WO2000039918A1 - Analogue modulation method and monolithic integrated circuit with mixer stage comprising non-polarised field-effect transistors - Google Patents

Analogue modulation method and monolithic integrated circuit with mixer stage comprising non-polarised field-effect transistors Download PDF

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Publication number
WO2000039918A1
WO2000039918A1 PCT/FR1999/003276 FR9903276W WO0039918A1 WO 2000039918 A1 WO2000039918 A1 WO 2000039918A1 FR 9903276 W FR9903276 W FR 9903276W WO 0039918 A1 WO0039918 A1 WO 0039918A1
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Prior art keywords
modulation
signal
analog
transistors
low frequency
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PCT/FR1999/003276
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French (fr)
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Cyrille Boulanger
Luc Lapierre
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Centre National D'etudes Spatiales (C.N.E.S.)
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Publication of WO2000039918A1 publication Critical patent/WO2000039918A1/en

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C1/00—Amplitude modulation
    • H03C1/52—Modulators in which carrier or one sideband is wholly or partially suppressed
    • H03C1/54—Balanced modulators, e.g. bridge type, ring type or double balanced type
    • H03C1/542—Balanced modulators, e.g. bridge type, ring type or double balanced type comprising semiconductor devices with at least three electrodes
    • H03C1/547—Balanced modulators, e.g. bridge type, ring type or double balanced type comprising semiconductor devices with at least three electrodes using field-effect transistors
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C7/00—Modulating electromagnetic waves
    • H03C7/02—Modulating electromagnetic waves in transmission lines, waveguides, cavity resonators or radiation fields of antennas
    • H03C7/025—Modulating electromagnetic waves in transmission lines, waveguides, cavity resonators or radiation fields of antennas using semiconductor devices

Definitions

  • the invention relates to a method for analog modulation of a high frequency carrier signal with a low frequency analog modulation signal, and to a monolithic integrated circuit comprising at least one mixer stage intended to form a signal modulated from a signal. high frequency carrier and a low frequency analog modulation signal.
  • the expressions “high frequency” and “low frequency” mean that the frequency of the carrier signal is higher than that of the analog modulation signal without prejudging the absolute value of these frequencies.
  • the invention is advantageously, but not exclusively, applicable to the case of carrier signals whose frequency is located in the microwave range (frequency between 1 GHz and 300 GHz), the integrated circuit then being called MMIC.
  • the low frequency analog modulation signals have a frequency which can be between 0 Hz (continuous signal) and 1 GHz.
  • Analog linear I / Q modulator circuits are necessary for certain types of modulation, such as square raised cosine (SRC) modulation in order to minimize spectral congestion and increase the number of communication channels in each allocated frequency band.
  • SRC square raised cosine
  • the mixer circuits are formed essentially of polarized FET transistors (cf. "GaAs Monolithic Direct Linear (1-2.8) GHz QPSK Modulator ", R. Pyndiah, P. Jean, R. Leblanc, JC Meunier, 19 ⁇ EuMC ConfInterconnect, 4-7 Sep 1989, London;” A 10-14 GHz Linear MMIC Vector Modulator With Less Than. 0.1 and 0.8 ° Amplitude and phase error "Flm Nan den Bogaart, R. Pyndiah, 1990, IEEE MTT-S Digest, p.465- 468).
  • the mixer circuits have a high electrical consumption, which can be a drawback in many applications, in particular in space systems.
  • they require the installation of numerous auxiliary polarization circuits and impose numerous adjustments. They are therefore complex and require a complex environment, which puts a strain not only on their manufacturing cost, but also on the overall size and the time required for their design, their manufacture and their implementation, an increasingly parameter important in the modern integrated circuit industry.
  • the mixer circuits are formed essentially of diodes (cf. "Conventional and New Applications for the Quadrature IF Microwave Mixer", D. Neuf, S. Spohrer, Microwave Journal, January 1983, p.
  • the invention aims to overcome these drawbacks by proposing an analog modulation method and a monolithic integrated circuit comprising at least one mixer stage, which do not modify the spectral bulk of the signal, without power consumption, and compatible with the reliability constraints of space systems.
  • the invention also aims to allow the realization of an analog linear I / Q modulator circuit.
  • the invention further aims to provide such a circuit which is compact (maximum dimension of the order of 3mmx3mm in the microwave domain).
  • the invention further aims to propose such an integrated circuit in which the low frequency analog modulating signal is isolated in a simple manner from the high frequency carrier signal.
  • the invention also aims to propose stages, called adaptation stages, having the function of generating analog signals modulating low frequency adapted to the mixing stages, in particular which do not themselves harm the linearity of the mixing stages.
  • the invention further aims to propose such an integrated circuit incorporating on the same substrate stages for adapting analog signals modulating low frequency.
  • the invention also aims to propose such a circuit which can be designed, manufactured, and implemented in a simple, rapid and economical manner.
  • the invention aims to propose an integrated circuit compatible with the constraints of development times imposed by the space industry. We know that the success of the development of a modern space system depends not only on the solutions and technical components implemented, but also for a large part on the time necessary for its concrete realization.
  • the invention relates to an analog modulation method as mentioned above, characterized in that:
  • a monolithic integrated circuit comprising at least one mixer stage comprising:
  • modulation transistors mounted with the sources connected in common to ground
  • a modulated signal is recovered on an output connected to each of the drains of the modulation transistors by means of a stage vectorally summing on the output the signals formed on the drains of the modulation transistors,
  • each mixer stage comprises: - an input, called carrier input, receiving the carrier signal at high frequency,
  • modulation transistors mounted with the sources connected in common to ground and with the non-polarized drains receiving high frequency signals from the carrier input, centered on a zero voltage, so that the modulation transistors are not polarized
  • non-polarized field effect transistors have a resistance whose value varies non linearly according to the gate-source voltage Vgs. Nevertheless, the inventors have noted with surprise, and contrary to what we thought until now, that despite this lack of linearity, it is possible to obtain a linear modulated signal with respect to the modulation signal thanks to the invention . Thus, in a circuit according to the invention, the non-polarized modulation field effect transistors do not have the function of performing switching or chopping as in the prior art. It should be noted that there are already known modulators by phase displacement with two phase states, called BPSK, (FR-2 760 301 or "High bit rate four phase MMIC remodulation demodulator and modulator", A.
  • BPSK phase displacement with two phase states
  • the assembly described has many shortcomings and drawbacks: filters are necessary to separate the high frequency and the low frequency; the couplers ensure a phase shift of the high frequency signals without actually making them opposite as is imposed by theory, hence operational imperfections; in the case of 180 ° couplers, the circuit presents unacceptable problems of adaptation on the high frequency inputs; the circuit has a dimension of 2.4mmx2.8mm at 26-29 GHz while it achieves only one mixer stage, and its size would become prohibitive for lower frequencies.
  • the gate of the transistors receiving a high level signal the transistors have pure switching operation (all or nothing) over the entire range where the drain-source resistance Rds has non-linear variations as a function of the gate-source voltage Vgs. Consequently, this document does not teach a solution for obtaining a linear analog mixer stage with respect to the signal applied to the gate of the transistors.
  • analog signals modulating at low frequency I or Q, ⁇ or Q centered on a voltage Vn chosen of the order of the pinch voltage Vp of the modulation transistors to minimize losses.
  • the pinch voltage Vp of a field effect transistor is the gate-source voltage Vgs for which there is no more current between the drain and the source when the transistor is in the polarized state in standard conditions.
  • the inventors have found that there is a value for the voltage on which the analog signals modulating I, Q; ⁇ , Q are centered, which has the effect of minimizing the losses of the mixer stage, that is to say for which the power of the modulated signal obtained at output is maximum.
  • the circuit comprises means of -90 ° phase shift of the high frequency carrier signal between the carrier input and the drain of one of the modulation transistors, and means of + phase shift. 90 ° of the high frequency carrier signal between the carrier input and the drain of the other modulation transistor.
  • the circuit incorporates means, called shaping means, capable of generating at least one pair I, ⁇ ; Q, Q of analog signals modulating at low frequency complementary to each other from the analog low frequency modulation signal I; Q.
  • the amplitude of variation of the modulating analog signals is linked to the amplitude of the modulation signal, itself controlled by means external to the circuit according to the invention.
  • said shaping means comprise a current source; a differential amplifier stage generating, from the current source and a low frequency analog modulation signal î; Q, two analog signals modulating at low frequency I, î; Q, Q complementary delivered on the grids of two field effect transistors, each of them being mounted in common drain with its source connected to a divider bridge providing at output one of the two analog signals modulating at low complementary frequency I , ⁇ ; Q, Q centered on a voltage Vn, and intended to be applied to the gate of a modulation transistor.
  • a circuit according to the invention can be adapted to form an analog I / Q modulator.
  • it is characterized in that it comprises at least two stages mel ⁇ angeu / r. s each receiving one of the two analog modulation signals I; Q low frequency, a main high frequency input receiving a high frequency carrier signal, means for applying this high frequency carrier signal to the carrier inputs of the mixer stages with between them a predetermined non-zero phase shift ⁇ et, and means for summing in phase on a common output the two modulated signals from the mixer stages, so as to form an analog linear I / Q modulator circuit.
  • ⁇ ⁇ 90 °.
  • a circuit according to the invention is formed by a single integrated circuit chip produced in MMIC technology, the frequency of the high frequency carrier signal being greater than 1 Gigahertz.
  • the invention also relates to a method and a circuit characterized in combination by all or some of the characteristics mentioned above or below.
  • Other objects, characteristics and advantages of the invention appear from the following description, given only by way of nonlimiting example, and which refers to the appended figures in which:
  • FIG. 1 is a diagram of an analog linear I / Q modulator circuit according to the invention
  • FIG. 2 is a diagram of a mixer stage of a circuit according to the invention.
  • FIG. 3 is a diagram illustrating a stage for shaping the analog signals of a circuit according to the invention
  • FIG. 4 is an example of topography of an analog linear I / Q modulator circuit according to the diagram of the figure 1 ,
  • - Figure 6 is a diagram illustrating the variations in the power of the modulated signal obtained at the output of the circuit of FIG. 4 according to the level of the analog modulation signal.
  • the circuit according to the invention shown in Figure 1 is an I / Q modulator circuit.
