Patent US3813602A successfully refreshed from Google Patents.
US3813602A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Input circuit for a television tuner
Assignee: US Philips Corp
•
Filing: 1971-06-02
•
Granted: 1974-05-28
•
Expires: 1991-06-02
Abstract
Abstract A television tuner having an AGC controlled PIN-diode attenuator between the aerial terminals and the first transistor. The attenuator is formed in such a manner that its output impedance in case of continuing control deviates to an increasing extent from the transistor input impedance so that a considerable improvement of the signal-to-noise ratio is obtained.
Inventors
- 👤 Dijum A Van
- 👤 T Uittenbogaard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 07:17
CPC Classifications
F; F23; F23C; F23C99/00; H; H03; H03G; H03G1/00; H03G1/0005; H03G1/0035; H03G1/0052; H03G1/0058; H03G3/00; H03G3/20; H03G3/30; H03G3/3052; H03G3/3057; H03H; H03H2/00; H03H2/005; H03H2/008; F23C2700/00; F23C2700/04; F23C2700/043
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
177 words
An attenuator for a common base transistor amplifier circuit having a given input impedance, said attenuator comprising an input means for receiving an input signal, a shunt controllable impedance element coupled in parallel with said input means, an output means for applying a signal to said circuit, a series controllable impedance element coupled between said input and output means, and means for controlling the attenuation of said attenuator both for changing the transfer impedance function thereof and by causing the output impedance thereof to rise and become increasingly mismatched with respect to said circuit input impedance as the amplitude of the input signal increases, said controlling means comprising means coupled to said elements for applying a direct current that is a function of said input signal thereto, whereby the impedance of said elements changes, and wherein said attenuator has an optimum output impedance at which the noise figure of said circuit is a minimum, said output impedance being slightly lower than said optimum impedance at small input signal levels and is greater at large input signal levels.
Claim 2
Dependent Claim
177 words
An attenuator for a common base transistor amplifier circuit having a given input impedance, said attenuator comprising an input means for receiving an input signal, a shunt controllable impedance element coupled in parallel with said input means, an output means for applying a signal to said circuit, a series controllable impedance element coupled between said input and output means, and means for controlling the attenuation of said attenuator both for changing the transfer impedance function thereof and by causing the output impedance thereof to rise and become increasingly mismatched with respect to said circuit input impedance as the amplitude of the input signal increases, said controlling means comprising means coupled to said elements for applying a direct current that is a function of said input signal thereto, whereby the impedance of said elements changes, and wherein said attenuator has an optimum output impedance at which the noise figure of said circuit is a minimum, said output impedance being slightly lower than said optimum impedance at small input signal levels and is greater at large input signal levels.
Claim 3
Dependent Claim
16 words
An attenuator as claimed in claim 1 wherein said attenuation elements each comprise a PIN diode.
Claim 4
Dependent Claim
30 words
An attenuator as claimed in claim 1 wherein the direct current in said series element decreases and the direct current in said shunt element increases as said input signal increases.
Claim 5
Dependent Claim
134 words
An attenuator for a common base transistor amplifier circuit having a given input impedance, said attenuator comprising an input means for receiving an input signal, a shunt controllable impedanCe element coupled in parallel with said input means, an output means for applying a signal to said circuit, a series controllable impedance element coupled between said input and output means, and means for controlling the attenuation of said attenuator both for changing the transfer impedance function thereof and by causing the output impedance thereof to rise and become increasingly mismatched with respect to said circuit input impedance as the amplitude of the input signal increases, said controlling means comprising means coupled to said base for applying a direct current that is a function of said input signal thereto, whereby the impedance of said elements changes.
Claim 6
Dependent Claim
134 words
An attenuator for a common base transistor amplifier circuit having a given input impedance, said attenuator comprising an input means for receiving an input signal, a shunt controllable impedanCe element coupled in parallel with said input means, an output means for applying a signal to said circuit, a series controllable impedance element coupled between said input and output means, and means for controlling the attenuation of said attenuator both for changing the transfer impedance function thereof and by causing the output impedance thereof to rise and become increasingly mismatched with respect to said circuit input impedance as the amplitude of the input signal increases, said controlling means comprising means coupled to said base for applying a direct current that is a function of said input signal thereto, whereby the impedance of said elements changes.
Claim 7
Dependent Claim
49 words
An attenuator as claimed in claim 4 wherein said attenuator has an optimum output impedance at which the noise figure of said circuit is a minimum, said output impedance is slightly lower than said optimum impedance at small input signal levels and is greater at large input signal levels.
Claim 8
Dependent Claim
16 words
An attenuator as claimed in claim 4 wherein said attenuation elements each comprise a PIN diode.
Claim 9
Dependent Claim
30 words
An attenuator as claimed in claim 4 wherein the direct current in said series element decreases and the direct current in said shunt element increases as said input signal increases.
References Cited (Backward Citations)
US3012138A
Cited
US3121198A
Cited
US3153189A
Cited
US3243719A
Cited
US3325754A
Cited
US3518585A
Cited
US3581210A
Cited
US3613008A
Cited
US3588894A
Cited
US3624561A
Cited
US3631333A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-05-27 | 1977-11-26 | 1978-05-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-27 | 1981-11-26 | 1982-05-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-27 | 1985-11-26 | 1986-05-28 | $7700.00 | Window Closed / Lapsed |