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WO2007019509A2 - Reseau a retroaction pour amplification de gain eleve a commande de bande passante et de gain amelioree - Google Patents

Reseau a retroaction pour amplification de gain eleve a commande de bande passante et de gain amelioree Download PDF

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Publication number
WO2007019509A2
WO2007019509A2 PCT/US2006/030899 US2006030899W WO2007019509A2 WO 2007019509 A2 WO2007019509 A2 WO 2007019509A2 US 2006030899 W US2006030899 W US 2006030899W WO 2007019509 A2 WO2007019509 A2 WO 2007019509A2
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WO
WIPO (PCT)
Prior art keywords
resistor
amplifier
gain
tee
circuit
Prior art date
Application number
PCT/US2006/030899
Other languages
English (en)
Other versions
WO2007019509A3 (fr
Inventor
Robert D. Washburn
Robert F. Mcclanahan
Original Assignee
Thunder Creative Technologies, Inc.
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 Thunder Creative Technologies, Inc. filed Critical Thunder Creative Technologies, Inc.
Publication of WO2007019509A2 publication Critical patent/WO2007019509A2/fr
Publication of WO2007019509A3 publication Critical patent/WO2007019509A3/fr

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/04—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements with semiconductor devices only
    • H03F3/08—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements with semiconductor devices only controlled by light
    • H03F3/087—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements with semiconductor devices only controlled by light with IC amplifier blocks
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/08—Modifications of amplifiers to reduce detrimental influences of internal impedances of amplifying elements
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/34—Negative-feedback-circuit arrangements with or without positive feedback
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/42—Modifications of amplifiers to extend the bandwidth
    • H03F1/48—Modifications of amplifiers to extend the bandwidth of aperiodic amplifiers
    • H03F1/486—Modifications of amplifiers to extend the bandwidth of aperiodic amplifiers with IC amplifier blocks
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/45—Differential amplifiers
    • H03F3/45071—Differential amplifiers with semiconductor devices only
    • H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
    • H03F3/45475—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using IC blocks as the active amplifying circuit
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/36—Indexing scheme relating to amplifiers the amplifier comprising means for increasing the bandwidth
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45101—Control of the DC level being present
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45166—Only one input of the dif amp being used for an input signal
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45522—Indexing scheme relating to differential amplifiers the FBC comprising one or more potentiometers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45528—Indexing scheme relating to differential amplifiers the FBC comprising one or more passive resistors and being coupled between the LC and the IC