  • This circuit includes a main high frequency input 1 receiving a high frequency carrier signal, two low frequency inputs 2,
  • This circuit also includes two mixer stages 5, 6 each allowing amplitude modulation of the carrier signal by one of the analog modulation signals I, Q.
  • Each mixer stage 5, 6 comprises an input, called the carrier input 7, 8, receiving the high frequency carrier signal from the main input 1 via a phase shifting circuit 9, 10, for example formed by an LC filter, and a Wilkinson power divider 11 making it possible to split the high-frequency carrier signal in phase into two identical signals attacking the inputs of the phase-shifting circuits 9, 10.
  • one of the phase-shifting circuits 9 is for example constituted by an LC circuit phase-shifting the signal by + 45 °, while the other phase-shifting circuit 10 is an LC circuit phase-shifting the signal by -45 °, so that the carrier inputs of the mixer stages 5, 6 have between them a phase shift ⁇ non-zero predetermined equal to 90 °.
  • Each mixer stage 5, 6 receives two analog signals modulating at low complementary frequency I, ⁇ , respectively Q, Q complementary to each other from a stage, called shaping stage 12, 13, which generates these complementary analog signals from each low frequency analog modulation signal I, Q applied to the low frequency inputs 2, 3.
  • Examples of complementary low frequency analog modulating signals I, I, Q, Q have been shown as received by the mixer stages 5, 6.
  • the signals I and I are complementary in that at each instant their sum I + î is equal to a constant. The same goes for Q and Q.
  • Each mixer stage 5, 6 delivers an amplitude modulated signal from the high frequency carrier signal it receives, and the low frequency analog modulation signal I, respectively
  • This modulated signal is supplied on an output 14, 15 of the stage mixer 5, 6, and the two outputs 14, 15 of the mixer stages 5, 6 are summed vectorially by a Wilkinson coupler 16 on the common output 4.
  • the analog signals modulating low frequency I, ⁇ or respectively Q, Q are delivered by the shaping stages 12, 13 to each mixer stage 5, 6 on two separate inputs 17, 18, or respectively 19, 20, of these stages mixers 5, 6.
  • FIG. 2 represents the diagram of a mixer stage 5, 6 of a circuit according to the invention.
  • This mixer stage 5, 6 comprises two identical field effect transistors 21, 22, called modulation transistors 21, 22, mounted in common source, that is to say with the two sources 23, 24 connected in common to the circuit mass.
  • the drains 25, 26 of the two transistors 21, 22 receive high frequency signals from the carrier input 7, 8 which are centered on a zero DC voltage (ground), so that the modulation transistors 21, 22 do not are not polarized.
  • the high frequency signals applied to the drains 25, 26 result from the high frequency carrier signal applied to the carrier input 7, 8, transformed by phase shift circuits 27, 28 into two high frequency signals, the first of which is phase-shifted by -90 ° relative to the carrier signal by the phase shift circuit 27, while the second is phase-shifted by + 90 ° by the phase shift circuit 28 relative to the carrier signal.
  • the phase shift circuits 27, 28 are interposed between the carrier input 7, 8 and the drains 25, 26 of the modulation transistors 21, 22. They may simply consist of low-pass T or low-pass T filters 27 28.
  • the carrier input 7, 8 is therefore split into two branches, one of which goes to the first phase shift circuit 27 while the other goes to the second phase shift circuit 28.
  • the carrier input 7, 8 can be provided with a series inductor for impedance matching (not shown).
  • the two drains 25, 26 are combined in phase by a combiner circuit 29 with star inductances and parallel capacitance delivering the modulated signal on output 14, 15 of the mixer stage 5, 6.
  • the gates 30, 31 of the two modulation transistors 21, 22 are driven by the low frequency modulating analog signals themselves received on the low frequency inputs 17, 19, or 18, 20.
  • the first modulation transistor 21 receives the analog signal I or Q modulating at low frequency on its gate 30, while the second modulation transistor 22 receives on its gate 31 an analog signal I or Q modulating at complementary low frequency.
  • This voltage Vn is chosen to be of the order of the pinch voltage Vp of the modulation transistors 21, 22 in order to minimize the losses. Indeed, it is found that there is a value, of the order of the pinch voltage Vp, for which the losses are minimum, and that when one moves away from this value, the losses of the circuit increase rapidly.
  • Vmax-Vn Vn-Vmin ⁇ Amax.
  • Amax depends on the technology used to make the modulation transistors 21, 22.
  • FIG. 3 represents a diagram of a shaping stage 12, 13 making it possible to generate the complementary low frequency modulating analog signals from a low frequency analog modulation signal I, Q.
  • the diagram in FIG. 3 therefore represents one of the shaping stages 12, 13 of the circuit according to the invention shown in FIG. 1.
  • This circuit comprises a current source 40 formed by a field effect transistor whose gate is connected to the negative voltage VE (for example equal to -5 volts) whose source is connected by a series resistance to the negative voltage VE, and the drain provides the output of this current source via a series resistance; a differential amplifier stage 41 generating, from the current source 40 and the low frequency analog modulation signal I, Q, the two analog signals modulating at low frequency I, Q and, Q delivered on the gates 42, 43 of two field effect transistors 44, 45, each of them being mounted as a common drain with its source 46, 47 connected to a divider bridge 48, 49 supplying one of the two analog signals modulating at low frequency complementary I, ⁇ , Q, Q on the gates 30, 31 of the two modulation transistors 21, 22.
  • VE negative voltage
  • the differential amplifier stage 41 is also formed of two field effect transistors 50, 51, one of which receives the analog low-frequency modulation signal I, Q, on its gate 52 with a parallel matching resistor 60 of value R (for example 50 ⁇ ) connected to ground, while gate 53 of the other transistor 51 is connected to ground by an ad resistance aptitude 61 of R / 2 value connected to ground.
  • These two transistors 50, 51 have their sources 54, 55 connected together to the output of the current source 40 (series resistance of the drain of the field effect transistor of this source 40) and their drains 62, 63 connected to the gates 42, 43 of the two transistors 44, 45.
  • Resistors 56, 57 are interposed between the grids 42, 43 and the drains 58, 59 of the transistors 44, 45 which are connected to the positive voltage Vcc (for example of the order of +5 volts).
  • Vcc positive voltage
  • Each of the shaping stages 12, 13 can advantageously be produced on the same integrated circuit chip as the mixer stages 5, 6.
  • the two mixer stages 5, 6 are produced on the same circuit chip integrated with connection means capable of receiving signals I, ⁇ , Q, Q from external shaping circuits.
  • This circuit is entirely realized on a chip of
  • inputs I, ⁇ , Q, Q are also provided to allow, as a variant, the piloting of the circuit from the outside, for example at for testing purposes, from external shaping circuits.
  • FIG. 6 represents, for the circuit of FIG. 4, the variations of the power of the output signal obtained with this circuit according to the level of the analog modulation signals I, Q at low frequency.
  • the sum Pe of the powers of the analog modulation signals î and Q is shown on the abscissa (in dBm: decibels relative to the milliwatt) and on the ordinate the power Ps (in dBm) of the output signal obtained on output 4.
  • the analog signals modulating I, î, Q Q must have a sufficient amplitude, greater than a minimum value Amin, for the circuit to have sufficient precision (amplitude and phase of the modulated signal obtained), according to the requirements of its use.
  • the modulator circuit it is supplied by two sinusoidal signals phase shifted by 90 ° forming the modulation signals î,
  • phase pads decreases when the amplitude of the modulating signal decreases but remains very good over a dynamic range of 10 dB.
  • the following table 1 thus gives, for three different frequencies F, the values of the precision ⁇ A of amplitude and ⁇ of phase of the output signal of the circuit according to the input power Pe of the low frequency analog modulation signals I, Q.

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Abstract

The invention concerns a method and a circuit for analogue phase and/or amplitude modulation of a high frequency carrier signal with an Î or Q low frequency analogue modulation signal, comprising at a least mixer stage (5, 6) including two field-effect transistor, called modulation transistors (21, 22), mounted with the sources (23, 24) jointly connected to ground, and whereof the drains (25, 26) are not polarised. The method consists in applying on the gates (30, 31) of the modulation transistors (21, 22) I or Q modulating analog electric signals, <o>I</o> or <o>Q</o> at low frequency matching each other, whereof the amplitude is less than a maximum value Amax beyond which the power of the signal modulated in output is no longer proportional to the power of the modulating signal.

Description

PROCEDE DE MODULATION ANALOGIQUE ET CIRCUIT INTEGRE ANALOG MODULATION METHOD AND INTEGRATED CIRCUIT
MONOLITHIQUE A ETAGE MELANGEUR COMPRENANT DESMONOLITHIC MIXED STAGE COMPRISING
TRANSISTORS A EFFET DE CHAMP NON POLARISESNON-POLARIZED FIELD-EFFECT TRANSISTORS
L'invention concerne un procédé de modulation analogique d'un signal de porteuse à haute fréquence avec un signal de modulation analogique basse fréquence, et un circuit intégré monolithique comprenant au moins un étage mélangeur destiné à former un signal modulé à partir d'un signal de porteuse à haute fréquence et d'un signal de modulation analogique basse fréquence.The invention relates to a method for analog modulation of a high frequency carrier signal with a low frequency analog modulation signal, and to a monolithic integrated circuit comprising at least one mixer stage intended to form a signal modulated from a signal. high frequency carrier and a low frequency analog modulation signal.
Dans tout le texte, les expressions "haute fréquence" et "basse fréquence" signifient que la fréquence du signal de porteuse est plus élevée que celle du signal de modulation analogique sans préjuger de la valeur absolue de ces fréquences. L'invention est avantageusement, mais non exclusivement, applicable au cas de signaux de porteuse dont la fréquence est située dans le domaine des hyperfréquences (fréquence comprise entre 1 GHz et 300 GHz) le circuit intégré étant alors dit MMIC. Dans ce cas, les signaux de modulation analogiques à basse fréquence ont une fréquence qui peut être comprise entre 0 Hz (signal continu) et 1 GHz.Throughout the text, the expressions “high frequency” and “low frequency” mean that the frequency of the carrier signal is higher than that of the analog modulation signal without prejudging the absolute value of these frequencies. The invention is advantageously, but not exclusively, applicable to the case of carrier signals whose frequency is located in the microwave range (frequency between 1 GHz and 300 GHz), the integrated circuit then being called MMIC. In this case, the low frequency analog modulation signals have a frequency which can be between 0 Hz (continuous signal) and 1 GHz.
