JP7807282B2 - Oscillator - Google Patents

Description

The present invention relates to an oscillator device that achieves low power consumption and a short rise time.

In communications systems, clock signals are essential for transmitting and receiving signals as desired, and oscillators that generate clock signals are essential. Furthermore, oscillators that consume low power and have short rise times are desirable.

For example, Patent Document 1 (Patent Document 1) discloses a technique for shortening the rise time of a crystal oscillator circuit used as a clock signal generating circuit. Specifically, the technique involves two oscillator circuits sharing a single crystal oscillator. The crystal oscillator, which is oscillating in one oscillator circuit, is switched to the other oscillator circuit for operation (see, for example, the claims of Patent Document 1). This technique involves placing the crystal oscillator in a standby oscillation state in one oscillator circuit, and adding a trigger when switching to the other oscillator circuit, thereby achieving stable oscillation in the other oscillator circuit in a short time (see, Patent Document 1, page 2, left column, lines 6-10).

Patent Document 2 also discloses technology for shortening the startup time of a VCXO (Voltage Controlled Crystal Oscillator). Specifically, when the oscillator is started, a high-speed startup circuit operates to minimize the capacitance of the varactor diode within the oscillator, thereby shortening the startup time of the oscillation circuit (see, for example, paragraph 13 and Figure 3 of Patent Document 2).

Special Publication No. 5-6362 Special Publication No. 2008-507894

By the way, one type of communication system is a communication system in which a link is established between multiple communication devices through authentication, and information is transmitted and received within a predetermined period T determined at the time of authentication. A typical example of such a system is Bluetooth (Bluetooth:
Bluetooth is a registered trademark of the Bluetooth Special Interest Group.
Although Bluetooth (registered trademark) has the advantage of low power consumption, further reduction in power consumption is desired. Therefore, even in Bluetooth (registered trademark), an oscillator device that can further reduce power consumption and has a short rise time is desired for generating a clock signal.
Although each of the above-mentioned conventional techniques can improve the rise time of an oscillator circuit, they do not aim to reduce power consumption or shorten the rise time in consideration of the communication algorithm of a communication system.
This application has been filed in consideration of these points, and therefore, the object of this application is to provide a novel oscillator device that can reduce power consumption and shorten the rise time, taking into account operation within the communication algorithm of a specified communication system.

In order to achieve this object, according to the present invention, there is provided an oscillator device that is incorporated into and used in a communication system in which links between a plurality of communication devices are established by authentication between the communication devices, and in which information is transmitted and received within a period T determined at the time of the authentication, and that generates a reference clock signal for the transmission and reception, the oscillator device comprising:
a first operation of inducing a preliminary oscillation of the reference clock signal at a first time t1 before the period T arrives, the preliminary oscillation being lower than the level of the reference clock signal;
The present invention is characterized in that an operation is started at a second time t2 after the first time t1 and before the period T arrives, and a second operation is performed in which the preliminary oscillation is used as an oscillation source and the reference clock signal is formed at least when the period T arrives.

When implementing this invention, it is preferable that the oscillator device outputs a reference clock signal during initial operation after the authentication, and performs the first and second operations from a first time t1 before the arrival of the first period T.

When implementing this invention, it is preferable that the oscillator device exchanges information regarding the third time t3, which is the end time of the second operation, during the authentication, and terminates the oscillation operation when time t3 arrives.

In carrying out the present invention, the communication system is a Bluetooth Classic standard or a Bluetooth Low Energy standard.
It is preferable that the fuel cell meets the Energy (Energy) standard.

According to the oscillator device of the present invention, a stepwise oscillation operation can be performed using a first operation and a second operation, utilizing the time from a first time before the arrival of the period T until the arrival of the period T. Here, since the first operation is a preliminary oscillation operation, it consumes little power. Moreover, the preliminary oscillation during the first operation contributes to triggering the second operation, which also shortens the rise time of the reference clock. Therefore, it is possible to provide a novel oscillator device that can achieve low power consumption and a short rise time, taking into account operation within the communication algorithm of a specified communication system.
Furthermore, in a preferred example configuration in which information regarding the third time t3 is received at the time of authentication to start operation of the communication system and the output of the reference clock signal is stopped at this third time, the reference clock signal can be generated for only the minimum necessary time, thereby further reducing the power consumption of the oscillator that generates the reference clock signal.

