JPH0454722A - Circuit for generating control signal while depending upon generation of extremal value of sine wave vibration and utilization of such circuit - Google Patents

Abstract

PURPOSE: To generate a control signal within the relatively wide frequency range of sine wave oscillation and to make the signal usable by controlling the a circuit with the charged voltage of a storage element so that the circuit can output the control signal while the charged voltage is smaller than the extremal value of a sine wave voltage. CONSTITUTION: When a sine wave is inputted to a high-frequency input terminal 12, a circuit point 32 oscillates and a capacitor 22 is caused to discharge through an FET 26. The time constant of the discharge is set so that the potential at the point 32 can change in the positive direction during the duration of the period of the sine wave oscillation. When the sine wave oscillation at the terminal 12 again approaches the minimum value and the potential at the point 32 again becomes lower, the FET 20 is again conducted and a charging current flows to the capacitor 22 and, in addition, the potential at the point 32 is again pulled toward the minimum value of the sine wave oscillation. Because of the short current pulse which flows to recharge the capacitor 22, the FET 24 is changed to a conducted state during the duration of the current pulse. Consequently, a negative pulse at an output terminal 14 relates to the minimum value of the sine wave oscillation.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a circuit arrangement for generating control pulses depending on the occurrence of extrema of sinusoidal oscillations and to the resonance during oscillations consisting of a coil and a capacitor. The present invention relates to the use of such circuits to maintain circuit oscillations by means of instantaneous high frequency carrier pulses.

SUMMARY OF THE INVENTION Resonant circuits have the property of continuing to vibrate when stimulated at a resonant frequency even when the supply of excitation energy is removed.

However, since the components of the resonant circuit have losses, and other elements connected to the resonant circuit can also affect the attenuation, high energy is resupplied to the resonant circuit to sufficiently offset the attenuation loss. Unless otherwise specified, the vibrations will in principle decay very rapidly at irregular intervals. In order for the energy supply to take place in an automatic sense and to maintain the oscillations, this supply must take place at the correct moment. Therefore, a circuit is required which is capable of generating a control signal and thus of energy supply to the resonant circuit and whose purpose is to maintain the oscillation of the resonant circuit.

The invention therefore provides a circuit of the type mentioned at the outset,
This circuit is based on the problem that such a control signal can be generated and used in a relatively large frequency range of sinusoidal oscillations without requiring large expenditures.

According to the invention, this problem is solved by a storage element that is charged via a diode to one of the extreme values of the sinusoidal oscillation, a discharge path of this storage element, and a discharge path of the storage element within the period of the sinusoidal oscillation. the time constant of the discharge path determined so that
controllable by the charging voltage of the memory element, and
and a switch element that provides a control signal to the output while the charging voltage is below the extreme value of the sinusoidal voltage.

With the circuit according to the invention, one pulse can be generated at each extreme value of the sinusoidal oscillations, but this relationship is maintained over a relatively large range of the sinusoidal oscillations.

A preferred use of the circuit arrangement according to the invention is characterized by paragraph 3 of the disclosure below.

In this application, the resonant circuit is stimulated to oscillate by instantaneous high-frequency carrier pulses, and the resonant circuit is constantly supplied with the necessary energy to continue the oscillation. This is because the generated control signal closes the switch, via which the energy supply to the resonant circuit takes place in each case in phase. Since the control signals are generated at the extremes of the sinusoidal oscillations, the energy supply is necessarily in phase. Therefore, in effect, supplying energy to the resonant circuit ends up being self-help.

An advantageous development of the use of the circuit according to the invention is characterized by paragraph 4 of the disclosure below.

In this development, the resonant circuit is part of the transponder, and the vibrations of the resonant circuit of the transponder are used to generate a clock signal that controls the functional sequence of the transponder. A special feature of the invention is that the transponder does not have its own supply voltage source, but is only provided with a storage capacitor. This storage capacitor is charged by a high frequency carrier frequency pulse, and this high frequency carrier frequency pulse also stimulates the resonant circuit to vibrate. Immediately after the conclusion of the high-frequency carrier pulse, the circuit of the invention begins to generate a control signal depending on one of the extreme values of the sinusoidal oscillations in the resonant circuit. The generated control signal also causes energy to then be supplied from the storage capacitor to the resonant circuit.

This supply continues until the energy in the storage capacitor is exhausted. This period is used to transfer the message stored in the transponder to the receiving device under the control of a clock signal derived from the sinusoidal oscillations of the resonant circuit.

EXAMPLES The present invention will now be described by way of examples and with reference to the drawings.