Les circuits dits modulateurs I/Q linéaires analogiques sont nécessaires pour certains types de modulation, tels que la modulation SRC ("square raised cosine") dans le but de minimiser l'encombrement spectral et d'augmenter le nombre de canaux de communication dans chaque bande de fréquence allouée.Analog linear I / Q modulator circuits are necessary for certain types of modulation, such as square raised cosine (SRC) modulation in order to minimize spectral congestion and increase the number of communication channels in each allocated frequency band.
On connaît essentiellement deux types de circuits mélangeurs permettant d'obtenir des modulateurs I/Q linéaires analogiques.Essentially two types of mixing circuits are known, making it possible to obtain analog linear I / Q modulators.
Dans un premier type connu, les circuits mélangeurs sont formés essentiellement de transistors FET polarisés (cf. "GaAs Monolithic Direct Linear (1-2.8) GHz Q.P.S.K Modulator", R. Pyndiah, P. Jean, R. Leblanc, J-C Meunier, 19ώ EuMC Conférence, 4-7 sept. 1989, London ; "A 10-14 GHz Linear MMIC Vector Modulator With Less Than. 0.1 and 0.8° Amplitude and phase error" F.l.m. Nan den Bogaart, R. Pyndiah, 1990, IEEE MTT-S Digest, p.465- 468).In a first known type, the mixer circuits are formed essentially of polarized FET transistors (cf. "GaAs Monolithic Direct Linear (1-2.8) GHz QPSK Modulator ", R. Pyndiah, P. Jean, R. Leblanc, JC Meunier, 19 ώ EuMC Conférence, 4-7 Sep 1989, London;" A 10-14 GHz Linear MMIC Vector Modulator With Less Than. 0.1 and 0.8 ° Amplitude and phase error "Flm Nan den Bogaart, R. Pyndiah, 1990, IEEE MTT-S Digest, p.465- 468).
Ces circuits présentent une consommation électrique élevée, ce qui peut constituer un inconvénient dans de nombreuses applications, notamment dans les systèmes spatiaux. En outre, ils nécessitent l'implantation de nombreux circuits annexes de polarisation et imposent de nombreux réglages. Ils sont donc complexes et nécessitent un environnement complexe, ce qui grève non seulement leur coût de fabrication, mais également l'encombrement de l'ensemble et le temps nécessaire à leur conception, leur fabrication et leur mise en œuvre, paramètre de plus en plus important dans l'industrie moderne des circuits intégrés. Dans un deuxième type connu, les circuits mélangeurs sont formés essentiellement de diodes (cf. "Conventional and New Applications for the Quadrature IF Microwave Mixer", D. Neuf, S. Spohrer, Microwave Journal, January 1983, p. 99-109) dont l'utilisation est proscrite dans les circuits intégrés car les diodes disponibles ne sont pas fiables dans les modes de fonctionnement correspondant à la réalisation de mélangeurs. De plus, dans les mélangeurs d'architecture simple, le signal de porteuse et le signal modulant sont appliqués sur les mêmes bornes, et il est difficile de les isoler l'un de l'autre. Ces circuits sont donc nécessairement réalisés en technologie hybride (et non monolithique), incorporent nécessairement de nombreux filtres et composants passifs et ne peuvent donc pas être de taille réduite.These circuits have a high electrical consumption, which can be a drawback in many applications, in particular in space systems. In addition, they require the installation of numerous auxiliary polarization circuits and impose numerous adjustments. They are therefore complex and require a complex environment, which puts a strain not only on their manufacturing cost, but also on the overall size and the time required for their design, their manufacture and their implementation, an increasingly parameter important in the modern integrated circuit industry. In a second known type, the mixer circuits are formed essentially of diodes (cf. "Conventional and New Applications for the Quadrature IF Microwave Mixer", D. Neuf, S. Spohrer, Microwave Journal, January 1983, p. 99-109) whose use is prohibited in integrated circuits because the available diodes are not reliable in the operating modes corresponding to the production of mixers. In addition, in simple architecture mixers, the carrier signal and the modulating signal are applied to the same terminals, and it is difficult to isolate them from each other. These circuits are therefore necessarily made in hybrid technology (and not monolithic), necessarily incorporate many filters and passive components and therefore cannot be reduced in size.
L'invention vise à pallier ces inconvénients en proposant un procédé de modulation analogique et un circuit intégré monolithique comprenant au moins un étage mélangeur, qui ne modifient pas l'encombrement spectral du signal, sans consommation électrique, et compatibles avec les contraintes de fiabilité des systèmes spatiaux.The invention aims to overcome these drawbacks by proposing an analog modulation method and a monolithic integrated circuit comprising at least one mixer stage, which do not modify the spectral bulk of the signal, without power consumption, and compatible with the reliability constraints of space systems.
L'invention vise également à permettre la réalisation d'un circuit modulateur I/Q linéaire analogique. L'invention vise en outre à proposer un tel circuit qui soit peu encombrant (dimension maximum de l'ordre de 3mmx3mm dans le domaine des hyperfréquences).The invention also aims to allow the realization of an analog linear I / Q modulator circuit. The invention further aims to provide such a circuit which is compact (maximum dimension of the order of 3mmx3mm in the microwave domain).
L'invention vise en outre à proposer un tel circuit intégré dans lequel le signal modulant analogique basse fréquence est isolé de façon simple du signal de porteuse à haute fréquence.The invention further aims to propose such an integrated circuit in which the low frequency analog modulating signal is isolated in a simple manner from the high frequency carrier signal.
A ce titre, l'invention vise également à proposer des étages, dits étages d'adaptation, ayant pour fonction de générer des signaux analogiques modulant basse fréquence adaptés aux étages mélangeurs, notamment qui ne nuisent pas eux-mêmes à la linéarité des étages mélangeurs. L'invention vise en outre à proposer un tel circuit intégré incorporant sur le même substrat des étages d'adaptation des signaux analogiques modulant basse fréquence.As such, the invention also aims to propose stages, called adaptation stages, having the function of generating analog signals modulating low frequency adapted to the mixing stages, in particular which do not themselves harm the linearity of the mixing stages. . The invention further aims to propose such an integrated circuit incorporating on the same substrate stages for adapting analog signals modulating low frequency.
L'invention vise aussi à proposer un tel circuit qui peut être conçu, fabriqué, et mis en œuvre de façon simple, rapide et économique. En particulier, l'invention vise à proposer un circuit intégré compatible avec les contraintes de durées de développement imposées par l'industrie spatiale. On sait en effet que le succès d'un développement d'un système spatial moderne dépend non seulement des solutions et composants techniques mis en œuvre, mais aussi pour une grande part de la durée nécessaire à sa réalisation concrète.The invention also aims to propose such a circuit which can be designed, manufactured, and implemented in a simple, rapid and economical manner. In particular, the invention aims to propose an integrated circuit compatible with the constraints of development times imposed by the space industry. We know that the success of the development of a modern space system depends not only on the solutions and technical components implemented, but also for a large part on the time necessary for its concrete realization.
Pour ce faire, l'invention concerne un procédé de modulation analogique tel que mentionné ci-dessus, caractérisé en ce que :To do this, the invention relates to an analog modulation method as mentioned above, characterized in that:
- on choisit un circuit intégré monolithique comprenant au moins un étage mélangeur comprenant :- a monolithic integrated circuit is chosen comprising at least one mixer stage comprising:
. une entrée, dite entrée de porteuse, recevant le signal de porteuse à haute fréquence, . deux transistors à effet de champ identiques, dits transistors de modulation, montés avec les sources reliées en commun à la masse,. an input, called carrier input, receiving the high frequency carrier signal, . two identical field effect transistors, called modulation transistors, mounted with the sources connected in common to ground,
- on applique sur les drains des transistors de modulation, des signaux à haute fréquence issus de l'entrée de porteuse, déphasés l'un de l'autre de 180° et centrés sur une tension nulle, de sorte que les drains des transistors de modulation ne sont pas polarisés,- applying to the drains of the modulation transistors, high frequency signals from the carrier input, phase shifted from one another by 180 ° and centered on a zero voltage, so that the drains of the transistors modulation are not polarized,
- on récupère un signal modulé sur une sortie reliée à chacun des drains des transistors de modulation par l'intermédiaire d'un étage sommant vectoriellement sur la sortie les signaux formés sur les drains des transistors de modulation,a modulated signal is recovered on an output connected to each of the drains of the modulation transistors by means of a stage vectorally summing on the output the signals formed on the drains of the modulation transistors,
- on applique sur les grilles des transistors de modulation des signaux analogiques modulant I ou Q, I ou Q à basse fréquence issus dudit signal de modulation analogique basse fréquence I ou Q, complémentaires l'un de l'autre, dont l'amplitude est inférieure à une valeur maximum Amax au-delà de laquelle la puissance du signal modulé n'est plus proportionnelle à la puissance- Low-frequency analog signals modulating I or Q, I or Q from the said low-frequency analog modulation signal I or Q are applied to the gates of the modulation transistors, complementary to each other, the amplitude of which is less than a maximum value Amax beyond which the power of the modulated signal is no longer proportional to the power
Λ Λ du signal de modulation analogique basse fréquence I ou Q.Λ Λ of the low frequency analog modulation signal I or Q.
