US3857047A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Detector employing a current mirror
Assignee: RCA Corp
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Filing: 1973-06-08
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Granted: 1974-12-24
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Expires: 1993-06-08
Abstract
Abstract A differential amplifier is connected at one output terminal to the input terminal of a current mirror and at its other output terminal to the second terminal of the current mirror and to a load in shunt with the current mirror. In response to one polarity of an input signal applied to the amplifier, the current mirror saturates receiving substantially all of the amplifier current. In response to another polarity of the input signal, the current mirror operates in a linear mode receiving a portion of the amplifier current, and the shunt load receives the remaining current. In one embodiment the shunt load includes a series connected diode and resistor.
Inventors
- 👤 M Knight
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:27
CPC Classifications
H; H03; H03D; H03D1/00; H03D1/02; H03D1/06; H03D1/14; H03D1/18
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
206 words
A detector for amplitude modulated input signals comprising: current source means for producing an operating current; current divider means for dividing said operating current into first and second paths and proportioning the current therebetween in response to said amplitude modulated input signal; a circuit node for receiving the second path current; a current mirror having an input terminal for receiving the first path current, a common terminal for receiving a reference potential, and an output terminal connected to said node; and diode means and load means connected in series between said node and said common terminal, said diode means for causing said current mirror to saturate and clamp said node to said common terminal at a saturation voltage level characteristic of said current mirror when said first path current exceeds said second path current, said diode means further providing an offsetting potential drop when said mirror is saturated for minimizing saturation voltage induced current flow to said load, said diode means enabling linear operation of said current mirror when the second path current exceeds the first path current by conducting excess second path current, not received by said mirror, to said load thereby producing an output voltage across said load linearly related to said excess current.
Claim 2
Dependent Claim
206 words
A detector for amplitude modulated input signals comprising: current source means for producing an operating current; current divider means for dividing said operating current into first and second paths and proportioning the current therebetween in response to said amplitude modulated input signal; a circuit node for receiving the second path current; a current mirror having an input terminal for receiving the first path current, a common terminal for receiving a reference potential, and an output terminal connected to said node; and diode means and load means connected in series between said node and said common terminal, said diode means for causing said current mirror to saturate and clamp said node to said common terminal at a saturation voltage level characteristic of said current mirror when said first path current exceeds said second path current, said diode means further providing an offsetting potential drop when said mirror is saturated for minimizing saturation voltage induced current flow to said load, said diode means enabling linear operation of said current mirror when the second path current exceeds the first path current by conducting excess second path current, not received by said mirror, to said load thereby producing an output voltage across said load linearly related to said excess current.
Claim 3
Dependent Claim
47 words
The detector recited in claim 1 further comprising a circuit output terminal and wherein said diode means comprises at least one diode connected between said node and said output terminal and wherein said load means comprises a resistor connected between said output terminal and said common terminal.
Claim 4
Dependent Claim
76 words
The combination recited in claim 1 wherein said current source means comprises at least one transistor having a conduction path and a control electrode for controlling the conduction of the path, said conduction path coupled between a point of fixed operating potential and a circuit point in said current divider means, said control electrode responsive to a bias signal of a value for maintaining said operating current through said conduction path representative of said bias signal.
Claim 5
Dependent Claim
55 words
The combination recited in claim 3 wherein said transistor is a bipolar transistor having base, emitter and collector electrodes, the emittter and collector electrodes coupled to said point of fixed operating potential and said circuit point in said current divider means, respectively, the base electrode coupled to a bias point for receiving said bias signal.
Claim 6
Dependent Claim
69 words
The combination recited in claim 3 wherein said current divider means comprises: first and second transistors, each having base, emitter and collector electrodes; means for applying a quiescent bias current to each of said base electrodes; means for conducting said amplitude modulated input signal to a selected one of said base electrodes; and means for conducting said operating current to each emitter electrode of said first and second transistors.
Claim 7
Dependent Claim
34 words
The combination recited in claim 5 wherein said means for applying a quiescent bias current to each of said base electrodes comprises separate resistors coupled between each base electrode and a reference potential point.
Claim 8
Dependent Claim
31 words
The combination recited in claim 5 wherein said means conducting said operating current comprises a separate resistor coupled between said circuit point in said current divider means and each emitter electrode.
