WO2000008762A1

WO2000008762A1 - Method and device for automatically controlling a periodic signal generator supply current

Info

Publication number: WO2000008762A1
Application number: PCT/CH1999/000353
Authority: WO
Inventors: Walter Hammer
Original assignee: Walter Hammer
Priority date: 1998-08-03
Filing date: 1999-07-28
Publication date: 2000-02-17
Also published as: CH693080A5; AU4893599A

Abstract

The invention concerns a device comprising a periodic signal generator (1) supplied with a controlled current (Iass). The signal (Vgen) of the periodic generator signal (1) is amplified by an amplifier (2) which produces a signal (Vout) with amplitude controlled by the detectors (31 and 32). The low-level detector (31) controls, via a low-pass filter (41), a transistor (T1) which supplies a first controlled current (Iass1) to the generator (1). The high-level detector (32) controls, via a low-pass filter (42), a transistor (T2) which supplies a second controlled current (Iass2) to the generator. Thus the device enables to supply the generator with the minimal current (Iass) which ensures sufficient amplitude for the signal (Vout) to control digital circuits.

Description

Method and device for controlling the supply current of a periodic signal generator

The present invention relates to a method and a device for controlling the supply current of a periodic signal generator. This can be a quartz oscillator, an LC oscillator or any other periodic signal generator whose amplitude of the output voltage is a function of the current which supplies it.

There are known periodic signal generators whose supply current is fixed and not controlled. A high current must be supplied to these oscillators so as to obtain with certainty a sufficient amplitude of the signal. A high gain amplifier with high current consumption is then necessary to amplify the signal of these oscillators in order to obtain with certainty an amplified signal usable by digital circuits. This double security comes at the cost of high current consumption.

There are other known periodic signal generators (for example that described in Swiss patent CH 682019 A5) whose signal amplitude is controlled in order to reduce the current consumption of the oscillator. Such an oscillator guarantees an amplitude of the oscillator signal at least equal to the value of a voltage reference. However, a high gain amplifier with high current consumption remains necessary to amplify the signal of this oscillator in order to obtain with certainty an amplified signal compatible with the switching thresholds of digital circuits. This oscillator is not immune to variations in amplifier gain, voltage reference, supply voltage, temperature and element parameters.

A first object of the invention is to propose a method for controlling the supply current of a periodic signal generator which does not meet the known drawbacks, mentioned, of known methods. Another object of the invention is to propose a method for controlling the supply current of a periodic signal generator by which said supply current is minimized, while ensuring a sufficient amplitude of the amplified signal of the generator, for be able to be used by digital circuits.

Another object of the invention is to propose a method for controlling the supply current of a periodic signal generator by which the possibility of using the signal amplified by digital circuits is ensured over a wide range of variation of supply voltage, temperature, parameters of active electronic elements (transistors, amplifier, etc.) and parameters of passive or non-electronic elements (quartz, inductance, capacitance, etc.).

Yet another object of the invention is to propose a method for controlling the supply current of a periodic signal generator which does not require the use of any stable or precise voltage reference.

Yet another object of the invention is to propose a method for controlling the supply current of a periodic signal generator allowing a start-up current of the oscillator much higher than the normal operating current, which ensures a start-up fast oscillator.

Yet another object of the invention is to provide a device for controlling the supply current of a periodic signal generator capable of achieving the preceding aims, that is to say ensuring minimum current consumption, a output signal usable by digital circuits, quick start and operation of the oscillator in a very wide range of variation of the parameters of the elements (such as transistor, amplifier, quartz, inductance, capacitance, etc.).

These various aims are obtained by a method as described in independent claims 1 and 15 as well as by a device having the characteristics mentioned in the independent claims 18, 19 and 30 to 32. Particular or alternative embodiments are described in the dependent claims.

Several embodiments of a servo device according to the invention will be described below, as well as their operation. This description is to be considered with regard to the appended drawing comprising the figures where:

FIG. 1 a shows a block diagram of a servo device according to a first embodiment of the invention,

FIG. 1 b shows a diagram showing various signals supplied by the device of FIG. 1 a,

FIG. 2a shows a block diagram of a servo device according to a second embodiment of the invention,

FIG. 2b shows a diagram showing various signals supplied by the device of FIG. 2a

FIG. 3 shows a servo device according to the first embodiment associated with a quartz oscillator, and

Figure 4 shows a servo device according to the second embodiment associated with an LC oscillator.