Definitions

  • the network relates to the field of high gain, wide bandwidth amplifiers.
  • FIG. 1 shows the transimpedance amplifier in a common application, converting a photodiode current into an output voltage.
  • reverse biased photo detector diode DlOO couples the positive terminal of bias voltage source +VD D at node NlOO to the negative input of operational amplifier AlOO at node NlOl.
  • the negative terminal of source +VDD and the positive input of operational amplifier AlOO are connected to ground.
  • Feedback resistor RlOO couples the output of operational amplifier AlOO at node N102 to the negative input of operational AlOO at node NlOl.
  • the transimpedance of the amplifier circuit of Figure 1 is set by the Value of resistor RlOO.
  • Gain is a dimensionless quantity representing the ratio of powers, voltages, or currents at 2 nodes in a circuit or a ratio of one the quantity at one node to a defined standard value for the quantity.
  • Transimpedance is a ratio between a voltage (output) and a current (input) and has the basic unit of ohm. Particularly with transimpedance amplifiers, the transimpedance functions in a like manner as voltage gain in a voltage input- voltage output amplifier. The transimpedance is set by the feedback resistor value which functions as the proportionality constant between the input and output. For convenience, the term gain will be used as a substitute for transimpedance in the remainder of this application.
  • Transimpedance amplifiers frequently have high gain.
  • An example is the Analog Devices AD8015, which is described by the manufacturer as "...a wide bandwidth, single supply transimpedance amplifier optimized for use in a fiber optic receiver circuit".
  • the AD8015 has an internal lOK-ohm feedback resistor. Of course the high resistance value makes the feedback resistor a relatively large thermal noise source.
  • the AD8015 die has a typical input capacitance of 0.2pF and a SOIC package capacitance of approximately 0.4pF. Allowing approximately 0.5pF for the circuit board pad and input node trace capacitance implies a total input capacitance of approximately IpF.
  • the resulting RC time constant is 10ns with an associated transfer function pole at 15.9MHz. Both significantly limit practical performance and bandwidth.
  • the system is a feedback network structure, used in one embodiment with high gain, wide bandwidth amplifiers. It allows realization of substantially more of the potential amplifier bandwidth capability made possible by modern semiconductor fabrication techniques and equipment than has been achieved using conventional gain setting, feedback circuits.
  • the system overcomes a limitation imposed by the presence of a pole in the transfer function of an amplifier, formed by the feedback resistor and the parasitic capacitance of the amplifier input.
  • high gain requires a large value feedback resistor, use of which results in a low frequency of the pole, and severely limited useable bandwidth.
  • the RC time constant formed by the feedback resistor and the parasitic capacitance significantly limit the large signal transient response time of the amplifier.
  • the system provides for use of lower value resistors, substantially increasing the pole frequency and allowing significantly greater realizable bandwidth.
  • the system includes a Tee resistor network to perform feedback and gain setting functions for an amplifier.
  • the system includes a Tee resistor network to perform feedback and gain setting functions for an operational amplifier.
  • the system includes a Tee network to perform feedback and gain setting functions for a voltage amplifier circuit.
  • the system includes a Tee resistor network to perform feedback and gain setting functions for a transimpedance amplifier.
  • the system includes a Tee resistor network to perform feedback and gain setting functions for an amplifier, wherein the resistor-capacitor time constant formed by the equivalent resistance of the Tee resistor network and the parasitic capacitance coupling the amplifier input to ground is substantially less than the resistor-capacitor time constant formed by the resistance of the feedback resistor of the present art and the parasitic capacitance coupling the amplifier input to ground, wherein the amplifiers and the gains of both amplifier circuits are substantially the same.
  • the system includes multiple Tee resistor networks to perform feedback and gain setting functions, wherein the Tee resistor networks are connected in cascade, wherein series connected resistors in the cascade connection are or are not combined into a single resistor of equivalent value.
  • the system includes one or more Tee resistor networks to perform feedback and gain setting for an amplifier circuit, wherein the resistance of one or more shunt legs of the Tee resistor networks is a variable resistance and wherein the variation of the variable resistance varies the gain of the amplifier circuit.
  • the system includes one or more Tee resistor networks to perform feedback and gain setting for an amplifier circuit, wherein the resistance of one or more shunt legs of the Tee resistor networks is a variable resistance and wherein the variable resistance is set in whole or in part by a digitally controlled variable resistor such as a digital potentiometer.
  • the system includes a Tee resistor network wherein the shunt resistor is coupled to a DC offset voltage source.
  • the system includes a compensated Tee resistor- capacitor network to perform feedback and gain setting functions for an amplifier.
  • Figure 1 is a circuit diagram of a transimpedance amplifier of the present art.
