Method for enhancing the start-up of an oscillator of a super-regenerative receiver and receiver for implementing the method

Abstract

A method for enhancing detection of the start-up time of a reference oscillator (4) of a super-regenerative receiver (1) is provided. The receiver (1) comprises a reference oscillator (4), a bias current generator (7) for supplying a bias current (i_vco) to the reference oscillator (4) upon reception of at least one activation control signal (Sosc), an oscillation detector (6) connected between an output (coilp) of the reference oscillator (4) and the bias current generator (7) for detecting oscillations in the reference oscillator (4), and an impedance matching unit (3) disposed between a terminal or pad (2) of the receiver (1) for receiving RF signals and the reference oscillator (4). Upon reception of the activation control signal (Sosc), the bias current (i_vco) is supplied, oscillation detection is performed by the oscillation detector (6), and once oscillations are detected, in addition to the bias current, an additional boost current (iboost) of an amplification current generation circuit dependent on an envelope of the detected oscillations is supplied to the reference oscillator (4) to amplify the oscillation signal above a critical oscillation start-up threshold in order to accurately define the start-up time of the oscillator and to enable the oscillation detector (6) to command oscillation stop of the reference oscillator (4).

Description

Technical Field

[0001] The present invention relates to a method for detecting the start-up time of an oscillator in an enhanced super-regenerative receiver, and a receiver for implementing the method. Background Technology

[0002] Shortwave receivers, invented by Edwin Howard Armstrong in the 1920s, have been known. These initially included three lamps, which were expensive, and his invention enabled the reduction of receiver operation to a single lamp. As discussed below, this invention of the super-regenerative receiver uses this principle to reduce power consumption and simplify the receiver's architecture.

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

[0004] In super-regenerative receivers, for example, LC-type VCO-type oscillators can be used. This type of LC oscillator starts oscillating when the losses of the L and C resonators are compensated using the negative conductance of the active devices. This limit corresponds to the minimum current required to start the oscillator, also known as the critical current required to start oscillation.

[0005] In a super-regenerative receiver, an RF signal is directly injected into the resonant coil of an oscillator. Depending on the frequency (close to or not close to the oscillator's resonant frequency) and the amplitude of the RF signal, the oscillator starts with a more or less current and a more or less time. This startup current and the associated startup time are detected.

[0006] To quantify the initiation current and associated start-up time, an oscillator is triggered. An increasing current is injected into the oscillator. This current starts below a critical current and increases until the oscillator starts oscillating. The current can have, for example, the form of a linear ramp. The oscillator starts oscillating at a given current corresponding to the start-up time.

[0007] Patent application US 5,613,231 A describes an oscillator equipped with an active component or amplifier and a reactive power stabilizing component. The active component is a bipolar transistor deployed in a common base circuit, while the reactive power component is a dielectric resonator fully coupled to the collector of the transistor. 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, and the emitter of the bipolar transistor is connected to the same terminal via a third resistor. The resonator core is connected between the common point and the collector of the bipolar transistor. No description is made regarding the startup time of the oscillator for enhancing a super-regenerative receiver.

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

[0009] Patent application US 2010 / 237935 A1 describes a logarithmic detector comprising an amplifier element; means for adjusting the operating frequency of the detector; and a controller, wherein an input signal to the amplifier element is arranged to induce oscillations in the amplifier element. The controller can be used to detect a predetermined threshold indicating the oscillations, and in response to detecting the threshold, to interrupt the oscillations of the amplifier, thereby interrupting a frequency proportional to the logarithm of the power of the input signal. A super-regenerative receiver is not described.

[0010] Referring to the article by Patrick Favre et al., “A 2-V 600-A 1-GHz BiCMOS Super-Regenerative Receiver for ISM Applications,” IEEE JOURNAL OF SOLID-STATECIRCUITS, IEEE, USA, vol. 33, no. 12, 1 December 1998, XP011060882, ISSN: 0018-9200, a super-regenerative receiver is described, comprising: a bias current generator for supplying a bias current to a reference oscillator upon receiving a first activation control signal; and an oscillation detector connected between the input and output of the reference oscillator and the bias current generator for detecting oscillations in the reference oscillator. An additional amplified current generation circuit is also provided for supplying an additional amplified current to the reference oscillator in addition to the conventional bias current. In addition to the regular bias current, this additional amplification current is also supplied to the reference oscillator to amplify the oscillation signal so that it exceeds the critical oscillation start-up threshold to limit the oscillator's start-up time, and until the detector is allowed to command the reference oscillator to stop. However, a drawback is the lack of a gradual increase in the bias current to better limit the start-up time.

