Electronic generator of pulsed signals under modulated carrier and associated radio frequency signal transmitter

Abstract

Electronic generator of pulse signals under modulated carrier and associated radio frequency signal transmitter This electronic generator of pulse signals under modulated carrier includes a module (15) for modulating a pulse train whose position and amplitude are controllable, forming a switching signal (S3); a switching module (16), connected at the output of the pulse train modulation module (15), comprising at least one transistor (22), controlled by said switching signal (S3); a voltage-controlled frequency-locked oscillation module (18), having a frequency-locked band around a free oscillation frequency controlled by a control voltage, connected at the output of the switching module (16); the switching module allowing the injection of a periodic pulse signal (S4) having a frequency spectrum comprising at least one frequency line in said frequency-locked band.This arrangement allows the output of the oscillation module to produce pulsed signals (S5) with a modulated carrier controlled in frequency, phase, and amplitude. See Figure 1 for abbreviations.

Description

Title of the invention: Electronic generator of pulsed signals under modulated carrier and associated radio frequency signal transmitter

[0001] The present invention relates to an electronic pulse signal generator under modulated carrier and an associated radio frequency signal transmitter.

[0002] The invention lies in the field of the generation of ultra-wideband pulsed signals under phase- and amplitude-modulated carrier.

[0003] It finds many applications, in particular in high-speed telecommunications, in low-power telecommunications, in particular in low-power pulse radars, in the field of object localization, in the field of self-powered sensors, in the field of radio frequency sensors.

[0004] In the prior art, ultra-wideband pulsed modulation systems are known, notably those using pulse position modulation (PPM), on-off keying (OOK), quadrature amplitude modulation (QAM), or a combination thereof. QAM, such as binary phase-shift keying (BPSK), requires the generation of a reference signal, the carrier, with significant constraints in terms of phase noise. One of the limitations of these pulsed vector modulation techniques lies, among other things, in the complexity and power consumption of the blocks generating the reference signal (carrier) and the modulation blocks.

[0005] Most direct generators of ultra-wideband pulsed signals synthesize the carrier frequency using a phase-locked loop (PLL) block, which is an electronic device that locks the output phase or frequency to the phase or frequency of a reference input signal. This synthesized signal requires complex modulation blocks to ensure the generation of a pulsed envelope signal with vector modulation. To synthesize high carrier frequencies, on the order of tens of GHz, it is necessary to develop complex PLLs with significant power consumption and size. Furthermore, one of the objectives is to reduce the phase noise of the output signals.

[0006] The invention aims to remedy the aforementioned drawbacks of the prior art.

[0007] To this end, the invention proposes, according to one aspect, an electronic generator of pulsed signals under a modulated carrier comprising: - a modulation module for a pulse train whose position and amplitude are controllable, forming a switching signal; - a switching module, connected to the output of the modulation module of a pulse train, comprising at least one transistor, the switching of which is controlled by said switching signal, - a voltage-controlled frequency-locked oscillation module, having a frequency-locked band around a free oscillation frequency controlled by a control voltage, the oscillation module being connected to the output of the switching module, the switching module allowing the injection of a periodic pulsed signal into the oscillation module, - the periodic impulse signal having a frequency spectrum comprising at least one frequency line in said frequency-locked band, the arrangement of said modules allowing to obtain at the output of the oscillation module impulse signals under modulated carrier controlled in frequency, phase and amplitude.

[0008] Advantageously, the proposed generator allows for the direct generation of pulsed signals under a modulated carrier, locked by pulsed injection, controlled in frequency, phase, amplitude and pulse width, without using a phase-locked loop.

[0009] The electronic pulse signal generator under modulated carrier according to the invention may also have one or more of the characteristics below, taken independently or according to all technically conceivable combinations.

[0010] The pulse train modulation module includes a periodically repeated pulse generator forming an input signal, connected to the input of a delay module configured to introduce programmable delays so as to generate a position-modulated signal, said position-modulated signal being supplied to the input of a switching signal generation module, controlled by a voltage signal.

[0011] The pulse signals under modulated carrier are further controlled in pulse width as a function of said input signal.

[0012] The delay module configured to introduce programmable delays is a voltage-time or current-time converter module.

[0013] The switching signal generation module includes at least one electrical signal amplification component with a very short switching time, the amplitude of which is controlled by said voltage signal.

