US3723910A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Mixing circuit utilizing linear resistances
Assignee: Motorola Solutions Inc
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Filing: 1971-05-20
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Granted: 1973-03-27
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Expires: 1991-05-20
Abstract
Abstract The mixing circuit employs the linear portions of the voltagecurrent characteristics of a plurality of field-effect transistors to amplitude modulate a first signal, having a first frequency, with a second signal having a second frequency thus providing an amplitude modulated signal. A differential amplifier is connected to the field-effect transistors and to the source of the first signal so that the common-mode rejection characteristic thereof is utilized to eliminate the undesired component at the first frequency from the amplitude modulated signal. As a result, virtually only the desired signal components having frequencies equal to the sum and difference of the first and second frequencies occur at the output of the amplifier.
Inventors
- 👤 J Cannon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:23
CPC Classifications
H; H03; H03D; H03D7/00; H03D7/14; H03D7/1425; H03D7/1441; H03C; H03C1/00; H03C1/52; H03C1/54; H03C1/542; H03C1/547; H03D7/12; H03D7/125; H03D7/1466; H03C2200/00; H03C2200/0037; H03C2200/0079
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
386 words
A signal processing circuit for combining a first signal having a first frequency with second and third signals each having a second frequency to form a mixing product including virtually only signal components having frequencies equal to the sum and the difference of the first and second frequencies, the signal processing circuit including in combination: first voltage variable resistance means having a linear characteristic and first, second and third electrodes, said first electrode being adapted to receive the first signal, said second electrode being adapted to receive the second signal; second voltage variable resistance means having a linear characteristic and first, second and third electrodes, said third electrode of said second voltage variable resistance means being connectEd to said third electrode of said first voltage variable resistance means, said second electrode of said second voltage variable resistance means being adapted to receive the third signal; said first and second voltage variable resistance means being responsive to said second and third signals such that the resistance between said first electrode of said first voltage variable resistance means and said first electrode of said second voltage variable resistance means is substantially constant, and the resistance of said second voltage variable resistance means being responsive to said third signal to amplitude modulate said first signal to produce a first amplitude modulated signal occurring at said third electrode of said first voltage variable resistance means having first frequency components at said first frequency and at frequencies equal to the sum and difference of said first and second frequencies; amplifier means having a common-mode rejection characteristic, first and second input terminals and an output terminal; first circuit means including third resistance means connecting said first electrode of said first voltage variable resistance means to said first input terminal of said amplifier means to enable second signal components at the first frequency of said first signal to be applied thereto, said third resistance means having a resistance characteristic which equalizes the amplitudes of said second signal components to the amplitudes of said first frequency components; second circuit means connecting said third electrode of said second voltage variable resistance means to said second input terminal of said amplifier means so that said first amplitude modulated signal is applied thereto; and said amplifier means developing the desired mixing product at said output terminal thereof.
Claim 2
Dependent Claim
386 words
A signal processing circuit for combining a first signal having a first frequency with second and third signals each having a second frequency to form a mixing product including virtually only signal components having frequencies equal to the sum and the difference of the first and second frequencies, the signal processing circuit including in combination: first voltage variable resistance means having a linear characteristic and first, second and third electrodes, said first electrode being adapted to receive the first signal, said second electrode being adapted to receive the second signal; second voltage variable resistance means having a linear characteristic and first, second and third electrodes, said third electrode of said second voltage variable resistance means being connectEd to said third electrode of said first voltage variable resistance means, said second electrode of said second voltage variable resistance means being adapted to receive the third signal; said first and second voltage variable resistance means being responsive to said second and third signals such that the resistance between said first electrode of said first voltage variable resistance means and said first electrode of said second voltage variable resistance means is substantially constant, and the resistance of said second voltage variable resistance means being responsive to said third signal to amplitude modulate said first signal to produce a first amplitude modulated signal occurring at said third electrode of said first voltage variable resistance means having first frequency components at said first frequency and at frequencies equal to the sum and difference of said first and second frequencies; amplifier means having a common-mode rejection characteristic, first and second input terminals and an output terminal; first circuit means including third resistance means connecting said first electrode of said first voltage variable resistance means to said first input terminal of said amplifier means to enable second signal components at the first frequency of said first signal to be applied thereto, said third resistance means having a resistance characteristic which equalizes the amplitudes of said second signal components to the amplitudes of said first frequency components; second circuit means connecting said third electrode of said second voltage variable resistance means to said second input terminal of said amplifier means so that said first amplitude modulated signal is applied thereto; and said amplifier means developing the desired mixing product at said output terminal thereof.