L'invention s'étend, en outre, à un circuit intégré monolithique tel que mentionné ci-dessus, caractérisé en ce que chaque étage mélangeur comprend : - une entrée, dite entrée de porteuse, recevant le signal de porteuse à haute fréquence,The invention also extends to a monolithic integrated circuit as mentioned above, characterized in that each mixer stage comprises: - an input, called carrier input, receiving the carrier signal at high frequency,
- deux transistors à effet de champ identiques, dits transistors de modulation, montés avec les sources reliées en commun à la masse et avec les drains non polarisés recevant des signaux à haute fréquence issus de l'entrée de porteuse, centrés sur une tension nulle, de sorte que les transistors de modulation ne sont pas polarisés,- two identical field effect transistors, called modulation transistors, mounted with the sources connected in common to ground and with the non-polarized drains receiving high frequency signals from the carrier input, centered on a zero voltage, so that the modulation transistors are not polarized,
- des moyens de déphasage de 180° entre le signal de porteuse à haute fréquence appliqué sur le drain de l'un des transistors de modulation et celui appliqué sur le drain de l'autre transistor de modulation, - une sortie reliée à chacun des drains des transistors de modulation par l'intermédiaire d'un étage sommant vectoriellement sur la sortie les signaux formés sur les drains des transistors de modulation pour délivrer un signal modulé sur la sortie, - des moyens pour appliquer sur les grilles des transistors de modulation, des signaux analogiques modulant I ou Q, ï ou Q à basse fréquence issus dudit signal de modulation analogique basse fréquence I ou Q , complémentaires l'un de l'autre, dont l'amplitude est inférieure à une valeur maximum Amax au-delà de laquelle la puissance du signal modulé n'est plus proportionnelle à la puissance du signal de modulation analogique bassemeans of 180 ° phase shift between the high frequency carrier signal applied to the drain of one of the modulation transistors and that applied to the drain of the other modulation transistor, - an output connected to each of the drains of the modulation transistors by means of a stage vectorally summing on the output the signals formed on the drains of the modulation transistors to deliver a modulated signal on the output, - means for applying to the gates of the modulation transistors, of analog signals modulating I or Q, ï or Q at low frequency originating from said analog low frequency modulation signal I or Q, complementary to each other, the amplitude of which is less than one maximum value Amax beyond which the power of the modulated signal is no longer proportional to the power of the low analog modulation signal
Λ Λ fréquence I ou Q.Λ Λ frequency I or Q.
On sait que les transistors à effet de champ non polarisés présentent une résistance dont la valeur varie non linéairement selon la tension grille-source Vgs. Néanmoins, les inventeurs ont constaté avec surprise, et contrairement à ce qu'on pensait jusqu'à maintenant, que malgré ce défaut de linéarité, il est possible d'obtenir un signal modulé linéaire par rapport au signal de modulation grâce à l'invention. Ainsi, dans un circuit conforme à l'invention, les transistors à effet de champ de modulation non polarisés n'ont pas pour fonction de réaliser une commutation ou un hâchage comme dans l'art antérieur. II est à noter que l'on connaît déjà des circuits modulateurs par déplacement de phase à deux états de phase, dits BPSK, (FR-2 760 301 ou "High bit rate four phase MMIC remodulation demodulator and modulator", A. Primerose et al, Proceedings of the GAAS 92 European Gallium Arsenide and related III-V compounds applications, Symposium, 27-29 avril 1992, NOORDWIJK) comprenant deux transistors à effet de champ non polarisés faisant office de commutateurs pour la modulation du signal de porteuse par un signal de commande numérique à deux états logiques. Dans ces circuits, les transistors sont utilisés en commutateurs traditionnels, et rien ne pouvait laisser penser qu'un montage similaire peut être utilisé avec des signaux modulant analogiques pour obtenir une modulation analogique linéaire.We know that non-polarized field effect transistors have a resistance whose value varies non linearly according to the gate-source voltage Vgs. Nevertheless, the inventors have noted with surprise, and contrary to what we thought until now, that despite this lack of linearity, it is possible to obtain a linear modulated signal with respect to the modulation signal thanks to the invention . Thus, in a circuit according to the invention, the non-polarized modulation field effect transistors do not have the function of performing switching or chopping as in the prior art. It should be noted that there are already known modulators by phase displacement with two phase states, called BPSK, (FR-2 760 301 or "High bit rate four phase MMIC remodulation demodulator and modulator", A. Primerose and al, Proceedings of the GAAS 92 European Gallium Arsenide and related III-V compounds applications, Symposium, 27-29 April 1992, NOORDWIJK) comprising two non-polarized field effect transistors acting as switches for modulation of the carrier signal by a digital control signal with two logic states. In these circuits, the transistors are used in traditional switches, and nothing could leave think that a similar assembly can be used with analog modulating signals to obtain a linear analog modulation.
Il est à noter également que le document "High performance résistive EHF mixers using InGaAs HEMTs", K.w. Chang et al, IEEE MTT-S Digest, 1992, p 1409, décrit un circuit intégré monolithique mélangeur comprenant deux transistors FET HEMT recevant un signal de porteuse haute fréquence sur leur grille par l'intermédiaire d'un coupleur de Lange et de filtres passe-haut, et un signal RF haute fréquence sur leur drain par l'intermédiaire d'un coupleur de Lange et de filtres passe-haut. Ce circuit permet d'obtenir un signal basse fréquence à partir des deux signaux haute fréquence. Ce document n'enseigne donc pas un circuit mélangeur servant à moduler un signal de porteuse haute fréquence par un signal basse fréquence. En outre, le montage décrit présente de nombreux défauts et inconvénients : des filtres sont nécessaires pour séparer la haute fréquence et la basse fréquence ; les coupleurs assurent un déphasage des signaux haute fréquence sans les rendre réellement opposés comme cela est imposé par la théorie, d'où des imperfections de fonctionnement ; dans le cas de coupleurs à 180°, le circuit présente des problèmes rédhibitoires d'adaptation sur les entrées haute fréquence ; le circuit présente une dimension de 2,4mmx2,8mm à 26-29 GHz alors qu'il ne réalise qu'un étage mélangeur, et sa taille deviendrait redhibitoire pour des fréquences plus basses. En outre, et surtout, la grille des transistors recevant un signal à haut niveau, les transistors présentent un fonctionnement en commutation pure (en tout ou rien) sur toute la plage où la résistance drain-source Rds présente des variations non linéaires en fonction de la tension Vgs grille-source. Dès lors, ce document n'enseigne pas une solution pour l'obtention d'un étage mélangeur analogique linéaire par rapport au signal appliqué sur la grille des transistors.It should also be noted that the document "High performance resistive EHF mixers using InGaAs HEMTs", K.w. Chang et al, IEEE MTT-S Digest, 1992, p 1409, describes a monolithic mixer integrated circuit comprising two FET HEMT transistors receiving a high frequency carrier signal on their gate via a Lange coupler and pass filters -high, and a high frequency RF signal on their drain via a Lange coupler and high-pass filters. This circuit makes it possible to obtain a low frequency signal from the two high frequency signals. This document therefore does not teach a mixer circuit used to modulate a high frequency carrier signal by a low frequency signal. In addition, the assembly described has many shortcomings and drawbacks: filters are necessary to separate the high frequency and the low frequency; the couplers ensure a phase shift of the high frequency signals without actually making them opposite as is imposed by theory, hence operational imperfections; in the case of 180 ° couplers, the circuit presents unacceptable problems of adaptation on the high frequency inputs; the circuit has a dimension of 2.4mmx2.8mm at 26-29 GHz while it achieves only one mixer stage, and its size would become prohibitive for lower frequencies. In addition, and above all, the gate of the transistors receiving a high level signal, the transistors have pure switching operation (all or nothing) over the entire range where the drain-source resistance Rds has non-linear variations as a function of the gate-source voltage Vgs. Consequently, this document does not teach a solution for obtaining a linear analog mixer stage with respect to the signal applied to the gate of the transistors.
En outre, il a été constaté qu'avec un circuit selon l'invention les pertes d'insertion (puissance du signal modulé par rapport à la puissance du signal de porteuse) sont peu affectées par une augmentation de fréquence du signal de porteuse.In addition, it has been found that with a circuit according to the invention the insertion losses (power of the modulated signal with respect to the carrier signal strength) are little affected by an increase in the carrier signal frequency.
Par exemple, ces pertes sont de l'ordre de 3 dB plus importante lorsque la fréquence passe de 2 GHz à 60 GHz. Au contraire, avec le circuit décrit dans la publication précitée, l'augmentation des pertes d'insertion serait beaucoup plus importante (de l'ordre de 15 dB) du fait que le signal attaquerait la capacité grille-source des transistors.For example, these losses are around 3 dB higher when the frequency goes from 2 GHz to 60 GHz. On the contrary, with the circuit described in the abovementioned publication, the increase in insertion losses would be much greater (of the order of 15 dB) because the signal would attack the gate-source capacitance of the transistors.
Avantageusement et selon l'invention, on applique sur les grilles des transistors de modulation des signaux analogiques modulant à basse fréquence I ou Q, ï ou Q centrés sur une tension Vn choisie de l'ordre de la tension de pincement Vp des transistors de modulation pour minimiser les pertes.Advantageously and according to the invention, on the gates of the modulation transistors are applied analog signals modulating at low frequency I or Q, ï or Q centered on a voltage Vn chosen of the order of the pinch voltage Vp of the modulation transistors to minimize losses.
De façon usuelle, la tension de pincement Vp d'un transistor à effet de champ est la tension grille-source Vgs pour laquelle il n'y a plus de courant entre le drain et la source lorsque le transistor est à l'état polarisé dans des conditions normalisées. Les inventeurs ont constaté qu'il existe une valeur de la tension sur laquelle les signaux analogiques modulant I, Q ; ï , Q sont centrés, qui a pour effet de minimiser les pertes de l'étage mélangeur, c'est- à-dire pour laquelle la puissance du signal modulé obtenu en sortie est maximale.Usually, the pinch voltage Vp of a field effect transistor is the gate-source voltage Vgs for which there is no more current between the drain and the source when the transistor is in the polarized state in standard conditions. The inventors have found that there is a value for the voltage on which the analog signals modulating I, Q; ï, Q are centered, which has the effect of minimizing the losses of the mixer stage, that is to say for which the power of the modulated signal obtained at output is maximum.
Avantageusement et selon l'invention, le circuit comprend des moyens de déphasage de -90° du signal de porteuse à haute fréquence entre l'entrée de porteuse et le drain de l'un des transistors de modulation, et des moyens de déphasage de +90° du signal de porteuse à haute fréquence entre l'entrée de porteuse et le drain de l'autre transistor de modulation.Advantageously and according to the invention, the circuit comprises means of -90 ° phase shift of the high frequency carrier signal between the carrier input and the drain of one of the modulation transistors, and means of + phase shift. 90 ° of the high frequency carrier signal between the carrier input and the drain of the other modulation transistor.
