US3369173A - Attenuator apparatus - Google Patents

Attenuator apparatus Download PDF

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Publication number
US3369173A
US3369173A US508784A US50878465A US3369173A US 3369173 A US3369173 A US 3369173A US 508784 A US508784 A US 508784A US 50878465 A US50878465 A US 50878465A US 3369173 A US3369173 A US 3369173A
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United States
Prior art keywords
attenuator
switch
input
section
capacitance
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US508784A
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English (en)
Inventor
Roland E Andrews
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tektronix Inc
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Tektronix Inc
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Filing date
Publication date
Application filed by Tektronix Inc filed Critical Tektronix Inc
Priority to US508784A priority Critical patent/US3369173A/en
Priority to NL6614872A priority patent/NL6614872A/xx
Priority to DE19661541874 priority patent/DE1541874A1/de
Priority to GB49125/66A priority patent/GB1116730A/en
Priority to FR83165A priority patent/FR1501221A/fr
Application granted granted Critical
Publication of US3369173A publication Critical patent/US3369173A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/24—Frequency- independent attenuators

Definitions

  • a shunt connection is provided from the first switch to a simultaneously selected contact of the fourth switch, for bypassing the various attenuator sections as well as the second and third switches so that circuit input capacitance is reduced.
  • This invention relates to attenuator apparatus and particularly to attenuator apparatus having low input capacitance and adaptable for accurately adjusting an input signal presented to an oscilloscope.
  • the basic deflection factor of the device determines the amplitude of the input signal as displayed on the viewing screen of the oscilloscopes cathode ray I tube.
  • an oscilloscope is usually quite sensitive and may therefore display signals of extremely small amplitude.
  • suitable attenuator apparatus is employed.
  • An aten'uator apparatus found extremely useful heretofore involves the cascading of selected attenuator sections in varying combinations by switching means having a plurality of switch sections and a plurality of switch positions.
  • an attenuator section designed for reducing an input signal by a factor of 2.5 can be employed in series with other attenuator sections having a selectable attenuation ratio of and 100 thereby resulting in an overall reduction selectable between 2.5, 25 and 250.
  • a larger range of attenuation is possible with this type of cascaded arrangement than in a circuit employing a separate attenuator for each attenuation required.
  • An attenuator apparatus also desirably employs one or more switch positions wherein no attenuation is inserted in the circuit. In these switch positions the basic deflection factor of an oscilloscope will hold true. It has been the usual practice'with attenuator apparatus of the gatorded type to provide one or more switch positions which include no attenuator sections and involve direct connections between switch sections at the points where series attenuator sections would normally be located.
  • Attenuator apparatus comprises first and second groups of attenuating means wherein different attenuating means establish different degrees of attenuation.
  • Switching means couple selected attenuating means from the first group with selected attenuating means of the second group, such switching means including a coupling section intermediate the first and second groups.
  • the switching means has, however, at least one switching position for bypassing the groups of attenuating means and also bypassing the switching means coupling section therebetween to provide a low capacitance, low attenuation circuit.
  • an attenuator apparatus includes first, second, third and fourth multiple position switching means which are preferably ganged together to form a multi-position attenuator switch.
  • Various attenuator sections are included between first and second switching means and other attenuating sections are included between the third and fourth switching means, the second and third switching means being coupled together.
  • the switching means are connected to place an attenuator section from a first group between first and second switching means in a cascaded relationship with a selected attenuator section from a second group between the third and fourth switching means.
  • a shunt connection is provided in at least one position of said switching means from the first switching means to corresponding or simultaneously selected contact of the fourth switching means, in this manner bypassing the second and third switching means.
  • the capacitance to ground thereof is avoided and the input capacitance of the attenuator apparatus, in what would otherwise be a high capacitance position, is substantially reduced. Moreover, not only is capacitance reduced in this position, but the input capacitance of other switch positions may be reduced while still maintaining constant input impedance for all switch positions.
  • FIG. 1 is a schematic diagram of attenuator apparatus in accordance with the prior art
