Classifications

• • 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
  • H03F1/30—Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters
• • 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
  • H03F1/30—Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters
  • H03F1/306—Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters in junction-FET amplifiers
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
  • H03F3/189—High-frequency amplifiers, e.g. radio frequency amplifiers
  • H03F3/19—High-frequency amplifiers, e.g. radio frequency amplifiers with semiconductor devices only
  • H03F3/193—High-frequency amplifiers, e.g. radio frequency amplifiers with semiconductor devices only with field-effect devices
  • H03F3/1935—High-frequency amplifiers, e.g. radio frequency amplifiers with semiconductor devices only with field-effect devices with junction-FET devices
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
  • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
  • H03F3/24—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers of transmitter output stages
  • H03F3/245—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers of transmitter output stages with semiconductor devices only
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
  • H03F3/60—Amplifiers in which coupling networks have distributed constants, e.g. with waveguide resonators
  • H03F3/601—Amplifiers in which coupling networks have distributed constants, e.g. with waveguide resonators using FET's, e.g. GaAs FET's
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F2200/00—Indexing scheme relating to amplifiers
  • H03F2200/18—Indexing scheme relating to amplifiers the bias of the gate of a FET being controlled by a control signal
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F2200/00—Indexing scheme relating to amplifiers
  • H03F2200/447—Indexing scheme relating to amplifiers the amplifier being protected to temperature influence
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F2200/00—Indexing scheme relating to amplifiers
  • H03F2200/451—Indexing scheme relating to amplifiers the amplifier being a radio frequency amplifier
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F2200/00—Indexing scheme relating to amplifiers
  • H03F2200/504—Indexing scheme relating to amplifiers the supply voltage or current being continuously controlled by a controlling signal, e.g. the controlling signal of a transistor implemented as variable resistor in a supply path for, an IC-block showed amplifier