[0014] The switching signal generation module comprises a number N of transistor inverters connected in series.

[0015] Each of said modulation module, switching module and oscillation module is implemented in the form of CMOS components.

[0016] According to another aspect, the invention relates to a radio frequency signal transmitter comprising an electronic pulse signal generator under modulated carrier as briefly introduced and a transmitting antenna connected to said electronic pulse signal generator under modulated carrier. According to one feature, the radio frequency signal transmitter further comprises a power amplifier connected between the output of said electronic pulse signal generator under modulated carrier and said transmitting antenna.

[0017] Other features and advantages of the invention will become apparent from the description given below, by way of example and not limitation, with reference to the accompanying figures, among which:

[0018] [Fig-1] [Fig.1] is a block diagram of a radio frequency signal transmitter comprising an electronic pulse signal generator under modulated carrier according to an embodiment of the invention;

[0019] [Fig.2] [Fig.2] schematically represents a signal waveform impulsive under-carrier generated;

[0020] [Fig.3] [Fig.3] schematically represents an embodiment of an electronic pulse signal generator under modulated carrier.

[0021] Fig. 1 schematically represents a radio frequency signal transmitter 2 comprising an electronic generator 4 of pulsed signals under modulated carrier, the input of which is connected to a pulse generator 6 and the output of which is connected to a power amplifier 8 and a transmitting antenna 10.

[0022] The power amplifier is optional; it may not be present in some embodiments.

[0023] According to one variant, the pulse generator 6 is integrated into the electronic generator 4 of pulse signals under modulated carrier.

[0024] The pulse generator 6 provides a periodic input signal Si consisting of periodically repeated pulse trains, with a pulse repetition period PRP=1 / PRF where PRF is the pulse repetition frequency.

[0025] The electronic generator 4 of pulsed signals under modulated carrier, hereinafter referred to as generator 4, comprises: - a module 15, a modulation module for a pulse train forming a switching signal S3, whose position and amplitude are controllable; the module 15 includes, in the illustrated embodiment, a delay module 12 configured to introduce programmable delays on the input signal Si, generating at the output a signal modulated in position S2, and a switching signal generation module 14, with amplitude controlled by a voltage signal VA m, receiving at the input the signal modulated in position S2; - a switching module 16, connected to the output of module 15, comprising at least one transistor, whose switching is controlled by the switching signal S3, the switching module 16 allowing the injection, into the input of an oscillator 18, of a signal composed of the modulated periodic pulse signal S4; - an oscillation module 18 (or oscillator), having a free oscillation frequency controlled by a control voltage VT, connected to the output of the switching module 16. Such an oscillator is also known as a VCO (for "Voltage-Controlled Oscillator"). The oscillator 18 has a frequency-locked band around its free oscillation frequency.

[0026] The modulated periodic pulse signal S4 has a frequency spectrum comprising at least one frequency line in the frequency-locked band of the oscillator 18.

[0027] Thus, advantageously, the switching times in the switching module 16, controlled by the module 14, ensure the shortest possible transitions in order to generate a line spectrum of which at least one of the lines is present with enough energy to ensure locking in the frequency locking band of the oscillator 18.

[0028] Pulsed signals under carrier S5 are obtained at the output of the oscillator 18, having the following characteristics: • a relative phase controlled by the delay signal r of module 12, • an amplitude controlled by the VA m signal of module 14, • a locking frequency and a phase controlled by the VT signal of the oscillator, • a pulse width controlled by the impulse signal of the input signal Si.

[0029] The arrangement of said modules makes it possible to obtain pulsed signals under modulated carrier, controlled in frequency, position (or phase), width and amplitude.

[0030] Figure 2 illustrates an example of a subcarrier impulse signal as a function of time. In other words, Figure 2 illustrates an example of a generated waveform.

[0031] The S5 pulse signal under modulated carrier is characterized by:

[0032] -its power Pout, or indirectly its amplitude,

[0033] -its center frequency Foqui is an integer submultiple of the pulse repetition frequency of the signal Si,

[0034] -the phase relative to the previous pulse q>0,

[0035] -the width at half-height of the envelope Tw,

[0036] -the PRP repetition period.