[0011] Patent application GB 2433365A describes a super-regenerative receiver comprising a reference oscillator powered by an activated polarization current from an oscillator and a pulse width controller. The oscillator remains active at a certain oscillation level before being deactivated. A drawback is the lack of a gradual increase in the bias current to better define the startup time. Summary of the Invention

[0012] The object of the present invention is therefore to provide a method for enhancing the detection of oscillator startup in a super-regenerative receiver for receiving one or more RF signals by overcoming the disadvantages of the prior art mentioned above, while simultaneously reducing power consumption for operation of the super-regenerative receiver. Furthermore, the receiver is capable of implementing the method for enhancing oscillator startup in the receiver.

[0013] Therefore, the present invention relates to a method for enhancing the startup of an oscillator in a super-regenerative receiver, the method including the features defined in independent claim 1.

[0014] The specific steps of the method are defined in dependent claims 2 to 7.

[0015] The advantage of the method for detecting the startup of an oscillator in a super-regenerative receiver is that it enables a smooth transition between the idle and active states of the receiver oscillator before and after a well-defined startup time proportional to the amplitude and frequency of the detected RF signal. To achieve this, an additional amplifying current is supplied to the oscillator at least from the detected startup of the oscillation, following an increased bias current and particularly when a first low voltage threshold corresponding to the critical oscillation startup bias current is crossed. This also makes it possible to accurately determine the oscillator startup time, since without this additional amplifying current (defined as a "boost" current), it would be difficult to accurately determine this startup time, which depends on the detected RF signal.

[0016] Advantageously, once oscillation is detected, it is possible to cut off the bias current and the additional amplification current to reduce the receiver's power consumption. Typically, a series of successive cycles spaced apart over time are provided to supply the bias current from the bias current generator, enabling the measurement of the RF signal's progression.

[0017] Advantageously, in addition to the bias current generator for the oscillator, circuitry for generating an amplified current is also provided. This amplified current generating circuitry can be adapted to supply an additional amplified current to the oscillator from the start of oscillation detected at a first low voltage threshold. This allows for the rapid cutoff of both the bias current and the additional amplified current for the oscillator upon detection of oscillation, thereby reducing power consumption in the receiver circuitry. This amplified current can be kept constant above the low voltage threshold to rapidly supply the additional amplified current, clearly determining the oscillation start-up time of the oscillator without being affected by any noise from variations in the oscillator signal amplitude.

[0018] The reference oscillator of the receiver is preferably a high-frequency VCO-type oscillator that corresponds to the frequency of the RF signal detected by the receiver. To reduce power consumption, the reference oscillator must, in principle, be stopped precisely after the oscillation start-up time of the oscillator is determined. This VCO-type oscillator is preferably an LC oscillator essentially composed of an inductor and a capacitor connected in parallel.

[0019] Advantageously, the external RF signal collected by the receiver antenna is directly carried on the resonant circuit of the oscillator, thus creating initial oscillation conditions that are more or less conducive to a faster or slower start-up of the oscillator. Furthermore, the subsequently determined start-up time depends directly on the detected RF signal.

[0020] Therefore, the present invention also relates to a super-regenerative receiver for implementing the method, which includes the features defined in independent claim 8.

[0021] Specific embodiments of the receiver are defined in dependent claims 9 to 13. Attached Figure Description

[0022] The purpose, advantages, and features of the method for enhancing the startup of the reference oscillator of an ultra-regenerative receiver will become more apparent from the following description, which is based on non-limiting embodiments and illustrated by the accompanying drawings, in which:

[0023] - Figure 1 To illustrate in a simplified manner, a first embodiment of the super-regenerative receiver according to the present invention includes a set of electronic components for detecting the presence of an RF signal at the input and detecting the initiation of oscillations of an enhanced oscillator.