Definitions

• the invention relates to temperature compensation of a bias voltage of an amplifier.
• An object of the invention is to provide an improved temperature compensating circuit.
• a temperature compensating circuit for an amplifier comprising a voltage regulator having at least three terminals, a voltage between a first pair of terminals being adjustable and a reference voltage between a second pair of terminals being thermally stable, and at least part of the output voltage of the temperature compensating circuit being provided from the first pair of terminals; a component arrangement including at least one component with a known temperature dependency of voltage, the at least one component with a known temperature dependency being coupled between the first pair of termi- nals of the voltage regulator; a resistor coupling of at least two resistor units for forming a slope coefficient as a ratio of values of the resistors in the resistor coupling, each of the resistor units including at least one resistor, and the resistor coupling is coupled to the at least one component having a known temperature dependency and being coupled between the first pair of terminals of the voltage regulator for providing the temperature compensating circuit with an output voltage having a temperature dependency which
• a temperature compensating circuit for an amplifier comprising means for regulating voltage, the means for regulating voltage having at least three terminals, a voltage between a first pair of terminals being adjustable and a reference voltage between a second pair of terminals being thermally stable, and at least part of the output voltage of the temperature compensating circuit being provided from the first pair of terminals; means for providing a known temperature dependency; means for forming a slope coefficient; and the circuit is configured to provide an output voltage having a temperature dependency which is a function of the slope coefficient and the known temperature dependency.
• a temperature compensating circuit for an amplifier comprising a voltage regulator having at least three terminals, a voltage between a first pair of terminals being adjustable and a reference voltage between a second pair of terminals being thermally stable, and at least part of the output voltage of the temperature compensating circuit being the voltage from the first pair of terminals; a component arrangement including at least one diode with a known temperature dependency of voltage, the at least one diode with a known temperature dependency being forward biased between the first pair of terminals of the voltage regulator; a resistor coupling of at least two resistors for forming a slope coefficient as a ratio of values of the resistors in the resistor coupling, the at least one diode with a known temperature dependency being coupled in series with a series resistor, and the series coupling of the component arrangement and the series resistor being coupled in parallel with a parallel resistor, the parallel resistor and the series resistor being the resistors of the resistor coupling; and the resistor coupling is
• an amplifier including a temperature compensating circuit, the temperature compensating circuit comprising a voltage regulator having at least three terminals, a voltage between a first pair of terminals being adjustable and a reference voltage between a second pair of terminals being thermally stable, and at least part of the output voltage of the temperature compensating circuit being provided from the first pair of terminals; a component arrangement including at least one component with a known temperature dependency of voltage, the at least one component with a known temperature dependency being coupled between the first pair of terminals of the voltage regulator; a resistor coupling of at least two resistor units for forming a slope coefficient as a ratio of values of the resistors in the resistor coupling, each of the resistor units including at least one resistor, and the resistor coupling is coupled to the at least one component having a known temperature dependency and being coupled between the first pair of terminals of the voltage regulator for providing the temperature compensating circuit with an output voltage having a temperature dependency which is a function of the slope coefficient and the known temperature dependency of the at
• a transmitter including an amplifier with a temperature compensating circuit, the temperature compensating circuit of the transmitter comprising a voltage regulator having at least three terminals, a voltage between a first pair of terminals being adjustable and a reference voltage between a second pair of terminals being thermally stable, and at least part of the output voltage of the temperature compensating circuit being provided from the first pair of terminals; a component arrangement including at least one component with a known temperature dependency of voltage, the at least one component with a known temperature dependency being coupled between the first pair of terminals of the voltage regulator; a resistor coupling of at least two resistor units for forming a slope coefficient as a ratio of values of the resistors in the resistor coupling, each of the resistor units including at least one resistor, and the resistor coupling is coupled to the at least one component having a known temperature dependency and being coupled between the first pair of terminals of the voltage regulator for providing the temperature compensating circuit with an output voltage having a temperature dependency which is a function of the slope coefficient and