  • FIG. 2 is a schematic diagram of an improved attenuator apparatus in accordance with the present invention.
  • FIG. 3 is a schematic diagram of an attenuator section employed in the circuit of FIG. 2;
  • FIG. 4 is a schematic diagram of a second attenuator section employed in the circuit of FIG. 2;
  • FIG. 5 is a schematic diagram of a third section employed in the circuit of FIG. 2;
  • FIG. 6 is a schematic diagram of a fourth section employed in the circuit of FIG. 2.
  • the circuit includes attenuator sections 3, 4, 5 and 6 and also includes input terminals 10 and 12, the latter terminal being grounded and the former terminal being connected to movable contact 14 of a multiple position switch section 16.
  • Switch section 16 is ganged to form a control switch with similar switch sections 18, 20 and 22, as well as a switch (not shown) within amplifier 24.
  • the switch sections are operable together, for example by means of a single control.
  • Switch section 18 has a movable contact 26 coupled via small resistor 28 to movable contact 30 of switch section 20.
  • Movable contact 32 of the switch section 22 is connected attenuator attenuator to input resistor 34 of amplifier 24 with the lower end of the resistor returned to ground.
  • resistor 34 and amplifier 24 series resistors 36 and 38 are interposed with the former having a capacitor 40 shunted thereacross.
  • a variable capacitor 42 is located between the interconnection of resistor 36 and 38 and ground.
  • the input contacts of switch section 16 are connected to the first three output contacts of switch section 18.
  • the first three input contacts of switch section 20 are connected to the first three output contacts of switch section 22.
  • the fourth and fifth input contacts of switch section 16 are connected to the fourth and fifth output contacts of switch sections 18.
  • the attenuator section 5 having the property of attenuating a signal presented thereto by a factor of ten.
  • attenuator section 5 is labeled with the designation +10.
  • the attenuator section 6 for dividing the signal presented thereto by one hundred.
  • the attenuator section 3 has a division factor of 2.5 and is connected between the fourth, seventh and tenth input contacts of switch section 20 and the fourth, seventh, and tenth output contacts of switch section 22. Furthermore, the attenuator section 4 having a division factor of 5 is connected between the fifth, eighth and eleventh input contacts of switch section 24] and corresponding output contacts of switch section 22. A direct or divide by 1 connection is present between the sixth and ninth input contacts of switch section 20 and the sixth and nineth output contacts of switch section 22.
  • the circuit of FIG. 1 illustrates an attenuator apparatus employing a switching arrangement of the general type as heretofore utilized.
  • This apparatus of the cascaded attenuator type, accomplishes the purpose of selectively reducing or dividing the input signal presented across terminals 10 and 12 by selected predetermined amounts.
  • a principal use of this type of circuit is in the input circuit of an oscilloscope.
  • An input signal may have a wide variety of values but in each case the waveform portrayed on the screen of an oscilloscope cathode ray tube should occupy a reasonable portion of such screen and moreover the size of the waveform on the cathode ray tube screen may be used as an accurate measure of the waveform amplitude.
  • position III in the device of FIG. 1 the amplitude of the input signal can be determined from the basic deflection factor of the oscilloscope apparatus. However, in all other positions of the switching means, the input signals amplitude is altered by a predetermined factor.
  • Attenuator section 5 causes a reduction of ten in the amplitude of the signal and the switch sections 20 and 22 provide straightthrough connections.
  • position VII of the switching means both attenuator section 5 and attenuator section 3 are cascaded for a total of attenuation of 25.
  • successive combinations of attenuator sections 3, 4, 5, and 6 are cascaded.
  • the cascaded attenuator arrangement reduces the number of attenuator sections and component parts required for a given range of attenuation values. A great deal more attenuation circuitry would be required, for example, if a separate attenuator section had to be inserted in series with the input and output for each desired value of attenuation.
  • the foregoing circuitry is not without disadvantages inasmuch as the attenuator apparatus presents an input capacitance tending to increase the rise time and reduce the high frequency response of signals presented at the input terminal.
  • Some switch positions of the attenuator apparatus contribute a greater effective shunt capacitance to ground than certain other switch positions of the attenuator apparatus, or the shunt capacitance at all switch positions is made equal to the switch position which would otherwise provide the greatest shunt capacitance.
  • FIGS. 3 through 6 more fully illustrating attenuator sections 3 through 6 respectively, and in which similar elements are referred to with the same reference numerals.
  • Each of the attenuator sections of FIGS. 3 through 6 includes an input terminal 44, an output terminal 46 and a voltage divider comprising resistors 48 and 50 connected between terminal 44 and ground.