[0024] - Figure 2 This indicates a second simplified embodiment of the RF signal receiver according to the present invention, in which the RF signal receiver is adapted to enhance the detection of the start-up time of a reference oscillator, such as a voltage-tuned VCO, by utilizing a bias current for generating oscillations of the oscillator and an additional amplification current.

[0025] - Figure 3 This illustrates a third simplified embodiment of a circuit for generating an additional amplified current for a super-regenerative receiver, the additional amplified current preferably being supplied to the oscillator at oscillation initiation, and wherein the input of the circuit is directly connected to... Figure 1 and Figure 2 The output terminal of the reference oscillator is shown in the figure.

[0026] - Figure 4 Indicates that for what appears Figure 1 and Figure 2The figure shows the progression of the amplitude of the reference oscillator's output signal over time with respect to different amplitudes of the RF signal on the input RF pads, and illustrates the difference with and without the addition of additional amplification current when the receiver and bias current generator are activated.

[0027] - Figure 5 The additional amplification current for the VCO oscillator is represented as a function of the amplitude of the input signal, where the current increases rapidly beyond a certain amplitude of the output signal. This allows for a significant increase in the growth of the output signal through positive feedback, and this faster amplitude increase makes it easier to detect the oscillation start-up time of the oscillator. Detailed Implementation

[0028] In the following description, reference is made to a method for enhancing the accuracy of oscillator startup for a detection super-regenerative receiver while reducing power consumption. Obviously, all components well-known in the art and used in receivers will be described in a simplified manner. Essentially, the reference is to enhance the accuracy of startup for a detection reference oscillator, which may be a VCO oscillator, such as an LC-type VCO oscillator.

[0029] Figure 1 A first embodiment of an RF signal receiver 1 is shown in full. The RF signal receiver 1 is arranged to enhance the accuracy of the startup time for detecting a reference oscillator 4, particularly after detecting the reception of at least one RF signal. The startup time directly depends on the RF signal detected by the receiver. For this purpose, the receiver 1 first includes input terminals or pads 2 for receiving RF signals. The receiver 1 includes a reference oscillator 4 for generating oscillations in the oscillator and a bias current generator 7 for supplying a bias current i_vco to the reference oscillator 4. The bias current i_vco is supplied to the reference oscillator 4, particularly after receiving at least one activation control signal, i.e., a startup signal. Preferably, the bias current generator 7 is provided with a period of activation control signal Sosc that is spaced out over time.

[0030] The super-regenerative receiver 1 further includes an oscillation detector 6 connected between the output coil of the reference oscillator 4 and the bias current generator 7, in order to control the generator 7, particularly after the receiver 1 receives an RF signal and detects an oscillation of the oscillator. An impedance matching unit 3 of the receiver 1 is deployed between the terminal or pad 2 for receiving signals from the receiver 1 and the reference oscillator 4.

[0031] Receiver 1 further includes Figure 1The circuit for generating the additional amplified current iboost is not shown. In addition to the bias current i_vco, the additional amplified current iboost is also supplied to the oscillator to enhance the detection of the oscillator's start-up time. Preferably, the additional amplified current iboost is generated and supplied to the oscillator upon detection of the first oscillation of the oscillator, so as to stop the oscillator from the start of oscillation in the reference oscillator 4, but at least after the supply of the additional amplified current iboost. This also allows for a clear definition of the start-up time of the oscillation of the reference oscillator 4, since the additional amplified current iboost is preferably greater than the bias current i_vco. After the additional amplified current iboost is supplied and the oscillation of the oscillator has been detected, a rapid cutoff occurs between the bias current i_vco and the additional amplified current iboost. This allows for a direct and rapid reduction in power consumption compared to conventional receivers. It should be noted that the additional amplified current generator can be activated from the moment the oscillation detector first detects the oscillator's oscillation. Once the additional amplified current has been supplied to the reference oscillator, the start-up time is well defined, and oscillation is well established. This allows the oscillation to be completely stopped by disabling the bias current generator and the additional amplifying current generation circuitry.

[0032] The start-up time depends on at least one RF signal detected by the receiver. Any information related to the received RF signal makes it possible to accurately determine the start-up time.

[0033] It should be noted that the additional amplified current generator can be activated from the moment the oscillator is first detected by the oscillation detector 6. Once the additional amplified current has been supplied to the reference oscillator 4, the start-up time is well-defined, and the oscillation is well established. This makes it possible to command the complete cessation of the oscillation by disabling the bias current generator 7 and the additional amplified current generation circuit.