• a base station including an amplifier with a temperature compensating circuit, the temperature compensating circuit of the transmitter comprising a voltage regulator having at least three terminals, a voltage between a first pair of terminals being adjustable and a reference voltage between a second pair of terminals being thermally stable, and at least part of the output voltage of the temperature compensating circuit being provided from the first pair of terminals; a component arrangement including at least one component with a known temperature dependency of voltage, the at least one component with a known temperature dependency being coupled between the first pair of terminals of the voltage regulator; a resistor coupling of at least two resistor units for forming a slope coefficient as a ratio of values of the resistors in the resistor coupling, each of the resistor units including at least one resistor, and the resistor coupling is coupled to the at least one component having a known temperature dependency and being coupled between the first pair of terminals of the voltage regulator for providing the temperature compensating circuit with an output voltage having a temperature dependency which is a function of the slope coefficient
• a user terminal including an amplifier with a temperature compensating circuit, the temperature compensating circuit of the transmitter comprising a voltage regulator having at least three terminals, a voltage between a first pair of terminals being adjustable and a reference voltage between a second pair of ter- minals being thermally stable, and at least part of the output voltage of the temperature compensating circuit being provided from the first pair of termi- nals; a component arrangement including at least one component with a known temperature dependency of voltage, the at least one component with a known temperature dependency being coupled between the first pair of terminals of the voltage regulator; a resistor coupling of at least two resistor units for forming a slope coefficient as a ratio of values of the resistors in the resistor coupling, each of the resistor units including at least one resistor, and the resistor coupling is coupled to the at least one component having a known temperature dependency and being coupled between the first pair of terminals of the voltage regulator for providing the temperature compensating circuit with an output voltage having a temperature dependency which is
• an amplifier including a temperature compensating circuit, the temperature com- pensating circuit comprising means for regulating voltage having at least three terminals, a voltage between a first pair of terminals being adjustable and a reference voltage between a second pair of terminals being thermally stable, and at least part of the output voltage of the temperature compensating circuit being provided from the first pair of terminals; means for providing a known temperature dependency; means for forming a slope coefficient; and the circuit is configured to provide an output voltage having a temperature dependency which is a function of the slope coefficient and the known temperature dependency.
• a transmitter including an amplifier with a temperature compensating circuit, the temperature compensating circuit of the transmitter comprising means for regulating voltage, the means for regulating voltage having at least three terminals, a voltage between a first pair of terminals being adjustable and a reference voltage between a second pair of terminals being thermally stable, and at least part of the output voltage of the temperature compensating circuit being provided from the first pair of terminals; means for providing a known temperature dependency; means for forming a slope coefficient; and the temperature compensating circuit is configured to provide an output voltage having a temperature dependency which is a function of the slope coefficient and the known temperature dependency.
• a base station including an amplifier with a temperature compensating circuit, the temperature compensating circuit of the transmitter comprising means for regulating voltage, the means for regulating voltage having at least three ter- minals, a voltage between a first pair of terminals being adjustable and a reference voltage between a second pair of terminals being thermally stable, and at least part of the output voltage of the temperature compensating circuit being provided from the first pair of terminals; means for providing a known temperature dependency; means for forming a slope coefficient; and the temperature compensating circuit is configured to provide an output voltage having a temperature dependency which is a function of the slope coefficient and the known temperature dependency.