Par ailleurs, avantageusement et selon l'invention, le circuit incorpore des moyens, dits moyens de mise en forme, aptes à générer au moins une paire I, ï ; Q, Q de signaux analogiques modulant à basse fréquence complémentaires l'un de l'autre à partir du signal de modulation analogique basse fréquence I ; Q . L'amplitude de variation des signaux analogiques modulant est liée à l'amplitude du signal de modulation, elle-même contrôlée par des moyens externes au circuit selon l'invention.Furthermore, advantageously and according to the invention, the circuit incorporates means, called shaping means, capable of generating at least one pair I, ï; Q, Q of analog signals modulating at low frequency complementary to each other from the analog low frequency modulation signal I; Q. The amplitude of variation of the modulating analog signals is linked to the amplitude of the modulation signal, itself controlled by means external to the circuit according to the invention.
Avantageusement et selon l'invention, lesdits moyens de mise en forme comprennent une source de courant ; un étage amplificateur différentiel générant, à partir de la source de courant et d'un signal de modulation analogique basse fréquence î ; Q, deux signaux analogiques modulant à basse fréquence I, î ; Q, Q complémentaires délivrés sur les grilles de deux transistors à effet de champ, chacun d'entre eux étant monté en drain commun avec sa source reliée à un pont diviseur fournissant en sortie l'un des deux signaux analogiques modulant à basse fréquence complémentaires I, ï ; Q, Q centré sur une tension Vn, et destiné à être appliqué sur la grille d'un transistor de modulation.Advantageously and according to the invention, said shaping means comprise a current source; a differential amplifier stage generating, from the current source and a low frequency analog modulation signal î; Q, two analog signals modulating at low frequency I, î; Q, Q complementary delivered on the grids of two field effect transistors, each of them being mounted in common drain with its source connected to a divider bridge providing at output one of the two analog signals modulating at low complementary frequency I , ï; Q, Q centered on a voltage Vn, and intended to be applied to the gate of a modulation transistor.
Un circuit selon l'invention peut être adapté pour former un modulateur analogique I/Q. Dans ce cas, il est caractérisé en ce qu'il comprend au moins deux étages mél Λangeu /r. s recevant chacun l'un des deux signaux de modulation analogique I ; Q basse fréquence, une entrée principale haute fréquence recevant un signal de porteuse à haute fréquence, des moyens pour appliquer ce signal de porteuse à haute fréquence aux entrées de porteuse des étages mélangeurs avec entre elles un déphasage Δ φ non nul prédéterminé, et des moyens pour sommer en phase sur une sortie commune les deux signaux modulés issus des étages mélangeurs, de façon à former un circuit modulateur I/Q linéaire analogique. Avantageusement et selon l'invention, Δ φ=90°.A circuit according to the invention can be adapted to form an analog I / Q modulator. In this case, it is characterized in that it comprises at least two stages mel Λangeu / r. s each receiving one of the two analog modulation signals I; Q low frequency, a main high frequency input receiving a high frequency carrier signal, means for applying this high frequency carrier signal to the carrier inputs of the mixer stages with between them a predetermined non-zero phase shift Δ et, and means for summing in phase on a common output the two modulated signals from the mixer stages, so as to form an analog linear I / Q modulator circuit. Advantageously and according to the invention, Δ φ = 90 °.
Par ailleurs, avantageusement, un circuit selon l'invention est formé d'une seule puce de circuit intégré réalisée en technologie MMIC, la fréquence du signal de porteuse à haute fréquence étant supérieure à 1 Gigahertz.Furthermore, advantageously, a circuit according to the invention is formed by a single integrated circuit chip produced in MMIC technology, the frequency of the high frequency carrier signal being greater than 1 Gigahertz.
L'invention concerne aussi un procédé et un circuit caractérisés en combinaison par tout ou partie des caractéristiques mentionnées ci-dessus ou ci-après. D'autres buts, caractéristiques et avantages de l'invention apparaissent de la description suivante, donnée uniquement à titre d'exemple non limitatif, et qui se réfère aux figures annexées dans lesquelles :The invention also relates to a method and a circuit characterized in combination by all or some of the characteristics mentioned above or below. Other objects, characteristics and advantages of the invention appear from the following description, given only by way of nonlimiting example, and which refers to the appended figures in which:
- la figure 1 est un schéma d'un circuit modulateur I/Q linéaire analogique selon l'invention,FIG. 1 is a diagram of an analog linear I / Q modulator circuit according to the invention,
- la figure 2 est un schéma d'un étage mélangeur d'un circuit selon l'invention,FIG. 2 is a diagram of a mixer stage of a circuit according to the invention,
- la figure 3 est un schéma illustrant un étage de mise en forme des signaux analogiques d'un circuit selon l'invention, - la figure 4 est un exemple de topographie d'un circuit modulateur I/Q linéaire analogique selon le schéma de la figure 1 ,- Figure 3 is a diagram illustrating a stage for shaping the analog signals of a circuit according to the invention, - Figure 4 is an example of topography of an analog linear I / Q modulator circuit according to the diagram of the figure 1 ,
- la figure 5 est un diagramme illustrant un exemple de caractéristique Rds=f(Vgs) d'un transistor à effet de champ non polarisé formant l'un des transistors de modulation du circuit de la figure 4, - la figure 6 est un diagramme illustrant les variations de la puissance du signal modulé obtenu en sortie du circuit de la figure 4 selon le niveau du signal de modulation analogique.- Figure 5 is a diagram illustrating an example of characteristic Rds = f (Vgs) of a non-polarized field effect transistor forming one of the modulation transistors of the circuit of Figure 4, - Figure 6 is a diagram illustrating the variations in the power of the modulated signal obtained at the output of the circuit of FIG. 4 according to the level of the analog modulation signal.
Le circuit selon l'invention représenté figure 1 est un circuit modulateur I/Q. Ce circuit comprend une entrée principale haute fréquence 1 recevant un signal de porteuse à haute fréquence, deux entrées basse fréquence 2,The circuit according to the invention shown in Figure 1 is an I / Q modulator circuit. This circuit includes a main high frequency input 1 receiving a high frequency carrier signal, two low frequency inputs 2,
3 recevant respectivement l'un de deux signaux de modulation analogiques I , respectivement Q basse fréquence, et une sortie commune 4 délivrant un signal modulé en phase et/ou en amplitude. Le signal modulé par le signal analogique3 receiving respectively one of two analog modulation signals I, respectively Q low frequency, and a common output 4 delivering a signal modulated in phase and / or in amplitude. The signal modulated by the analog signal
I est en phase avec le signal de porteuse à haute fréquence tandis que le signal modulé par le signal analogique Q est en quadrature de phase avec le signal de porteuse à haute fréquence.I is in phase with the high frequency carrier signal while the signal modulated by the analog signal Q is in phase quadrature with the high frequency carrier signal.
Ce circuit comprend également deux étages mélangeurs 5, 6 permettant chacun la modulation en amplitude du signal de porteuse par l'un des signaux de modulation analogiques I , Q . Chaque étage mélangeur 5, 6 comprend une entrée, dite entrée de porteuse 7, 8, recevant le signal de porteuse à haute fréquence issu de l'entrée principale 1 par l'intermédiaire d'un circuit déphaseur 9, 10, par exemple formé d'un filtre LC, et d'un diviseur de puissance de Wilkinson 11 permettant de scinder en phase le signal de porteuse haute fréquence en deux signaux identiques attaquant les entrées des circuits déphaseurs 9, 10. En pratique, l'un des circuits déphaseurs 9 est par exemple constitué d'un circuit LC déphasant le signal de +45°, alors que l'autre circuit déphaseur 10 est un circuit LC déphasant le signal de -45°, de sorte que les entrées de porteuse des étages mélangeurs 5, 6 présentent entre elles un déphasage Δφ non nul prédéterminé égal à 90°.This circuit also includes two mixer stages 5, 6 each allowing amplitude modulation of the carrier signal by one of the analog modulation signals I, Q. Each mixer stage 5, 6 comprises an input, called the carrier input 7, 8, receiving the high frequency carrier signal from the main input 1 via a phase shifting circuit 9, 10, for example formed by an LC filter, and a Wilkinson power divider 11 making it possible to split the high-frequency carrier signal in phase into two identical signals attacking the inputs of the phase-shifting circuits 9, 10. In practice, one of the phase-shifting circuits 9 is for example constituted by an LC circuit phase-shifting the signal by + 45 °, while the other phase-shifting circuit 10 is an LC circuit phase-shifting the signal by -45 °, so that the carrier inputs of the mixer stages 5, 6 have between them a phase shift Δφ non-zero predetermined equal to 90 °.
Chaque étage mélangeur 5, 6 reçoit deux signaux analogiques modulant à basse fréquence complémentaires I, ï , respectivement Q, Q complémentaires l'un de l'autre issus d'un étage, dit étage de mise en forme 12, 13, qui génère ces signaux analogiques complémentaires à partir de chaque signal de modulation analogique à basse fréquence I, Q appliqué sur les entrées basse fréquence 2, 3.Each mixer stage 5, 6 receives two analog signals modulating at low complementary frequency I, ï, respectively Q, Q complementary to each other from a stage, called shaping stage 12, 13, which generates these complementary analog signals from each low frequency analog modulation signal I, Q applied to the low frequency inputs 2, 3.
Sur la figure 1, on a représenté des exemples de signaux modulant analogiques basse fréquence complémentaires I, I , Q, Q tels que reçus par les étages mélangeurs 5, 6. Les signaux I et î sont complémentaires en ce sens qu'à chaque instant leur somme I + î est égale à une constante. Il en va de même de Q et Q.In FIG. 1, examples of complementary low frequency analog modulating signals I, I, Q, Q have been shown as received by the mixer stages 5, 6. The signals I and I are complementary in that at each instant their sum I + î is equal to a constant. The same goes for Q and Q.
Les signaux analogiques modulant à basse fréquence I, î , Q, Q sont centrés sur la même tension négative Vn=l/2 (I+ I ) = 1/2 (Q+ Q) et ont leur amplitude qui varie dans une plage de tension comprise entre une valeur Vmin et une valeur Vmax prédéterminées.The analog signals modulating at low frequency I, î, Q, Q are centered on the same negative voltage Vn = l / 2 (I + I) = 1/2 (Q + Q) and have their amplitude which varies within a voltage range included between a predetermined Vmin value and a Vmax value.
