METHOD FOR IMPROVING THE STARTING PROCESS OF AN OSCILLATOR OF A SUPER RESPONSE RECEIVER AND RECEIVER FOR EXECUTING THIS METHOD

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to a method for improving the detection of the start-up time of the oscillator of a super-regenerative receiver, as well as the receiver for implementing the method. STATE OF THE ART

[0002] Known since the 1920s and invented by Edwin Howard Armstrong, this shortwave receiver initially included three expensive vacuum tubes, and Armstrong's invention reduced the receiver's operation to a single tube. As discussed later, this principle is used in the present invention of the super-regenerative receiver to reduce power consumption and simplify its architecture.

[0003] In the patent filed in his name US 1,342,885 A, a method for receiving high-frequency oscillations by a shortwave receiver is described.

[0004] In a superfeedback receiver, an oscillator such as a VCO (Variable Voltage Regulator) of the LC type can be used. This type of LC oscillator begins to oscillate when the losses in the L and C resonator are compensated by the negative conductance of active devices. This limit corresponds to a minimum current, also called the critical current of the oscillator, which is required to initiate oscillation.

[0005] In a superfeedback receiver, the RF signal is directly injected into the oscillator's resonant coil. Depending on whether the frequency is close to or far from the oscillator's resonant frequency, and on the amplitude of the RF signal, the oscillator starts with more or less current and for a shorter or longer time. This starting current and the associated starting time are detected.

[0006] To quantify this starting current and its associated start-up time, the oscillator is triggered. A rising current is injected into the oscillator. This current begins below the critical current and increases until the oscillator starts. The current can, for example, follow a linear ramp. The oscillator begins to oscillate at a given current corresponding to a specific start-up time.

[0007] US patent application 5,613,231 A describes an oscillator with an active component or amplifier and a reactive stabilizing component. The active component is a bipolar transistor arranged in a common-base circuit, while the reactive component is a dielectric resonator fully coupled to the transistor's collector. The base of the bipolar transistor is connected to one terminal of a power supply via a first resistor and to a common point via a second resistor, with its emitter connected to the same terminal via a third resistor. A resonator core is connected between the collector of the bipolar transistor and the common point. No details are provided regarding the improvement of the startup time of an oscillator in a super-regenerative receiver.

[0008] It should also be noted that it is difficult to detect or determine the exact start-up time of the reference oscillator because the oscillation amplitude is generally low at startup, typically below 100 mV. Furthermore, typical amplitude detection circuits in CMOS technology are not very sensitive to amplitudes below 100 mV.

[0009] US patent application 2010 / 237935 A1 describes a logarithmic detector comprising an amplifier element, means for setting an operating frequency of the detector, and a controller in which an input signal to the amplifier element is arranged to cause oscillation in the amplifier element. The controller is usable to detect a predetermined threshold, indicative of oscillation, and, in response to threshold detection, to interrupt the oscillation of the amplifier so that the frequency of the interruption is proportional to the logarithm of the power of the input signal. No superfeedback receiver is described.

[0010] The article by Patrick Favre et al., "A 2-V 600-A 1-GHz BiCMOS Super-Regenerative Receiver for ISM Applications," published in the IEEE Journal of Solid-State Circuits, IEEE, USA, vol. 33, no. 12, December 1, 1998, XP011060882, ISSN: 0018-9200, is cited. It describes a super-regenerative receiver that includes a bias current generator to provide bias current to a reference oscillator upon receiving the first on-state control signal, an oscillation detector connected between an input and output of the reference oscillator and the bias current generator to detect oscillation in the reference oscillator, and an additional amplification current generation circuit to provide supplementary amplification current to the reference oscillator in addition to the conventional bias current.This additional amplification current is supplied to the reference oscillator, in addition to the traditional bias current, to amplify the oscillation signal above a critical oscillation start threshold. This threshold defines the oscillator's start time and allows the detector to control the reference oscillator's shutdown. However, a gradual increase in the bias current is not provided to better define the start time, which is a drawback.