[0034] Clearly, for the super-regenerative receiver 1, a unit for processing all signals must be provided within the receiver. This unit may include a processor or microprocessor timed by a separate oscillator. Control signals for the various electronic components of the receiver may be transmitted by a processing unit (not shown). The processing unit may take into account the reception of the first RF signal to command the activation of the bias current generator. The processing unit may also be used to supply at least one activation control signal to activate the bias current generator 7 and to activate an additional amplifying current generation circuit, iboost, from the start of the detected oscillation.

[0035] During the period of the control signal Sosc, a first control signal start is first present to supply the polarization command to the reference oscillator 4. From this point onward, after the activation control signal start of the bias current generator 7, the bias current i_vco increases linearly, for example, until a critical value of the bias current is reached. From this critical value, the reference oscillator 4 can start oscillating at a high frequency, for example, on the order of 2.4 GHz. The envelope of this high-frequency signal can be considered for oscillation detection. From this oscillation time of the reference oscillator 4, detection is performed in the oscillation detector 6, which is at least connected to the bias current generator 7 and directly or by means of the bias current generator 7 to the circuitry for generating the additional amplified current iboost. Once oscillation has been detected, and after the additional amplified current iboost is supplied, a stop signal stop is supplied to the bias current generator 7 and to the additional current generation circuitry to immediately stop the oscillation of the reference oscillator 4. This is the objective of the present invention, namely, to completely stop the supply of bias current and additional amplification current to reference oscillator 4 once oscillation of reference oscillator 4 has been detected. By immediately stopping the supply of bias current i_vco and additional amplification current iboost to oscillator 4 once oscillation is detected, a reduction in power consumption is achieved. This is achieved by the oscillation detector 6 supplying bias current to bias current generator 7 and, as described below... Figure 3 After the additional amplified current generating circuit discussed supplies the stop command, the oscillator immediately stops oscillating.

[0036] Under normal circumstances, after the bias current i_vco is supplied, the envelope of the high-frequency signal created by the oscillator increases slowly at startup and becomes difficult to accurately detect the startup time by observing the envelope of the high-frequency signal, because the envelope voltage detected near a given threshold may be slightly modified by ambient noise (noise present in all active components of the oscillator and amplitude detector).

[0037] According to the invention, an additional amplified current iboost, which depends on the detected envelope, can be provided and this current, along with the bias current i_vco, is directly sent to the polarization of the oscillator, thus creating positive feedback. This positive feedback enables the oscillator to rapidly increase the envelope of the oscillation signal (which exists once the oscillation signal is started), and therefore carries the envelope detection signal through a given threshold corresponding to the critical oscillation start current threshold with a much more significant slope and faster speed.

[0038] The oscillation detector 6 will detect oscillation after supplying an additional amplified current iboost, which, due to the additional amplified current iboost, ensures that the envelope of the second oscillation signal is well above the oscillation start-up threshold. After this detection by the oscillation detector 6 using a well-defined start-up time, a stop signal is sent to the bias current generator 7 and the circuitry for generating the additional amplified current iboost. The oscillation detector 6 can provide a first oscillation detection to activate the additional amplified current generation circuitry and supply an additional amplified current to the oscillator. Finally, after the second oscillation detection in the case of an amplified oscillation signal, the oscillation detector supplies a stop control signal.

[0039] Refer to the following text Figure 3 As explained, according to an alternative embodiment, the additional amplifying current generating circuit can be integrated into the bias current generator 7. However, it is also possible to provide an additional amplifying current generating circuit external to the bias current generator. Under these conditions, the additional amplifying current generating circuit can be directly controlled by the oscillation detector 6 to supply the additional amplifying current iboost, particularly from the start of detecting the oscillation.