[0037] Fig. 3 illustrates an embodiment of a generator 6, in which modules 12, 14, 16, 18 are implemented with electronic components according to CMOS technology (for "Complementary Metal Oxide Semiconductor").

[0038] Module 12 is adapted to introduce programmable rm(t) delays.

[0039] In the illustrated embodiment, module 12 is implemented by a delay circuit which performs a voltage-time conversion, from the voltage signal Vin, for example implemented using a shunt capacitor circuit.

[0040] Of course, any other controllable delay circuit can be used, for example a current starved delay circuit, or a variable resistance circuit.

[0041] The delay signals act as control signals allowing the start-up time of the oscillator 18 to be defined with a high degree of granularity.

[0042] In one embodiment, the delay module 12 is controlled by three delay signals (or control signals), corresponding respectively to phase shifts of 45°, 90° and 180° for a sinusoidal reference signal, for example with a frequency of 60 GHz.

[0043] At the output of the delay module 12 is obtained a position-modulated signal S2 (PPM), which results in a phase modulation in the pulse signal under modulated carrier S5.

[0044] The signal S2 is transmitted as input to the switching signal generation module 14 S3, the amplitude of the output signal of this module being controlled by a voltage VA m-

[0045] In one embodiment, module 14 is implemented by a number N of inverters connected in series, N being equal to 3 in the example. Module 14 comprises N=3 transistor inverters 14b, 142 and 143, which have the advantage of short switching times, for example less than 10 picoseconds in 65nm SOI CMOS technology.

[0046] The transistors of the inverters 14b, 142, and 143 are sized according to the frequency-locked band of the oscillator 18 and the free oscillation frequency of the oscillator 18, in order to allow the rising-edge switching of module 16 with the shortest possible switching time. For example, the switching time of module 16 is less than 10 picoseconds for a free oscillation frequency of 60 GHz.

[0047] Indeed, the use of a number N of inverters in series asymptotically allows obtaining the shortest possible transition times, and more particularly rise times.

[0048] If the number N of inverters is even, the pulse signal S5 at the output of generator 6 starts on a rising edge of the input signal Sb. If the number N of inverters is odd, the pulse signal S5 at the output of generator 6 starts on a falling edge of the input signal Sb.

[0049] The switching signal S3 obtained at the output of module 14 is supplied at the input of the switching module 16, which performs a switch between a blocked mode (“off”) and a passing mode (“on”).

[0050] When the switching signal S3 is low (0V by convention), no current flows through module 16. When the switching signal S3 goes high (voltage equal to VAm by convention), module 16 becomes conducting, and a current flows to the oscillation module 18. This current includes the amplitude-controlled pulse current, denoted S4, which is rich in harmonics of the input signal Si

[0051] In the embodiment of [Fig.3], the switching module 16 consists of a transistor 22. More generally, the switching module 16 comprises at least one transistor.

[0052] The control voltage on the gate of transistor 22 allows control of the current injected into the main branch of oscillator 18, and thus control of the output power of this oscillator and promote injection locking.

[0053] The supply voltage VAm of module 14 allows control of the control voltage on the gate of transistor 22. Thus, the supply voltage VAm allows control of the output power of this oscillator.

[0054] The oscillator 18 includes variable capacitance diodes 24, 26, also called varactor or varcap diodes, driven by the control voltage VT, a field-effect transistor 28 and a capacitor 30.

[0055] The free oscillation frequency fO of the oscillator 18 is a function of the control voltage VT. Modulating the applied voltage around the control voltage changes the instantaneous phase of the center output frequency. For example, in a In this implementation example, the average center frequency is between 55 and 65 GHz.

[0056] The pulse signal S4 and the control voltage VT enable the output frequency of the oscillator 18 to be locked to an integer multiple of the frequency of the input signal Si. This phenomenon is known as oscillator injection locking.

[0057] An oscillator of this type starts from a low energy from a harmonic component present in its frequency locking band AF, close to its free oscillation frequency f0.

[0058] The locking phenomenon is transient and depends strongly on the external quality coefficient of the oscillator Qext, the power of the oscillator Posc and the power of the injected signal S4, denoted Pinj.

[0059] The locking band is defined by Adler's formula:

[0060] / , E~

[0061] During ignition, in transient regime, the two powers Posc(t) and Pinj(t) are a function of time.