[0011] Patent application GB 2 433 365 A describes a superfeedback receiver comprising a reference oscillator powered by bias currents immediately upon oscillator activation and a pulse-width controller. The oscillator remains active up to a certain oscillation level before being deactivated. The lack of a gradual increase in bias current to better define the start-up time is a drawback. SUMMARY OF THE INVENTION

[0012] The invention aims to provide a method for improving the detection of the start-up of an oscillator in a super-regenerative receiver for receiving one or more RF signals, overcoming the aforementioned drawbacks of the prior art while reducing power consumption for its operation. Furthermore, the receiver is capable of implementing the method for improving the start-up of its oscillator.

[0013] To this end, the invention relates to a method for improving the starting of an oscillator of a super-regenerative receiver, which includes the characteristics defined in independent claim 1.

[0014] Specific steps of the process are defined in dependent claims 2 to 5.

[0015] One advantage of this method for improving the detection of the start-up of a super-regenerative receiver's oscillator lies in its ability to provide a smoother transition between the receiver's inactive and active states around a well-defined start-up time, which is proportional to the amplitude and frequency of the received RF signal. To achieve this, following an increasing bias current, and specifically upon passing a first low voltage threshold corresponding to a critical bias current at the start of the oscillation, an additional amplification current is supplied to the oscillator, at least from the very beginning of the detected oscillation. This also allows for the precise determination of the oscillator's start-up time, because without this additional amplification current (defined as a "boost" current), accurately determining this start-up time, which is dependent on the received RF signal, becomes difficult.

[0016] Advantageously, once the oscillation is detected, it can be considered to cut off the bias current as well as the additional amplification current in order to reduce the receiver's power consumption. Several successive, time-spaced cycles of bias current supply from a bias current generator are generally planned, allowing the evolution of the RF signal to be measured at regular intervals.

[0017] Advantageously, a circuit is provided for generating an amplification current in addition to the oscillator's bias current generator. This amplification current generation circuit can be adapted to supply additional amplification current to the oscillator as soon as the oscillation is detected at the first low voltage threshold. This allows for the rapid switching off of both the bias current and the additional amplification current for the oscillator upon oscillation detection, thereby reducing the power consumption of the receiving circuit. This amplification current can be constant above the low voltage threshold, providing a rapid additional amplification current to accurately determine the oscillator's oscillation start time without being influenced by potential noise from amplitude variations in the oscillator signal.

[0018] The receiver's reference oscillator is preferably a high-frequency VCO-type oscillator corresponding to the frequency of an RF signal received by the receiver. To reduce power consumption, the reference oscillator should ideally be switched off immediately after the oscillator's oscillation start-up time is determined. This VCO-type oscillator is preferably an LC oscillator consisting primarily of an inductor and a capacitor in parallel.

[0019] Advantageously, the external RF signal, which is collected by the receiver's antenna, is fed directly into the oscillator's resonant circuit, thus creating an initial oscillation condition that is more or less favorable to the oscillator's faster or slower startup. Furthermore, the subsequent startup time is directly dependent on the received RF signal.

[0020] To this end, the invention also relates to a super reaction receiver for implementing the process, which includes the features defined in independent claim 6.

[0021] Specific shapes of the receiver are defined in dependent claims 7 to 11. BRIEF DESCRIPTION OF THE FIGURES

[0022] The goals, advantages, and characteristics of the method for improving the startup of a reference oscillator in a super-regenerative receiver will become clearer in the following description, based on non-limiting embodiments illustrated by the drawings in which: there figure 1 represents, in simplified form, a first embodiment of a super-regenerative receiver with a set of electronic components for detecting the presence of an RF signal at the input and improving the detection of the start of the oscillator's oscillation according to the present invention, the figure 2represents a second simplified embodiment of the RF signal receiver adapted to improve the detection of the start-up time of a reference oscillator such as a voltage-matched VCO with a bias current for generating an oscillator oscillation and an additional amplification current according to the present invention, the figure 3 represents a simplified implementation of a circuit for generating additional amplification current to be supplied preferably to the oscillator at the beginning of oscillation for the super-regenerative receiver, and where the input of this circuit is directly connected to an output terminal of the reference oscillator shown in figures 1 and 2 , there figure 4 represents the time evolution of the amplitude of the output signal of the reference oscillator at startup for different amplitudes of the RF signal present on the input RF pad shown in figures 1 and 2and showing the difference with or without the addition of an extra amplification current at the time of activation of the receiver and the bias current generator, and the figure 5 represents the additional amplification current for the VCO oscillator as a function of the output signal amplitude, where this current increases rapidly beyond a certain output signal amplitude, which makes it possible to noticeably increase the growth of the output signal by positive feedback, and this faster amplitude growth makes it easier to detect the oscillator's oscillation start time. DETAILED DESCRIPTION OF THE INVENTION