• a user terminal including an amplifier with a temperature compensating circuit, the temperature compensating circuit of the transmitter comprising means for regulating voltage, the means for regulating voltage having at least three terminals, a voltage between a first pair of terminals being adjustable and a reference voltage between a second pair of terminals being thermally stable, and at least part of the output voltage of the temperature compensating circuit being provided from the first pair of terminals; means for providing a known temperature dependency; means for forming a slope coefficient; and the temperature compensating circuit is configured to provide an output voltage having a temperature dependency which is a function of the slope coefficient and the known temperature dependency.
• Preferred embodiments of the invention are described in the dependent claims. The method and system of the invention provide several advantages.
• the temperature slope can be determined as a ratio of resistors and can be arbitrary in magnitude.
• the slope can be predetermined for the amplifying component and adjusted in production by a proper resistor selection. Furthermore, the slope is independent of the nominal voltage setting thus facilitating production alignment.
• Figure 1A shows a radio system
• Figure 1B shows a transmitter
• Figure 2A shows an embodiment of a temperature compensating circuit
• Figure 2B illustrates an amplifier
• Figure 3 illustrates an embodiment of a temperature compensating circuit
• Figure 4 illustrates an embodiment of a temperature compensating circuit
• Figure 5 illustrates an embodiment of a temperature compensating circuit
• Figure 6 illustrates an embodiment of a temperature compensating circuit
• Figure 7 illustrates an embodiment of a temperature compensating circuit
• Figure 8 illustrates performance of the circuit.
• a typical digital radio system comprises subscriber equipment 10 to 14, at least one base station 16, and a base station controller 18, which can also be called a radio network controller.
• the subscriber equipment 10 to 14 communicates with the base station 16 using signals 20 to 24.
• the base station 16 can be connected to the base station controller 18 by a digital transmission link 26.
• the subscriber equipments 10 to 14 may be fixedly installed terminals, user equipment installed in a vehicle or portable mobile terminals.
• the signals 20 to 24 between the subscriber equipment 10 to 14 and the base station 16 carry digitised information, which is e.g. speech, data information or control information produced by subscribers or by other elements in the radio system.
• Figure 1B shows a transmitter.
• the transmitter may include an encoder 50 to code an input signal (or many input signals), a modulator 52 to modulate and possibly to spread the signal, a mixer 54 to mix the signal with a carrier having a desired radio frequency, a power amplifier 56 to amplify the signal to a desired extent, an antenna 58 to transmit the RF signal as electromagnetic radiation, and a controller 60 to control the blocks 50 to 56.
• the controller 60 may be used to control the slope of the temperature compensating circuit.
• a battery or any other DC (Direct Current) power source 100 may provide a constant voltage to the circuit.
• a source resistor unit R s 102 can be an internal resistor of the power source 100, but it may also represent a combination of an internal resistor and an external resistor.
• a voltage regulator 104 such as a programmable precision shunt regulator TL431 or the like, may be coupled between the source resistor 102 and a negative terminal of the power source 100.
• the voltage regulator 106 may have three terminals 106 to 110. A voltage between the first pair of terminals, referring to the cathode 106 and the reference terminal 110, is adjustable and depends on the values of the components between the terminals.
• a resistor coupling 130 of at least two resistor units is coupled between the first pair of terminals.
• This and other resistor units mentioned in this application comprise at least one resistor.
• the resistor coupling 130 is coupled to a component arrangement 114 of at least one compo- nent having a known temperature dependency of voltage wherein the component having a known temperature dependency may be a semiconductor or a temperature dependent resistor.
• the semiconductor component can be a forward biased diode or a bipolar junction transistor (NPN) whose base and collector are coupled together.
• V d V do + (T - To)dV/dT, (1 )
• V d o a voltage over the diode at a nominal temperature T 0
• dV/dT is a coefficient defining a change in voltage when the temperature changes.
• a voltage over certain pair of terminals of a temperature dependent component or combination of temperature dependent components can be ap- proximated in a similar manner.
• a thermally stable reference voltage is formed over a reference resistor R r 118 between the second pair of terminals, referring to the anode 108 of the voltage regulator and the reference terminal 110.
• the value of the reference resistor 116 defines the current flowing through the reference resistor 116.
• a positive terminal 120 of the temperature compensating circuit which is in the same potential as the cathode 106 of the temperature dependent component 104 can provide an amplifier 124 with a positive output voltage. This can be the gate voltage V ga t e of a FET (Field Effect Transistor).