Chaque étage mélangeur 5, 6 délivre un signal modulé en amplitude à partir du signal de porteuse à haute fréquence qu'il reçoit, et du signal de modulation analogique basse fréquence I , respectivementEach mixer stage 5, 6 delivers an amplitude modulated signal from the high frequency carrier signal it receives, and the low frequency analog modulation signal I, respectively
Q correspondant. Ce signal modulé est fourni sur une sortie 14, 15 de l'étage mélangeur 5, 6, et les deux sorties 14, 15 des étages mélangeurs 5, 6 sont sommées vectoriellement par un coupleur de Wilkinson 16 sur la sortie commune 4.Q corresponding. This modulated signal is supplied on an output 14, 15 of the stage mixer 5, 6, and the two outputs 14, 15 of the mixer stages 5, 6 are summed vectorially by a Wilkinson coupler 16 on the common output 4.
Les signaux analogiques modulant basse fréquence I, ï ou respectivement Q, Q sont délivrés par les étages de mise en forme 12, 13 à chaque étage mélangeur 5, 6 sur deux entrées distinctes 17, 18, ou respectivement 19, 20, de ces étages mélangeurs 5, 6.The analog signals modulating low frequency I, ï or respectively Q, Q are delivered by the shaping stages 12, 13 to each mixer stage 5, 6 on two separate inputs 17, 18, or respectively 19, 20, of these stages mixers 5, 6.
La figure 2 représente le schéma d'un étage mélangeur 5, 6 d'un circuit selon l'invention. Cet étage mélangeur 5, 6 comprend deux transistors à effet de champ identiques 21, 22, dits transistors de modulation 21, 22, montés en source commune, c'est-à-dire avec les deux sources 23, 24 reliées en commun à la masse du circuit. Les drains 25, 26 des deux transistors 21, 22 reçoivent des signaux à haute fréquence issus de l'entrée de porteuse 7, 8 qui sont centrés sur une tension continue nulle (masse), de sorte que les transistors de modulation 21, 22 ne sont pas polarisés.FIG. 2 represents the diagram of a mixer stage 5, 6 of a circuit according to the invention. This mixer stage 5, 6 comprises two identical field effect transistors 21, 22, called modulation transistors 21, 22, mounted in common source, that is to say with the two sources 23, 24 connected in common to the circuit mass. The drains 25, 26 of the two transistors 21, 22 receive high frequency signals from the carrier input 7, 8 which are centered on a zero DC voltage (ground), so that the modulation transistors 21, 22 do not are not polarized.
Les signaux à haute fréquence appliqués sur les drains 25, 26 résultent du signal de porteuse à haute fréquence appliqué sur l'entrée de porteuse 7, 8, transformés par des circuits de déphasage 27, 28 en deux signaux à haute fréquence, dont le premier est déphasé de -90° par rapport au signal de porteuse par le circuit de déphasage 27, tandis que le deuxième est déphasé de +90° par le circuit de déphasage 28 par rapport au signal de porteuse. Les circuits de déphasage 27, 28 sont interposés entre l'entrée de porteuse 7, 8 et les drains 25, 26 des transistors de modulation 21, 22. Ils peuvent être simplement constitués de filtres LC en T passe-bas 27 ou passe-haut 28. L'entrée de porteuse 7, 8 est donc scindée en deux branches, dont l'une va au premier circuit de déphasage 27 tandis que l'autre va au deuxième circuit de déphasage 28. Avantageusement, avant la séparation de ces deux branches, l'entrée de porteuse 7, 8 peut être dotée d'une inductance série d'adaptation d'impédance (non représentée). En sortie, les deux drains 25, 26 sont combinés en phase par un circuit 29 combineur à inductances en étoile et capacité parallèle délivrant le signal modulé sur la sortie 14, 15 de l'étage mélangeur 5, 6.The high frequency signals applied to the drains 25, 26 result from the high frequency carrier signal applied to the carrier input 7, 8, transformed by phase shift circuits 27, 28 into two high frequency signals, the first of which is phase-shifted by -90 ° relative to the carrier signal by the phase shift circuit 27, while the second is phase-shifted by + 90 ° by the phase shift circuit 28 relative to the carrier signal. The phase shift circuits 27, 28 are interposed between the carrier input 7, 8 and the drains 25, 26 of the modulation transistors 21, 22. They may simply consist of low-pass T or low-pass T filters 27 28. The carrier input 7, 8 is therefore split into two branches, one of which goes to the first phase shift circuit 27 while the other goes to the second phase shift circuit 28. Advantageously, before the separation of these two branches , the carrier input 7, 8 can be provided with a series inductor for impedance matching (not shown). At the output, the two drains 25, 26 are combined in phase by a combiner circuit 29 with star inductances and parallel capacitance delivering the modulated signal on output 14, 15 of the mixer stage 5, 6.
Les grilles 30, 31 des deux transistors de modulation 21, 22 sont attaquées par les signaux analogiques modulant à basse fréquence eux- mêmes reçus sur les entrées basse fréquence 17, 19, ou 18, 20. Ainsi, le premier transistor de modulation 21 reçoit le signal I ou Q analogique modulant à basse fréquence sur sa grille 30, tandis que le deuxième transistor de modulation 22 reçoit sur sa grille 31 un signal ï ou Q analogique modulant à basse fréquence complémentaire.The gates 30, 31 of the two modulation transistors 21, 22 are driven by the low frequency modulating analog signals themselves received on the low frequency inputs 17, 19, or 18, 20. Thus, the first modulation transistor 21 receives the analog signal I or Q modulating at low frequency on its gate 30, while the second modulation transistor 22 receives on its gate 31 an analog signal I or Q modulating at complementary low frequency.
Ainsi, on applique sur les grilles des transistors de modulation 21, 22 des signaux analogiques modulant I, Q ou ï , Q à basse fréquence issus du signal de modulation analogique basse fréquence qui sont centrés sur la tension négative Vn. Cette tension Vn est choisie de l'ordre de la tension de pincement Vp des transistors de modulation 21, 22 pour minimiser les pertes. En effet, on constate qu'il existe une valeur, de l'ordre de la tension de pincement Vp, pour laquelle les pertes sont minimum, et que lorsqu'on s'éloigne de cette valeur, les pertes du circuit augmentent rapidement.Thus, on the gates of the modulation transistors 21, 22 are applied analog signals modulating I, Q or ï, Q at low frequency originating from the analog low frequency modulation signal which are centered on the negative voltage Vn. This voltage Vn is chosen to be of the order of the pinch voltage Vp of the modulation transistors 21, 22 in order to minimize the losses. Indeed, it is found that there is a value, of the order of the pinch voltage Vp, for which the losses are minimum, and that when one moves away from this value, the losses of the circuit increase rapidly.
L'amplitude des signaux analogiques modulant à basse fréquence I, ï , Q, Q doit rester inférieure à une valeur maximum Amax au-delà de laquelle la puissance du signal modulé obtenu en sortie de chaque étage mélangeur 5, 6 n'est plus proportionnelle à la puissance du signal de modulation analogique basse fréquence I ouQ. Autrement dit, Vmax-Vn=Vn-Vmin < Amax. La valeur de Amax dépend de la technologie utilisée pour réaliser les transistors de modulation 21, 22.The amplitude of analog signals modulating at low frequency I, ï, Q, Q must remain below a maximum value Amax beyond which the power of the modulated signal obtained at the output of each mixer stage 5, 6 is no longer proportional to the power of the low frequency analog modulation signal I or Q. In other words, Vmax-Vn = Vn-Vmin <Amax. The value of Amax depends on the technology used to make the modulation transistors 21, 22.
