US4567363A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Switched capacitor transresistance amplifier
Assignee: Raytheon Co
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Filing: 1983-06-20
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Granted: 1986-01-28
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Expires: 2003-06-20
Abstract
Abstract A transresistance amplifier particularly adapted for use in a radiation detection system. The amplifier includes a feedback gain stage with a switched capacitor load. The amplifier is arranged to provide an average detector voltage approximating zero thus substantially reducing detector noise and also providing a low equivalent input impedance for increasing injection efficiency. A switched capacitor output load is also provided which allows the total transresistance to be determined by simply selecting an appropriate capacitance value.
Inventors
- 👤 Mark A. Goodnough
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:43
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/04; H03F3/08; H03F3/082; H03F3/005
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
280 words
A transresistance amplifier for measuring the amount of current flowing to a photovoltaic detector such that the average voltage across said detector is maintained at a value to minimize the electrical noise associated with said detector comprising: a first MOSFET amplifier having a gate electrode and drain and source terminals; a first MOSFET switch coupled to the drain terminal of said first MOSFET amplifier; a first capacitor coupled to the drain terminal of said first amplifier, a switching signal of frequency f s being coupled to said first switch for enabling a first source of voltage to be connected to said first capacitor for a first portion of said switching signal frequency cycle, the voltage across said first capacitor during the remaining portion of said cycle representing the current flowing to said detector through said first amplifier; a second MOSFET amplifier having a gate electrode and drain and source terminals, the drain terminal of said second amplifier being connected to the gate electrode of said first amplifier, the gate electrode of said second amplifier being connected to said detector; a second MOSFET switch coupled to the drain terminal of said second amplifier; and a second capacitor coupled to the output of said second amplifier, said switching signal being coupled to said second switch means for enabling a second source of voltage to be connected to said second capacitor for said first portion of said switching signal frequency cycle, the current flowing through said first amplifier being controlled in a manner such that the average current over a cycle of said switching frequency is of a value to maintain the average value of said detector voltage at said noise minimization value.
Claim 2
Dependent Claim
280 words
A transresistance amplifier for measuring the amount of current flowing to a photovoltaic detector such that the average voltage across said detector is maintained at a value to minimize the electrical noise associated with said detector comprising: a first MOSFET amplifier having a gate electrode and drain and source terminals; a first MOSFET switch coupled to the drain terminal of said first MOSFET amplifier; a first capacitor coupled to the drain terminal of said first amplifier, a switching signal of frequency f s being coupled to said first switch for enabling a first source of voltage to be connected to said first capacitor for a first portion of said switching signal frequency cycle, the voltage across said first capacitor during the remaining portion of said cycle representing the current flowing to said detector through said first amplifier; a second MOSFET amplifier having a gate electrode and drain and source terminals, the drain terminal of said second amplifier being connected to the gate electrode of said first amplifier, the gate electrode of said second amplifier being connected to said detector; a second MOSFET switch coupled to the drain terminal of said second amplifier; and a second capacitor coupled to the output of said second amplifier, said switching signal being coupled to said second switch means for enabling a second source of voltage to be connected to said second capacitor for said first portion of said switching signal frequency cycle, the current flowing through said first amplifier being controlled in a manner such that the average current over a cycle of said switching frequency is of a value to maintain the average value of said detector voltage at said noise minimization value.
Claim 3
Dependent Claim
19 words
The transresistance amplifier of claim 1 wherein said transresistance amplifier is maintained at a temperature of approximately 77° K.
Claim 4
Dependent Claim
40 words
The transresistance amplifier of claim 1 wherein said first and second MOSFET amplifiers are operated above their threshold values during said first portion of said switching cycle and in the sub-threshold region during the remaining portion of said switching cycle.
Claim 5
Dependent Claim
43 words
The transresistance amplifier of claim 1 further including a capacitor and switch arrangement for sampling and storing the voltage across said first capacitor at a time when said sampled voltage represents the current generated by said detector in response to radiation incident thereon.
Claim 6
Dependent Claim
27 words
The transresistance amplifier of claim 1 wherein said second switch, said second capacitor and switching signal in combination function as a resistive load for said second amplifier.
Claim 7
Dependent Claim
30 words
The transresistance amplifier of claim 5 wherein the value of said resistive load is related to the capacitance value of said second capacitor and said switching frequency f s .
Claim 8
Dependent Claim
29 words
The transresistance amplifier of claim 1 wherein the equivalent input impedance of said transresistance amplifier is at least an order of magnitude less than the impedance of said detector.
Claim 9
Dependent Claim
28 words
The transresistance amplifier of claim 1 wherein the total transresistance thereof is related to the capacitance value of said first capacitor and said switching freqency f s .
Claim 10
Dependent Claim
41 words
The transresistance amplifier of claim 1 wherein said current flowing through said first amplifier rises during said first portion of said cycle then rapidly decreases to a value which causes the voltage across said detector to be reduced to approximately zero.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-01-27 | 1989-07-29 | 1990-01-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-01-27 | 1993-07-29 | 1994-01-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-01-27 | 1997-07-29 | 1998-01-28 | $7700.00 | Window Closed / Lapsed |