[0040] Preferably, the reference oscillator 4 is an LC-type VCO voltage-controlled oscillator, which includes at least one inductor L1 and a capacitor C1 connected in parallel. Figure 1 In the configuration shown, inductor L1 is split into two interconnected inductors, and the connection between these two inductor sections is powered by a tuning voltage Vdd. The inductors define an oscillating circuit whose resonant frequency is controlled by a variable capacitor (Vtune). Figure 2 Adjusted (not shown in the image). For this purpose, receiver 1 further includes components that depend on an external frequency reference (…). Figure 1 (Not shown in the diagram) and connected between the output coilp of the VCO oscillator 4 and the control voltage (Vtune) of the variable capacitor, a PLL phase-locked loop 5. The tuning voltage Vtune at the output of the PLL loop 5 is the control voltage for the oscillation frequency of the VCO voltage-controlled oscillator 4. The PLL loop 5 may include an analog memory to store the voltage Vtune in memory. Obviously, since the oscillator operates in differential mode, the output terminal coiln (not shown) can also be used instead of the output terminal coilp of the reference oscillator 4. Figure 2 In the case shown, the terminal coil (not shown) is the input of the reference oscillator 4, which is connected to the terminal or pad 2 of the RF signal receiver 1 via the impedance matching unit 3.

[0041] As in Figure 1As shown in the diagram, the impedance matching unit 3 is used to tune the RF signal received by the receiver 1 before it enters the reference oscillator 4 (preferably a VCO oscillator). The impedance matching unit 3 firstly includes a first capacitor 31, which is connected on one end to the input terminal or pad 2 of the RF signal and on the other end to a second capacitor 32. The other end of the second capacitor 32 is connected to the input of the reference oscillator 4, which serves as the VCO oscillator. The impedance matching unit 3 further 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.

[0042] Figure 3 This describes an embodiment of a circuit for generating an additional amplified current iboost, supplied to a reference oscillator 4 (which may be a VCO oscillator), in addition to the bias current, during the oscillator's operating mode. Preferably, the circuit for generating the additional amplified current iboost includes first detection stages M11 and M12, which are connected to current mirrors M13 and M14 for supplying the additional amplified current iboost to the oscillator. As described below, such a circuit for generating the additional amplified current can even be more... Figure 3 The circuit shown in the diagram is simpler.

[0043] Different stages M11, M12, and M13, M14 are constructed, for example, using CMOS technology transistors. Figure 3 In the configuration shown, the first detection stages M11 and M12 are composed of two NMOS transistors M11 and M12. These two transistors M11 and M12 are, for example, two identical NMOS transistors of the same size with weak inversion polarization. The current mirrors M13 and M14 are composed of two NMOS transistors M13 and M14. These two transistors M13 and M14 are, for example, two NMOS transistors with strong inversion polarization.

[0044] The first transistor M11 of the first detection stage is connected to the input capacitor C. Figure 1 The signal coil of oscillator 4 is connected to the gate terminal. 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 to its gate terminal by means of an input resistor R and connected to the first current source 11, which is connected to the power supply voltage Vdd and supplies current I to the first transistor M11. When the receiver and the bias current generator are engaged, the voltage increases very slowly before reaching a critical threshold due to the relatively low bias current, thereby initiating oscillation in the oscillator.

[0045] The current from the first current source 11 polarizes the NMOS transistor M11 in a non-linear amplitude detection mode, and the voltage Vmeas decreases as the amplitude of the oscillation signal coilb increases. The gate terminal of the NMOS transistor M12 is connected to this voltage Vmeas and has the effect of completely diverting the current from the second current source 12 (slightly lower than the current source 11) to ground. As the amplitude of the signal coilb increases, the detected voltage Vmeas decreases, and the current from source 12 is gradually sent to the current mirror composed of NMOS transistors M13 and M14, which then determines the increased current Iboost. Preferably, the current source 11 is adjusted to supply a current slightly larger than that from source 12. To control the current mirrors M13 and M14, the drain terminal of the second NMOS transistor M12 of the amplitude detector is connected to the drain terminal and gate terminal 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 second NMOS transistor M14 of the current mirror connects its gate terminal to the gate terminal and drain terminal 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 transistor M14 of the current mirror supplies additional amplification current iboost to the reference oscillator.

[0046] Other embodiments of the additional amplified current generating circuit are described above. Figure 3 The described embodiments are examples.