The circuit 10 illustrated in FIG. 1 includes a high frequency input terminal 12 to which sinusoidal vibrations are applied during operation.

The circuit also includes an output terminal 14 to which control signals can be supplied.

The terminal 6 serves as a power supply voltage terminal, and the input terminal 18 serves as a ground terminal.

The high frequency input terminal 12 is connected to one plate of a capacitor 22 via a field effect transistor 20 connected as a diode. And this capacitor 22
serves as a storage element, as will be explained later. The other plate of the capacitor 22 is
It is connected to the power supply voltage terminal 16. In addition, the high frequency input terminal 12 is connected to one field effect transistor 24 of two field effect transistors 24 and 25 connected in series.
The drain of the other field effect transistor 25 is connected to the power supply voltage terminal 16. Output 14 is obtained from the source-drain connection by field-effect transistors 24,25. Field effect transistor 20 connected to function as a diode
is connected to the gate of field effect transistor 24 and to the drain of field effect transistor 26. Further, the source of this field effect transistor 26 is connected to the power supply voltage terminal 1.
6, while its gate is connected to the gate of a field effect transistor 25.

Furthermore, connected to the gate of the field effect transistor 26 is the junction of two resistors 28, 30 connected in series between the supply voltage terminal 16 and the ground terminal 18.

Field effect transistor 20 as described in the circuit of FIG.
24 is an N-channel metal oxide semiconductor field effect transistor, and field effect transistors 25 and 26 are P-channel
It is a channel metal oxide semiconductor field effect transistor.

The field effect transistors 25, 26 are: - resistors 28 and 3
Since it is connected to a voltage divider consisting of 0, a fixed bias voltage is applied, so it functions as a constant current power supply. The field effect transistor 25 is the field effect transistor 24
acts as a load resistance.

The circuit of FIG. 1 operates as follows: When a sinusoidal vibration, or sine wave, is applied to the high frequency input terminal 12,
Circuit point 32 oscillates according to the sinusoidal oscillation until it reaches its minimum value. As soon as the sinusoidal oscillation begins to increase again, the blocking action of the field effect transistor 20 takes effect, so that the circuit point 32 is held at the potential of the minimum value of the sinusoidal oscillation. Capacitor 22 acts as a storage element for the potential of the minimum value of the sinusoidal oscillation. In parallel to the capacitor 22, the capacitor 22 is
A discharge occurs. The discharge time constant is then set such that the voltage divider consisting of the resistors 28 and 30 causes a significant discharge of the storage element within the duration of the period of the sinusoidal oscillation, i.e. the potential at the circuit point 32 is in the positive direction. Set to change.

The sinusoidal oscillation at the high-frequency input terminal 12 approaches its minimum value again and, in particular, again reaches a voltage value lower than the potential of the circuit point 32 (apart from the threshold voltage of the field-effect transistor 20 connected as a diode). As soon as the field effect transistor 20 becomes conductive again, a charging current flows through the capacitor 22, so that the potential at the circuit point 32 is again drawn towards the minimum of the sinusoidal oscillation.

A short current pulse flowing to recharge capacitor 22 causes field effect transistor 24 to change into a conductive state for the duration of the current pulse. As a result, output terminal 1
4, a negative pulse appears, which is clearly associated with the minimum value of the sinusoidal oscillation of the high-frequency input terminal 12.

A preferred use of the circuit arrangement of FIG. 1 is illustrated in FIG. 2 using a schematic circuit diagram.

The circuit specifically illustrated in FIG. 2 is part of a transponder, and only those elements necessary to explain the use of the circuit of FIG. 1 are shown. The resonant circuit included in the circuit of FIG. 2 and consisting of capacitors 36 and 38 can be caused to oscillate when stimulated using high frequency carrier pulses emitted by a transmitting device. Although the pulses can be received by an antenna, not shown in FIG. 2, which is fed to the resonant circuit, only the coil 38 can be part of the antenna.

A resistor 40 located in parallel to the resonant circuit 34 is
It is shown to be representative of all factors that dampen the resonant circuit 34.

Diode 42 is connected to ground from a parallel circuit consisting of resistor 40, capacitor 36, and coil 38. In parallel with this diode is a switch 44 which can be closed by a control signal from the circuit 10. In practice, switch 44 is an electronic switch that changes from a non-conductive state to a conductive state upon receiving a control signal from output terminal 14 .