  • Figure 2 is a circuit diagram of a fixed gain embodiment of the system.
  • Figure 3 is a circuit diagram of a variable gain embodiment of the system.
  • Figure 4 is a circuit diagram of a variable gain embodiment of the system with feedback circuit comprised of multiple Tee networks.
  • the system is directed to the feedback network used in high gain, wide band amplifiers.
  • numerous specific details are set forth to provide a more thorough description of embodiments of the system. It is apparent, however, to one skilled in the art, that the system may be practiced without these specific details. In other instances, well known features have not been described in detail so as not to obscure the system.
  • the system enables electronic circuit designers to realize wider useable bandwidth and faster large signal response in high gain, feedback amplifiers than is achieved using classic (prior art) feedback network configurations. This is accomplished by replacing the classic feedback network configuration with a Tee structure that is implemented with relatively low value resistors while achieving equal or higher gain than realized with the classic feedback network configurations and their higher value resistors.
  • circuits are typically shown as purely resistive networks. This is done for purposes of example only and is not intended to be a limitation of the system. This does not imply that parasitic reactive elements and networks are not present, but that the significance of the reactive elements is dependent on the detailed implementation for a specific application and set of performance specifications.
  • Amplifier Tee Resistor Feedback Networks for High Gain and Wide Bandwidth
  • transimpedance amplifier configuration with the same input source, overall gain (transimpedance), and output signal level as shown in Figure 1 and discussed as part of the present background art.
  • the illustration represents one embodiment of the system for a transimpedance amplifier and is illustrated in Figure 2.
  • the values for resistors R200 and R201 maybe chosen or estimated based upon required amplifier performance characteristics and then adjusted as part of a design optimization. In one embodiment, desired performance is achieved when the values of resistors R200 and R202 are approximately equal.
  • the value of resistor R200 may not be set arbitrarily small as the overall amplifier gain would not be realizable with a resistor R202 of approximately equal value.
  • a larger value for resistor R202 could provide the necessary gain while reducing the basic benefits of the system.
  • the loss of benefit occurs because the larger resistance value for resistor R202 and the parasitic capacitance associated with the physical resistors and mounting pads form a transfer function pole at a lower frequency and a larger RC time constant than for the case where resistors R200 and R202 are of similar value. However, this typically is not a problem due to the low RC time constant on the T-node (Node 200) due to the relatively low resistance value for resistor R201.
  • a larger resistance value for resistor R202 may also increase thermal noise.
  • resistor R201 should be chosen to be significantly lower than the value of resistor R200, yet not so small that the parasitic inductance of resistor R201 becomes significant in determining the impedance of the shunt resistor branch of the Tee network. All other elements of the amplifier circuit being equal, the lower the value of resistor R201, the higher the gain of the amplifier circuit. Although small values for resistor R201 are not precluded, it is generally preferred to keep the value of resistor R201 at or above 10-ohms for non-integrated implementations to avoid effects of parasitic inductance of resistor R201 at high frequencies.
  • resistors R200 and R201 Selecting values for resistors R200 and R201 to be 300-ohms and 10-ohms respectively, for example, the value of resistor R202 calculates to be approximately 334-ohms. Assuming the same lpf amplifier input parasitic capacitance previously discussed, the RC time constant has been reduced from 10ns to 0.3ns and the associated pole in the transfer function has been moved from a frequency of approximately 15.9MHz to a frequency of approximately 530.5MHz where it poses far less potential to limit amplifier performance capability.
  • Amplifier Tee Resistor Feedback Networks with Variable Gain Control
  • the mathematical expression for overall gain of the amplifier circuit includes elements that are or include the ratio of a series to shunt resistor value. Making either resistor a variable resistor such as a potentiometer can then make the overall gain variable and controllable.
  • the shunt resistor(s) is typically chosen since the controller mechanism is much easier to implement than one for a series resistor that requires a differential control signal.
  • Figures 3 and 4 illustrated typical implementations of a variable gain capability.
  • Particularly useful embodiments include a digital potentiometer, which is readily available with up to 1024 selectable values. Use of a digital potentiometer can allow the system processor to set the gain as part of an overall configuration of an entire system.
  • the digital potentiometer, or any other form of variable resistor can be used as a single component implementation for resistors R201 of Figure 3 as well as R401 and R403 of Figure 4. It is also extremely useful to use one or more fixed resistors in conjunction with the variable resistor to form a series, parallel, or series-parallel network configuration to replace the single variable resistor.