[0062] Initially, the power of the oscillator Posc(t) is much less than the power of the injected signal, Pinj(t), and the locking band is large.

[0063] In steady state, the oscillator power Posc(t) is greater than the power of the injected signal, Pinj(t), and the locking band decreases. To ensure that the oscillator is locked, in other words, to ensure the presence of a harmonic component in the oscillator's locking band, the control voltage VT is applied to modulate the frequency f0.

[0064] Advantageously, the electrical power consumption of an electronic pulse signal generator under modulated carrier as described is low. When the oscillator is not operating, only a leakage current of low amplitude flows.

[0065] When CMOS technology is used, the generator consumption is a function of the pulse repetition rate and the oscillator consumption.

[0066] For example, for a peak emission power of Pout=10mW (1OdBm) and an energy efficiency q=20% (i.e. a static consumption of the oscillator of 50 mW), if the RF pulse is on for TON=500 ps (i.e. 30 periods for a carrier at 60 GHz and an occupied bandwidth of 4 GHz), the energy consumed per RF pulse is 50 mWx300 ps=15 pJ.

[0067] Advantageously, the invention allows for a rapid and time-controlled ignition of an oscillation module using pulses with short transition times.

[0068] Advantageously, the programmable delay introduced makes it possible to determine the start time of the oscillator.

[0069] Advantageously, in the described electronic pulsed-carrier signal generator, the initial start-up conditions of the oscillator, in particular the start-up time, are determined before frequency synthesis.

[0070] Advantageously, the applied control voltage VT allows the phase to be controlled during the start-up of the oscillator.

[0071] Advantageously, the electronic pulse signal generator under modulated carrier allows for n-PSK phase modulation, n-AM amplitude modulation and / or n-QAM joint phase and amplitude modulation, with a number of phase states for example between 2 and 16.

Claims

Demands

1. Electronic generator of pulsed signals under modulated carrier, characterized in that it comprises: - a modulation module (15) for a pulse train whose position and amplitude are controllable, forming a switching signal (S3); - a switching module (16), connected to the output of the modulation module (15) for a pulse train, comprising at least one transistor (22), the switching of which is controlled by said switching signal (S3); - a voltage-controlled frequency-locked oscillation module (18), formed of an oscillator (18) having a frequency-locked band around a free oscillation frequency controlled by a control voltage, the oscillation module (18) being connected to the output of the switching module (16), the switching module (16) injecting a periodic pulsed signal (S4) into the oscillation module (18).- the periodic pulsed signal (S4) having a frequency spectrum comprising at least one frequency line in said frequency-locked band, the arrangement of said modules enabling the output of the oscillation module (18) to produce pulsed signals (S5) under a modulated carrier controlled in frequency, phase and amplitude.

2. Generator according to claim 1, wherein the pulse train modulation module (15) comprises a periodically repeated pulse generator (6) forming an input signal (SJ), connected to the input of a delay module (12) configured to introduce programmable delays so as to generate a position-modulated signal (S2), said position-modulated signal (S2) being supplied to the input of a switching signal generation module (14) (S3), controlled by a voltage signal (VA m)

3. Generator according to claim 2, wherein said pulse signals (S5) under modulated carrier are further controlled in pulse width as a function of said input signal (Si).

4. Generator according to any one of claims 2 or 3, wherein the delay module (12) configured to introduce programmable delays is a voltage-time or current-time converter module.

5. Generator according to any one of claims 2 to 4, wherein the switching signal generation module (14) (S3) comprises at least one electrical signal amplification component with a very short switching time, the amplitude of which is controlled by said voltage signal (VA m)-

6. Generator according to claim 5, wherein said switching signal generation module (14) comprises a number N of transistor inverters (14b 142, 143) connected in series.

7. Electronic generator according to any one of claims 1 to 6, wherein each of said modulation module (15), switching module (16) and oscillation module (18) is made in the form of CMOS components.

8. Radio frequency signal transmitter comprising an electronic pulse signal generator under modulated carrier (4) according to claims 1 to 7 and a transmitting antenna (10) connected to said electronic pulse signal generator under modulated carrier (4).

9. Radio frequency signal transmitter according to claim 8, further comprising a power amplifier (8) connected between the output of said electronic pulse signal generator under modulated carrier (4) and said transmitting antenna (10).

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