• the drain voltage V dd can be taken straight from the power source 100 as shown in Figure 2A.
• a negative output voltage can be coupled to the amplifier 124 from a negative terminal 122 which is in the same potential as the anode 108 of the temperature dependent component.
• the output voltage V ou t(i) between the positive output terminal 120 and the negative output terminal 122 can be expressed as:
• the alternative output voltage V out ( 2 ) natu- rally has the same temperature dependent term as in the equation (2).
• the slope can be changed by changing the values of the resistors.
• One of the resistor units can also have a constant value. Thus, the value of only one resistor unit needs to be varied. This can take place by selecting a suitable resistor or by adjusting the resistor.
• V d o 0.3V
• T 0 25°C
• V ref 2.5V.
• the maximum slope obtainable is that of the temperature dependent component 114 used.
• the slope is typically about -2mV/°C.
• the output voltage is dependent on the number of the threshold voltages of the temperature dependent component.
• the combined slope is a linear function of the number of the temperature dependent components and can simply be expressed as a similar man- be expressed as
• Figure 2B shows a circuit 170 of an amplifier 150.
• the input signal may be fed through a capacitor 152 and an input-matching network 154 to the amplifying component 150 which may be a FET (Field Effect Transistor).
• the input matching network 154 matches the impedances between the signal source and the amplifying component.
• the gate of the FET may be coupled to a gate voltage V ga t e formed by the temperature compensating circuit through a resistor, coil or a transmission line 156 proving proper impedance.
• the source may be connected to ground and the drain may be coupled to operational voltage V dd through a coil or a transmission line 158 having proper impedance.
• the output of the amplifier i.e.
• FIG. 3 With reference to Figure 3, consider another example of a temperature compensating circuit. This circuit is basically similar to Figure 2A except that a different kind of voltage regulator, such as LM4041-ADJ or the like, is used. Another difference is the use of an adjustable resistor unit R epo t 212.
• the resistor unit 212 may be mechanically or electronically adjustable.
• the reference voltage V ref is formed between the cathode 206 (positive terminal 120 of the circuit) and the reference terminal 210, and the adjustable voltage is formed between the reference terminal 210 and the anode 208 (negative terminal 122 of the circuit).
• the output voltage can be expressed as:
• the slope can be controlled by the selection of the resistor units R p and R d .
• the range of the output voltage can be adjusted by the adjustable resistor unit R epo t 212 which may include an adjustable potentiometer.
• the potentiometer may be an electrically controlled potentiometer.
• V out _max 4.0V
• V ou t_min 2.5V
• nominal slope dV/dT 0 -1.888mV/°C
• nominal temperature T 0 25°C
• N 2
• R d 15690 ⁇
• R p 11790 ⁇
• V out _ ma ⁇ 4.006V
• Vout_m!n 2.503V
• slope dV/dT -1 .948mV/°C.
• the reference voltage V ref is formed over the reference resistor unit 118 between the cathode of the voltage regulator 204 and the reference terminal 210.
• the adjustable voltage which in this example depends on the values of the limiting resistor unit 308, the adjustable resistor unit 310, the transis- tor Q1 300 and the resistor coupling 130, is formed between the reference terminal 210 and the anode 208 of the voltage regulator 204.
• Vb e V b n e om + (T - T 0 )dV be /dT, (6)
• V b n e om means the voltage between the base and the emitter at the nominal temperature T 0 and dV be /dT is a coefficient defining a change in voltage when the temperature changes.
• the node voltage V b at the base of the transistor Q1 can be expressed as:
• l c is a collector current and ⁇ is a current gain.
• the collector current can be determined as - ' ref 2 - c +v b r + - ⁇ 0 )dv be /d ⁇ (8)
• the output voltage V ou t(i) can be expressed as J. Ri V b r - T 0 R 2 dV be /dT - To ⁇ dV /dT + R 2 V / b n n o°m r V ref ( R 3 + Repot ) +v, R ref (10) ref
• the temperature slope dV/dT of the output voltage V out( i ) in the first term is ⁇ R + R .
• dV/dT ⁇ - — — dV be /dT .
• the transistor Q2 306 is not necessary in R 1 principle, the output voltage is "pushed and pulled" without it by the input signal and that may cause linearity defects.
• the output voltage V g of the transistor Q2 306 can be expressed as v + R 1 V b n e om - T 0 R 2 dV be /dT - To ⁇ dV ⁇ /dT + R 2 V, v ref (R 3 + Repot ) +v r ⁇ f - v b r - ⁇ - ⁇ 0 )dv be /d ⁇ (11) R ref
• the first term — ! — — - — — has a R 1 temperature dependency, the other terms being constant with respect to the temperature.
• the function of the limiting resistor unit R 3 308 is to restrict the range of R 1 adjustment made by the adjusting resistor unit R epot 310.
• Figure 5 illustrates a circuit version that is different from the one in Figure 4.
• the adjusting resistor unit R epot 310 is coupled between the resistor 300 and ground instead of coupling it between the resistor 302 and the resistor 308 in Figure 4, the effective operation of the circuits in Figures 4 and 5 is the same.
