US4500848A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Field effect transistor microwave amplifier
Assignee: LMT Radio Professionnelle
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Filing: 1982-08-20
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Granted: 1985-02-19
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Expires: 2002-08-20
Abstract
Abstract In a microwave preamplifier of a Doppler radar system used for Earth observation, three pre-matched and self-biassed field effect microwave transistors are provided. By supplying these transistors by means of a voltage regulator, whose output voltage varies under the action of a control circuit, the gain of this pre-amplifier may be varied without modifying the standing wave ratio, thereby obtaining modulation of the microwave signal amplified by the amplifier. Thus, additional modulation may be obtained, speech modulation for example, on the transmission signal of an Earth observation Doppler radar system.
Inventors
- 👤 Maurice Marchand
- 👤 Yan Haentjens
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:20
CPC Classifications
G; G01; G01S; G01S7/00; G01S7/003; G01S7/006; G01S7/02; G01S7/28; G01S7/282; H; H03; H03F; H03F1/00; H03F1/02; H03F1/0205; H03F1/0261; H03F3/00; H03F3/189; H03F3/19; H03F3/193; H03F3/1935; H03G; H03G3/00; H03G3/004; H03G3/20; H03G3/30; H03G3/3036
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
148 words
A microwave amplifier for Doppler radar, comprising: an input matching circuit for receiving an input signal to be amplified; at least one pre-amplifier stage connected to said input matching circuit, said at least one pre-amplifier stage having a self-biassed field effect transistor whose standing wave ratio is substantially constant under a variable supply voltage; an output matching circuit connected to said at least one pre-amplifier stage for delivering the amplified output signal; and an adjustable voltage regulator for supplying said at least one pre-amplifier stage with a variable voltage which modifies the gain of the amplifier, said voltage regulator comprising: a transistor operating as a variable resistor, depending on the signal received at its gate, for regulating the output voltage of the regulator; and an amplifier for receiving an analog modulation signal and applying this amplified signal to the gate of the transistor operating as a variable resistor.
Claim 2
Dependent Claim
148 words
A microwave amplifier for Doppler radar, comprising: an input matching circuit for receiving an input signal to be amplified; at least one pre-amplifier stage connected to said input matching circuit, said at least one pre-amplifier stage having a self-biassed field effect transistor whose standing wave ratio is substantially constant under a variable supply voltage; an output matching circuit connected to said at least one pre-amplifier stage for delivering the amplified output signal; and an adjustable voltage regulator for supplying said at least one pre-amplifier stage with a variable voltage which modifies the gain of the amplifier, said voltage regulator comprising: a transistor operating as a variable resistor, depending on the signal received at its gate, for regulating the output voltage of the regulator; and an amplifier for receiving an analog modulation signal and applying this amplified signal to the gate of the transistor operating as a variable resistor.
Claim 3
Dependent Claim
46 words
An amplifier as claimed in claim 1, wherein the voltage regulator comprises an input for receiving a reference voltage and which further comprises: a circuit for generating the reference voltage; and a means for cancelling the reference voltage under the control of a digital modulation signal.
Claim 4
Dependent Claim
41 words
An amplifier as claimed in claim 2, which further comprises means for supplying the voltage regulator with a primary regulated voltage, said supplying means further allowing the primary regulated voltage to be cut off under the control of a cut-off signal.
Claim 5
Dependent Claim
25 words
An amplifier as claimed in claim 3, which comprises three series connected pre-amplifier stages, said self-biassed field effect transistors being of the THC 9311-9312 type.
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) | 1988-02-19 | 1988-08-20 | 1989-02-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-02-19 | 1992-08-20 | 1993-02-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-02-19 | 1996-08-20 | 1997-02-19 | $7700.00 | Window Closed / Lapsed |