US3732490A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Impedance probe for swept network analyzer system
Assignee: HP Inc
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Filing: 1971-06-07
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Granted: 1973-05-08
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Expires: 1991-06-07
Abstract
Abstract A probe for use with a network analyzer for measuring the impedance and phase of a network or component under test over a wide swept frequency band comprising three transformers; a driver transformer for supplying power to a current loop including the test terminals connected across the device under test, a current measurement transformer in the current loop for measuring the current supplied from the driver transformer to the device under test, and a voltage measurement transformer coupled across the test terminals for measuring the voltage across the device. An adjustable balancing circuit including an additional winding on the driver transformer is utilized for balancing out the effect of parasitic capacitance across the test terminals. A small coupling circuit is provided between the current loop and the voltage measurement channel to compensate for the slight voltage drop in series with the device under test due to the probe tip socket and also for undesired leakage between the driver, current, and voltage measurement circuits of the probe structure. An annular grounding ring utilized on the measurement end of the probe is included in the current measurement circuit and the voltage measurement circuit, equal portions of the ring being included in each of said two circuits as measured from the null or midpoint of the grounding ring.
Inventors
- 👤 J Botka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 19:52
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/28; G01R27/32; G01R19/00; G01R19/145; G01R19/165; G01R19/16533; G01R19/16561; G01R27/02
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
188 words
An impedance measuring circuit comprising a current measurement channel including a first transformer having a primary winding and a secondary winding, a voltage measurement channel including a second transformer having a primary winding and a secondary winding, a pair of test terminals for coupling across the device under test, a third transformer having a primary winding adapted for connection to an AC power source and a secondary winding connected in series with the primary winding of said first transformer and with said test terminals to deliver driving current to the device under test, the current in the secondary of said first transformer serving as a measure of said driving current, additional circuit means for couplinG the primary winding of said second transformer across said test terminals, the current induced in the secondary winding of said second transformer serving as a measure of the voltage across the device under test, and a current balancing circuit including a capacitor coupled in shunt across the primary winding of said first transformer to bypass from the current flow therein the current flow due to a parasitic capacitance path across said test terminals.
Claim 2
Dependent Claim
188 words
An impedance measuring circuit comprising a current measurement channel including a first transformer having a primary winding and a secondary winding, a voltage measurement channel including a second transformer having a primary winding and a secondary winding, a pair of test terminals for coupling across the device under test, a third transformer having a primary winding adapted for connection to an AC power source and a secondary winding connected in series with the primary winding of said first transformer and with said test terminals to deliver driving current to the device under test, the current in the secondary of said first transformer serving as a measure of said driving current, additional circuit means for couplinG the primary winding of said second transformer across said test terminals, the current induced in the secondary winding of said second transformer serving as a measure of the voltage across the device under test, and a current balancing circuit including a capacitor coupled in shunt across the primary winding of said first transformer to bypass from the current flow therein the current flow due to a parasitic capacitance path across said test terminals.
Claim 3
Dependent Claim
38 words
An impedance measuring circuit as claimed in claim 1 wherein said secondary winding on said third transformer comprises a plurality of turns to increase the impedance of the driving current circuit above the impedance of said power source.
Claim 4
Dependent Claim
30 words
An impedance measuring circuit as claimed in claim 2 wherein said current balancing circuit also includes an additional secondary winding on said third transformer connected in series with said capacitor.
Claim 5
Dependent Claim
29 words
An impedance measuring circuit as claimed in claim 3 wherein said current balancing circuit includes a delay line connected in series with said additional secondary winding and said capacitor.
Claim 6
Dependent Claim
181 words
An impedance measuring circuit comprising a current measurement channel including a first transformer having a primary winding and a secondary winding, a voltage measurement channel including a second transformer having a primary winding and a secondary winding, a pair of test terminals for coupling across the device under test, a third transformer having a primary winding adapted for connection to an AC power source and a secondary winding connected in series with the primary winding of said first transformer and with said test terminals to deliver driving current to the device under test, the current in the secondary of said first transformer serving as a measure of said driving current, additional circuit means for coupling the primary winding of said second transformer across said test terminals, the current induced in the secondary winding of said second transformer serving as a measure of the voltage across the device under test, and a coupling transformer having a first winding in series with the primary winding of said first transformer and a secondary winding in series with the primary winding of said second transformer.
Claim 7
Dependent Claim
181 words
An impedance measuring circuit comprising a current measurement channel including a first transformer having a primary winding and a secondary winding, a voltage measurement channel including a second transformer having a primary winding and a secondary winding, a pair of test terminals for coupling across the device under test, a third transformer having a primary winding adapted for connection to an AC power source and a secondary winding connected in series with the primary winding of said first transformer and with said test terminals to deliver driving current to the device under test, the current in the secondary of said first transformer serving as a measure of said driving current, additional circuit means for coupling the primary winding of said second transformer across said test terminals, the current induced in the secondary winding of said second transformer serving as a measure of the voltage across the device under test, and a coupling transformer having a first winding in series with the primary winding of said first transformer and a secondary winding in series with the primary winding of said second transformer.
