Patent US4978907A successfully refreshed from Google Patents.
US4978907A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus and method for expanding the frequency range over which electrical signal amplitudes can be accurately measured
Assignee: Nokia Bell Labs
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Filing: 1989-05-10
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Granted: 1990-12-18
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Expires: 2009-05-10
Abstract
Abstract It has been found that the ground lead of a measurement instrument probe has an inductance which, when coupled with the capacitance of the rest of the probe, forms a resonant circuit. The net result is a peak in the frequency response of the probe which interferes with accurate amplitude measurements of test signals having a frequency above some threshold. Pursuant to the present invention, a resistor is added to the measurement instrument probe whose value substantially flattens the frequency response of the probe and permits accurate amplitude measurements over a substantially greater frequency range. This resistor, either having a fixed or adjustable value, can be added to the measurement instrument probe or can be included in an adjunct which fits over a probe end.
Inventors
- 👤 Douglas C. Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 16:47
CPC Classifications
G; G01; G01R; G01R1/00; G01R1/02; G01R1/06; G01R1/067; G01R1/06772
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
139 words
A probe for use with measurement equipment, said probe having an input impedance and comprising a probe tip for receiving signals from a circuit under test, a signal conducting lead having a capacitance and having a first end connected to said probe tip, and a ground lead for connection to said circuit under test, said ground lead having an inductance, the respective capacitance and inductance of said signal conducting lead and said ground lead forming a resonant circuit having a non-flat frequency response, and said probe further including a resistor serially connected between said probe tip and said first end of said signal conducting lead, said resistance providing a resistance value substantially less than said input impedance so as to substantially flatten said frequency response, whereby accurate amplitude measurements of signals over a wide range of frequencies are provided.
Claim 2
Dependent Claim
139 words
A probe for use with measurement equipment, said probe having an input impedance and comprising a probe tip for receiving signals from a circuit under test, a signal conducting lead having a capacitance and having a first end connected to said probe tip, and a ground lead for connection to said circuit under test, said ground lead having an inductance, the respective capacitance and inductance of said signal conducting lead and said ground lead forming a resonant circuit having a non-flat frequency response, and said probe further including a resistor serially connected between said probe tip and said first end of said signal conducting lead, said resistance providing a resistance value substantially less than said input impedance so as to substantially flatten said frequency response, whereby accurate amplitude measurements of signals over a wide range of frequencies are provided.
Claim 3
Dependent Claim
12 words
The probe of claim 1 wherein said resistor is a fixed resistor.
Claim 4
Dependent Claim
12 words
The probe of claim 1 wherein said resistor is a variable resistor.
Claim 5
Dependent Claim
129 words
An adjunct for use with a measurement probe having an input impedance, a signal conducting lead having a capacitance and a ground lead for connection to a circuit under test, said ground lead having an inductance, the respective capacitance and inductance of said signal conducting lead and said ground lead forming a resonant circuit having a non-flat frequency response, and said adjunct fitting over an end of said probe and having an electrically conductive member connected to said signal conducting lead, said probe adjunct further comprising a resistor serially connected to said electrically conductive member, said resistor providing a resistance value substantially less than said input impedance so as to substantially flatten said frequency response and thereby provide accurate amplitude measurements of signals over a wide range of frequencies.
Claim 6
Dependent Claim
129 words
An adjunct for use with a measurement probe having an input impedance, a signal conducting lead having a capacitance and a ground lead for connection to a circuit under test, said ground lead having an inductance, the respective capacitance and inductance of said signal conducting lead and said ground lead forming a resonant circuit having a non-flat frequency response, and said adjunct fitting over an end of said probe and having an electrically conductive member connected to said signal conducting lead, said probe adjunct further comprising a resistor serially connected to said electrically conductive member, said resistor providing a resistance value substantially less than said input impedance so as to substantially flatten said frequency response and thereby provide accurate amplitude measurements of signals over a wide range of frequencies.
Claim 7
Dependent Claim
12 words
The adjunct of claim 4 wherein said resistor is a fixed resistor.
Claim 8
Dependent Claim
12 words
The adjunct of claim 4 wherein said resistor is a variable resistor.
Claim 9
Independent Claim
130 words
A method of providing an electrical signal to measurement apparatus, said method comprising the steps of introducing said electrical signal to a measurement probe connected to said measurement apparatus, said measurement probe having an input impedance, a probe tip connected to an end of a signal conducting lead having a capacitance, and a ground lead for connection to a circuit under test, said ground lead having an inductance, the capacitance of said signal conducting lead and the inductance of said ground lead forming a resonant circuit having a non-flat frequency response, and providing an electrical resistance in series between said probe tip and said end of said signal conducting lead, said resistance having a value which is substantially less than said input impedance and which substantially dampens said frequency response.
Claim 10
Independent Claim
130 words
A method of providing an electrical signal to measurement apparatus, said method comprising the steps of introducing said electrical signal to a measurement probe connected to said measurement apparatus, said measurement probe having an input impedance, a probe tip connected to an end of a signal conducting lead having a capacitance, and a ground lead for connection to a circuit under test, said ground lead having an inductance, the capacitance of said signal conducting lead and the inductance of said ground lead forming a resonant circuit having a non-flat frequency response, and providing an electrical resistance in series between said probe tip and said end of said signal conducting lead, said resistance having a value which is substantially less than said input impedance and which substantially dampens said frequency response.
Claim 11
Dependent Claim
110 words
A probe for use with measurement equipment, said probe comprising a signal conducting lead, a ground lead for connection to a circuit under test and a signal attenuation circuit having an impedance connected to said signal conducting lead, said probe having a non-flat frequency response due to resonance between said ground lead and said attenuation circuit, and said probe further including a resistor serially connected between an end of said probe and said attenuation circuit, said resistor having a value which is substantially less than that of said attenuation network, said resistor substantially flattening said frequency response whereby accurate measurements of signals over a wide range of frequencies are provided.
Claim 12
Dependent Claim
110 words
A probe for use with measurement equipment, said probe comprising a signal conducting lead, a ground lead for connection to a circuit under test and a signal attenuation circuit having an impedance connected to said signal conducting lead, said probe having a non-flat frequency response due to resonance between said ground lead and said attenuation circuit, and said probe further including a resistor serially connected between an end of said probe and said attenuation circuit, said resistor having a value which is substantially less than that of said attenuation network, said resistor substantially flattening said frequency response whereby accurate measurements of signals over a wide range of frequencies are provided.
Claim 13
Dependent Claim
12 words
The probe of claim 8 wherein said resistor is a fixed resistor.
Claim 14
Dependent Claim
12 words
The probe of claim 8 wherein said resistor is a variable resistor.
References Cited (Backward Citations)
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1993-12-17 | 1994-06-18 | 1994-12-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-12-17 | 1998-06-18 | 1998-12-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-12-17 | 2002-06-18 | 2002-12-18 | $7700.00 | Window Closed / Lapsed |