US3595998A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polarity independent preamplifier for sound transmitters
Assignee: AKG Acoustics GmbH
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Filing: 1969-07-01
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Granted: 1971-07-27
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Expires: 1989-07-01
Abstract
Abstract A preamplifier for sound transmitters includes at least one field effect transistor having a gate electrode and first and second output electrodes. An output circuit is connected across the output electrodes, a first output electrode resistor is connected between a feed voltage input terminal and the first output electrode and a second output electrode resistor is connected between a reference potential terminal and the second output electrode. The output electrode resistors have substantially the same resistance. A polarity dependent biasing circuit is connected between the feed voltage input terminal and the gate electrode, and maintains, at the gate, substantially a predetermined negative bias potential relative to the potential at the first output electrode if a potential which is negative by a predetermined amount relative to the potential at the reference potential terminal is applied to the feed voltage input terminal, and relative to the potential at the second output electrode if a potential which is positive by the predetermined amount relative to the potential at the reference potential terminal is applied to the feed voltage input terminal.
Inventors
- 👤 Werner Fidi
- 👤 Bernhard Weingartner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:23
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/181; H03F3/183; H03F3/185
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
211 words
In combination with a sound transmitter, a preamplifier circuit arrangement comprising at least one field effect transistor having first and second output electrodes and a gate electrode; means providing a low impedance path connecting said gate electrode said sound transmitter; a feed voltage input terminal; a reference potential terminal; an output circuit connected across said first and second output electrodes; a first output electrode resistor connected between said feed voltage input terminal and said first output electrode; a second output electrode resistor connected between said reference potential terminal and said second output electrode; said first and second output electrode resistors having substantially the same resistance; and a polarity dependent biasing circuit connected between said feed voltage input terminal and said gate electrode, said polarity dependent biasing circuit maintaining, at said gate electrode, substantially a predetermined negative bias potential, relative to the potential at said first output electrode if a potential which is negative by a predetermined amount relative to the potential at said reference potenTial terminal is applied to said feed voltage input terminal, or relative to the potential at said second output electrode if a potential which is positive by said predetermined amount relative to the potential at said reference potential terminal is applied to said feed voltage input terminal.
Claim 2
Dependent Claim
211 words
In combination with a sound transmitter, a preamplifier circuit arrangement comprising at least one field effect transistor having first and second output electrodes and a gate electrode; means providing a low impedance path connecting said gate electrode said sound transmitter; a feed voltage input terminal; a reference potential terminal; an output circuit connected across said first and second output electrodes; a first output electrode resistor connected between said feed voltage input terminal and said first output electrode; a second output electrode resistor connected between said reference potential terminal and said second output electrode; said first and second output electrode resistors having substantially the same resistance; and a polarity dependent biasing circuit connected between said feed voltage input terminal and said gate electrode, said polarity dependent biasing circuit maintaining, at said gate electrode, substantially a predetermined negative bias potential, relative to the potential at said first output electrode if a potential which is negative by a predetermined amount relative to the potential at said reference potenTial terminal is applied to said feed voltage input terminal, or relative to the potential at said second output electrode if a potential which is positive by said predetermined amount relative to the potential at said reference potential terminal is applied to said feed voltage input terminal.
Claim 3
Dependent Claim
15 words
The combination claimed in claim 1, in which said sound transmitter is a condenser microphone.
Claim 4
Dependent Claim
40 words
An apparatus as claimed in claim 1, in which said biasing circuit comprises a polarity dependent voltage divider arranged to divide a direct current voltage, applied thereacross, in different ratios in dependence on the polarity of said direct current voltage.
Claim 5
Dependent Claim
18 words
An apparatus as claimed in claim 3, in which said voltage divider comprises three resistors and a diode.
Claim 6
Dependent Claim
72 words
An apparatus as claimed in claim 1, in which said biasing circuit comprises an auxiliary voltage source; a first deriving circuit deriving first direct current voltage from said auxiliary voltage source; a second deriving circuit deriving a second circuit current voltage from the potential applied to said feed voltage input terminal; and a combining circuit superimposing said first and second direct current voltages and applying the resulting voltage to said gate electrode.
Claim 7
Dependent Claim
16 words
An apparatus as claimed in claim 5, in which said auxiliary voltage source is a battery.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-07-26 | 1975-01-25 | 1975-07-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-07-26 | 1979-01-25 | 1979-07-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-07-26 | 1983-01-25 | 1983-07-27 | $7700.00 | Window Closed / Lapsed |