Figure 1a shows a block diagram of a servo device according to a first embodiment of the invention, in which there is recognized a periodic signal generator 1 which delivers a periodic signal V _gen for example a sinusoidal voltage (see fig. 1b). The signal V _gen is amplified by an amplifier 2 which delivers an amplified output signal V _out which must be able to be used to control digital circuits. In the device according to this first embodiment, a low level comparator 31 compares the voltage of the signal V _or t with a low level V | _0W that one wishes to reach and delivers a signal V _det i to the low-pass filter 41. The low-pass filter filters the signal V _d eti of which it achieves a weighted average V _ass ι used to control a transistor T1 which plays the role of a current source controlled by a voltage. The transistor T1 delivers a first current l _aS if to the generator 1. This current l _ass ι provides sufficient amplitude for the voltage of the signal V _ge n delivered by the generator 1 and supplied to the amplifier 2, so that the signal V _out supplied by this amplifier 2 has a minimum instantaneous voltage which is less than the value Vi _o w supplied to the comparator 31.

We can examine the operation of the circuit which has just been described. Assume that the signal voltage V _or t does not reach the low level V | _0W supplied to comparator 31, that is to say that the instantaneous value of the voltage of signal V _or t is always greater than Viow This has the effect that comparator 31 cannot supply a pulse by signal Vdeti to filter 41 The weighted average of the signal V _ass ι supplied by this filter decreases, causing the transistor T1 to deliver a higher current to the generator 1. The signal V _gen sees its amplitude increasing, as does the signal V _or t- L ' increase in the current the _asse continues as long as the signal voltage V _or t does not reach the low level V | _ow supplied to the comparator and that the pulses of the signal Vde i are nonexistent or of too short duration.

Let us now assume the opposite case where the instantaneous value of the signal voltage V _out exceeds the low level V | _OW supplied to comparator 31 for too much of the period. The comparator 31 in this case delivers a signal V _e i whose pulse lasts longer than necessary. The filter 31 achieves a weighted average such that the transistor T- [delivers a weaker current to the generator 1. The signal V _gen sees its amplitude decreasing, as does the signal V _or t- The decrease in the current _ss i also continues as long as the signal voltage V _or t reaches the low level V | _OW supplied to comparator 31 during too much of the period, that is to say as long as the pulses Vdeti are of too long duration. There is therefore a good enslavement of the supply current l _aS if of the oscillator 1 so that the instantaneous voltage of the output signal V _out of the amplifier 2 reaches the low level V | _0W supplied to the comparator during a determined part of the oscillation period, fixed by the weighting of the filter 31.

According to this embodiment and in order to ensure that the signal V _out has a maximum instantaneous voltage greater than V, _g h which can be used by digital circuits, a high level detector 32, a low pass filter 42 and a transistor T2 form a second control loop which delivers a second current l _aS s ₂ to the generator. The operation of this second loop is similar to that of the first loop.

The two loops work in parallel and therefore ensure that the output signal V _or t of amplifier 2 has both a minimum instantaneous voltage lower than the low voltage V | _ow supplied to the first comparator 31 and a maximum instantaneous voltage greater than the high voltage Vhig _h supplied to the second comparator 32.

The sufficient condition for the signal V _out to be used as the input signal of the digital circuits placed downstream (these circuits are not shown in the figures but may consist, for example, of one or more inverters or frequency dividers) is that this signal has an amplitude compatible with said digital circuits. Consequently, the levels of V | _ow and Vhigh are fixed very precisely.

Figure 2a shows a block diagram of a servo device according to a second embodiment of the invention, comprising a single adjustment loop. Certain oscillators deliver a signal V _gen whose instantaneous voltage is such that it ensures by itself that there is at the output of the amplifier a signal V _or t having a minimum instantaneous voltage lower than the desired low voltage or a maximum instantaneous voltage greater than the desired high voltage. For such oscillators, only one adjustment loop is required.