  • Output terminal 46 is coupled to the midpoint of this divided via damping resistor 52.
  • This voltage divider is an effective means for reducing the amplitudes of DC or low frequency signals substantially in the proportion the resistance of resistor 50 bears to the sum of the resistance of resistors 48 and 50.
  • Capacitor 54 is shunted across resistor 48 and capacitor 56 is shunted across resistor 50.
  • the capacitor 56 is shown dotted since the capacitance thereof is contributed by portions of the circuit including any circuit to which the output terminal 46 is connected, as hereinafter described.
  • an acual capacitor 56 is also included in the other three attenuator sections illustrated.
  • Capacitor 58 is a standardizing element for balancing the different attenuators whereby to provide substantially equal input capacitance for each.
  • the input capacitance seen at the input terminal of the attentuator can be less than the input capacitance of the amplifier to which the attenuator section connects. Since series capacitance 54 is placed in series with capacitance 56, including the input capacitance of the amplifier stage to which terminal 46 is coupled, the input capacitance seen at terminal 44 is reduced. For example, the input capacitance at terminal 44 is equal to The capacitance in the attenuator section thus has the effect of reducing the input capacitance of the apparatus as seen at terminal 44 and approximately by the attenuator ratio.
  • the apparatus of FIG. 2 like FIG. 1, includes ganged switching means for cascading attenuating sections 3, 4, 5, and 6 in various combinations to provide a wide range of attenuation values with a minimum of attenuator structure.
  • the principal difference between the circuit of FIG. 1 and that of FIG. 2 is that in the circuit of FIG. 2 a shunt connection 60 is provided betwen switch section 16 and switch section 22 in the positions I to III of the ganged switching means, that is, for those positions involving no attenuation.
  • the circuit of FIG. 2 differs from the prior apparatus in that intermediate switch sections 18 and 20 are bypassed in straight-through positions of the switching means and the function of damping resistor 28 in FIG. 1 is provided by means of resistors 62, 64 and 66 in the FIG. 2 apparatus.
  • a connection 60 extends directly between the first 3 contacts 68, 70 and 72 of the switch section 16 (those for the .005, the .01, and the .02 volt positions in this particular attenuator apparatus) and corresponding contacts 74, 76 and 78 of switch section 22.
  • the input capacitance to the attenuator apparatus is reduced fifty percent, with a consequent fifty percent improvement in rise time.
  • Reduction in capacitance is principally attributable to reduction in the switch capacitance present in the positions which insert no attenuating sections into the circuit.
  • Attenuator section 3 is interposed between the input contact of switch section 20 and the output contact of switch section 22. Attenuator section 3 has been illustrated in FIG. 3 and explained in connection therewith.
  • attenuator section 4 illustrated in FIG. 4 is connected between the input contact of switch section 20 and the output contact of switch section 22.
  • Attenuator section 5, illustrated in FIG. 5 is connected between input contacts of switch section 16 and output contacts of switch section 18 in positions VI, VII and VIII.
  • the input contact of switch section 20 is coupled to the output contact of switch section 22 via a damping resistance 66.
  • a capaci-' tance shunted across resistance 66 aids the high frequency response of the circuit.
  • This combination is similarly interposed between the input contact of the switch section 20 in switch position IX thereof, and the output contact of switch section 22.
  • Attenuator section 6, illustrated in FIG. 6, connects the input contacts of switch section 16 to the output contacts of switch section 18 for switch positions IX, X and XI of the apparatus.
  • Resistors 36, 62 and 64 are damping resistances, 36 and 62 being bypassed with capacitors 40 and 41 to aid the high frequency response of the circuit.
  • one of the straight-through positions of the switching apparatus for example, position III or the 0.2 volt position, represents the standard straight-through or non-attenuating position for the apparatus. In this position,-the basic deflection factor for an oscilloscope apparatus employing the present circuit is selected. In positions I and II of the switching apparatus, additional amplification is provided by the amplifier 24 and hence amplifier 24 is shown ganged to the switching apparatus.
  • a variable input capacitor 82 is connected across input resistor 34 of amplifier 24 in order to adjust or standardize the input capacitance of the amplifier. This capacitor is adjusted in the non-attenuating position of the switching apparatus, for example, in position III, or the .02 volt position.
  • Resistor 84 is another high frequency damping resistor.
  • the capacitance of capacitor 82 is chosen to be of a value to provide a part of the voltage divider, specifically part of capacitor 56 in FIG. 3. In FIGS. 4, 5 and 6, the capacitance 56 is selected to provide the proper voltage division and time constant for the attenuating sections taking the input capacitance of the amplifier including the capacitance of capacitor 82 into consideration.