[0023] The following description refers to a method for improving the start-up detection accuracy of the oscillator in a superfeedback receiver while reducing power consumption. Naturally, all the components used in the receiver, which are well-known in the technical field, will only be described in simplified form. The primary focus is on improving the start-up detection accuracy of the reference oscillator, which could be, for example, an LC-type VCO oscillator.

[0024] There figure 1This fully represents a first implementation of an RF signal receiver 1 arranged to improve the accuracy of detecting the start-up time of a reference oscillator 4, particularly following the detection of at least one RF signal reception. The start-up time depends directly on the RF signal received by the receiver. To achieve this, the receiver 1 includes, firstly, an input terminal or pad 2 for receiving an RF signal. The receiver 1 includes a reference oscillator 4 for generating an oscillation in the oscillator, and a bias current generator 7 to supply a bias current i_vco to the reference oscillator 4. The bias current i_vco is supplied to the reference oscillator 4, particularly following the reception of at least one start control signal.Preferably, a time-spaced cycle of activation control signals Sosc is provided for the bias current generator 7.

[0025] The super-regenerative receiver 1 further includes an oscillation detector 6, which is connected between a coil output of the reference oscillator 4 and the bias current generator 7 so as to control the generator 7, particularly after an RF signal is received by the receiver 1 and an oscillation of the oscillator is detected. An impedance matching unit 3 of the receiver 1 is arranged between the receiver terminal or pad 2 of the receiver 1 and the reference oscillator 4.

[0026] Receiver 1 also includes a circuit for generating an additional amplification current, not shown in the figure 1The additional amplification current iboost is supplied in addition to the bias current i_vco to the oscillator to improve the detection of the oscillator's start-up time. The additional amplification current iboost is preferably generated and supplied to the oscillator as soon as the first oscillation of the oscillator is detected, so as to stop the oscillator at the beginning of the oscillation in the reference oscillator 4, but at least after the supply of this additional amplification current iboost. This also allows for a more precise determination of the start-up time of the oscillation of the reference oscillator 4, as the additional amplification current iboost is preferably larger than the bias current i_vco.After the supply of this additional amplification current (iboost) and the detection of the oscillator's oscillation, the bias current (i_vco) and the additional amplification current (iboost) are rapidly cut off. This allows for a direct and rapid reduction in power consumption compared to a traditional receiver. It should be noted that the additional amplification current generation circuit can be activated as soon as the oscillation detector first detects an oscillator oscillation. Once the additional amplification current has been supplied to the reference oscillator, the start-up time is well-defined and the oscillation is well-established. This allows for the complete shutdown of the oscillator, specifically by deactivating the bias current generator and the additional amplification current generation circuit.

[0027] This startup time depends on at least one RF signal being received by the receiver. Any information related to the received RF signal allows the startup time to be precisely determined.

[0028] It should be noted that the additional amplification current generation circuit can be activated as soon as the oscillation detector 6 first detects an oscillation of the oscillator. Once the additional amplification current has been supplied to the reference oscillator 4, the start-up time is well defined and the oscillation is well established. This allows for the complete shutdown of the oscillator, notably by deactivating the bias current generator 7, as well as the additional amplification current generation circuit.

[0029] Of course, for the super-regenerative receiver 1, the receiver must include a signal processing unit, which may comprise a processor clocked by another oscillator or a microprocessor. Control signals for the various electronic components of the receiver can be transmitted by the processing unit (not shown). The processing unit can handle the reception of an initial RF signal to trigger the bias current generator. The processing unit can also provide at least one activation control signal to activate the bias current generator 7 and also to activate the additional amplification current generation circuit iboost as soon as a detected oscillation begins.