Claim 3
Dependent Claim
79 words
The signal processing circuit of claim 1 wherein said first and second voltage variable resistance means are first and second field-effect transistor means having a pinch-off voltage and said first, second and third electrodes thereof are the respective source, gate and drain thereof; and said first, second and third signals have amplitudes which are relatively small compared to said pinch-off voltage so that said first and second field-effect transistor means are operated on the linear portion of their characteristics.
Claim 4
Dependent Claim
15 words
The signal processing circuit of claim 1 wherein said third resistance means is a potentiometer.
Claim 5
Dependent Claim
317 words
The signal processing circuit of claim 1 wherein said first circuit means includes: third voltage variable resistance means having a linear characteristic and first, second and third electrodes, said first electrode of said third voltage variable resistance means being connected to said first electrode of said first voltage variable resistance means, said second electrode of said third voltage variable resistance means being adapted to receive the third signal; third circuit means connecting said third electrode of said third voltage variable resistance means to said first input terminal of said amplifier means; fourth voltage variable resistance means having a linear characteristic and first, second and third electrodes, said third electrode of said fourth voltage variable resistance means being connected to said third electrode of said third voltage variable resistance means, said second electrode of said fourth voltage variable resistance means being adapted to receive the second signal; said third and fourth voltage variable resistance means being responsive to the first, second and third signals to provide a second amplitude modulated signal to said first input terminal of said amplifier means having said second frequency components of equal frequency and in phase with said first frequency components being applied to said second input terminal of said amplifier means, and second frequency components of equal frequency but 180* out-of-phase with said first frequency components at said sum and diffeRence of said first and second frequencies being applied to said second input terminal of said amplifier means; and said amplifier means being responsive to said frequency components being applied to said first and second input terminals thereof to cancel said first and second components at said first frequency and reverse the phase of said first and second components occurring at said frequencies equal to the sum and difference of said first and second frequencies so that they occur in phase with each other at said output terminal of said amplifier means.
Claim 6
Dependent Claim
74 words
The signal processing circuit of claim 4 wherein said third voltage variable resistance means is a third field-effect transistor having a pinch-off voltage and said first, second and third electrodes thereof are the respective source, gate and drain electrodes thereof; and said first and third signals having amplitudes which are relatively small compared to said pinch-off voltage so that said third field-effect transistor means is operated only on the linear portion of its characteristic.
Claim 7
Dependent Claim
81 words
The signal processing circuit of claim 4 wherein said fourth voltage variable resistance means is a fourth field-effect transistor having a pinch-off voltage and said first, second and third electrodes thereof are the source, gate and drain electrodes of said fourth field-effect transistor; and said second input signal has a relatively low amplitude with respect to said pinch-off voltage of said fourth field-effect transistor means so that said fourth field-effect transistor is operated only on the linear portion of its characteristic.
Claim 8
Dependent Claim
16 words
The signal processing circuit of claim 4 wherein said second and third circuit means are potentiometers.
Claim 9
Dependent Claim
34 words
The signal processing circuit of claim 1 wherein said amplifier means having a common mode rejection characteristic is a differential amplifier having first and second differential inputs corresponding to said first and second inputs.
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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) | 1976-03-26 | 1976-09-25 | 1977-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-26 | 1980-09-25 | 1981-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-26 | 1984-09-25 | 1985-03-27 | $7700.00 | Window Closed / Lapsed |