  • Variable capacitor 58 in FIGS. 3, 4, 5, and 6 is employed as a standardizing capacitor and is adjusted to provide the same apparatus input capacitance in the various switch positions.
  • the capacitors 58 for attenuator sections 5 and 6 are adjusted in switch positions VI and IX respectively, wherein the output terminals of these attenuator sections are connected to the input circuit of amplifier 24, However, in switch positions VII, VIII, X and XI wherein these attenuating sections are placed in cascaded relation with either attenuator sections 3 or 4, an additional shunt capacitance is needed for further standardizing purposes, because of the isolating effect of attenuator sections 3 and 4.
  • Attenuator apparatus having an input terminal and an output terminal, said apparatus being adapted for the cascading of attenuating means selected from a first group with attenuating means selectedfrom a second group and comprising first switching means having input and output sections for selecting and placing therebetween one of a first group of attenuating means in circuit between said input and output terminals, second switching means having input and output sections for selecting and placing therebetween one of a second group of attenuating means in cascade relation with said one of first group of attenuating means,
  • Attenuator apparatus having multiple selectable switching positions for cascading a selected one of a first group of attenuating means having input and output terminals with a selected one of a second group of attenuating means having input and output terminals
  • multiple position ganged switching means including a switch section for connecting to an input terminal of a selected attenuating means of a first group, a second switch section for simultaneously connecting to the output terminal of the same attenuating means of said first group, a third switch section for conmeeting to the input terminal of a selected cascaded attenuating means of said second group, a fourth switch section for simultaneously connecting to the output terminal of the same cascaded attenuating means of said second group,
  • Attenuator apparatus comprising a first group of attenuating means each having respective input and output terminals, different of said attenuating means establishing a different degree of attenuation between said input and output terminals,
  • switching means for coupling a selected attenuating means from said first group in cascaded relation with a selected attenuating means of said second group, said switching means having a coupling section intermediate said first group and said second group to complete a cascaded circuit relation,
  • said switching means having at least one switching position connected for bypassing said first group and said second group and also bypassing said section between said first and said second group of attenuating means to provide a low capacitance, low attenuation circuit.
  • each of said attenuating means comprises a resistance voltage divider including a pair of resistors in series connected between input and output terminals thereof, and a capacitor coupled across each resistor for also providing a capacitance voltage divider.
  • switching means is Wired for coupling one attenuating means from said first group to selected different attenuating means of said second group in diiferent switching positions of said switching means, and wherein further positions of said switching means connect further attenuating means from said first group to the said selected dilferent attenuating means of said second group.
  • Attenuator apparatus having multiple selectable switch positions for cascading selected ones of a first group of attenuating means with a selected one of a second group of attenuating means comprising an apparatus input terminal,
  • a first multiple position switch for coupling said apparatus input terminal to a selected input of one of a first group of attenuating means
  • a second multiple position switch for connecting said apparatus output terminal to an output of one of said second group of attenuating means
  • a third multiple position switch for coupling an output of one of said first group of attenuating means to said intermediate coupling means
  • a fourth multiple position switch for connecting said intermediate coupling means to the input of a selected one of said second group of attenuating means
  • said switches being interconnected with said attenuating means such that in various positions of the said switches differing possible combinations of attenuating means from said first and second groups are cascaded,
  • said switches having at least one low attenuation switching position for coupling the apparatus input terminal and the apparatus output terminal via said'first switch and said second switch bypassing said third and fourth switches in order to reduce the shunt capacitance associated with such switchingposition.
  • the apparatus according to claim 6 including means directly connecting a selected contact of said first switch in said low attenuation switching position to a selected contact ofsaid second switch in the said low attenuation switching position.