[0047] In order to describe the method for starting the reference oscillator used to enhance the receiver, there are different signals used to start the receiver 1, especially when an RF signal is received. These signals will be briefly described. It is also specified that the super-regenerative receiver 1 is preferably a wake-up receiver, which must continue to operate, but in a manner as follows: Figure 1 The control signal Sosc described herein operates continuously for a very short period of time, and the control signal Sosc is supplied to the bias current generator 7 over time to engage the bias current generator 7 or activate the bias current generator 7 by a series of successive start control signals start.

[0048] In the case of the VCO oscillator, the VCO oscillator is an LC type VCO oscillator. This oscillator is provided to be frequently in a triggered state and is arranged to start very frequently and very quickly within short time periods at high frequencies (e.g., at 2.4 GHz). The VCO oscillator can be quickly engaged within short time periods to respond to the critical elements of the oscillation that must be started rapidly with very few components. It is possible for the activation control signal Sosc (start) to start the oscillation within a 1µs time period, and there are approximately 1000 Sosc activation or engagement control periods for the VCO oscillator 4 within 1 second. This means that the receiver 1 is only fully engaged for 1ms within 1 second, which substantially reduces power consumption, and this is what is desired. As explained above, after the first start control signal start is supplied to the bias current generator 7, a linear increase in the bias current value occurs until a critical bias current value is reached, but this is relatively slow. Once the critical current is reached, the VCO reference oscillator 4 starts oscillating, which is directly detected by the oscillation detector 6. The oscillation detector 6 sends an oscillation stop control signal (stop) to the bias current generator 7. The oscillation of the VCO reference oscillator is canceled, which means that the RF signal has indeed been detected, and at the same time, it ensures a significant reduction in the power consumption of receiver 1 compared to receivers known in the prior art.

[0049] Obviously, the frequency of these start control signals Sosc (start) used for bias current generator 7 can be manually or automatically modified to suit the conditions of reference oscillator 4.

[0050] It should be noted further that, in the initial frequency centering mode, the VCO oscillator is started in this type of loop to determine the voltage, such as the voltage Vtune corresponding to the receiving frequency, particularly in a conventional frequency synthesizer. The voltage is then stored in memory via a DAC, and the synthesizer is disabled. VCO oscillator 4 is turned off, and the RF signal can be sent to the oscillation circuit of VCO oscillator 4 via, for example, tuning network 3, to perform demodulation via super-regeneration. The start-up time of the VCO is measured with a ramp present in its bias current. Therefore, it is possible in such a super-regenerative receiver not to reduce the frequency used for demodulation.

[0051] Reference is made in the description of patent application EP 3573241 A1. Figure 4 A frequency synthesizer including a VCO oscillator is described. If such a frequency synthesizer is used to center the frequency of the VCO oscillator of this invention, this patent application is incorporated herein by reference.

[0052] Now refer to Figure 2The super-regenerative receiver is further described in other embodiments.

[0053] Figure 2 The second embodiment of the receiver is shown, illustrating only the receiver's input 2, impedance matching unit 3, and reference oscillator 4, which is a VCO oscillator 4. Figure 2 Although the oscillation detector and PLL are not shown, they function at the same point in the receiver, as described above. The VCO oscillator consists of a first inductor L1 and a capacitor C1 connected in parallel with inductor L1. As described above, inductor L1 is split into two interconnected inductors, and the connection between these two inductor portions is powered by the supply voltage Vdd. At the bottom, the VCO oscillator 4 further includes a first transistor M1 at the first connection point of inductor L1 and capacitor C1, which is preferably a MOS transistor, for example, an NMOS transistor in this configuration, and a second transistor M2 at the second connection point of inductor L1 and capacitor C1, the second transistor M2 being 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 connection point of inductor L1 and capacitor C1, while the drain terminal of the second transistor M2 is connected to the second connection point of inductor L1 and capacitor C1. The gate of the first transistor M1 is connected to the drain of the second transistor M2, and 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 bias current from bias current generator 7. The output coil of the VCO oscillator can be supplied by the drain of the second transistor M2.

[0054] Impedance matching unit 3 includes a first capacitor 31 connected on a first side to the input terminal or pad 2 of receiver 1, and a second side of the first capacitor 31 connected to a first end of an additional inductor 33, the second end of which is connected to a first side of a second capacitor 32. The additional inductor 33 is split into two interconnected inductors, and the connection point between these two inductor portions can be connected to ground. The connection point of the first capacitor 31 and the additional inductor 33 is further connected to a first side of a third capacitor 34 and a first side of a fourth capacitor 35, the second side of which is connected to ground. A fifth capacitor 36 is connected on a first side to the connection point of the second capacitor 32 and the additional inductor 33. The second side of the fifth capacitor 36 is connected to ground.