[0030] In the Sosc activation control signal cycle, there is first a start control signal to provide a bias command for the reference oscillator 4. From this point on, following the start activation control signal of the bias current generator 7, the bias current i_vco increases, for example, linearly until it reaches a critical value. At this point, the reference oscillator 4 can begin to oscillate, for example, at a high frequency of around 2.4 GHz. It is the envelope of this high-frequency signal that can be used for oscillation detection.From the moment the reference oscillator 4 begins to oscillate, a detection is performed in the oscillation detector 6, which is connected at least to the bias current generator 7, as well as to the additional amplification current generation circuit iboost, either directly or via the bias current generator 7. Once the oscillation detection is performed and after the additional amplification current iboost has been supplied, a stop signal is provided to the bias current generator 7, as well as to the additional amplification current generation circuit, to immediately stop the oscillation of the reference oscillator 4. This is the objective of the present invention: to completely stop the supply of the bias current and the additional amplification current to the reference oscillator 4 as soon as the oscillation of the reference oscillator 4 is detected.A reduction in power consumption is thus achieved by immediately stopping the supply of the bias current i_vco and the additional amplification current iboost to the oscillator 4 once the oscillation has been detected. The oscillator immediately stops oscillating after the stop command provided by the oscillation detector 6 to the bias current generator 7 and the additional amplification current generation circuit discussed with reference to the [reference missing]. figure 3 next.

[0031] In a classic situation, the envelope of the high-frequency signal created by the oscillator grows slowly at startup following the supply of the bias current i_vco, and it becomes difficult to accurately detect the startup time by observing the envelope of the high-frequency signal, because a slight change in the envelope voltage detected in the vicinity of a given threshold can easily be induced by ambient noise (noise present in all active components of the oscillator and amplitude detector).

[0032] According to the present invention, it is possible to generate an additional amplification current, iboost, dependent on the detected envelope, and to send this current directly to the oscillator bias along with the bias current, i_vco, thus creating a positive feedback. This positive feedback allows the oscillator to rapidly increase the envelope of the oscillating signal (as soon as an oscillating signal begins to exist) and thus to pass the envelope detection signal much more quickly and with a much steeper slope through a given threshold corresponding to the critical oscillation start current threshold.

[0033] The oscillation detector 6 will detect oscillations following the supply of the additional amplification current iboost, for which the envelope of the second oscillation signal is well above the oscillation start threshold. Following this detection by the oscillation detector 6, with a well-defined start time, a stop signal is transmitted to the bias current generator 7 as well as to the circuit generating the additional amplification current iboost. For the oscillation detector 6, an initial oscillation detection may be provided to allow the additional amplification current generation circuit to be activated and supply the additional amplification current to the oscillator. Finally, the oscillation detector provides a stop control signal after the second oscillation detection with amplification of the oscillating signal.

[0034] As explained below with reference to the figure 3 In one embodiment, the additional amplification current generation circuit can be integrated into the bias current generator 7. However, it is also possible to have an additional amplification current generation circuit located outside the bias current generator. In this case, the additional amplification current generation circuit can be directly controlled by the oscillation detector 6 to supply the additional amplification current, particularly from the onset of the detected oscillation.

[0035] Preferably, the reference oscillator 4 is a voltage-controlled VCO oscillator of the LC type, which includes in parallel at least one inductor L1 and one capacitor C1. In the configuration shown in the figure 1The inductor L1 is split into two inductors connected to each other, and the connection between the two inductor parts is supplied with a matching voltage Vdd. The inductor defines an oscillating circuit, whose resonant frequency is adjusted using a variable capacitor (not shown in the diagram). figure 2 ), which is controlled by a Vtune voltage. To do this, receiver 1 also includes a phase-locked loop PLL 5 dependent on an external frequency reference (not shown in the figure 1) and connected between the coilp output of VCO oscillator 4 and the control voltage of the variable capacitor (Vtune). The matching voltage Vtune at the output of PLL 5 is a control voltage for the oscillation frequency of the voltage-controlled VCO oscillator 4. PLL 5 may include analog memory to store the Vtune voltage. Of course, since the oscillator operates differentially, the unshown coiln output terminal can also be used instead of the coilp output terminal of the reference oscillator 4. In this case, as shown in the figure 2 , the coiln terminal not shown is the input of the reference oscillator 4 connected by the impedance matching unit 3 to the terminal or pad 2 of the RF signal receiver 1.

