US5396132A
Expired / Lapsed
US
⏱️ 0.0 years remaining
MESFET mixer circuit having a pulse doped structure
Assignee: Sumitomo Electric Industries Ltd
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Filing: 1993-03-02
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Granted: 1995-03-07
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Expires: 2013-03-02
Abstract
Abstract An FET mixer circuit having a stable input impedance uses two tandem-connected GaAs MESFET's (1) and (2) of pulse doped structure instead of a conventional MESFET or a HEMT, as an active device. A gate biasing point for the FET (1) is set around a pinch-off point of a mutual conductance, and a gate biasing point for the FET (2) is set in a region which assures non-change of a mutual conductance with respect to the increase of a gate voltage. Thus, a mixer circuit having a good isolation characteristic for an RF signal and a local oscillation signal and exhibits substantially no change in the input impedance is attained.
Inventors
- 👤 Nobuo Shiga
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 12:22
CPC Classifications
H; H03; H03D; H03D7/00; H03D7/12; H03D7/125
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
183 words
A mixer circuit comprising: a first input terminal for receiving a local oscillation signal; a second input terminal for receiving an RF signal; a first GaAs MESFET having a gate electrode, a drain electrode, and a source electrode, said gate electrode being connected to said first input terminal; a second GaAs MESFET having a pulse doped structure, a gate electrode, a drain electrode, and a source electrode, said gate electrode being connected to said second input terminal, said drain electrode of said second MESFET being connected to said gate electrode of said first MESFET, a first bias voltage source connected to said gate electrode of said first MESFET; a second bias voltage source connected to said gate electrode of said second MESFET; an output terminal connected to said drain electrode of said first MESFET; wherein said second MESFET has a mutual conductance-gate voltage characteristic such that the mutual conductance of said second MESFET remains constant during a change in gate electrode voltage applied to said gate electrode of said second MESFET when a predetermined bias is applied by said second bias voltage source.
Claim 2
Dependent Claim
183 words
A mixer circuit comprising: a first input terminal for receiving a local oscillation signal; a second input terminal for receiving an RF signal; a first GaAs MESFET having a gate electrode, a drain electrode, and a source electrode, said gate electrode being connected to said first input terminal; a second GaAs MESFET having a pulse doped structure, a gate electrode, a drain electrode, and a source electrode, said gate electrode being connected to said second input terminal, said drain electrode of said second MESFET being connected to said gate electrode of said first MESFET, a first bias voltage source connected to said gate electrode of said first MESFET; a second bias voltage source connected to said gate electrode of said second MESFET; an output terminal connected to said drain electrode of said first MESFET; wherein said second MESFET has a mutual conductance-gate voltage characteristic such that the mutual conductance of said second MESFET remains constant during a change in gate electrode voltage applied to said gate electrode of said second MESFET when a predetermined bias is applied by said second bias voltage source.
Claim 3
Dependent Claim
60 words
The mixer according to claim 1, wherein said pulse doped structure of said second MESFET has laminated epitaxial layers on a substrate, said layers comprising an upper, an intermediate and a lower epitaxial layer each being of a same material as said substrate, said intermediate layer having an impurity level greater than that of said upper and lower epitaxial layers.
Claim 4
Dependent Claim
25 words
A mixer circuit according to claim 1 wherein a gate width of said second GaAs MESFET is shorter than that of said first GaAs MESFET.
Claim 5
Dependent Claim
29 words
A mixer circuit according to claim 3 wherein an impedance matching circuit is provided between the gate electrode of said second GaAs MESFET and the RF signal input terminal.
Claim 6
Dependent Claim
31 words
A mixer circuit according to claim 4 wherein a coupling capacitor is provided between the drain electrode of said second GaAs MESFET and the gate electrode of said first GaAs MESFET.
Claim 7
Dependent Claim
29 words
A mixer circuit according to claim 5 wherein a low pass filter is provided between the drain electrode of said first GaAs MESFET and the IF signal output terminal.
Claim 8
Dependent Claim
48 words
A mixer circuit according to claim 6 wherein a filter is provided between the gate electrode of said first GaAs MESFET and the local oscillation signal input terminal to prevent the IF signal mixed down by the mixer circuit from leaking to the local oscillation signal input terminal.
References Cited (Backward Citations)
US4308473A
Cited
US4459556A
Cited
US4751744A
Cited
FR2587154A1
Cited
US4723113A
Cited
JPS6272210A
Cited
US4845389A
Cited
US4814649A
Cited
US5091759A
Cited
US5039891A
Cited
US5070376A
Cited
US5083050A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1998-03-06 | 1998-09-05 | 1999-03-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-03-06 | 2002-09-05 | 2003-03-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-03-06 | 2006-09-05 | 2007-03-07 | $7700.00 | Window Closed / Lapsed |