The description below is limited to the case of a loop ensuring the low level of the voltage of the output signal of the amplifier V ₀ ut-

As before, we recognize a periodic signal generator 1 which delivers a periodic signal V _gen, for example a sinusoidal voltage (see fig. 2b). The signal V _gen is amplified by an amplifier 2 which delivers an amplified output signal V _or t for which compatibility is desired with digital circuits. To this end, a low level comparator 3 compares the voltage of the signal V _or t with the low level V | _0W that one wishes to reach and delivers a signal Vdet to the low-pass filter 4. The low-pass filter filters the signal V _d and of which it achieves a weighted average V _aS s used to control a transistor T1 which plays the role of '' a current source controlled by a voltage. The transistor T1 delivers a current l _aSs to the generator 1. This current l _aSs ensures a sufficient amplitude for the voltage of the signal V _gen delivered by the generator 1 and supplied to the amplifier 2, so that the signal V _out supplied by this amplifier 2 has a minimum instantaneous voltage which is less than the value V | _OW supplied to comparator 3.

Depending on the type of periodic signal generator and associated amplifier, we could just as easily have a servo device having only one adjustment loop, capable of ensuring that the maximum instantaneous voltage of the signal V _or t supplied by the amplifier is greater than a desired Vhigh value.

Figure 3 shows a servo device according to the first embodiment associated with a quartz oscillator. The periodic signal generator 1 here comprises: a quartz Q10, a transistor T10, a resistor R10 and two capacitors C10 and C11. The output signal V _gen of this oscillator is either at the terminals of the capacitor C10, or at the terminals of the capacitor C11, or between the two terminals of the quartz Q10, as in the case represented here. The V _gen signal is amplified by the differential amplifier OP20, constituting the amplifier 2 seen previously, which delivers the amplified signal V _or t.

The contours of blocks 31 + 41 and 32 + 42 have been transferred to the figure, grouping together the corresponding blocks of FIG. 1a.

The current source S0 delivers a reference current necessary for the control blocks 31 + 41 and 32 + 42.

The transistor T310 essentially forms the low level detector which delivers a current lo when the instantaneous voltage of the signal V _out exceeds the low level V | _0W and a zero current when the instantaneous voltage of the signal V _out does not reach this low level V w The value of the voltage of the low level V | _ow depends in a known manner on the dimensions of the transistors T00 and T310 as well as on the value of the current of the current source S0. The current mirror formed by the transistors T311 and T312 multiplies the current delivered by the transistor T310. Thus, the current n * lo delivered by the transistor T312 is a multiple greater than 1 (for example n = 10) of the current delivered by the transistor T310.

The first low-pass filter is formed essentially by the capacitor C410 and by the transistors T312 and T313. The capacitor C410 receives a fixed current lo from the transistor T313 and a current n * lo from the transistor T312. The latter current only flowing when the signal voltage V _or ta reaches or exceeds the low level V w

The voltage of the output signal V _ass ι of the first low-pass filter controls the transistor T1 which supplies a first controlled current l _aS if to the oscillator.

The transistor T320 essentially forms the high level detector and the current multiplier which delivers a current m * lo when the instantaneous voltage of the signal V _or t exceeds the high level Vhigh and a zero current when the instantaneous voltage of the signal V _or t n '' does not reach the high level V _h ig _h - Multiplication of the current by the factor m greater than 1 (by example m = 10) is produced by the corresponding dimensioning of the transistors T01 and T320. The value of the high level voltage Vhi _gh depends in a known manner on the dimensions of the transistors T01 and T320 as well as on the value of the current of the current source S0.

The second low-pass filter is formed essentially by the capacitor C420 and by the transistors T320 and T321. The capacitor C420 receives a fixed current lo from the transistor T321 and a current m * lo from the transistor T320. The latter current only flowing when the signal voltage V _or ta reaches or exceeds the high level Vhigh.

The voltage of the output signal V _a5S2 of the second low-pass filter controls the transistor T2 which supplies a second current controlled by the _asS2 to the oscillator.

Figure 4 shows a servo device according to the second embodiment associated with an LC oscillator. The periodic signal generator 1 here comprises: two transistors T100 and T1 10, an inductance L100 and a capacitor C100. The output signal V _gen of this oscillator is located at the terminals of the capacitor C100. It is amplified by an inverter Inv20, corresponding to the amplifier 2 seen previously, which delivers the output signal V _or t.

As previously, the block 3 + 4 has been transferred to the figure, grouping together the corresponding blocks of FIG. 2a.

In this case, only a low level detector is necessary, the oscillator LC delivering a voltage V _gen whose minimum instantaneous value is negative, which ensures that the output signal of the inverting amplifier V _{out always has} an instantaneous maximum voltage. at the desired high voltage Vhi _g h. The current source S0 delivers a reference current necessary for the servo block 3 + 4.

