Patent US3739197A successfully refreshed from Google Patents.
US3739197A
Expired / Lapsed
US
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Track and hold buffer amplifier
Assignee: Singer Co
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Filing: 1971-11-08
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Granted: 1973-06-12
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Expires: 1991-11-08
Abstract
Abstract An improved track and hold buffer amplifier is provided which is capable of tracking wide band video analog input signals, and which responds to an appropriate binary command to isolate itself from the analog input and effectively to hold the last received value of the analog input. The circuit to be described comprises a single wide band amplifier which provides the function of the two amplifiers required in the prior art closed loop system, and yet which has the stability of the prior art open loop type of system. A unique switching system is also provided which is nonfloating, and which serves to switch the amplifier from its tracking mode into its isolation mode. The stray capacitance directly within the loop of the track and hold amplifier of the system provides the memory during the isolation hold mode, and this capacitance is used advantageously as the dominant 6 db/octave roll-off for the system.
Inventors
- 👤 R Prill
- 👤 M Metzger
- 👤 B Eaton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 20:17
CPC Classifications
G; G11; G11C; G11C27/00; G11C27/02; G11C27/024; G11C27/026
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
184 words
A track and hold buffer amplifier system including: input circuit means for receiving a video analog input signal; a differential amplifier including first and second transistors and having a first input connected to said input circuit means; a cascode amplifier including a third transistor and said second transistor of said differential amplifier; a follower circuit including a device exhibiting a high input impedance and low output impedance and having an input connected to the output of said cascode amplifier and having an output connected to a second input of said differential amplifier, said follower circuit providing a control signal for said differential amplifier to maintain the output thereof at a predetermined level with respect to the amplitude of said analog input; an output circuit connected to said output of said follower circuit; and a switching circuit connected to said transistors and responsive to a hold command for back-biasing said transistors so as to isolate said device from said analog input so that the charge across the input capacitance of said device represents the last value of the analog input prior to said hold command.
Claim 2
Dependent Claim
184 words
A track and hold buffer amplifier system including: input circuit means for receiving a video analog input signal; a differential amplifier including first and second transistors and having a first input connected to said input circuit means; a cascode amplifier including a third transistor and said second transistor of said differential amplifier; a follower circuit including a device exhibiting a high input impedance and low output impedance and having an input connected to the output of said cascode amplifier and having an output connected to a second input of said differential amplifier, said follower circuit providing a control signal for said differential amplifier to maintain the output thereof at a predetermined level with respect to the amplitude of said analog input; an output circuit connected to said output of said follower circuit; and a switching circuit connected to said transistors and responsive to a hold command for back-biasing said transistors so as to isolate said device from said analog input so that the charge across the input capacitance of said device represents the last value of the analog input prior to said hold command.
Claim 3
Dependent Claim
20 words
The amplifier system defined in claim 1, in which the device in said follower circuit comprises a field effect transistor.
Claim 4
Dependent Claim
59 words
The system defined in claim 1, in which the cascode amplifier of said second and third transistors exhibits an extremely wide bandwidth combination, and in which the collector voltage of said second transistor is clamped to nearly a constant voltage by the base-emitter junction of said third transistor so that Miller capacity of said second transistor is virtually eliminated.
Claim 5
Dependent Claim
28 words
The system defined in claim 3, in which said third transistor in said cascode amplifier is connected as a common base stage with respect to the collector thereof.
Claim 6
Dependent Claim
44 words
The system defined in claim 1, in which said cascode amplifier is connected to said follower circuit so that the collector capacitance of said third transistor cooperates with the input capacitance of said device to provide the dominant roll-off of the buffer amplifier system.
Claim 7
Dependent Claim
40 words
The system defined in claim 1, in which said switching circuit includes individual electronic switches respectively connected to the emitters of the aforesaid transistors effectively to produce a back-bias on said transistors upon the receipt of the aforesaid hold command.
Claim 8
Dependent Claim
26 words
The system defined in claim 6, in which each of said electronic switches is formed of a pair of transistors connected together as a differential amplifier.
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) | 1976-06-11 | 1976-12-11 | 1977-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-11 | 1980-12-11 | 1981-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-11 | 1984-12-11 | 1985-06-12 | $7700.00 | Window Closed / Lapsed |