[0055] The second side of the second capacitor 32 is connected to the first terminal of the inductor L1 and the capacitor C1, and is also connected to the gate of the second transistor M2 and the drain of the first transistor M1. The second side of the third capacitor 34 is connected to the second terminal of the inductor L1 and the capacitor C1, and is also connected to the gate of the first transistor M1 and the drain of the second transistor M2. A frequency tuning voltage can be applied to either the first terminal or the second terminal of the inductor L1 and the capacitor C1.

[0056] As explained above, a reference oscillator 4 other than a conventional VCO oscillator can be used, as long as it can operate at a high frequency of, for example, around 2.4 GHz.

[0057] Figure 4 This represents the different values ​​of the envelope coilp for different amplitude values ​​of the RF signal applied to the receiver input, and shows the difference with and without the addition of additional amplification current when the receiver and bias current generator are activated. (As shown in...) Figure 4 As can be seen, signal s1 is represented by a solid line and has an RF signal input value of -30dBm. Signal s2 is represented by a dashed line and has an RF signal input value of -40dBm. Signal s3 is represented by a long dashed line and has an RF signal input value of -50dBm. Finally, signal s4 is represented by a thick solid line and has an RF signal input value of -60dBm.

[0058] In Figure 4 The difference between the applied additional amplifying current iboost, which depends on the amplitude envelope of the signal coilp, and the additional amplifying current iboost is added to the regular bias current i_vco to clearly determine the oscillator's startup time. Adding this additional amplifying current iboost allows for better detection of the oscillation of the reference oscillator 4. The voltage on the gates of the current mirror transistors M13 and M14 quickly crosses above the threshold voltage. This allows for faster oscillation detection of the oscillator, enabling accurate detection of the oscillator's startup time detected by the oscillation detector.

[0059] Figure 4The diagram illustrates the different envelopes of the signal coilp, corresponding to different levels of the RF signal present at the receiver input. It is clearly seen that if only bias current is supplied to the oscillator, the increase in the envelope of the oscillating signal coilp is relatively small. Due to ambient noise, it is difficult to detect the transition of the coilb envelope above a given threshold using only bias current. For this reason, an additional amplification current is added to enable faster oscillation of the oscillator, and this is true for the four signals s1, s2, s3, and s4, represented with or without amplification.

[0060] Figure 5 This refers to the additional amplifying current used in the VCO oscillator, and the rapid increase in amplitude once a given threshold is reached. This larger amplitude makes it easier to detect the oscillation start-up time. This is attributed to the positive feedback, the additional amplifying current, and the rapid increase in amplitude once the threshold is reached. This larger amplitude makes it easier to detect the start-up time, which is the desired outcome.

[0061] Based on the above description, several alternative embodiments of the method for enhancing the startup of the reference oscillator of the super-regenerative receiver can be conceived without departing from the scope defined by the claims.

Claims

1. A method for enhancing detection of start-up time of a reference oscillator (4) of a super-regenerative receiver (1), the receiver (1) comprising: Reference oscillator (4); A bias current generator (7) is used to supply a bias current (i_vco) to the reference oscillator (4) upon receiving at least one activation control signal (Sosc); an oscillation detector (6) is connected between the output (coilp) of the reference oscillator (4) and the bias current generator (7) for detecting oscillations in the reference oscillator (4); and an impedance matching unit (3) is deployed between the terminal or pad (2) of the receiver (1) for receiving RF signals and the reference oscillator (4). After receiving the activation control signal (Sosc) and supplying a bias current (i_vco), the oscillation detector (6) detects the first oscillation of the reference oscillator (4) so ​​that the additional amplified current generating circuit can be activated and an additional amplified current is supplied, which depends on the envelope of the oscillation detected at the reference oscillator. After detecting the second oscillation with the amplified oscillation signal, the oscillation detector (6) supplies a stop control signal (stop) to stop the reference oscillator (4). The feature is that, under each activation control signal (Sosc) supplied to the bias current generator (7), the bias current gradually increases until it reaches at least one critical current value. From said at least one critical current value, the oscillation of the reference oscillator (4) is initiated, and the oscillation detector (6) detects the first oscillation of the reference oscillator (4). The feature is that when the oscillation detector (6) detects a second oscillation with an amplified oscillation signal, a stop control signal is supplied to the bias current generator (7) and the additional amplified current generation circuit to immediately cut off the current supply to the reference oscillator (4) to immediately stop the reference oscillator (4) and thus reduce the power consumption of the receiver.