The transistor T30 essentially forms the low level detector which delivers a current lo when the instantaneous voltage of the signal V _or t exceeds low level V | _0W and zero current when the instantaneous signal voltage V _or t does not reach the low level V | ₀ w The value of the low level voltage V | _OW depends in a known manner on the dimensions of the transistors TO and T30 as well as on the value of the current of the current source S0. The current mirror formed by the transistors T31 and T32 achieves a multiplication of the current delivered by the transistor T30. Thus, the current n * lo delivered by the transistor T32 is a multiple greater than 1 (for example n = 10) of the current delivered by the transistor T30.

The low-pass filter is formed essentially by the capacitor C40 and by the transistors T32 and T33. The capacitor C40 receives a fixed current lo from the transistor T33 and a current n * lo from the transistor T32. The latter current only flowing when the signal voltage V _or ta reaches or exceeds the low level Viow

The voltage of the output signal V _ass of the low-pass filter controls the transistor T1 which supplies the controlled current l _ass to the oscillator.

It can therefore be seen that the method as well as the device described, according to one or other of the embodiments mentioned, makes it possible to minimize the supply current of the periodic signal generator, since the signal V _gen has an amplitude just sufficient for the signal V _out from the amplifier to control the digital circuits placed downstream.

Since all the constituent components of the circuit delivering the signal V _out , including the amplifier 2, are included inside the control loop, their characteristics as well as their variations are taken into account by the control. The constituent components of the control loop, that is to say those contained in blocks 3 and 4, respectively 31 and 41 as well as 32 and 42, also being included inside the control loop, their characteristics as well as their variations are also taken into account by the control. On the other hand, since when the device is powered up, the signal V _out has an amplitude which does not yet reach the prescribed level or levels, it follows that the servo signal or signals reach saturation and therefore impose a maximum servo current. Therefore, the periodic signal generator starts quickly.

Such a servo device, associated with a quartz oscillator, with a resonant circuit or of any other type, can advantageously be used in any electronic device, in particular in those where the consumption of electrical energy must be minimized, such as for example watchmaking, especially for quartz watches without batteries or on-board electronics.

The servo device, according to one or other of the embodiments described in detail above, corresponds to a particular use of said servo circuit and is described and represented here only by way of example. Depending on the needs and the intended use, other arrangements or elements than those shown here can be envisaged, the person skilled in the art being able to adapt the solutions presented here to his particular problem.

Claims

1. Method for controlling the supply current (l _ass ) of a periodic signal generator (1) in which:

the signal (V _gen ) delivered by said periodic signal generator is supplied to an amplifier (2) which amplifies it and delivers an amplified signal

(Vout),

characterized in that

the supply current (l _aS s) of the periodic signal generator is controlled from a signal taken downstream from the output of said amplifier (2).

2. Method according to claim 1, characterized in that said signal taken downstream of the output of the amplifier is the amplified signal

(Vout).

3. Method according to claim 2, characterized in that the instantaneous value of the voltage of the amplified signal (V _out ) is compared, in at least one comparator (3; 31,32) with a reference voltage (V w; V _h i _g h), and in that said comparator provides a signal

(Vde _t ; Vd _e tι; V _d e 2) according to the result of the comparison, said signal being used for the control of the supply current (l _ass ) of said periodic signal generator.

4. Method according to claim 3, characterized in that the low reference voltage (V | _OW ) is lower than the minimum switching voltage of a digital circuit.

5. Method according to claim 3, characterized in that the high reference voltage (V _h igh) is greater than the maximum switching voltage of a digital circuit.

6. Method according to claim 3, characterized in that the signal provided by the comparator is a digital signal (Vdet; Vde ι; Vdet2).

7. Method according to one of claims 3 to 6, characterized in that said signal (V _d and; Vd _e tι; Vdet2) supplied by the comparator is delivered to a filter (4; 41; 42) capable of providing a voltage (V _ass ; V _aS si; V _aS s2) used for the control of the supply current (l _a s _S ) of said periodic signal generator.

8. Method according to claim 7, characterized in that the average voltage of the signal (V _ass ; V _aS si; V _aS s2) supplied by said filter (4; 41; 42) is a function of the duty cycle of the signal (Vdet; Vdetι; Vd _e t2) supplied by the comparator.

9. Method according to claim 8, characterized in that the average voltage of the signal (V _ass ; V _aS si; V _asS 2) supplied by said filter (4; 41; 42) is zero for a zero duty cycle of the signal ( Vde; Vd _e tι; Vd _e t2) supplied by the comparator.

