US3792375A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Suppression of spurious bias circuit oscillations in impatt oscillators
Assignee: AT&T Inc
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Filing: 1972-11-08
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Granted: 1974-02-12
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Expires: 1992-11-08
Abstract
Abstract Spurious oscillations in the dc bias circuit of an Impatt oscillator are suppressed by including in the bias circuit a filter which is external of the microwave resonator. The filter includes an inductance for shunting a dissipative resistance and for providing a low-loss path for the dc bias current. Specific design criteria for the filter are disclosed.
Inventors
- 👤 C Brackett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 10:43
CPC Classifications
H; H03; H03B; H03B9/00; H03B9/12; H03B9/14; H03B9/145; H03B2009/126
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
153 words
A microwave negative resistance device comprising: an Impatt diode contained within a cavity resonator resonant at a microwave frequency; means for deriving a useful output from said resonator at said microwave frequency; means comprising a bias circuit for applying a dc bias voltage to the Impatt diode; means for preventing submicrowave oscillations in the bias circuit comprising a submicrowave frequency filter in the bias circuit; said filter comprising a resistance element connected in parallel with an inductance element; means comprising the inductance element for providing a dc shunt path around the resistance element, thereby substantially to avoid dissipative loss of dc bias current; and wherein, at zero frequency the bias circuit, including the filter, has a bias circuit impedance ZB which conforms to the relationship ZB > Rn - Rsc where Rsc is the space-charge resistance of the Impatt diode and Rn is a negative resistance of the diode at said submicrowave frequency.
Claim 2
Dependent Claim
153 words
A microwave negative resistance device comprising: an Impatt diode contained within a cavity resonator resonant at a microwave frequency; means for deriving a useful output from said resonator at said microwave frequency; means comprising a bias circuit for applying a dc bias voltage to the Impatt diode; means for preventing submicrowave oscillations in the bias circuit comprising a submicrowave frequency filter in the bias circuit; said filter comprising a resistance element connected in parallel with an inductance element; means comprising the inductance element for providing a dc shunt path around the resistance element, thereby substantially to avoid dissipative loss of dc bias current; and wherein, at zero frequency the bias circuit, including the filter, has a bias circuit impedance ZB which conforms to the relationship ZB > Rn - Rsc where Rsc is the space-charge resistance of the Impatt diode and Rn is a negative resistance of the diode at said submicrowave frequency.
Claim 3
Dependent Claim
44 words
The microwave device of claim 1 wherein: the bias circuit has an impedance ZB which is of an appropriate value such that ZB(f1) -> lim ZQ(f2)f f where ZQ is the diode quenching impedance of the bias circuit and f1 and f2 are frequencies.
Claim 4
Dependent Claim
19 words
The microwave device of claim 2 wherein: the filter is substantially completely electrically external of the microwave cavity resonator.
Claim 5
Dependent Claim
48 words
The microwave device of claim 3 wherein: the microwave cavity resonator comprises part of a waveguide having a direction of wave propagation; And the bias circuit comprises a conductor extending from the Impatt diode across the microwave resonator in a direction transverse to the direction of wave propagation.
Claim 6
Dependent Claim
43 words
The microwave device of claim 1 wherein: the bias circuit has a bias circuit impedance as a function of frequency ZB(f1) and a diode quenching impedance as a function of frequency ZQ(f2); and ZB(f1) equals ZQ(f2) only when f1 is smaller than f2.
Claim 7
Dependent Claim
66 words
The microwave device of claim 5 wherein: ZQ(f2) (Rn/1 + j omega 2/a) - Rsc where Rn is the negative resistance of the diode, Rsc is the space-charge resistance of the Impatt diode, omega 2 is the angular frequency of f2, and a is given by a about ( omega O/QL) where omega O is the microwave frequency and QL is the microwave circuit loaded Q.
Claim 8
Dependent Claim
172 words
A microwave oscillator comprising: an Impatt diode contained within a cavity resonator resonating at a microwave frequency; means for deriving a useful output from said resonator at said microwave frequency; a source of dc bias voltage; a bias circuit for applying the dc bias voltage to the Impatt diode; said bias circuit comprising reactance and resistance elements and having an impedance such that the DC power loss between the source and the Impatt diode is substantially zero, and which produces an impedance locus such that ZB(O)> Rn - Rsc and, when plotted on a Smith chart, does not intersect the impedance locus ZQ (Rn/1 + j omega /a) - Rsc at any angular frequency f that complies with the relation f fM a/2 pi Square Root Rn/Rsc - 1 where fM is the maximum frequency of oscillation, Rn is the negative resistance of the diode, Rsc is the space-charge resistance of the diode, ZB(O) is the bias circuit impedance at zero frequency, and a is given by a about ( omega O/QL).
Claim 9
Dependent Claim
172 words
A microwave oscillator comprising: an Impatt diode contained within a cavity resonator resonating at a microwave frequency; means for deriving a useful output from said resonator at said microwave frequency; a source of dc bias voltage; a bias circuit for applying the dc bias voltage to the Impatt diode; said bias circuit comprising reactance and resistance elements and having an impedance such that the DC power loss between the source and the Impatt diode is substantially zero, and which produces an impedance locus such that ZB(O)> Rn - Rsc and, when plotted on a Smith chart, does not intersect the impedance locus ZQ (Rn/1 + j omega /a) - Rsc at any angular frequency f that complies with the relation f fM a/2 pi Square Root Rn/Rsc - 1 where fM is the maximum frequency of oscillation, Rn is the negative resistance of the diode, Rsc is the space-charge resistance of the diode, ZB(O) is the bias circuit impedance at zero frequency, and a is given by a about ( omega O/QL).
Claim 10
Dependent Claim
27 words
The microwave oscillator in claim 7 wherein: said bias circuit reactance and resistance elements constitute a filter which is substantially completely external of the microwave cavity resonator.
Claim 11
Dependent Claim
33 words
The microwave oscillator of claim 8 wherein: the filter comprises an inductance element for providing a dc shunt path around a resistance element, thereby substantially to avoid dissipative loss of dc bias current.
Claim 12
Dependent Claim
48 words
The microwave oscillator of claim 9 wherein: the microwave cavity resonator comprises part of a waveguide having a direction of wave propagation; and the bias circuit comprises a conductor extending from the Impatt diode across the cavity resonator in a direction transverse to the direction of wave propagation.
Claim 13
Dependent Claim
26 words
The microwave oscillator of claim 9 wherein: the dc bias source is substantially a constant current source; and the bias source is shunted by a capacitance.
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) | 1977-02-11 | 1977-08-13 | 1978-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-11 | 1981-08-13 | 1982-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-11 | 1985-08-13 | 1986-02-12 | $7700.00 | Window Closed / Lapsed |