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  • Attenuators (AREA)
US508784A 1965-11-19 1965-11-19 Attenuator apparatus Expired - Lifetime US3369173A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US508784A US3369173A (en) 1965-11-19 1965-11-19 Attenuator apparatus
NL6614872A NL6614872A (en:Method) 1965-11-19 1966-10-21
DE19661541874 DE1541874A1 (de) 1965-11-19 1966-10-26 Daempfungs-Schaltung
GB49125/66A GB1116730A (en) 1965-11-19 1966-11-02 Attenuator apparatus
FR83165A FR1501221A (fr) 1965-11-19 1966-11-09 Réduction de l'amplitude d'un oscillogramme

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Application Number Priority Date Filing Date Title
US508784A US3369173A (en) 1965-11-19 1965-11-19 Attenuator apparatus

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US3369173A true US3369173A (en) 1968-02-13

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US508784A Expired - Lifetime US3369173A (en) 1965-11-19 1965-11-19 Attenuator apparatus

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US (1) US3369173A (en:Method)
DE (1) DE1541874A1 (en:Method)
FR (1) FR1501221A (en:Method)
GB (1) GB1116730A (en:Method)
NL (1) NL6614872A (en:Method)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3479609A (en) * 1966-06-13 1969-11-18 Us Army Attenuation circuit using a tuned amplifier whose q is varied by shunting resistors
US3541430A (en) * 1966-06-13 1970-11-17 Paul P Luger Digital potentiometers made with fixed impedances
US3594632A (en) * 1970-03-13 1971-07-20 Paul P Luger Adjustable attenuators and filter apparatus
JPS4724033U (en:Method) * 1971-04-06 1972-11-17
US3753170A (en) * 1971-02-10 1973-08-14 Tektronix Inc Step attenuator apparatus having attenuator stages selectively connected in cascade by cam actuated switches
US3908178A (en) * 1974-05-28 1975-09-23 Bejed Inc Plug-in adjustable attenuator construction
DE3404191A1 (de) * 1983-02-07 1984-08-16 Tektronix, Inc., Beaverton, Oreg. Verfahren und schaltungsanordnung zur frequenzkompensation in daempfungsschaltungsanordnungen

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2948834B1 (fr) * 2009-07-31 2011-08-26 Thales Sa Pont electronique d'asservissement serigraphie compense en frequence

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2999202A (en) * 1956-06-04 1961-09-05 Gilfillan Bros Inc Voltage divider setting device
US3014187A (en) * 1960-05-16 1961-12-19 United Telecontrol Electronics Variable step attenuator
US3252080A (en) * 1963-05-13 1966-05-17 Honeywell Inc Digitally adjustable attenuator

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2999202A (en) * 1956-06-04 1961-09-05 Gilfillan Bros Inc Voltage divider setting device
US3014187A (en) * 1960-05-16 1961-12-19 United Telecontrol Electronics Variable step attenuator
US3252080A (en) * 1963-05-13 1966-05-17 Honeywell Inc Digitally adjustable attenuator

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3479609A (en) * 1966-06-13 1969-11-18 Us Army Attenuation circuit using a tuned amplifier whose q is varied by shunting resistors
US3541430A (en) * 1966-06-13 1970-11-17 Paul P Luger Digital potentiometers made with fixed impedances
US3594632A (en) * 1970-03-13 1971-07-20 Paul P Luger Adjustable attenuators and filter apparatus
US3753170A (en) * 1971-02-10 1973-08-14 Tektronix Inc Step attenuator apparatus having attenuator stages selectively connected in cascade by cam actuated switches
JPS4724033U (en:Method) * 1971-04-06 1972-11-17
US3908178A (en) * 1974-05-28 1975-09-23 Bejed Inc Plug-in adjustable attenuator construction
DE3404191A1 (de) * 1983-02-07 1984-08-16 Tektronix, Inc., Beaverton, Oreg. Verfahren und schaltungsanordnung zur frequenzkompensation in daempfungsschaltungsanordnungen

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Publication number Publication date
GB1116730A (en) 1968-06-12
DE1541874A1 (de) 1969-10-23
FR1501221A (fr) 1967-11-10
NL6614872A (en:Method) 1967-05-22

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