US4673889A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus and method for muting an output signal in a switching amplifier
Assignee: STMicroelectronics SRL
•
Filing: 1985-12-16
•
Granted: 1987-06-16
•
Expires: 2005-12-16
Abstract
Abstract In an audio switching power amplifier, muting apparatus provided for eliminating noise signals associated with turn-on and turn-off operations of the apparatus is disclosed. The muting apparatus disables the output power amplifiers and controls signal levels at various positions in the power amplifier to reduce transient conditions. Control apparatus applies the muting signals to the power amplifier during a predetermined period during start-up of the amplifier and applies the muting conditions immediately upon the turning off of power to the power amplifier.
Inventors
- 👤 Carlo Cini
- 👤 Claudio Diazzi
- 👤 Pietro Erratico
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:25
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/20; H03F3/21; H03F3/217; H03F1/00; H03F1/30; H03F1/305; H03F3/30; H03F3/3001; H03F3/3044
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
70 words
In a power switching amplifier in which an integrating circuit, responding to an input audio signal and signals from output power amplifiers, controls a pulse width of output signals activating a speaker system, apparatus for controlling noise signals resulting from transient conditions comprising: switching apparatus for maintaining said output power amplifiers in a non-conducting state; and transistor apparatus for controlling a signal at an output terminal of said integrating circuit.
Claim 2
Dependent Claim
70 words
In a power switching amplifier in which an integrating circuit, responding to an input audio signal and signals from output power amplifiers, controls a pulse width of output signals activating a speaker system, apparatus for controlling noise signals resulting from transient conditions comprising: switching apparatus for maintaining said output power amplifiers in a non-conducting state; and transistor apparatus for controlling a signal at an output terminal of said integrating circuit.
Claim 3
Dependent Claim
31 words
The noise control apparatus of claim 1 wherein said switching apparatus and said transistor apparatus are activated for a predetermined period of time when said power switching amplifier is turned on.
Claim 4
Dependent Claim
25 words
The noise controlling apparatus of claim 2 wherein said noise control apparatus is activated upon removal of a supply voltage from said power switching amplifier.
Claim 5
Independent Claim
57 words
The method of preventing noise signals in a power switching amplifier during transient supply voltage conditions in a switching power amplifier comprising the steps of: switching off output transistors of said power switching amplifier; and establishing a predetermined voltage level at an output of an amplifier circuit controlling a pulse width of signals activating said output transistors.
Claim 6
Independent Claim
57 words
The method of preventing noise signals in a power switching amplifier during transient supply voltage conditions in a switching power amplifier comprising the steps of: switching off output transistors of said power switching amplifier; and establishing a predetermined voltage level at an output of an amplifier circuit controlling a pulse width of signals activating said output transistors.
Claim 7
Dependent Claim
18 words
The method of preventing noise signals of claim 4 further including the step of disabling said amplifier circuit.
Claim 8
Dependent Claim
53 words
The method of preventing noise signals of claim 4 further including the steps of: activating said switching off and said establishing steps immediately after application of supply voltage to said switching power amplifier; and, disabling said switching off and said establishing steps a predetermined period of time after said application of supply voltage.
Claim 9
Dependent Claim
127 words
An audio power switching amplifier for driving a speaker circuit comprising: a plurality of power transistors; driving circuit means coupled to said plurality of power transistors for applying current in alternative directions through said speaker circuit; a Schmitt trigger circuit for activating said driving circuit means; differential amplifier means coupled to said power transistors and to an input audio signal for controlling output signals of said Schmitt trigger circuit, said Schmitt trigger output signals controlling current applied to said speaker circuit; and mute control apparatus means for applying a first signal to said driving circuit means, said first signal causing said power transistors to be in a non-conducting state, said mute control apparatus means applying a second signal to an output terminal of said differential amplifier means.
Claim 10
Dependent Claim
127 words
An audio power switching amplifier for driving a speaker circuit comprising: a plurality of power transistors; driving circuit means coupled to said plurality of power transistors for applying current in alternative directions through said speaker circuit; a Schmitt trigger circuit for activating said driving circuit means; differential amplifier means coupled to said power transistors and to an input audio signal for controlling output signals of said Schmitt trigger circuit, said Schmitt trigger output signals controlling current applied to said speaker circuit; and mute control apparatus means for applying a first signal to said driving circuit means, said first signal causing said power transistors to be in a non-conducting state, said mute control apparatus means applying a second signal to an output terminal of said differential amplifier means.
Claim 11
Dependent Claim
32 words
The audio power switching amplifier of claim 7 wherein said first and said second signals are applied for a predetermined time after application of a supply voltage to said driving circuit means.
Claim 12
Dependent Claim
26 words
The audio power switching amplifier of claim 7 wherein said first and said second signals are applied after removal of power from said driving circuit means.
References Cited (Backward Citations)
US3889202A
Cited
US3976955A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-06-15 | 1990-12-15 | 1991-06-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-15 | 1994-12-15 | 1995-06-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-15 | 1998-12-15 | 1999-06-16 | $7700.00 | Window Closed / Lapsed |