WO2001067595A1 - Amplificateur d'instrumentation - Google Patents

Amplificateur d'instrumentation Download PDF

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Publication number
WO2001067595A1
WO2001067595A1 PCT/NL2001/000178 NL0100178W WO0167595A1 WO 2001067595 A1 WO2001067595 A1 WO 2001067595A1 NL 0100178 W NL0100178 W NL 0100178W WO 0167595 A1 WO0167595 A1 WO 0167595A1
Authority
WO
WIPO (PCT)
Prior art keywords
negative input
capacitors
output
capacitor
amplifier
Prior art date
Application number
PCT/NL2001/000178
Other languages
English (en)
Inventor
Guijie Wang
Gerardus Cornelis Maria Meijer
Original Assignee
Stichting Voor De Technische Wetenschappen
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Stichting Voor De Technische Wetenschappen filed Critical Stichting Voor De Technische Wetenschappen
Priority to AU2001241279A priority Critical patent/AU2001241279A1/en
Publication of WO2001067595A1 publication Critical patent/WO2001067595A1/fr

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers
    • H03G3/001—Digital control of analog signals
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/005—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements using switched capacitors, e.g. dynamic amplifiers; using switched capacitors as resistors in differential amplifiers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/261—Amplifier which being suitable for instrumentation applications

Definitions

  • the invention relates to an instrumentation amplifier comprising an amplifier unit having a high open- loop amplification, a positive input, a negative input and an output, the closed-loop amplification of the amplifier unit being defined by a network of capacitors of which at least one capacitor is connected between the output and the negative input, and at least one capacitor is positioned in the signal line connecting to the negative input . It may be assumed that such an embodiment of an instrumentation amplifier is known from the general network theory.
  • the instrumentation amplifier is characterized in that the network comprises a predetermined number of substantially equivalent and switchable N+M capacitors, which number depends on a desired gain factor N/M, in that during a clock cycle, M-capacitors are always connected in parallel between the output and the negative input, and in that the remain- ing N-capacitors during that clock cycle are parallel- connected in the signal line which connects to the negative input, and in that in consecutive clock cycles the capacitors are connected such that after N+M consecutive clock cycles, each capacitor has been connected once be- tween the output and the negative input of the amplifier unit.
  • the said N+M consecutive clock cycles together form one complete measuring cycle within which the amplification of a signal is realized.
  • the instrumentation amplifier is particularly suitable for the amplification of thermocouples or other sources supplying a stable or relatively inert varying voltage that is to be amplified.
  • the instrumentation amplifier achieves that the ca- pacitors, which are substantially equivalent, can and may differ slightly, without thereby significantly influencing the gain factor N/M that is realized.
  • the same is characterized in that one pin of each capacitor is coupled with the negative input of the amplifier unit, and the other pin is coupled with a first and a second switch, the first switch serving for the connection of the other pin with the signal line, and the second switch serving for the connection of the other pin with the output of the amplifier unit.
  • a switch is provided for short-circuiting the connection between the output and the negative input of the amplifier. This is a simple method for resetting the capacitor in the feedback path and a compensation for the direc -current voltage drift of the amplifier unit.
  • this Figure shows the amplifier unit 1 that is provided with a high open- loop amplification, a positive input 2, a negative input 3, and an output 4.
  • the open-loop amplification of the amplifier unit 1 is defined by a network of capacitors C x to C N+M* M-capacitors C N+1 to C N+M being connected in parallel between the output 4 and the negative input 3. Inciden- tally, M may also be 1.
  • the remaining capacitors C to C N are all connected in parallel and included in the signal line 5.
  • the N+M capacitors C x to C N+M all are substantially equivalent to one another.
  • the number of N+M capacitors is determined by the desired closed-loop ampli- fication N/M of the amplifier unit 1.
  • FIG 1 shows that in the signal line 5, switches S x and S 2 are incorporated for sampling the input signal. Said input signal feeds the parallel -connected capacitors ⁇ to C N .
  • the switching sequence of the switches S x and S 2 is shown in Figure 2.
  • Fig- ure 1 further shows another switch S 3 by means of which the output 4 and the negative input 3 of the amplifier unit 1 can be short-circuited. The activity of this switch is also shown in Figure 2.
  • Figure 2 further shows the progress of the output voltage at the output 4 whereby the output signal V out acquires a value, which is represented by the formula, shown at the left-hand bottom of Figure 2.
  • the capacitors C x to C NtM sequentially all move up, such that after a number of cy- cles each of them will have occupied the place of the feedback capacitors shown in Figure 1 once.
  • FIG. 3 shows that one pin of each capacitor C x to C N+M is coupled with the negative input 3 of the amplifier unit 1, and the other pin is coupled with a first and a second switch. These are for capacitor C x the switches 5.1 and 5.2.
  • the first switch 5.1 serves to connect the other pin of the capacitor C : with the signal line 5, while the second switch 5.2 serves to connect said other pin of the capacitor ⁇ with the output 4 of the amplifier unit.
  • the switches pertaining to the capacitors C x to C N all assume a corre- sponding position, while the switches pertaining to the capacitors C Ntl to C N+M assume a different position in relation thereto.
  • the first and second switch pertaining to a capacitor are always active alternately, which means that when one switch is open, the other switch is closed and vice versa.
  • the switches 5.3 and 5.4 pertaining to capacitor C N+M are, for example, connected such that said capacitor C N+M is connected in the feedback path between the output 4 and the negative input 3 of the amplifier unit 1.
  • This also ap- plies to the other capacitors C N+1 to C ⁇ M . ! connected in the feedback.
  • the switches of the other capacitors C x to C N assume a different position, which entails that said capacitors C 1 to C N are parallel-connected in the signal line 5.
  • the position shown in Figure 3 corresponds with the situation during one particular clock cycle.
  • each capacitor C r to C N+M assume positions in the network such that after N+M of said consecutive clock cycles, each capacitor C r to C N+M has been connected between the output 4 and the negative input 3 of the amplifier unit 1 at least once.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)