10. Method according to one of claims 7 to 9, characterized in that the average voltage of the signal (V _aS s; V _ass ι; V _aS s2) supplied by said filter

(4; 41; 42) is weighted as a function of the duty cycle of the signal (Vdet; Vd _e tι; Vdet2) supplied by the comparator.

11. Method according to one of claims 8 to 10, characterized in that the signal voltage (V _aS s; V _ass ι; V _asS 2) supplied by the filter (4; 41; 42) controls a current source (T1; T2) capable of supplying at least a portion of the supply current (l _ass ) of the periodic signal generator (1).

12. Method according to one of claims 2 to 1 1, characterized in that the instantaneous value of the voltage of the amplified signal (V _or t) is compared with a low reference voltage (V | _0W ) in a comparator (3 ; 31), said comparator providing a signal (Vdet; Vd _e tι) according to the result of the comparison, said signal being supplied to a filter (4; 41), said filter (4; 41) being able to supply a voltage (V _ass ; V _ass ι) controlling a current source (T1) able to supply said supply current (l _ass ι) of the periodic signal generator (1).

13. Method according to one of claims 2 to 11, characterized in that

the instantaneous value of the amplified signal voltage (V _out ) is compared with a high reference voltage (Vhig _h ) in a comparator (3; 32),

said comparator supplies a signal (Vdet; Vde _t 2) according to the result of the comparison, said signal being supplied to a filter (4; 42),

said filter (4; 42) being able to supply a voltage (V _ass ; V _ass2 ) controlling a current source (T2) able to supply said supply current (l _ass2 ) of the periodic signal generator (1).

14. Method according to one of claims 2 to 11, characterized in that

the instantaneous value of the amplified signal voltage (V ₀ ut) is compared with a low reference voltage (V | _ow ) in a first comparator (31),

said first comparator supplies a first signal (Vdeti) according to the result of the comparison, said first signal being supplied to a first filter (41),

said first filter (41) being able to supply a first voltage (V _aS si) controlling a first current source (T1) able to supply a first portion of said supply current (l _ass ι) of the periodic signal generator ( 1), and in that

the instantaneous value of the amplified signal voltage (V _out ) is compared with a high reference voltage (V _h i _gh ) in a second comparator (32),

said second comparator supplies a second signal (Vd _e 2) according to the result of the comparison, said second signal being supplied to a second filter (42),

said second filter (42) being able to supply a second voltage (V _ass2 ) controlling a second current source (T2) able to supply a second portion of said supply current (l _aS s2) of the periodic signal generator (1).

15. Method for controlling the supply current of a periodic signal generator, characterized in that the generator signal is amplified, that the instantaneous value of the amplified signal is compared to a low voltage, that l filter the signal of this first comparator to obtain a first average voltage, use this first average voltage to control a first current source, compare the instantaneous value of the amplified signal with a high voltage, the signal of this second comparator is filtered to obtain a second average voltage, that this second average voltage is used to control a second current source and that the periodic signal generator is supplied with the sum of the first current and of the second current so as to ensure that during a period the amplified signal of the generator has a minimum instantaneous voltage which is lower than the low voltage of the first compar maximum instantaneous voltage which is greater than the high voltage of the second comparator.

16. The method of claim 15, characterized in that one only performs the comparison of the instantaneous value of the amplified signal at a low voltage, that one only filters the signal from this comparator to obtain a medium voltage , that only this average voltage is used to control a current source and that the periodic signal generator is only supplied with this current so as to ensure that during a period the signal amplified generator has a minimum instantaneous voltage which is lower than the comparator low voltage.

17. The method of claim 15, characterized in that one only performs the comparison of the instantaneous value of the amplified signal at a high voltage, that one filters only the signal of this comparator to obtain a medium voltage , that only this medium voltage is used to control a current source and that the periodic signal generator is only supplied with this current so as to ensure that during a period the amplified signal of the generator has a maximum instantaneous voltage which is greater than the high voltage of the comparator.

18. Device for controlling the supply current (l _ass ) of a periodic signal generator (1) for implementing a method according to one of the preceding claims.