[0036] As depicted in figure 1The impedance matching unit 3 allows the radio frequency (RF) signal received by the receiver 1 to be matched before entering the reference oscillator 4, which is preferably a VCO oscillator. This impedance matching unit 3 comprises, firstly, a capacitor 31 connected on one end to the RF signal input terminal or pad 2 and on the other end to a second capacitor 32, the other end of which is connected to the input of the reference oscillator 4, which is the VCO oscillator. The impedance matching unit 3 also includes an inductor 33, which is connected on one end to the junction of the two capacitors 31 and 32 and on the other end to ground.

[0037] There figure 3represents an implementation of the iboost supplemental amplification current generation circuit to be supplied to the reference oscillator 4, which may be a VCO oscillator, in addition to a bias current in one operating mode of the oscillator. Preferably, the iboost supplemental amplification current generation circuit includes a first sensing stage M11, M12 connected to a current mirror M13, M14 for supplying the iboost supplemental amplification current to the oscillator. As described later, such a supplemental amplification current generation circuit can be even simpler than what is already shown here. figure 3 .

[0038] The various stages M11, M12, M13, and M14 are composed, for example, of CMOS transistors. In the configuration presented at the figure 3The first detection stage, M11 and M12, consists of two NMOS transistors, M11 and M12. These two transistors, M11 and M12, are, for example, two identical NMOS transistors of the same size, biased in weak inversion. The current mirror, M13 and M14, consists of two NMOS transistors, M13 and M14. These two transistors, M13 and M14, are, for example, two NMOS transistors biased in strong inversion.

[0039] The first transistor M11 of the first detection stage has a gate terminal connected to the coilp signal of oscillator 4 of the figure 1via an input capacitor C. The source terminal of the first transistor M11 in the first detection stage is connected to the ground terminal at 0 V, while the drain terminal of transistor M11 is connected via an input resistor R to its gate terminal and to a first current source 11 connected to a supply voltage terminal Vdd and providing a current I for the first transistor M11. At the moment of switch-on of the receiver and the bias current generator, since the bias current is relatively low, the voltage increases very gently before reaching the critical threshold for oscillation to begin in the oscillator.

[0040] The current from the first current source 11 biases the NMOS transistor M11 in a nonlinear amplitude sensing mode, and the Vmeas voltage decreases as the amplitude of the oscillating coilb signal increases. The gate terminal of the NMOS transistor M12 is connected to this Vmeas voltage and has the effect of diverting all the current from the second current source 12 (slightly lower than source 11) to ground. As the amplitude of the coilb signal increases, the sensed Vmeas voltage decreases, and the current from source 12 is gradually fed into the current mirror formed by the NMOS transistors M13 and M14, which then determines an increasing Iboost current. Preferably, the current source 11 is adjusted to provide a current slightly higher than that of source 12.To control the current mirror M13, M14, the drain terminal of the second NMOS transistor M12 of the amplitude detector is connected to the drain and gate terminals of the first NMOS transistor M13 of the current mirror, while the source terminal of the first NMOS transistor M13 of the current mirror is connected to ground at 0 V. The gate terminal of the second NMOS transistor M14 of the current mirror is connected to the gate and drain terminals of the first NMOS transistor M13 of the current mirror. The source terminal of the second NMOS transistor M14 is connected to ground at 0 V, while the drain terminal of the second NMOS transistor M14 of the current mirror provides the additional amplification current boost for the reference oscillator.

[0041] Other implementations of the additional amplification current generation circuit can be considered, taking as an example the implementation described above with reference to the figure 3 .

[0042] To describe the process for improving the startup of the receiver's reference oscillator, there are various signals for activating receiver 1, particularly upon reception of an RF signal, which are briefly described. It is also specified that the super-regenerative receiver 1 is preferably a wake-up receiver, which must be continuously active but for very short periods, as defined in the cycle of control signals Sosc described in the... figure 1 , which are several successive start control signals supplied in time to the bias current generator 7 to switch it on or activate it.

