US3619786A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Solid-state vhf attenuator and tv receiver
Assignee: Texas Instruments Inc
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Filing: 1969-05-28
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Granted: 1971-11-09
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Expires: 1989-05-28
Abstract
Abstract Disclosed are television receivers of the type having voltagecontrolled AC signal attenuators including diodes which are advantageously suitable for use as an automatic gain control in a television receiver, for example, or for attenuating any UHF or high-frequency signals. These novel attenuators, when incorporated in a television receiver, (1) substantially eliminate pole-shifting distortion by permitting the RF and IF amplifiers to be operated at one biaspoint, (2) protect the amplifier from overload by preamplification attenuation of the incoming signals, (3) improve system cross modulation, (4) permit use of field effect transistors, and (5) assure minimum degradation of the amplifier noise figure.
Inventors
- 👤 Donald L Wilcox
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 16:02
CPC Classifications
H; H03; H03G; H03G1/00; H03G1/0005; H03G1/0035; H03G1/0052; H03G1/0058; H03G3/00; H03G3/20; H03G3/30; H03G3/3052; H03G3/3057; H03F; H03F2200/00; H03F2200/63
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
245 words
A television receiver comprising in combination: a. first and second attenuator means, each including a plurality of current controlled variable impedance members having an impedance which decreases from a relatively high value to a relatively low value as the forward current through said members increases from substantially zero; b. balum input means for coupling AC signals to the input of said first attenuator means; c. RF amplifier means coupled to the output of said first attenuator means; d. mixer means coupled to the output of said RF amplifier means and to the output of a local oscillator means for producing selected IF signals, said mixer means having its output coupled to the input of said second attenuator means; e. IF amplifier means coupled to the output of said second attenuator means and having its output coupled to the input of a demodulation and display network for producing AGC signals which are direct functions of the amplitude of said IF signals; and f. AGC amplifier means coupled to the output of said demodulation and display network and having two output circuits respectively coupled to the inputs of said first and second attenuator means; wherein g. said RF and IF amplifiers are operated at a common bias point for eliminating pole-shifting distortion; and wherein h. said first and second attenuator means provide relatively low attenuation when said IF signals are below a predetermined level and progressively increase attenuation as the amplitude of said IF signals progressively increase.
Claim 2
Dependent Claim
245 words
A television receiver comprising in combination: a. first and second attenuator means, each including a plurality of current controlled variable impedance members having an impedance which decreases from a relatively high value to a relatively low value as the forward current through said members increases from substantially zero; b. balum input means for coupling AC signals to the input of said first attenuator means; c. RF amplifier means coupled to the output of said first attenuator means; d. mixer means coupled to the output of said RF amplifier means and to the output of a local oscillator means for producing selected IF signals, said mixer means having its output coupled to the input of said second attenuator means; e. IF amplifier means coupled to the output of said second attenuator means and having its output coupled to the input of a demodulation and display network for producing AGC signals which are direct functions of the amplitude of said IF signals; and f. AGC amplifier means coupled to the output of said demodulation and display network and having two output circuits respectively coupled to the inputs of said first and second attenuator means; wherein g. said RF and IF amplifiers are operated at a common bias point for eliminating pole-shifting distortion; and wherein h. said first and second attenuator means provide relatively low attenuation when said IF signals are below a predetermined level and progressively increase attenuation as the amplitude of said IF signals progressively increase.
Claim 3
Dependent Claim
170 words
The television receiver of claim 1 wherein: a. said current controlled variable impedance members are diodes, and wherein a first diode thereof is coupled between the input and output thereof, and second and third diodes thereof are respectively coupled between the input and output thereof and a biasing network, said biasing network being coupled to the output of said AGC amplifier means; and wherein b. as the bias voltage of said variable biasing network progressively varies in a predetermined manner, the forward current through said first diode progressively decreases and the forward current through said second and third diodes progressivelY increases; and wherein c. for any set of forward current conditions, the attenuation of said AC signals through said first and second attenuator means will be a function of the ratio of the resistance of said first diode to the resistance of said second diode, and of the ratio of the impedance of the output load of said first and second attenuator means to the impedance of said third diode.