19. Device for controlling the supply current (l _aSs ) of a periodic signal generator (1), said periodic signal generator being able to supply a first signal (V _gen ) to an amplifier (2) able to amplifying said first signal and providing a second amplified signal (V _out ), characterized in that it comprises: a circuit (3; 31; 32; 4; 41; 42; T1; T2) capable of taking a signal downstream of said amplifier and slaving the supply current (Iass) of said periodic signal generator according to said sampled signal.

20. Control device according to claim 19, characterized in that it comprises at least one comparator (3; 31; 32) taking said second amplified signal (V _out ) and comparing its voltage with a reference voltage (Vι _ow ; Vhigh) and supplying a third signal (Vde _t ; _d e ι; V _d e _t2 ) used for controlling the supply current (l _ass ) of said periodic signal generator.

21. Control device according to claim 20, characterized in that the comparator (3; 31; 32) provides a third signal (Vd _and ; V _det ι; V _det2 ) which is a function of the difference between the instantaneous value of the voltage of the second amplified signal (V _or t) and the reference voltage (V | _ow ; _h , _gh ) associated with this instantaneous value of amplified signal voltage.

22. Control device according to claim 21, characterized in that the third signal is a digital signal

(V _det ; V _det ι, 'V _det2 ) whose duty cycle is a function of the difference between the instantaneous value of the voltage of the second amplified signal (V _or t) and the reference voltage (V | _0W ; Vhi _g h) associated with this extreme instantaneous value of amplified signal.

23. Control device according to one of claims .20 to 22, characterized in that the third signal (Vdet, 'Vdetι; Vdet2) is delivered to a filter (4; 41; 42).

24. Control device according to claim 23, characterized in that the voltage of the output signal (Vass, V _aS si; V _asS 2) of the filter is a function of the duty cycle of the digital signal (Vdet; Vdetι; Vdet2) -

25. Control device according to claim 24, characterized in that the average voltage of the output signal

(V _a ss; V _aS si, V _a ss2) of the filter is zero for a zero duty cycle of the digital signal (V _of t; V _of tι; V _det 2).

26. Control device according to one of claims 24 or 25 characterized in that the average signal voltage (V _ass ; V _ass ι; V _asS 2) of the filter (4; 41; 42) is weighted according to the duty cycle of the signal (Vdet; Vd _e tι; Vdet2) supplied by the comparator.

27. Control device according to one of claims 23 to

26, characterized in that the output signal (V _ass ; V _ass1 ; V _asS 2) of the filter controls a current source (T1; T2) capable of supplying at least a portion of the supply current (l _ass ) of the periodic signal generator.

28. Control device according to one of claims 18 to

27, characterized in that it comprises:

a comparator (3; 31) able to compare the voltage of said second amplified signal (V _out ) with a low reference voltage (V | _0W ) and to supply a third signal (V _det ; Vdetι) according to the result of this comparison ,

a filter (4; 41) capable of receiving said third signal and of supplying an output signal (V _ass ; V _aS si) as a function of a characteristic of said third signal,

a current source (T1) capable of receiving said filter output signal (V _ass , V _ass i) and supplying a supply current (l _ass ) to the periodic signal generator as a function of a characteristic of said filter output signal.

29. Control device according to one of claims 18 to 27, characterized in that it comprises:

a comparator (3; 32) able to compare the voltage of said second amplified signal (V _out ) with a high reference voltage (Vhigh) and to supply a third signal (V _of t; V _e t2) according to the result of this comparison,

a filter (4; 42) capable of receiving said third signal and of supplying an output signal (V _ass ; V _asS 2) as a function of a characteristic of said third signal,

a current source (T2) able to receive said filter output signal (V _ass ; V _ass2 ) and to supply a supply current (l _aS s) of the periodic signal generator as a function of a characteristic of said signal filter outlet.

30. Control device according to one of claims 18 to 27, characterized in that it comprises:

a comparator (31) able to compare the voltage of said second amplified signal (V _out ) with a low reference voltage (V | _ow ) and to supply a third signal (V _det i) according to the result of this comparison,

a filter (41) capable of receiving said third signal and of supplying an output signal (V _ass ι) as a function of a characteristic of said third signal,

a current source (T1) able to receive said filter output signal (V _ass1 ) and to supply a portion of the supply current (l _ass ι) of the periodic signal generator as a function of a characteristic of said output signal of the filter, as well as

a comparator (32) able to compare the voltage of said second amplified signal (V _out ) with a high reference voltage (V _h i _g h) and to supply a third signal (V _det2 ) according to the result of this comparison, - a filter (42) capable of receiving said third signal and of supplying an output signal (V _asS2 ) which is a function of a characteristic of said third signal,

a current source (T2) able to receive said filter output signal (V _ass2 ) and to supply a portion of the supply current (l _asS 2) of the periodic signal generator based on a characteristic of said signal