[0043] In the case of a VCO oscillator of the LC type, this oscillator is designed to be frequently in a triggered state and is configured to start very often for short periods and very quickly at high frequencies, for example, 2.4 GHz. The VCO oscillator can be rapidly switched on for short periods to react with few components to key elements of the oscillation that need to be initiated quickly. It is possible that the Sosc (start) activation control signal, where the oscillation begins, has a period of 1 µs, and that in one second there are approximately 1000 Sosc activation control periods, or VCO oscillator switching cycles. This means that receiver 1 is fully switched on for only 1 ms per second, which significantly reduces power consumption, which is the desired outcome.As explained previously, following an initial start command signal supplied to the bias current generator 7, the bias current value increases linearly until it reaches a critical value, but relatively slowly. As soon as the critical current value is reached, the VCO reference oscillator 4 begins to oscillate, which is directly detected by the oscillation detector 6. This detector transmits a stop oscillation command signal to the bias current generator 7. The oscillation of the VCO reference oscillator is then canceled, indicating that an RF signal has been detected. This also ensures a significant reduction in the power consumption of the receiver 1 compared to prior art.

[0044] Of course, the frequency of occurrence of these start Sosc control signals for the bias current generator 7 can be changed manually or automatically to adapt to the conditions of the reference oscillator 4.

[0045] It should also be noted that in an initial frequency centering mode, the VCO oscillator is started in a loop of this type to determine a voltage, such as the Vtune voltage corresponding to the reception frequency, particularly in a traditional frequency synthesizer. This voltage is then stored by a DAC, and the synthesizer is deactivated. VCO 4 is switched off, and the RF signal can be sent, for example, through the matching network 3 to the resonant circuit of VCO 4 to perform superfeedback demodulation. The VCO start-up time is measured in the presence of a ramp of its bias current. Thus, it is possible to avoid lowering the demodulation frequency in this superfeedback receiver.

[0046] Such a frequency synthesizer, which includes the VCO oscillator, was described in patent application EP 3 573 241 A1 with reference to the figure 4in the description. If such a frequency synthesizer is used for frequency centering of the VCO oscillator of the present invention, this patent application is incorporated herein by reference.

[0047] The super-reaction receptor will now be described again with reference to the figure 2 or other forms of execution.

[0048] There figure 2 represents a second execution form of the receiver by showing only the input 2 of the receiver, the impedance matching unit 3 and the reference oscillator 4 which is here a VCO oscillator 4. On this figure 2The oscillation detector and the phase-locked loop (PLL) are not shown, but as before, they operate at the same point in the receiver. The VCO oscillator consists of a first inductor L1 and a capacitor C1 connected in parallel with inductor L1. As before, inductor L1 is split into two inductors connected to each other, and the connection between the two inductor parts is powered by a supply voltage Vdd. VCO 4 also includes, below one end of the connection between inductor L1 and capacitor C1, a first transistor M1, which is preferably a MOS transistor, for example, in this configuration, an NMOS transistor, and at the other end of the connection between inductor L1 and capacitor C1, a second transistor M2 of the same type as the first transistor, for example, an NMOS transistor.The drain terminal of the first transistor, M1, is connected to the first end of the coupling between inductor L1 and capacitor C1, while the drain terminal of the second transistor, M2, is connected to the second end of the coupling between inductor L1 and capacitor C1. The gate of the first transistor, M1, is connected to the drain of the second transistor, M2, while the gate of the second transistor, M2, is connected to the drain of the first transistor, M1. The two sources of transistors M1 and M2 are connected to receive the bias current from the bias current generator 7. The coil output of the VCO oscillator can be provided by the drain of the second transistor, M2.

[0049] The impedance matching unit 3 comprises a first capacitor 31 connected on one side to the input terminal or pad 2 of the receiver 1, while a second side of the first capacitor 31 is connected to one end of an additional inductor 33, the other end of which is connected to one side of a second capacitor 32. The additional inductor 33 is divided into two inductors connected to each other, and the connection between the two inductor parts can be connected to ground. The connection between the first capacitor 31 and the additional inductor 33 is further connected to one side of a third capacitor 34 and to one side of a fourth capacitor 35, the other side of which is connected to ground. One side of a fifth capacitor 36 is connected to the connection of the second capacitor 32 and the additional inductance 33. The other side of the fifth capacitor 36 is connected to ground.