Claim 4
Dependent Claim
18 words
a first resistor coupled between the junction of said first and second diodes and a third voltage supply,
Claim 5
Dependent Claim
18 words
a first resistor coupled between the junction of said first and second diodes and a third voltage supply,
Claim 6
Dependent Claim
117 words
bias said second diode to a forward current value that provides minimum impedance when said bias terminal is at one voltage level; wherein h. when the bias voltage at said one terminal varies in a predetermined manner, the forward current through said second diode progressively decreases and the forward current through said first and third diodes progressively increases; and wherein i. for any set of forward current conditions the attenuation of said AC signals through said attenuator means will be a function of the ratio of the resistance of said second diode to the resistance of said first diode and of the ratio of the impedance of said output circuit to the impedance of said third diode.
Claim 7
Dependent Claim
117 words
bias said second diode to a forward current value that provides minimum impedance when said bias terminal is at one voltage level; wherein h. when the bias voltage at said one terminal varies in a predetermined manner, the forward current through said second diode progressively decreases and the forward current through said first and third diodes progressively increases; and wherein i. for any set of forward current conditions the attenuation of said AC signals through said attenuator means will be a function of the ratio of the resistance of said second diode to the resistance of said first diode and of the ratio of the impedance of said output circuit to the impedance of said third diode.
Claim 8
Dependent Claim
19 words
a second resistor coupled between the junction of said second and third diodes and a fourth voltage supply, wherein
Claim 9
Dependent Claim
19 words
a second resistor coupled between the junction of said second and third diodes and a fourth voltage supply, wherein
Claim 10
Dependent Claim
43 words
The television receiver of claim 2 wherein the impedance of said second diode approaches the impedance of said AC signals as the impedance of said first diode becomes relatively large to prevent the reflection of energy from said first and second attenuator means.
Claim 11
Dependent Claim
232 words
The television receiver of claim 1 wherein said first and second attenuator means each include: a. input and output circuits; b. a first diode; c. an input isolation capacitor and an output isolation capacitor for coupling said first diode between said input and output circuits; d. a second diode connected between the junction of said first diode and said input isolation capacitor and a first resistor, said first resistor DC coupling said second diode to a first voltage supply and being AC coupled to ground by a feedthrough capacitor; e. a second resistor coupled between the junction of said first and second diodes and a second voltage supply and being AC coupled to ground by a feedthrough capacitor; f. a third diode connected between the junction of said first diode and said output isolation capacitor and a third voltage supply, said third diode being AC coupled to ground by a feedthrough capacitor; g. a third resistor coupled between the junction of said first and third diodes and a fourth voltage supply, said resistor being DC coupled to ground wherein; h. when said first diode is biased forward and said second and third diodes are biased off, said first and second attenuator means provide minimum attenuation; and wherein i. when said first diode is biased off and said second and third diodes biased forward, said first and second attenuator means provide maximum attenuation.
Claim 12
Dependent Claim
39 words
said first resistor and said first and third diodes are each AC coupled to ground; and wherein d. said first, second and third diodes can be selectively biased by selectively varying said first, second, third and fourth voltage supplies.
Claim 13
Dependent Claim
39 words
said first resistor and said first and third diodes are each AC coupled to ground; and wherein d. said first, second and third diodes can be selectively biased by selectively varying said first, second, third and fourth voltage supplies.
Claim 14
Dependent Claim
134 words
The television receiver of claim 1 wherein said first and second attenuator means each include; a. input and output circuits; b. first, second, and third diodes, each having an impedance which decreases from a maximum to a minimum value as the forward current through said diodes increases from zero; c. said first and second diodes having common terminals connected together to form an input junction; d. said second and third diodes having common terminals connected together to form an output junction; e. first and second AC coupling means respectively coupling said first and third diodes to ground; f. first and second DC isolation means respectively coupling said input and output junctions to said input and output circuits; and g. a biasing network including at least one variable bias voltage terminal connected so as to
Claim 15
Dependent Claim
16 words
The television receiver of claim 5 wherein said first, second and third diodes are PIN diodes.
Claim 16
Dependent Claim
39 words
The television receiver of claim 5 wherein: a. said first and second AC coupling means each include a feedthroUgh capacitor; b. said first and second DC isolation means each include a coupling capacitor; and c. said biasing network includes;
Claim 17
Dependent Claim
25 words
The television receiver of claim 5 wherein variation of said second voltage supply proportionately varies the attenuation characteristics of said first and second attenuator means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-08 | 1975-05-10 | 1975-11-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-08 | 1979-05-10 | 1979-11-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-08 | 1983-05-10 | 1983-11-09 | $7700.00 | Window Closed / Lapsed |