Claim 9
Dependent Claim
40 words
The combination recited in claim 5 wherein said means conducting said amplitude modulated input signal to a selected one of said base electrodes comprises a capacitor coupled between a signal input terminal and said selected one of said base electrodes.
Claim 10
Dependent Claim
112 words
The combination recited in claim 4 wherein said current mirror comprises: an output transistor having base, emitter and collector electrodes, the collector electrode coupled to said output terminal and to the collector of the second transistor of the current divider means, the emitter coupled to said common terminal, the base coupled to said input terminal; and at least one semiconductor device coupled between said input terminal and said common terminal and arranged to regulate the potential at the base of the current mirror output transistor in accordance with current received by said input terminal, said input terminal being coupled to the collector electrode of the first transistor of said current divider means.
Claim 11
Dependent Claim
36 words
The combination recited in claim 9 wherein said semiconductor device comprises a diode poled in the same sense with respect to said reference terminal as a base-emitter diode junction associated with said current mirror output transistor.
Claim 12
Dependent Claim
74 words
The combination recited in claim 9 further comprising current sensing means coupled between said output transistor emitter and said common terminal and wherein said semiconductor device comprises another transistor the emitter-collector conduction path thereof coupled between said common terminal and said input terminal, the base thereof responsive to a signal produced by said current sensing means for regulating the current conducted by said another transistor thereby regulating the current conducted by said output transistor.
Claim 13
Dependent Claim
16 words
The combination recited in claim 2 further including a capacitor coupled in parallel with said resistor.
Claim 14
Dependent Claim
168 words
A detector circuit comprising, in combination: a differential amplifier comprising two semiconductor devices, each in a different path, each device having an input terminal for controlling the current through its path, means supplying a constant current to the two paths, and means quiescently biasing said amplifier so that substantially equal current flows in each of said paths; a current mirror having a common terminal and first and second input terminals, each input terminal receiving a current from a different one of said paths, the first of said input terminals of said current mirror comprising a control terminal for receiving a current which controls the amount of current which may flow into the second of said terminals; means applying an amplitude modulated carrier to one of said input terminals of said differential amplifier; a circuit output terminal; a resistor and a capacitor connected in parallel between said common terminal and said output terminal; and a diode connected between said output terminal and said second terminal of said current mirror.
Claim 15
Dependent Claim
168 words
A detector circuit comprising, in combination: a differential amplifier comprising two semiconductor devices, each in a different path, each device having an input terminal for controlling the current through its path, means supplying a constant current to the two paths, and means quiescently biasing said amplifier so that substantially equal current flows in each of said paths; a current mirror having a common terminal and first and second input terminals, each input terminal receiving a current from a different one of said paths, the first of said input terminals of said current mirror comprising a control terminal for receiving a current which controls the amount of current which may flow into the second of said terminals; means applying an amplitude modulated carrier to one of said input terminals of said differential amplifier; a circuit output terminal; a resistor and a capacitor connected in parallel between said common terminal and said output terminal; and a diode connected between said output terminal and said second terminal of said current mirror.
Claim 16
Dependent Claim
69 words
The combination recited in claim 13 wherein said two semiconductor devices comprise: first and second transistors each having a conduction path with emitter and collector electrodes at the ends thereof and a base electrode for controlling the conduction of the path; said emitter electrodes coupled to said means for supplying a constant current to the two paths, said base electrodes coupled to said means for quiescently biasing said amplifier.
Claim 17
Dependent Claim
33 words
The combination recited in claim 14 wherein said means for quiescently biasing said amplifier comprises a pair of resistors, each coupling a separate one of said base electrodes to a reference potential terminal.
Claim 18
Dependent Claim
84 words
The combination recited in claim 15 wherein said means supplying a constant current to the two paths comprises at least one transistor having a conduction path and a control electrode for controlling the conduction of the path, said conduction path coupled at one end to said emitter electrodes and at the other end to a point of fixed operating potential, said control electrode responsive to a bias signal of a value for maintaining said constant current at a value representative of said bias signal.
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) | 1977-12-23 | 1978-06-24 | 1978-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-23 | 1982-06-24 | 1982-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-23 | 1986-06-24 | 1986-12-24 | $7700.00 | Window Closed / Lapsed |