L'amplitude des signaux analogiques modulant I ou Q, ï ou Q à basse fréquence est liée à l'amplitude du signal de modulation analogique basse fréquence I , Q utilisé. La figure 3 représente un schéma d'un étage de mise en forme 12, 13 permettant de générer les signaux analogiques modulant à basse fréquence complémentaires à partir d'un signal de modulation analogique basse fréquence I , Q . Le schéma de la figure 3 représente donc un des étages de mise en forme 12, 13 du circuit selon l'invention représenté figure 1. Ce circuit comprend une source de courant 40 formée d'un transistor à effet de champ dont la grille est reliée à la tension négative VE (par exemple égal à -5 volts) dont la source est reliée par une résistance série à la tension négative VE, et le drain fournit la sortie de cette source de courant par l'intermédiaire d'une résistance série ; un étage amplificateur différentiel 41 générant, à partir de la source de courant 40 et du signal de modulation analogique basse fréquence I ,Q, les deux signaux analogiques modulant à basse fréquence I, Q et ï , Q délivrés sur les grilles 42, 43 de deux transistors 44, 45, à effet de champ, chacun d'entre-eux étant monté en drain commun avec sa source 46, 47 reliée à un pont diviseur 48, 49 fournissant en sortie l'un des deux signaux analogiques modulant à basse fréquence complémentaire I, ï, Q, Q sur les grilles 30, 31 des deux transistors de modulation 21, 22. L'étage amplificateur différentiel 41 est formé également de deux transistors à effet de champ 50, 51, dont l'un 50 reçoit le signal de modulation analogique à basse fréquence î , Q, sur sa grille 52 avec une résistance d'adaptation 60 parallèle de valeur R (par exemple de 50 Ω) reliée à la masse, tandis que la grille 53 de l'autre transistor 51 est reliée à la masse par une résistance d'adaptation 61 de valeur R/2 reliée à la masse. Ces deux transistors 50, 51 ont leurs sources 54, 55 reliées ensemble à la sortie de la source de courant 40 (résistance série du drain du transistor à effet de champ de cette source 40) et leurs drains 62, 63 reliés aux grilles 42, 43 des deux transistors 44, 45. Des résistances 56, 57 sont interposées entre les grilles 42, 43 et les drains 58, 59 des transistors 44, 45 qui sont reliés à la tension positive Vcc (par exemple de l'ordre de +5 volts). Chacun des étages de mise en forme 12, 13 peut être avantageusement réalisé sur la même puce de circuit intégré que les étages mélangeurs 5, 6. En variante ou en combinaison, les deux étages mélangeurs 5, 6 sont réalisés sur une même puce de circuit intégré dotée de moyens de connexion aptes à recevoir des signaux I, ï, Q, Q issus de circuits externes de mise en forme.The amplitude of the analog signals modulating I or Q, ï or Q at low frequency is related to the amplitude of the analog low frequency modulation signal I, Q used. FIG. 3 represents a diagram of a shaping stage 12, 13 making it possible to generate the complementary low frequency modulating analog signals from a low frequency analog modulation signal I, Q. The diagram in FIG. 3 therefore represents one of the shaping stages 12, 13 of the circuit according to the invention shown in FIG. 1. This circuit comprises a current source 40 formed by a field effect transistor whose gate is connected to the negative voltage VE (for example equal to -5 volts) whose source is connected by a series resistance to the negative voltage VE, and the drain provides the output of this current source via a series resistance; a differential amplifier stage 41 generating, from the current source 40 and the low frequency analog modulation signal I, Q, the two analog signals modulating at low frequency I, Q and, Q delivered on the gates 42, 43 of two field effect transistors 44, 45, each of them being mounted as a common drain with its source 46, 47 connected to a divider bridge 48, 49 supplying one of the two analog signals modulating at low frequency complementary I, ï, Q, Q on the gates 30, 31 of the two modulation transistors 21, 22. The differential amplifier stage 41 is also formed of two field effect transistors 50, 51, one of which receives the analog low-frequency modulation signal I, Q, on its gate 52 with a parallel matching resistor 60 of value R (for example 50 Ω) connected to ground, while gate 53 of the other transistor 51 is connected to ground by an ad resistance aptitude 61 of R / 2 value connected to ground. These two transistors 50, 51 have their sources 54, 55 connected together to the output of the current source 40 (series resistance of the drain of the field effect transistor of this source 40) and their drains 62, 63 connected to the gates 42, 43 of the two transistors 44, 45. Resistors 56, 57 are interposed between the grids 42, 43 and the drains 58, 59 of the transistors 44, 45 which are connected to the positive voltage Vcc (for example of the order of +5 volts). Each of the shaping stages 12, 13 can advantageously be produced on the same integrated circuit chip as the mixer stages 5, 6. As a variant or in combination, the two mixer stages 5, 6 are produced on the same circuit chip integrated with connection means capable of receiving signals I, ï, Q, Q from external shaping circuits.
EXEMPLE :EXAMPLE:
Un exemple de topographie de circuit intégré monolithique selon l'invention est représenté figure 4. Sur ce circuit, on a : Amax=0,3 V et Vn= -0,5 V, qui est de l'ordre de la tension de pincement Vp qui est égale à -0,6 V.An example of topography of a monolithic integrated circuit according to the invention is shown in FIG. 4. On this circuit, we have: Amax = 0.3 V and Vn = -0.5 V, which is of the order of the pinch voltage Vp which is equal to -0.6 V.
Ce circuit est entièrement réalisé sur une puce deThis circuit is entirely realized on a chip of
3mmx3mm, et incorpore les étages de mise en forme 12, 13. Il est à noter néanmoins que des entrées I, ï, Q, Q sont aussi prévues pour permettre, en variante, le pilotage du circuit de l'extérieur, par exemple à des fins de test, à partir de circuits externes de mise en forme.3mmx3mm, and incorporates the shaping stages 12, 13. It should however be noted that inputs I, ï, Q, Q are also provided to allow, as a variant, the piloting of the circuit from the outside, for example at for testing purposes, from external shaping circuits.
La figure 5 représente la caractéristique Rds=f(Vgs) des transistors de modulation 21, 22 obtenue avec ce circuit. Comme on le voit, cette résistance n'est pas linéaire sur toute la plage de variation de l'amplitude des signaux analogiques modulant, mais uniquement sur une partie de cette plage. Malgré cela, et pour une raison encore inexpliquée, le circuit obtenu est linéaire en ce sens que la puissance de sortie est proportionnelle à la puissance du signal de modulation.FIG. 5 represents the characteristic Rds = f (Vgs) of the modulation transistors 21, 22 obtained with this circuit. As can be seen, this resistance is not linear over the entire range of variation of the amplitude of the modulating analog signals, but only over part of this range. Despite this, and for a reason still unexplained, the circuit obtained is linear in the sense that the output power is proportional to the power of the modulation signal.
La figure 6 représente, pour le circuit de la figure 4, les variations de la puissance du signal de sortie obtenu avec ce circuit selon le niveau des signaux de modulation analogiques I , Q à basse fréquence.FIG. 6 represents, for the circuit of FIG. 4, the variations of the power of the output signal obtained with this circuit according to the level of the analog modulation signals I, Q at low frequency.
Sur cette figure, on a représenté en abscisses la somme Pe des puissances des signaux de modulation analogiques î et Q (en dBm : décibels par rapport au milliwatt) et en ordonnées la puissance Ps (en dBm) du signal de sortie obtenu sur la sortie 4.In this figure, the sum Pe of the powers of the analog modulation signals î and Q is shown on the abscissa (in dBm: decibels relative to the milliwatt) and on the ordinate the power Ps (in dBm) of the output signal obtained on output 4.
On constate ainsi que si l'amplitude des signaux analogiques modulant est augmentée au-delà d'une certaine valeur (Amax) le circuit n'est plus linéaire.It can thus be seen that if the amplitude of the modulating analog signals is increased beyond a certain value (Amax) the circuit is no longer linear.
Par ailleurs, les signaux analogiques modulant I, î , Q Q doivent avoir une amplitude suffisante, supérieure à une valeur minimum Amin, pour que le circuit présente une précision (amplitude et phase du signal modulé obtenu) suffisante, selon les exigences de son utilisation. Pour caractériser le circuit modulateur, on l'alimente par deux signaux sinusoïdaux déphasés de 90° formant les signaux de modulation î ,Furthermore, the analog signals modulating I, î, Q Q must have a sufficient amplitude, greater than a minimum value Amin, for the circuit to have sufficient precision (amplitude and phase of the modulated signal obtained), according to the requirements of its use. To characterize the modulator circuit, it is supplied by two sinusoidal signals phase shifted by 90 ° forming the modulation signals î,
Q. On relève le spectre en sortie et on mesure les réjections de la fréquence porteuse notée Crej et de la fréquence image notée Brej. La précision du circuit modulateur est majorée par : δA ≤ 201og(l + Crej +V2. Brej δθ < Arcto.n(Crej X- ^2. Bref)Q. We take the output spectrum and measure the rejection of the carrier frequency denoted Crej and the image frequency denoted Brej. The precision of the modulator circuit is increased by: δA ≤ 201og (l + Crej + V2. Brej δθ <Arcto.n (Crej X- ^ 2. Brief)
On note que la précision des plots de phase diminue quand l'amplitude du signal modulant diminue mais reste très bonne sur une dynamique de 10 dB.It is noted that the precision of the phase pads decreases when the amplitude of the modulating signal decreases but remains very good over a dynamic range of 10 dB.
Le tableau 1 suivant donne ainsi, pour trois fréquences F différentes, les valeurs de la précision δA d'amplitude et δθ de phase du signal de sortie du circuit selon la puissance d'entrée Pe des signaux de modulation analogiques I , Q basse fréquence.The following table 1 thus gives, for three different frequencies F, the values of the precision δA of amplitude and δθ of phase of the output signal of the circuit according to the input power Pe of the low frequency analog modulation signals I, Q.
Tableau 1 :Table 1:
Figure imgf000017_0001
Figure imgf000017_0001

Claims

REVENDICATIONS 1/ - Procédé de modulation analogique d'un signal de porteuse à haute fréquence avec un signal de modulation analogique basse fréquence î ou Q , caractérisé en ce que : - on choisit un circuit intégré monolithique comprenant au moins un étage mélangeur (5, 6) comprenant : CLAIMS 1 / - Method for analog modulation of a high frequency carrier signal with a low frequency analog modulation signal I or Q, characterized in that: - a monolithic integrated circuit is chosen comprising at least one mixer stage (5, 6) comprising:
. une entrée, dite entrée de porteuse (7, 8), recevant le signal de porteuse à haute fréquence,. an input, called carrier input (7, 8), receiving the high frequency carrier signal,
. deux transistors à effet de champ identiques, dits transistors de modulation (21, 22), montés avec les sources (23, 24) reliées en commun à la masse,. two identical field effect transistors, called modulation transistors (21, 22), mounted with the sources (23, 24) connected in common to ground,
- on applique sur les drains (25, 26) des transistors de modulation (21, 22), des signaux à haute fréquence issus de l'entrée de porteuse (7, 8), déphasés l'un de l'autre de 180° et centrés sur une tension nulle, de sorte que les drains (25, 26) des transistors de modulation (21, 22) ne sont pas polarisés,- applying to the drains (25, 26) modulation transistors (21, 22), high frequency signals from the carrier input (7, 8), phase shifted from one another by 180 ° and centered on a zero voltage, so that the drains (25, 26) of the modulation transistors (21, 22) are not polarized,
- on récupère un signal modulé sur une sortie (14, 15) reliée à chacun des drains (25, 26) des transistors de modulation (21, 22) par l'intermédiaire d'un étage (29) sommant vectoriellement sur la sortie (14, 15) les signaux formés sur les drains (25, 26) des transistors de modulation (21, 22),- a modulated signal is recovered on an output (14, 15) connected to each of the drains (25, 26) of the modulation transistors (21, 22) via a stage (29) summing vectorially on the output ( 14, 15) the signals formed on the drains (25, 26) of the modulation transistors (21, 22),
- on applique sur les grilles (30, 31) des transistors de modulation (21, 22) des signaux analogiques modulant I ou Q, ï ou Q à basse fréquence issus dudit signal de modulation analogique basse fréquence î ou Q , complémentaires l'un de l'autre, dont l'amplitude est inférieure à une valeur maximum Amax au-delà de laquelle la puissance du signal modulé n'est plus proportionnelle à la puissance du signal de modulation analogique basse fréquence I ou Q.- Is applied to the gates (30, 31) of the modulation transistors (21, 22) of the analog signals modulating I or Q, ï or Q at low frequency from said analog low frequency modulation signal î or Q, complementary one on the other, whose amplitude is less than a maximum value Amax beyond which the power of the modulated signal is no longer proportional to the power of the low frequency analog modulation signal I or Q.