Claim 8
Dependent Claim
189 words
An impedance measuring circuit comprising a current measurement channel including a first transformer having a primary winding and a secondary winding, a voltage measurement channel including a second transformer having a primary winding and a secondary winding, a source of AC current, a pair of test terminals for coupling across the device under test, a third transformer having a primary winding adapted for connection to an AC power source and a secondary winding connected in series with the primary winding of said first transformer and with said test terminals to deliver driving current to the device under test, the current in the secondary of said first transformer serving as a measure of said driving current, additional circuit means for coupling the primary winding of said second transformer across said test terminals, the current induced in the secondary winding of said second transformer serving as a measure of the voltage across the device under test, and an annular-shaped, split grounding ring coupled in series between the primary winding of said first transformer and the primary winding of said second transformer, said grounding ring serving as one of said test terminals.
Claim 9
Dependent Claim
189 words
An impedance measuring circuit comprising a current measurement channel including a first transformer having a primary winding and a secondary winding, a voltage measurement channel including a second transformer having a primary winding and a secondary winding, a source of AC current, a pair of test terminals for coupling across the device under test, a third transformer having a primary winding adapted for connection to an AC power source and a secondary winding connected in series with the primary winding of said first transformer and with said test terminals to deliver driving current to the device under test, the current in the secondary of said first transformer serving as a measure of said driving current, additional circuit means for coupling the primary winding of said second transformer across said test terminals, the current induced in the secondary winding of said second transformer serving as a measure of the voltage across the device under test, and an annular-shaped, split grounding ring coupled in series between the primary winding of said first transformer and the primary winding of said second transformer, said grounding ring serving as one of said test terminals.
Claim 10
Dependent Claim
178 words
An impedance measuring circuit as claimed in claim 6 comprising a current measurement channel including a first transformer having a primary winding and a secondary winding, a voltage measurement channel including a second transformer having a primary winding and a secondary winding, a source of AC current, a pair of test terminals for coupling across the device under test, circuit means for coupling the primary winding of said first transformer in series with said AC current source and said test terminals to deliver driving current to the device undEr test, the current in the secondary of said first transformer serving as a measure of said driving current, additional circuit means for coupling the primary winding of said second transformer across said test terminals, the current induced in the secondary winding of said second transformer serving as a measure of the voltage across the device under test, and a coupling transformer having a first winding in series with the primary winding of said first transformer and a secondary winding in series with the primary winding of said second transformer.
Claim 11
Dependent Claim
44 words
An impedance measuring circuit as claimed in claim 7 including an annular-shaped, split grounding ring coupled in series between the primary winding of said first transformer and the primary winding of said second transformer, said grounding ring serving as one of said test terminals.
Claim 12
Dependent Claim
181 words
An impedance measuring circuit as claimed in claim 8 comprising a current measurement channel including a first transformer having a primary winding and a secondary winding, a voltage measurement channel including a second transformer having a primary winding and a secondary winding, a source of AC current, a pair of test terminals for coupling across the device under test, circuit means for coupling the primary winding of said first transformer in series with said AC current source and said test terminals to deliver driving current to the device under test, the current in the secondary of said first transformer serving as a measure of said driving current, additional circuit means for coupling the primary winding of said second transformer across said test terminals, the current induced in the secondary winding of said second transformer serving as a measure of the voltage across the device under test, and an annular-shaped, split grounding ring coupled in series between the primary winding of said first transformer and the primary winding of said second transformer, said grounding ring serving as one of said test terminals.
Claim 13
Dependent Claim
51 words
An impedance measuring circuit as claimed in claim 9 wherein said source of AC current comprises a third transformer having a primary winding adapted for connection to an AC power source and a secondary winding connected in series with the primary winding of said first transformer and with said test terminals.
Claim 14
Dependent Claim
48 words
An impedance measuring circuit as claimed in claim 10 comprising a current balancing circuit including a capacitor coupled in shunt across the primary winding of said first transformer to bypass from the current flow therein the current flow due to a parasitic capacitance path across said test terminals.
Claim 15
Dependent Claim
30 words
An impedance measuring circuit as claimed in claim 11 wherein said current balancing circuit also includes an additional secondary winding on said third transformer connected in series with said capacitor.
Claim 16
Dependent Claim
29 words
An impedance measuring circuit as claimed in claim 12 wherein said current balancing circuit includes a delay line connected in series with said additional secondary winding and said capacitor.
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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) | 1976-05-07 | 1976-11-06 | 1977-05-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-07 | 1980-11-06 | 1981-05-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-07 | 1984-11-06 | 1985-05-08 | $7700.00 | Window Closed / Lapsed |