In FIG. 2, the supply voltage power source 46 is specifically illustrated. This supply voltage source can be configured by a capacitor in the case of the application outlined in the transponder. This capacitor is charged by rectifying a high frequency carrier pulse using a diode 42. The voltage on capacitor 46 serves as a supply voltage for circuit 10 and at the same time serves as an energy source. From this energy source, each time the switch 44 closes under the control of the control signal from the circuit 10, the resonant circuit 34
receives an energy pulse that maintains a sinusoidal oscillation within the resonant circuit 34. Of course, sinusoidal oscillations can only be maintained for a limited time, which depends on the capacitor 36 and the amount of energy stored in it.

The circuit 10 always generates a control signal at the output terminal 14 within the region of the minimum value of the sinusoidal oscillation of the resonant circuit 34, so that the closing of the switch also occurs in this region. this is,
This results in an in-phase energy supply to the resonant circuit, a prerequisite for maintaining sinusoidal oscillations.

It is pointed out that by modifying the circuit specifically illustrated in FIG. 1, it is possible to easily generate a control signal within the region of the maximum value of the sinusoidal vibration. To do this, a P-channel metal oxide field effect transistor is used in place of each N-channel metal oxide field effect transistor currently used, and vice versa. It would only be necessary to use an N-channel metal oxide field effect transistor instead of a channel metal oxide field effect transistor. The circuit of FIG. 2 could also be easily adapted to the polarity of the control signal from circuit 10.

The following matters are disclosed in connection with the above description.

1. In a circuit that generates a control signal depending on the occurrence of an extreme value of a sine wave oscillation, a memory element 22 that is charged via a diode to one of the extreme values of the sine wave oscillation; a discharge path, a time constant of the discharge path determined such that a substantial discharge of the storage element 22 occurs within a period of the sinusoidal oscillation; and a charging voltage of the storage element, the charging voltage being 1. A circuit comprising: a switch element that applies a control signal to an output terminal 14 during a period when the wave voltage is smaller than an extreme value.

2. The switching element is a field effect transistor 24, the charging voltage of the storage element 22 is applied to its gate electrode, a sine wave vibration is applied to its source electrode, and its drain electrode functions as a load resistance. 2. The circuit according to item 1, wherein the circuit is connected to a constant current power source 22.

3. said resonant circuit 34 is in series connection with a controllable switch 44, which controllable switch is in turn connected in parallel with a supply voltage source 46; and said controllable switch 44 is a switch element. 24, in which the controllable switch is switched to the closed state by a control signal supplied by the supply voltage source 4.
6 is applied to the resonant circuit, and the resonant circuit is composed of a coil and a capacitor, and is stimulated by an instantaneous high-frequency carrier wave pulse to maintain the vibration of the resonant circuit. circuit.

4. The coil 38 of the resonant circuit 34 is the receiving coil of the receiving part of the transponder, and the supply voltage source of this transponder is formed by a capacitor, and this capacitor is responsible for the high-frequency carrier pulses received by the coil 38 of the resonant circuit 34. 4. A circuit according to claim 3, characterized in that the circuit is charged by the rectification of the high-frequency carrier pulse, and that the oscillations of the resonant circuit after the conclusion of the high-frequency carrier pulse serve to generate the clock pulse of the transponder.

5. The circuit is described as being able to generate control signals with the help of which, depending on the occurrence of the extrema of the sinusoidal oscillations.

Circuit 10 includes a storage element 22 which is charged via diode 20 to one of each extreme value of the sinusoidal oscillation. A discharge path 26 is present in the storage element 22, the time constant of which is dimensioned such that a significant discharge of the storage element 22 occurs within the duration of a period of sinusoidal oscillation. A switch element 24 controllable by the charging voltage of the storage element 22 supplies a control signal to its output terminal 14 during the time when the charging voltage of the storage element 22 is less than the extreme value of the sinusoidal oscillation. This circuit can be utilized to maintain the oscillation of a resonant circuit that is stimulated to oscillate by an instantaneous high frequency carrier pulse.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram according to the present invention, and FIG. 2 is a basic circuit diagram for explaining an embodiment according to the present invention. 10... Circuit, 16... Power supply voltage terminal, 18... Ground terminal, 20.24... N-channel field effect transistor, 25.26. ...P-channel field effect transistor.

Claims (1)

[Claims] A circuit for generating a control signal depending on the occurrence of an extreme value of a sinusoidal oscillation, comprising: a memory element (22) charged via a diode to one of the extreme values of the sinusoidal oscillation; The discharge path for the storage element (22) is determined by the time constant of the discharge path, which is determined such that a substantial discharge of the storage element (22) occurs within the period of the sinusoidal oscillation, and by the charging voltage of said storage element. a switching element which is controlled and which provides a control signal to an output terminal (14) during a period in which said charging voltage is smaller than an extreme value of a sinusoidal voltage.