2/ - Procédé selon la revendication 1, caractérisé en ce qu'on applique sur les grilles (30, 31) des transistors de modulation (21, 22) des signaux analogiques modulant à basse fréquence I ou Q, ï ou Q centrés sur une tension Vn choisie de l'ordre de la tension de pincement Vp des transistors de modulation (21, 22) pour minimiser les pertes.2 / - Method according to claim 1, characterized in that one applies to the gates (30, 31) modulation transistors (21, 22) of analog signals modulating at low frequency I or Q, ï or Q centered on a selected voltage Vn of the order of the pinch voltage Vp of the modulation transistors (21, 22) to minimize losses.
3/ - Circuit intégré monolithique comprenant au moins un étage mélangeur (5, 6) destiné à former un signal modulé à partir d'un signal de porteuse à haute fréquence et d'un signal de modulation analogique basse3 / - Monolithic integrated circuit comprising at least one mixer stage (5, 6) intended to form a signal modulated from a high frequency carrier signal and a low analog modulation signal
Λ Λ fréquence I ou Q, caractérisé en ce que chaque étage mélangeur (5, 6) comprend :Λ Λ frequency I or Q, characterized in that each mixer stage (5, 6) comprises:
- une entrée, dite entrée de porteuse (7, 8), recevant le signal de porteuse à haute fréquence,- an input, called carrier input (7, 8), receiving the high frequency carrier signal,
- deux transistors à effet de champ identiques, dits transistors de modulation (21, 22), montés avec les sources (23, 24) reliées en commun à la masse et avec les drains (25, 26) non polarisés recevant des signaux à haute fréquence issus de l'entrée de porteuse (7, 8), centrés sur une tension nulle, de sorte que les transistors de modulation (21, 22) ne sont pas polarisés,- two identical field effect transistors, called modulation transistors (21, 22), mounted with the sources (23, 24) connected in common to ground and with the non-polarized drains (25, 26) receiving high signals frequency from the carrier input (7, 8), centered on a zero voltage, so that the modulation transistors (21, 22) are not polarized,
- des moyens (27, 28) de déphasage de 180° entre le signal de porteuse à haute fréquence appliqué sur le drain (25) de l'un (21) des transistors de modulation et celui appliqué sur le drain (26) de l'autre (22) transistor de modulation, - une sortie (14, 15) reliée à chacun des drains (25, 26) des transistors de modulation (21, 22) par l'intermédiaire d'un étage (29) sommant vectoriellement sur la sortie (4) les signaux formés sur les drains (25, 26) des transistors de modulation pour délivrer un signal modulé sur la sortie (14, 15),- means (27, 28) of 180 ° phase shift between the high frequency carrier signal applied to the drain (25) of one (21) of the modulation transistors and that applied to the drain (26) of the other (22) modulation transistor, - an output (14, 15) connected to each of the drains (25, 26) of the modulation transistors (21, 22) via a stage (29) summing vectorially on the output (4) the signals formed on the drains (25, 26) of the modulation transistors to deliver a modulated signal on the output (14, 15),
- des moyens (12, 13) pour appliquer sur les grilles (30, 31) des transistors de modulation (21, 22), des signaux analogiques modulant I ou Q, ï ou Q à basse fréquence issus dudit signal de modulation analogique basse fréquence I ou Q , complémentaires l'un de l'autre, dont l'amplitude est inférieure à une valeur maximum Amax au-delà de laquelle la puissance du signal modulé n'est plus proportionnelle à la puissance du signal de modulation analogique basse fréquence I ou Q.- Means (12, 13) for applying on the gates (30, 31) modulation transistors (21, 22), analog signals modulating I or Q, ï or Q at low frequency from said analog low frequency modulation signal I or Q, complementary to each other, whose amplitude is less than a maximum value Amax beyond which the power of the modulated signal no longer proportional to the power of the low frequency analog modulation signal I or Q.
4/ - Circuit selon la revendication 3, caractérisé en ce que les signaux analogiques modulant à basse fréquence I ou Q, î ou Q sont centrés sur une tension Vn choisie de l'ordre de la tension de pincement Vp des transistors de modulation (21, 22) pour minimiser les pertes.4 / - Circuit according to claim 3, characterized in that the analog signals modulating at low frequency I or Q, î or Q are centered on a voltage Vn chosen of the order of the pinch voltage Vp of the modulation transistors (21 , 22) to minimize losses.
5/ - Circuit selon l'une des revendications 3 et 4, caractérisé en ce qu'il comprend des moyens (27) de déphasage de -90° du signal de porteuse à haute fréquence entre l'entrée de porteuse (7, 8) et le drain (25) de l'un (21) des transistors de modulation, et des moyens (28) de déphasage de +90° du signal de porteuse à haute fréquence entre l'entrée de porteuse (7, 8) et le drain (26) de l'autre (22) transistor de modulation.5 / - Circuit according to one of claims 3 and 4, characterized in that it comprises means (27) of phase shift of -90 ° of the high frequency carrier signal between the carrier input (7, 8) and the drain (25) of one (21) of the modulation transistors, and means (28) of phase shift of + 90 ° of the high frequency carrier signal between the carrier input (7, 8) and the drain (26) of the other (22) modulation transistor.
6/ - Circuit selon l'une des revendications 3 à 5, caractérisé en ce qu'il incorpore des moyens, dits moyens (12, 13) de mise en forme, aptes à générer au moins une paire de signaux analogiques modulant à basse fréquence6 / - Circuit according to one of claims 3 to 5, characterized in that it incorporates means, called means (12, 13) for shaping, capable of generating at least one pair of analog signals modulating at low frequency
I» ï . Q> Q complémentaires l'un de l'autre à partir du signal de modulation analogique basse fréquence I ou Q .I " ï . Q > Q complementary to each other from the low frequency analog modulation signal I or Q.
Il - Circuit selon la revendication 6, caractérisé en ce que les moyens (12, 13) de mise en forme comprennent une source de courant (40) ; un étage amplificateur différentiel (41) générant, à partir de la source de courantII - Circuit according to claim 6, characterized in that the shaping means (12, 13) comprise a current source (40); a differential amplifier stage (41) generating, from the current source
(40) et d'un signal de modulation analogique basse fréquence I ; Q , deux signaux analogiques modulant à basse fréquence I, ï ; Q, Q complémentaires délivrés sur les grilles (42, 43) de deux transistors (44, 45) à effet de champ, chacun d'entre eux étant monté en drain commun avec sa source (46, 47) reliée à un pont diviseur (48, 49) fournissant en sortie l'un des deux signaux analogiques modulant à basse fréquence complémentaires I, î , Q, Q centré sur une tension Vn, et destiné à être appliqué sur la grille (30, 31) d'un transistor de modulation (21, 22). 8/ - Circuit selon l'une des revendications 3 à 7, caractérisé en ce qu'il comprend au moins deux étages mélangeurs (5, 6) recevant chacun l'un des deux signaux de modulation analogique I , Q basse fréquence, une entrée principale (1) haute fréquence recevant un signal de porteuse à haute fréquence, des moyens (9, 10, 11) pour appliquer ce signal de porteuse à haute fréquence aux entrées de porteuse (7, 8) des étages mélangeurs (5, 6) avec entre elles un déphasage Δφ non nul prédéterminé, et des moyens pour sommer en phase sur une sortie commune (4) les deux signaux modulés issus des étages mélangeurs (5, 6), de façon à former un circuit modulateur I/Q linéaire analogique.(40) and a low frequency analog modulation signal I; Q, two analog signals modulating at low frequency I, ï; Q, Q complementary delivered on the grids (42, 43) of two field effect transistors (44, 45), each of them being mounted in common drain with its source (46, 47) connected to a divider bridge ( 48, 49) supplying one of the two analog signals modulating at complementary low frequency I, î, Q, Q centered on a voltage Vn, and intended to be applied to the gate (30, 31) of a transistor modulation (21, 22). 8 / - Circuit according to one of claims 3 to 7, characterized in that it comprises at least two mixer stages (5, 6) each receiving one of the two low frequency analog modulation signals I, Q, an input main (1) high frequency receiving a high frequency carrier signal, means (9, 10, 11) for applying this high frequency carrier signal to the carrier inputs (7, 8) of the mixer stages (5, 6) with between them a predetermined non-zero phase shift Δφ, and means for summing in phase on a common output (4) the two modulated signals coming from the mixer stages (5, 6), so as to form an analog linear I / Q modulator circuit .
9/ - Circuit selon la revendication 8, caractérisé en ce que Δφ = 90°.9 / - Circuit according to claim 8, characterized in that Δφ = 90 °.
10/ - Circuit selon l'une des revendications 3 à 9, caractérisé en ce qu'il est formé d'une seule puce de circuit intégré réalisée en technologie MMIC, la fréquence du signal de porteuse à haute fréquence étant supérieure à 1 Gigahertz. 10 / - Circuit according to one of claims 3 to 9, characterized in that it is formed of a single integrated circuit chip produced in MMIC technology, the frequency of the high frequency carrier signal being greater than 1 Gigahertz.
PCT/FR1999/003276 1998-12-24 1999-12-23 Analogue modulation method and monolithic integrated circuit with mixer stage comprising non-polarised field-effect transistors WO2000039918A1 (en)

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US5280648A (en) * 1988-12-06 1994-01-18 Zenith Electronics Corporation Double-balanced high level wide band RF mixer
EP0432851A2 (en) * 1989-12-15 1991-06-19 Philips Electronics Uk Limited Variable bi-phase modulator circuits and variable resistors
FR2760301A1 (en) * 1997-02-28 1998-09-04 Centre Nat Etd Spatiales PHASE DISPLACEMENT MODULATOR ELECTRONIC CIRCUIT WITH DISTRIBUTED STRUCTURE
FR2762942A1 (en) * 1997-05-05 1998-11-06 Alsthom Cge Alcatel COMPACT DOUBLE BALANCED QUAD MIXER FROM COLD TECS IN MMIC TECHNOLOGY

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