Abstract

La présente invention concerne un amplificateur d'instrumentation dont le module d'amplificateur comprend une amplification haute en boucle ouverte, une entrée positive, une entrée négative et une sortie. L'amplification en boucle fermée du module d'amplificateur est définie par un réseau de condensateurs dont l'un au moins est monté entre la sortie et l'entrée négative, un condensateur au moins se trouvant sur la ligne de signal desservant l'entrée négative. Le réseau comprend un nombre défini N+M de condensateurs sensiblement équivalents et commutables dont le nombre est fonction d'un facteur de gain attendu N/M. Pendant un cycle d'horloge, un nombre M de condensateurs est en permanence commuté en parallèle entre la sortie et l'entrée négatif. Pendant ce cycle d'horloge, le nombre restant N des condensateurs est commuté en parallèle dans la ligne du signal qui est connectée à l'entrée négative. Pour les cycles d'horloge suivants, les condensateurs sont commutés de façon qu'après N+M cycles d'horloge consécutifs, chaque condensateur ait été commuté au moins une fois entre la sortie et l'entrée négative du module d'amplificateur.
PCT/NL2001/000178 2000-03-03 2001-03-05 Amplificateur d'instrumentation WO2001067595A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2001241279A AU2001241279A1 (en) 2000-03-03 2001-03-05 Instrumentation amplifier

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL1014551 2000-03-03
NL1014551A NL1014551C2 (nl) 2000-03-03 2000-03-03 Instrumentatieversterker.

Publications (1)

Publication Number Publication Date
WO2001067595A1 true WO2001067595A1 (fr) 2001-09-13

Family

ID=19770934

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NL2001/000178 WO2001067595A1 (fr) 2000-03-03 2001-03-05 Amplificateur d'instrumentation

Country Status (3)

Country Link
AU (1) AU2001241279A1 (fr)
NL (1) NL1014551C2 (fr)
WO (1) WO2001067595A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4438354A (en) * 1981-08-14 1984-03-20 American Microsystems, Incorporated Monolithic programmable gain-integrator stage
US5574457A (en) * 1995-06-12 1996-11-12 Motorola, Inc. Switched capacitor gain stage
EP0934626A1 (fr) * 1996-03-28 1999-08-11 Stichting Voor De Technische Wetenschappen Amplificateur d'appareil de mesure

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4438354A (en) * 1981-08-14 1984-03-20 American Microsystems, Incorporated Monolithic programmable gain-integrator stage
US5574457A (en) * 1995-06-12 1996-11-12 Motorola, Inc. Switched capacitor gain stage
EP0934626A1 (fr) * 1996-03-28 1999-08-11 Stichting Voor De Technische Wetenschappen Amplificateur d'appareil de mesure

Also Published As

Publication number Publication date
AU2001241279A1 (en) 2001-09-17
NL1014551C2 (nl) 2001-09-04

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