US3553500A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Microsensing network
Assignee: RCA Corp
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Filing: 1968-03-06
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Granted: 1971-01-05
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Expires: 1988-03-06
Abstract
Abstract Disclosed herein is an amplifier circuit arrangement for sensing very small currents (in the microampere region) whose accuracy is unaffected by variations of the input characteristics of the amplifying device. A current generating signal means is directly coupled to the input of the amplifying device, whose input parameters may vary with temperature and from unit-to-unit. A second current generating means, also directly coupled to the amplifying device input, is used to bias the input and to set a current threshold level which the current generating signal means must overcome, before the amplifying device can traverse from one region of operation to another. The use of current generating means with their high impedances renders the current threshold level insensitive to the variations of the amplifying device input.
Inventors
- 👤 Finnis C Easter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:51
CPC Classifications
H; H03; H03K; H03K3/00; H03K3/02; H03K3/26; H03K3/28; H03K3/281; H03K3/286; H03K3/2893
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
182 words
The combination comprising: an amplifying device having an input electrode; a first current generating means direct current coupled to said input electrode and generating a current of a first polarity relative to said input electrode; a second, signal responsive current generating means comprising a photodiode having an anode and a cathode, one of said anode and cathode being directly connected to a point of operating potential for reverse biasing the cathode with respect to the anode and the other one of said anode and cathode being directly connected to said input electrode and generating a current of a second polarity opposite to said first polarity; said first and second current generating means each having an equivalent circuit which reduces to a current generator whose current is substantially independent of variations in load impedance and of variations in sources of applied potential external to the current generating means; and said first current generating means generating a substantially constant threshold current which said second current generating means must overcome to change the direction of current flowing into said input electrode of said amplifying device.
Claim 2
Dependent Claim
182 words
The combination comprising: an amplifying device having an input electrode; a first current generating means direct current coupled to said input electrode and generating a current of a first polarity relative to said input electrode; a second, signal responsive current generating means comprising a photodiode having an anode and a cathode, one of said anode and cathode being directly connected to a point of operating potential for reverse biasing the cathode with respect to the anode and the other one of said anode and cathode being directly connected to said input electrode and generating a current of a second polarity opposite to said first polarity; said first and second current generating means each having an equivalent circuit which reduces to a current generator whose current is substantially independent of variations in load impedance and of variations in sources of applied potential external to the current generating means; and said first current generating means generating a substantially constant threshold current which said second current generating means must overcome to change the direction of current flowing into said input electrode of said amplifying device.
Claim 3
Dependent Claim
104 words
The combination as claimed in claim 1, wherein said amplifying device is a transistor having a base electrode and an emitter electrode, one of said base electrode and emitter electrode being said input electrode and the other one of said base electrode and emitter electrode being connected to a point of reference potential and wherein said first current generating means includes a resistor in series with a voltage source, said voltage source supplying a voltage of much greater amplitude than the base-to-emitter junction voltage of said transistor, and the value of said resistor being much greater than the base input impedance of said transistor.
Claim 4
Dependent Claim
144 words
The combination as claimed in claim 1, wherein said amplifying device is a transistor having a base electrode and an emitter electrode, one of said base electrode and emitter electrode being said input electrode and the other one of said base electrode and emitter electrode being connected to a point of reference potential; and wherein said first current generating means includes a resistor and a second transistor having a base, a collector and an emitter; means connecting said collector to the input electrode of the amplifying device; means connecting the base of said second transistor to a point of substantially fixed potential; and means connecting said emitter of said second transistor to one end of said resistor, the other end of said resistor being connected to a point of operating potential having a value to forward bias the base-to-emitter junction of said second transistor.
Claim 5
Dependent Claim
153 words
The combination comprising: an input node; a phototransistor having base, emitter and collector electrodes; means direct current connecting the base to said input node, the emitter to a point of reference potential and the collector to a source of operating potential poled in a direction to reverse-bias the collector-to-base junction; said base-to-collector junction being photosensitive and operating as a first signal responsive current generating means generating a current of a first polarity into said input node as a function of incident light intensity; a second current generating means direct current connected to said input node and generating a current of a second polarity opposite to said first polarity; and said second current means generating a substantially constant threshold current which said first current means must overcome to change the direction of current flowing into said input node and said phototransistor amplifying the current differential generated by a said first and second current means.
Claim 6
Dependent Claim
153 words
The combination comprising: an input node; a phototransistor having base, emitter and collector electrodes; means direct current connecting the base to said input node, the emitter to a point of reference potential and the collector to a source of operating potential poled in a direction to reverse-bias the collector-to-base junction; said base-to-collector junction being photosensitive and operating as a first signal responsive current generating means generating a current of a first polarity into said input node as a function of incident light intensity; a second current generating means direct current connected to said input node and generating a current of a second polarity opposite to said first polarity; and said second current means generating a substantially constant threshold current which said first current means must overcome to change the direction of current flowing into said input node and said phototransistor amplifying the current differential generated by a said first and second current means.
Claim 7
Dependent Claim
57 words
The combination as claimed in claim 4, wherein said second current generating means includes a resistor in series with a voltage source, said voltage source supplying a voltage of much greater amplitude than the base-to-emitter junction voltage of said phototransistor, and the value of said resistor being much greater than the base input impedance of said transistor.
Claim 8
Dependent Claim
101 words
The combination as claimed in claim 4, wherein said second current generating means includes a resistor and a second transistor having a base, a collector and an emitter; wherein the collector of said second transistor is connected to the base of said phototransistor, the base of said second transistor is connected to a point of fixed potential; and further providing means connecting the emitter of said second transistor to one end of said resistor, the other end of said resistor being connected to a point of operating potential having a value to forward bias the base-to-emitter junction of said second transistor.
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) | 1974-01-04 | 1974-07-06 | 1975-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-04 | 1978-07-06 | 1979-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-04 | 1982-07-06 | 1983-01-05 | $7700.00 | Window Closed / Lapsed |