• Figure 6 illustrates a circuit similar to that in Figures 4 and 5.
• resistor units R ⁇ 506 and R cp 508 allow setting the temperature slope from zero to that of a single b-e junction. Note that the temperature slopes of the transistors Q1 and Q3 should at least approximately cancel each other. Finally, a constant current source 510 is employed to maintain the slopes and current gains of the transistors.
• a voltage regulator such as the LM4041-ADJ can be employed and it generates an offset voltage 512 in the process. Assume simple temperature dependence for the transistor base- emitter saturation voltage
• V be _sat V be _nom + (T - T 0 )dV/dT, (12)
• Thevenin equivalent voltage source starts with the Thevenin equivalent voltage source to find the emitter voltage of the transistor Q1.
• the temperature coefficient of resistance (TCR) is broken into a common TCR to describe the change in the end-to-end resistance over temperature and a differential TCR to describe how well the two resistors track to each other.
• the resistors R i0 516 and R ⁇ 518 can be expressed as
• Rhi R ⁇ P ot(1 - k po t)[1 + (TCRc - TCR d /2)(T - T 0 )], (14)
• TCR C denotes common TCR
• TCR d denotes differential TCR
• k po. is a real number from 0 to 1 which would represent the position of the wiper in a mechanical analogy to the electronic potentiometer.
• the base current can be deduced from the collector emitter current. The latter is forced by the current source, Ibias, used to generate the fixed voltage offset.
• Ibias current source
• the base voltage of the transistor Q1 can now be expressed as
• Vb 1 Vthev + (RthevlbiasV ⁇ « Vthev, (17)
• V p rime lbias(RcpRcs/(Rcs + Rep)) + (RcpVb2 + RcsV c l)/(Rcp + Res), (21 )
• the base voltage of the transistor Q3 can be determined as
• V be _sat V be _sat
• the temperature slope at the nominal temperature T 0 can be expressed as ( ⁇ is assumed large)
• ⁇ -- ⁇ _l ( ⁇ Rcp + ADD1 + ADD2 + ADD3 + ADD4)/DENOM, (24) 3T..-, 5T
• the slope variation can be considered constant with respect to the settings from a practical point of view.
• the value of resistance of the electronically adjustable potentiometer and hence the nominal voltage can be adjusted not o ⁇ ly during manufactur- ing of a device but also during every day use of the device. For example, aging of the temperature dependent components can be taken into account and the bias voltage can be adapted to the changes in the temperature dependence. This can be performed by changing the voltage as a function of time or some other measurable performance metric.
• Figure 7 shows a circuit with a changeable voltage and temperature slope.
• the circuit is otherwise similar to the circuit in Figure 6 except that the resistor units 506, 508 have been replaced with an adjustable potenti- ometer 700 to provide an adjustable slope mechanism.
• the resistor coupling includes an adjustable potentiometer for adjusting the slope coefficient and the adjustable potentiometer provides the temperature compensating circuit with an output voltage having a temperature dependency which is an adjustable function of the slope coefficient and the known temperature de- pendency of at least one component in the component arrangement 114.
• the potentiometer 700 can be a mechanically adjustable potentiometer or an electronically adjustable potentiometer (similar to the potentiometer 310 in Figure 6).
• a resistor 702 having a value k»R pot can be considered to correspond to the resistor unit 506, where R pot is the total resistance of the potentiometer and k is a real number from 0 to 1.
• the adjustable potentiometer J00 substitutes for only one of the resistor units 506, 508.
• the amplifier can also be switched off when there is no input signal to the amplifier. This can be accomplished by setting the minimum output voltage of the temperature compensating circuit below a threshold of the amplifying component. For example, if the gate voltage of a LDMOS (Laterally Diffused Metal Oxide Semiconductor) transistor, which can be used as an amplifying component, is dropped below a certain threshold voltage determined by the manufacturer, no current can flow between the drain and the source and hence the component can be switched off.
• Figure 8 shows the operation of the temperature compensating circuit of Figures 4, 5 and its example.
• the slope can vary substantially such that, for example, a range of -1.5 mV/°C to -4.0 mV/°C may be needed.
• the voltage regulator may be any type of circuit that functions as a voltage comparator against a temperature compensated reference.
• the voltage regulator may be an integrated or a discrete device having at least three terminals.

Landscapes

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

Applications Claiming Priority (3)

Publications (1)

Family

ID=34921910

Family Applications (1)

Country Status (3)

Families Citing this family (1)

Family Cites Families (4)

• 2005
  • 2005-03-08 EP EP05717270A patent/EP1726091A1/de not_active Withdrawn
  • 2005-03-08 WO PCT/FI2005/000143 patent/WO2005086343A1/en active Application Filing
  • 2005-03-08 KR KR1020067019699A patent/KR100794774B1/ko not_active IP Right Cessation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events