  • the replacement network not only provides for precise limiting the range of gain variation, it also provides for finer resolution for gain settings within the limited range.
  • embodiments of the system can be realized using a wide variety of resistor values that depend on the overall gain to be realized and the chosen value of the feedback resistor coupled to the amplifier input (R200).
  • the lowest values for series resistors (R200 and R202) occur when the resistors are approximately equal in value. Realization of some gain levels may mean that resistor values remain unacceptably high.
  • Figure 4 illustrates a cascade of 2 Tee resistor networks with resistor R402 representing the series combination of the output resistor of the first Tee resistor network and the input resistor of the second Tee resistor network. It should be noted that there is a design tradeoff between the higher resistor value that results from combination into a single resistor R402 as opposed to 2 lower value resistors R402A and R402B (not shown) in series with resulting increased parasitic capacitance and inductance.
  • Figure 4 shows the shunt resistors as variable resistors, which provides embodiments with adjustable gain as discussed in the previous section. Cascaded embodiments can be implemented with either fixed or variable shunt resistors as appropriate for a particular application.
  • FIG. 4 The benefit of a cascade configuration can be readily seen by comparing the configuration shown in Figure 2 with a cascade configuration using a 30-ohm input resistor, 10- ohm shunt resistors, and resistors of approximately 30-ohms for the remaining series resistors. For purposes of illustration, the shunt resistor value of 10-ohms has been retained.
  • the circuit of Figure 4 will be used for element identification purposes when reference is made to the cascade configuration.
  • Figure 4 nominally illustrates a true voltage gain amplifier.
  • the circuits of Figures 3 and 4 can be analyzed as the previous transimpedance amplifiers if input signal source V300 and resistor R300 are replaced by a current source of value V300/R300 where the resistance value of resistor R300 is large.
  • a lOOuA input current and a 1 volt output signal requires a gain (transimpedance) is 10000 and the values of resistors R200, R201, and R202 to provide the gain are approximately 300-ohms, 10-ohms, and 334-ohms respectively.
  • R400 chosen to be 30-ohms or 10% of the value for resistor R200 in the configuration of Figure 2.
  • the magnitude of the voltage at node N400 is 3mv and the current through resistor R401 is 30OuA.
  • the current through resistor R402 is thus 40OuA, and the magnitude of the voltage at node N401 is 15mv.
  • this is the equivalent output voltage for the circuit of Figure 2 with the values of resistors R200, R201, and R202 being 30-ohms, 10-ohms, and 30-ohms respectively.
  • the gain of the configuration is 150.
  • the currents through resistors R403 and R404 are 1.5mA and 1.9mA respectively.
  • the magnitude of the voltage at node Nl 02 is 72mV and the overall gain is 720. It is again clear that either some of the resistor values are too low to achieve the overall gain or at least one additional Tee resistor network needs to be added in cascade.
  • resistor R404 Assuming an additional Tee resistor network is added and the value of resistor R404 remains unchanged (resistor R404 would couple node N401 to node N402, resistor R405 (10- ohms) would couple node N402 to ground and resistor R406 (30-ohms) would couple node N402 to node Nl 02.
  • the currents through resistors R405 and R406 are 7.2mA and 9.ImA respectively.
  • the magnitude of the voltage at node N102 is 0.345 and the overall gain is 3450.
  • the feedback current would be 43.6mA. This may be considered high for a low noise, low distortion, operational amplifier based system, a factor that will significantly influence the number of cascade stages and resistance values used.
  • Amplifier Tee Resistor Feedback Networks with DC Offset Voltage Control it may be beneficial to provide the capability to supply an external DC offset voltage to the feedback network of the configurations.
  • the configurations can include circuits using operational amplifiers with a high DC offset voltage specification or circuits wherein the operational amplifier positive input is not connected to ground.
  • the capability is realizable for various embodiments of the system by coupling one or more shunt resistor branches within the Tee resistor feedback network to a DC voltage source of the appropriate DC offset voltage value instead of ground. In so doing, it is necessary to insure that either the DC offset voltage sources adequately approximate the "zero" source impedance characteristic of an ideal voltage source or the impedance characteristics of the DC offset sources are incorporated within the desired impedance of the shunt resistor branches.
  • a well-known technique associated with resistor networks is frequency compensation. This technique replaces some or all of the individual resistors in a network with resistor-capacitor combinations.
  • Various circuit topologies can be employed depending on the nature and function of the overall network. Compensation is particularly useful with large resistor values (and resulting large R-C time constants), or at very high frequencies such as defined in relation to the upper frequency capabilities of associated amplifiers.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)
  • Control Of Amplification And Gain Control (AREA)
  • Optical Communication System (AREA)