[0050] One side of the second capacitor 32 is connected to the first end of inductor L1 and capacitor C1, and also to the gate of the second transistor M2 and the drain of the first transistor M1. The other side of the third capacitor 34 is connected to the second end of inductor L1 and capacitor C1, and also to the gate of the first transistor M1 and the drain of the second transistor M2. The frequency matching voltage can be applied to either the first or second end of the connection between inductor L1 and capacitor C1.

[0051] As previously stated, a reference oscillator other than a traditional VCO oscillator can be used as long as it can operate at high frequencies, for example around 2.4 GHz.

[0052] There figure 4represents different values ​​of the coilp envelope for different amplitude values ​​of the RF signal applied to the receiver input, and shows the difference with and without the addition of extra amplification current when the receiver and bias current generator are activated. As can be seen on the figure 4 Signal s1 is represented as a solid line with an RF input value of -30dBm. Signal s2 is represented as a dashed line with an RF input value of -40dBm. Signal s3 is represented as a dashed line with a broad dashed line and an RF input value of -50dBm. Finally, signal s4 is represented as a solid line with a bold dash and an RF input value of -60dBm.

[0053] On this figure 4The difference is clearly visible when an additional amplification current, iboost, dependent on the amplitude envelope of the coilp signal, is added to the traditional bias current, i_vco, to accurately determine the oscillator's start-up time. Adding this additional amplification current, iboost, allows for better oscillation detection of the reference oscillator 4. The voltage across the gates of transistors M13 and M14 in the current mirror quickly rises above the threshold voltage. This allows the oscillator to oscillate more rapidly, thus accurately detecting the oscillator's start-up time as measured by the oscillation detector.

[0054] Different envelopes of the coilp signal are represented on the figure 4These correspond to different levels of the RF signal present at the receiver input. The relatively small increase in the coilp oscillator's envelope is clearly visible if only the bias current is supplied to the oscillator. Due to ambient noise, detecting the coilp envelope transition above a given threshold is difficult using only the bias current. Therefore, an additional amplification current is added for faster oscillator oscillation start-up, as seen in the four signals s1, s2, s3, and s4 shown with and without amplification.

[0055] There figure 5This represents the additional amplification current for the VCO oscillator and also the amplitude, which increases rapidly once a given threshold is reached. This larger amplitude makes it easier to detect the oscillator's oscillation start time. This is due to positive feedback; the additional amplification current and the amplitude increase rapidly once the threshold is reached. This larger amplitude makes it easier to detect the start time, which is the desired characteristic.

[0056] From the description just given, several variants of the method for improving the starting of a reference oscillator of a super-regenerative receiver can be carried out without going out of the scope defined by the claims.

Claims

1. Method for enhancing the detection of the start time of a reference oscillator (4) of a super-regenerative receiver (1), the receiver (1) comprising the reference oscillator (4), a bias current generator (7) for supplying a bias current (i_vco) to the reference oscillator (4) on receiving at least one activation control signal (Sosc), an oscillation detector (6) connected between an input or an output (coilp) of the reference oscillator (4) and the bias current generator (7) for detecting an oscillation in the reference oscillator (4), and an impedance matching unit (3) disposed between a terminal or pad (2) for receiving an RF signal of the receiver (1) and the reference oscillator (4), following the supply of the bias current (i_vco) after receiving the activation control signal (Sosc), the oscillation detector (6) detect a first oscillation of the reference oscillator (4) and as soon as oscillation is detected, an additional amplification current (iboost) dependent on the envelope of the oscillation detected by an amplification current generation circuit is supplied to the reference oscillator (4) in addition to the bias current to amplify the oscillation signal to be above a critical oscillation start threshold so as to precisely define the oscillator start-up time, , at each activation control signal (Sosc) supplied to the bias current generator (7), a bias current which increases progressively until at least one critical current value is attained from which the oscillation of the reference oscillator (4) starts, in that the oscillation detector (6) detects the first oscillation of the reference oscillator (4), and characterised in that at the second oscillation detected by the oscillation detector (6) a stop control signal (stop) is supplied to the bias current generator (7), as well as an additional amplification current generation circuit for immediately cutting off the supply of the currents to the reference oscillator (4) to stop it immediately and thus reduce the electricity consumption of the receiver.