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31. Device for implementing the method according to claim 15, characterized in that it comprises a periodic signal generator (1), an amplifier (2) which amplifies the signal of the periodic generator (V _gen ), a comparator low level (31) which compares the instantaneous value of the amplifier signal (V _or t) with a low level (V | _ow ), a first low pass filter (41) which filters the signal of the low level comparator (V _d eti) and provides a first average voltage (V _ass ι) used by a first electronic circuit (T1) to provide a first current (l _aSs i), a high level comparator (32) which compares the instantaneous value of signal from the amplifier (V _or t) at a high level (Vhig _h ), a second low-pass filter (42) which filters the signal from the high level comparator (Vde 2) and provides a second average voltage (V _asS2 ) used by a second electronic circuit (T2) to supply a second current (l _aS s2), the sum of the two currents (l _ass = l _aS s1 + Iass ₂ ) being used to supply the periodic signal generator so as to ensure that during a period the amplified signal of the generator (V _or t) has a minimum instantaneous voltage which is lower than the low voltage of the first comparator and a maximum instantaneous voltage which is greater than the high voltage of the second comparator.

32. Device for implementing the method according to claim 16, characterized in that it comprises a periodic signal generator (1), an amplifier (2) which amplifies the signal of the periodic generator (V _gen ), a comparator low level (3) which compares the instantaneous value of the amplifier signal (V _or t) with a low level (V | _O ), a low-pass filter (4) which filters the low level comparator signal ( Vdet) and provides a medium voltage (V _ass ) used by an electronic circuit (T1) to supply a current (l _ass ), this current being used to supply the periodic signal generator so as to ensure that during a period the amplified signal of the generator (V _or t) has a minimum instantaneous voltage which is lower than the low voltage (Vι _ow ) of the comparator.

33. Device for implementing the method according to claim 17, characterized in that it comprises a periodic signal generator (1), an amplifier (2) which amplifies the signal of the periodic generator (V _gen ), a comparator high level (3) which compares the instantaneous value of the amplifier signal (V _or t) with a high level (V _h igh), a low pass filter (4) which filters the signal from the high level comparator ( V _det ) and provides a medium voltage (V _aS s) used by an electronic circuit (T1) to supply a current (l _ass ), this current being used to supply the periodic signal generator so as to ensure that during 'a period the amplified signal of the generator (V _or t) has a maximum instantaneous voltage which is higher than the high voltage (V _h i _gh ) of the comparator.

34. Device according to one of claims 18 to 33, characterized in that the amplifier (2) is a differential amplifier (OP20).

35. Device according to one of claims 18 to 33 characterized in that the amplifier (2) is an inverter (Inv20).

36. Device according to one of claims 18 to 35, characterized in that the level detector (31, 32; 3) is formed by a single transistor (T310, T320; T30) whose source receives the signal from the amplifier (V _or t) and the gate of which is biased at a constant voltage, so that said transistor is in a conductive state when the instantaneous value of the amplifier signal (V _out ) exceeds the level of said level detector (31 , 32; 3).

37. Device according to one of claims 18 to 36 characterized in that the low-pass filter (41, 42; 4) is formed of a capacity (C410, C420; C40) which receives two currents of different intensities, one of charge and the other of discharge, one constant (lo) and the other (n * lo or m * lo) equal to a multiple greater than 1 (n or m) of the first and circulating only when the instantaneous value of the amplifier signal (V _or t) exceeds the level of the level detector (31, 32; 3) associated with said filter.

38. Device according to one of claims 18 to 37, characterized in that the electronic circuits (T1, T2) are formed by a single transistor (T1, T2).

39. Device according to one of claims 18 to 38, characterized in that the dimensions of the transistors involved in the control loop determine the quiescent current of the device, in particular the starting current of the oscillator.

40. Control device according to one of claims 18 to 39, characterized in that it is associated with a quartz oscillator.

41. Control device according to one of claims 18 to

39, characterized in that it is associated with a resonant circuit oscillator.

42. Control device according to one of claims 40 or 41 associated with a clockwork movement.

43. Control device according to one of claims 40 or 41 associated with on-board electronics.