiving a single input signal and an output coupled to said amplifier inputs respectively; first and second feedback impedance networks for providing negative feedback around said amplifiers respectively, said networks comprising impedance means having different transfer functions, each having an input coupled to said common output terminal an an output coupled to said amplifier inputs respectively; and means coupled to said amplifiers for varying the gain of said amplifiers in opposite senses in accordance with a control signal.
Claim 3
Dependent Claim
81 words
Circuit arrangement as claimed in claim 1, wherein the two amplifiers each include a transistor differential-amplifier stage, the collectors and bases of said transistors being cross-coupled between a transistor of one stage to a transistor of another stage, like electrodes being coupled together, the control voltage being applied between said bases, two transistors which are each coupled to one of the emitter leads of said differential amplifier stage transistors and the bases of which comprises said inputs of the amplifiers respectively.
Claim 4
Dependent Claim
44 words
Circuit arrangement as claimed in claim 2, further comprising a high-gain amplifier which does not shift the phase of the signal having an input coupled to the collector of two of said differential amplifier transistors and an output which comprises the common output terminal.
Claim 5
Dependent Claim
98 words
Circuit arrangement as claimed in claim 1, wherein said first input network comprises a first impedance means for receiving the input signal and coupled to the input of said first amplifier, said second input network and said feedback means comprise a second impedance means coupled to the inputs of said first and second amplifiers, and a third impedance means coupled to the input of said second amplifier and to the common output terminal, the values of the impedance means providing that the gains of the two amplifiers depend upon the frequency of the input signal in opposite senses.
Claim 6
Dependent Claim
31 words
Circuit arrangement as claimed in claim 4, said second impedance means comprises a capacitor and said first and third impedance means each comprise a resistor, whereby the low frequencies are influenced.
Claim 7
Dependent Claim
31 words
Circuit arrangement as claimed in claim 4, said second impedance means comprises a resistor and the first and third impedance means each comprise a capacitor, whereby the high frequencies are influenced.
Claim 8
Dependent Claim
33 words
Circuit arrangement as claimed in claim 1, the values of the impedance means providing that the gains of the two amplifiers vary in opposite senses with increasing frequency and with decreasing frequency respectively.
Claim 9
Dependent Claim
98 words
Circuit arrangement as claimed in claim 7 further comprising means for influencing the lower frequencies, said networks including a first parallel combination of a first resistor and of a first capacitor coupled between the input means and the input of said first differential amplifier, a second capacitor coupled between said first amplifier input and said common output terminal, a third capacitor coupled between the input means and the input of said second differential amplifier, and a second parallel combination of a second resistor and a fourth capacitor coupled between said common output terminal and said other amplifier input.
Claim 10
Dependent Claim
97 words
Circuit arrangement as claimed in claim 7 further comprising means for influencing the higher frequencies, said networks including a first parallel combination of a first capacitor and a first resistor coupled between the input means and the input of said first differential amplifier, a second resistor coupled between said first amplifier input and said common output terminal, a third resistor coupled between the input means and the input of said second differential amplifier, and a second parallel combination of a second capacitor and a fourth resistor coupled between said common output terminal and said second amplifier inPut.
Claim 11
Dependent Claim
65 words
Circuit arrangement as claimed in claim 1, further comprising means for controlling the higher and lower frequencies, said networks including three resistors, two coupled between the input means and each of the inputs of the two amplifiers respectively, the third coupled between the common output terminal and first amplifier input, and a band filter coupled between the common output terminal and the second amplifier input.
Claim 12
Dependent Claim
29 words
Circuit arrangement as claimed in claim 10, wherein said filter is a bandpass filter which attenuates the higher and lower frequencies of said input signal relative to the midfrequencies.
Claim 13
Dependent Claim
46 words
Circuit arrangement as claimed in claim 11, further comprising means for providing an acoustically and physiologically correct volume control, wherein the control voltage applied to the differentialamplifier stages so depends upon the volume control that with decreasing volume the gain of the other amplifier is increased.
Claim 14
Dependent Claim
42 words
Circuit arrangement as claimed in claim 10 further comprising means for boosting the frequencies which are significant for speech intelligibility, said filter is a band-elimination filter the maximum attenuation of which lies in the range of the frequencies significant for speech intelligibility.
Claim 15
Dependent Claim
60 words
Circuit arrangement as claimed in claim 1, further comprising means for controlling the higher and lower frequencies, said means comprising a bandpass filter coupled between the common output terminal and one amplifier input and a band-elimination filter coupled between the common output terminal and the other amplifier input, and a resistor coupled between the two inputs and the input means.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-22 | 1979-03-24 | 1979-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-22 | 1983-03-24 | 1983-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-22 | 1987-03-24 | 1987-09-23 | $7700.00 | Window Closed / Lapsed |