1A and 1B are diagrams for explaining an oscillation device according to an embodiment. FIG. 1A is a block diagram illustrating the relationship between an oscillator device of an embodiment and a communication system, and FIG. 1B is a block diagram illustrating a specific example of the oscillator device of the embodiment. 1A and 1B are diagrams for explaining specific examples of an oscillation section included in an oscillation device according to an embodiment. (Figures (A) and (B) are diagrams for explaining oscillation, and in particular preliminary oscillation. 1 is a diagram for explaining the operation of a control unit included in the oscillator device of the embodiment, and is a flowchart for explaining the operation of device 1 (master) in particular. 10 is a diagram for explaining the operation of a control unit included in the oscillator device of the embodiment, and is a flowchart for explaining the operation of device 2 (slave) in particular. FIG. FIG. 10 is a diagram for explaining another embodiment of the present invention.

Embodiments of the oscillator device of the present invention will be described below with reference to the drawings. Note that each figure used in the description is merely a schematic illustration to enable an understanding of the invention. Furthermore, in each figure used in the description, similar components are designated by the same numbers, and their description may be omitted. Furthermore, the circuit configurations, components used, etc. described in the following description are merely preferred examples within the scope of the present invention. Therefore, the present invention is not limited to the following embodiments.

1. Description of the Configuration of the Oscillator First, the configuration of an oscillator according to an embodiment will be described with reference to Figures 1, 2, and 3. Here, Figure 1(A) is a block diagram for explaining the main points of the oscillator according to the present invention, Figure 1(B) is a diagram for explaining an image of the operation of the oscillator according to the present invention, Figure 2(A) is a block diagram for explaining an example of the relationship between the oscillator according to the present invention and a communication system, and Figure 2(B) is a diagram for explaining a specific configuration example of the oscillator. Furthermore, Figures 3(A) and (B) are diagrams showing examples of oscillation circuits provided in the oscillator.

The oscillator of the present invention is incorporated into a predetermined communication system for use. The predetermined communication system is a communication system in which communication between a plurality of communication devices is permitted through authentication between the communication devices, and information is transmitted and received within a predetermined interval within a period T determined at the time of authentication. This transmission and reception is performed under a reference clock signal, and the oscillator of the present invention generates this reference clock.
1A and 1B show an example in which an oscillator device of the present invention is incorporated into and used in a communication system consisting of two communication devices, device 1 and device 2. Moreover, the example of Fig. 1A shows an example in which device 1 acts as a master and device 2 acts as a slave. When device 2, which is the slave, sends a connection request to device 1, which is the master, device 1 determines whether or not to authenticate device 2, and if authenticated, device 1 transmits the specifications of the communication system to device 2. This establishes a link between device 1 and device 2.

To deepen understanding of the present invention, specific examples of device 1 and device 2 in FIG. 1 are as follows: device 1 is, for example, a personal computer, tablet, smartphone, etc. that supports the Bluetooth (registered trademark) standard, and device 2 is, for example, various devices that support the Bluetooth (registered trademark) standard, such as earphones, printers, speakers, etc.
The communication specifications may include, for example, the size of data to be transmitted and received, the number of communications (e.g., the number of packets), and the communication period T. The communication specifications may also include a time at which the transmission and reception of information during each period T is to end (the third time t3 in this invention). In this embodiment, an example in which the third time t3 is also transmitted is shown later. The third time t3 is determined taking into account the time required to transmit and receive the amount of information transmitted and received during the period T. It may be a fixed value determined according to the communication system, or a different time determined according to the amount of information transmitted and received for each period T. The latter case is particularly preferable from the perspective of low power consumption, since it allows the reference clock to be generated with the minimum necessary information. The third time t3 does not exceed the first time t1 for the next period T.