2. Method according to claim 1, characterised in that the bias current (i_vco) is supplied to the reference oscillator (4) particularly after receiving each activation control signal (Sosc) over the time of a cycle of activation control signals (Sosc) of the bias current generator (7).

3. Method according to claim 2, characterised in that the activation control signal (Sosc) starts over a period of 1 µs and that over one second, close to 1000 activation control periods (Sosc) of a cycle of successive control signals (Sosc) can be counted such that the receiver (1) is only fully engaged for 1 ms out of one second.

4. Method according to one of the preceding claims, for which the receiver (1) further comprises a PLL phase lock loop (5), characterised in that over time, a tuning voltage (Vtune) is supplied to the reference oscillator, which is a VCO oscillator (4) for tuning the oscillation frequency.

5. Method according to one of the preceding claims, characterised in that the bias current generator (7) is activated by at least one activation control signal after receiving an RF signal.

6. Super-regenerative receiver (1) configured for implementing the method for enhancing the detection of the start time of a reference oscillator (4) of a super-regenerative receiver (1) according to one of the preceding claims, the receiver comprising the reference oscillator (4), a bias current generator (7) for supplying a bias current (i_vco) to the reference oscillator (4) on receiving at least one activation control signal (Sosc), an oscillation detector (6) connected between an input and an output (coilp) of the reference oscillator (4) and the bias current generator (7) for detecting an oscillation in the reference oscillator (4), and an impedance matching unit (3) disposed between a terminal or pad (2) for receiving an RF signal of the receiver (1) and the reference oscillator (4), the receiver (1) comprising an additional amplification current generation circuit for supplying an additional amplification current (iboost) to the reference oscillator (4) in addition to the bias current after a first oscillation detected by the oscillation detector (6), an additional amplification current (iboost) being supplied to the reference oscillator (4) in addition to the bias current to amplify the oscillation signal to be above a critical oscillation start threshold so as to precisely define the start time of the oscillator, and enable the oscillation detector (6) to order the stoppage of the reference oscillator (4) during a second oscillation detected by the oscillation detector (6).

7. Super-regenerative receiver (1) according to claim 6, characterised in that it also comprises a PLL phase lock loop (5) for supplying a tuning voltage (Vtune) to the reference oscillator which is a VCO oscillator (4).

8. Super-regenerative receiver (1) according to claim 6, characterised in that the reference oscillator (4) operates at a frequency equal to or greater than 2.4 GHz and without lowering frequencies for demodulation operations.

9. Super-regenerative receiver (1) according to claim 6, characterised in that the additional amplification current generation circuit comprises at least one current mirror composed of a first NMOS type transistor (M13) and a second NMOS type transistor (14), the first NMOS transistor (M13) having the terminal thereof connected to the ground and the gate terminal and drain terminal connected together to be connected to a second current source (12), the second NMOS transistor (M14) having the gate terminal thereof connected to the gate terminal of the first NMOS transistor (M13), the source terminal thereof connected to the ground and the drain terminal supplying the additional amplification current (iboost) to the reference oscillator (4).

10. Super-regenerative receiver (1) according to claim 9, characterised in that the additional amplification current generation circuit intended to be activated after detecting the first oscillation comprises an amplitude detector (M11, M12) connected to the current mirror (M13, M14) for supplying the additional amplification current (iboost) for the reference oscillator (4), the first amplitude detector comprising a first NMOS transistor (M11) and a second NMOS transistor (M12), the first NMOS transistor (M11) being connected identically to the first NMOS transistor (M13) of the current mirror while being connected to a first current source (11), and the second NMOS transistor (M12), the drain terminal of the second NMOS transistor (M12) being connected to the gate and to the drain of the first NMOS transistor (13) of the current mirror.

11. Super-regenerative receiver (1) according to claim 10, characterised in that the NMOS transistors (M11, M12) of the amplitude detector are of the same size and polarised in weak inversion, while the NMOS transistors (M13, M14) of the current mirror are two NMOS transistors polarised in strong inversion.