2. The method according to claim 1, characterized in that, During the period of the activation control signal (Sosc) of the bias current generator (7), a bias current (i_vco) is supplied to the reference oscillator (4) after each activation control signal (Sosc) is received.

3. The method according to claim 2, characterized in that, The activation control signal (Sosc) is initiated within a 1 µs period, and 1000 activation control periods (Sosc) of the successive control signals (Sosc) can be counted within 1 second, so that the receiver (1) is only fully engaged for 1 ms within 1 second.

4. The method according to any one of claims 1 to 3, wherein the receiver (1) further comprises a PLL (phase-locked loop) (5) for the method, characterized in that, As time passes, a tuning voltage (Vtune) is supplied to the reference oscillator (4), which serves as the VCO oscillator, to tune the oscillation frequency.

5. The method according to any one of claims 1 to 3, characterized in that, After receiving the RF signal, the bias current generator (7) is activated by at least one activation control signal.

6. A super-regenerative receiver (1) for implementing a method for detecting the start-up time of a reference oscillator (4) for enhancing the super-regenerative receiver (1) according to any one of claims 1 to 5, the receiver comprising: Reference oscillator (4); A bias current generator (7) is used to supply a bias current (i_vco) to the reference oscillator (4) upon receiving at least one activation control signal (Sosc); an oscillation detector (6) is connected between the output (coilp) of the reference oscillator (4) and the bias current generator (7) for detecting oscillations in the reference oscillator (4); and an impedance matching unit (3) is deployed between the terminal or pad (2) for receiving RF signals of the receiver (1) and the reference oscillator (4), the receiver (1) including additional amplification circuitry. A current-generating circuit is provided to supply an additional amplified current (iboost) to the reference oscillator (4) in addition to the bias current after the first oscillation is detected by the oscillation detector (6). The additional amplified current (iboost) is also supplied to the reference oscillator (4) in addition to the bias current to amplify the oscillation signal above the critical oscillation start threshold so as to accurately limit the start time of the reference oscillator and enable the oscillation detector (6) to command the reference oscillator (4) to stop during the second oscillation detected by the oscillation detector (6).

7. The super-regenerative receiver (1) according to claim 6, characterized in that, The reference oscillator (4) operates at a frequency equal to or greater than 2.4 GHz and does not reduce the frequency used for demodulation.

8. The super-regenerative receiver (1) according to claim 6, characterized in that, The additional amplified current generating circuit includes at least one current mirror, which is composed of a first NMOS transistor (M13) and a second NMOS transistor (M14). The first NMOS transistor (M13) has its source terminal connected to ground, and its gate terminal and drain terminal are connected together to be connected to a second current source (12). The second NMOS transistor (M14) has its gate terminal connected to the gate terminal of the first NMOS transistor (M13), its source terminal connected to ground, and its drain terminal supplying additional amplified current (iboost) to the reference oscillator (4).

9. The super-regenerative receiver (1) according to claim 8, characterized in that, The additional amplified current generating circuit intended to be activated after the first oscillation is detected includes an amplitude detector (M11, M12), which is connected to a current mirror (M13, M14) for supplying additional amplified current (iboost) to the reference oscillator (4). The amplitude detector includes a third NMOS transistor (M11) and a fourth NMOS transistor (M12), which is connected to a first current source (11) and a fourth NMOS transistor (M12). The drain terminal of the fourth NMOS transistor (M12) is connected to the gate and drain of the first NMOS transistor (M13) of the current mirror.

10. The super-regenerative receiver (1) according to claim 9, characterized in that, The amplitude detector's NMOS transistors (M11, M12) are the same size and are weakly inverted polarized, while the current mirror's NMOS transistors (M13, M14) are two strongly inverted polarized NMOS transistors.

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