Abstract

Le système selon l'invention est un circuit amplificateur à rétroaction qui permet une augmentation significative de la bande passante utilisable avec un gain comparable comparé à des amplificateurs de l'état antérieur de la technique intégrant des topologies de circuits à rétroaction classiques. La bande passante accrue est obtenue par augmentation significative de la fréquence du pôle dans la caractéristique de transfert qui est formée par la résistance de rétroaction et la capacité d'entrée de l'amplificateur parasite. Dans des modes de réalisation, l'invention concerne l'application à un amplificateur d'adaptation d'impédance tel qu'utilisé avec des diodes photodétectrices dans des circuits récepteurs optiques. Dans un autre mode de réalisation, l'invention concerne un circuit amplificateur opérationnel à entrée de tension-sortie de tension de base. L'invention concerne enfin des moyens de commande du gain de l'amplificateur avec une résistance variable qui peut être mise en oeuvre avec un potentiomètre numérique.
PCT/US2006/030899 2005-08-05 2006-08-07 Reseau a retroaction pour amplification de gain eleve a commande de bande passante et de gain amelioree WO2007019509A2 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US70608605P 2005-08-05 2005-08-05
US60/706,086 2005-08-05
US46296606A 2006-08-07 2006-08-07
US11/462,966 2006-08-07

Publications (2)

Publication Number Publication Date
WO2007019509A2 true WO2007019509A2 (fr) 2007-02-15
WO2007019509A3 WO2007019509A3 (fr) 2007-07-26

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010025002A1 (fr) * 2008-08-28 2010-03-04 Qualitau, Inc. Source de courant modifiée (mcs) avec commutation de plage sans palier
CN108270410A (zh) * 2018-02-06 2018-07-10 华中科技大学 一种带宽与增益多级可调的程控放大器及控制方法
EP4247934A4 (fr) * 2020-11-17 2025-01-15 Nuclein, LLC Appareil et procédés de diagnostic moléculaire

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US3979670A (en) * 1973-08-17 1976-09-07 Western Electric Company, Inc. Apparatus for detecting and measuring peak-to-peak values in electrical signals
US4029976A (en) * 1976-04-23 1977-06-14 The United States Of America As Represented By The Secretary Of The Navy Amplifier for fiber optics application
US4470020A (en) * 1982-05-06 1984-09-04 Mohr Daniel R Virtual ground preamplifier for magnetic phono cartridge
US5973566A (en) * 1998-03-31 1999-10-26 Hewlett Packard Company Discrete step variable gain inverting amplifier with constant ratio between adjacent gains
US6140868A (en) * 1999-03-09 2000-10-31 Lucent Technologies, Inc. Master tuning circuit for adjusting a slave transistor to follow a master resistor
US7057454B2 (en) * 2004-05-27 2006-06-06 Infineon Technologies Ag Resistor and switch-minimized variable analog gain circuit

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010025002A1 (fr) * 2008-08-28 2010-03-04 Qualitau, Inc. Source de courant modifiée (mcs) avec commutation de plage sans palier
CN102138077A (zh) * 2008-08-28 2011-07-27 夸利陶公司 具有无缝范围切换的改进型电流源(mcs)
JP2012501584A (ja) * 2008-08-28 2012-01-19 クウォリタウ・インコーポレーテッド シームレスなレンジ切り替えを備えた変調電流源（ｍｃｓ）
CN102138077B (zh) * 2008-08-28 2014-03-05 夸利陶公司 具有无缝范围切换的改进型电流源(mcs)
TWI476556B (zh) * 2008-08-28 2015-03-11 Qualitau Inc 具有無縫範圍切換之修改的電流源（ｍｃｓ）及其操作方法
DE112009002052B4 (de) 2008-08-28 2019-03-21 Qualitau, Inc. Modifizierte Stromquelle mit übergangsloser Bereichsumschaltung
CN108270410A (zh) * 2018-02-06 2018-07-10 华中科技大学 一种带宽与增益多级可调的程控放大器及控制方法
CN108270410B (zh) * 2018-02-06 2020-05-19 华中科技大学 一种带宽与增益多级可调的程控放大器及控制方法
EP4247934A4 (fr) * 2020-11-17 2025-01-15 Nuclein, LLC Appareil et procédés de diagnostic moléculaire

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