Once a link is established as described above, the oscillator device of this invention generates a reference clock through two consecutive operations: a first operation and a second operation. That is, as shown in FIG. 1(B), the oscillator device performs a first operation at a predetermined first time t1 before the arrival of period T, which induces a preliminary oscillation to generate a reference clock signal whose level is lower than the reference clock signal level, and a second operation that begins at a second time t2 after the first time t1 but before the arrival of period T, using the preliminary oscillation as an oscillation source to generate a reference clock signal at least when period T arrives.

However, immediately after the link is established, i.e., during the initial operation of the oscillator in the communication system, the first time t1 and the second time t2 are undetermined (the initial operation section in FIG. 1B). Therefore, since communication itself cannot be performed if the clock signal is uncertain, the oscillator in this embodiment performs the initial operation of generating a reference clock (the "reference clock operation" in FIG. 1B). After the initial operation of generating the reference clock, the first and second operations of the present invention are repeatedly performed from the first time t1 immediately before the first period T arrives. Note that the first time t1 and the second time t2 can be detected, for example, by a timer (see FIG. 2) provided in the oscillator of the present invention. Specifically, the timer starts measuring time from the time the link is established and monitors the first time t1, the second time t2, the period T, and the third time t3.
The first time t1 and the second time t2 can be determined according to the design, for example, by determining them in advance according to the characteristics of the oscillation circuit provided in the oscillation device.

Next, the present invention will be described in more detail. Fig. 2(A) is a diagram showing a specific example of the present invention. A communication system 10 includes two devices: a master 11 and a slave 13. The master 11 includes an oscillator 11a according to the present invention and a communication device 11b, and the slave 13 includes an oscillator 13a according to the present invention and a communication device 13b. Each of the oscillators 11a and 13a includes an oscillator unit 15 and a control unit 17.
As shown in Fig. 2B, the oscillation unit 15 includes a crystal unit 15a as an oscillator 15a and circuit means for enabling the first operation 15b and the second operation 15c of the present invention. The circuit means for enabling the first operation 15b and the second operation 15c can be configured by a unique oscillation circuit, for example, as shown in Figs. 3A and 3B and described below.

The oscillator 15 shown in FIG. 3(A) comprises a first-stage C-MOS inverter 19a, a second-stage C-MOS inverter 19b, a switching element SW, a crystal oscillator 19c, a feedback resistor 19d, an input capacitor Cd, and an output capacitor Cgs. The first-stage C-MOS inverter 19a is connected to a power supply Vdd, while the second-stage C-MOS inverter 19b is connected to the power supply Vdd via a switching element SW. When a control signal Sc from the control unit 17 is turned on, for example, the switching element SW turns on, thereby supplying power to the second-stage C-MOS inverter 19b. Therefore, depending on whether the control signal Sc is turned on or off, the second-stage C-MOS inverter is turned on or off, changing the number of C-MOS inverter stages and thereby changing the amplification of the oscillator. In other words, when only the first-stage C-MOS inverter 19a is operating, the first operation of the present invention can be realized, and when both the first-stage C-MOS inverter 19a and the second-stage C-MOS inverter 19b are operating, the second operation of the present invention can be realized.

The oscillator unit 15 shown in Figure 3(B) includes a C-MOS inverter 21a, a switching element SW, a crystal oscillator 19c, a feedback resistor 19d, an input capacitor Cd, and an output capacitor Cgs. The C-MOS inverter 21a is connected to a power supply Vdd via the switching element SW. However, in this example, the switching element SW has a gate-like function that can vary the amount of current injected from the power supply Vdd into the C-MOS inverter 21a using a control signal Sc from the control unit 17. Therefore, by changing the amount of current injected from the power supply Vdd into the C-MOS inverter 21a, the first or second operation referred to in this invention can be achieved.

2. First Operation (Preliminary Oscillation) The first operation, or preliminary oscillation, as used in the present invention refers to a noise-level oscillation state before reaching normal oscillation equivalent to a desired reference clock. This will be described in detail below.
Currently, most devices used as oscillators to generate reference clocks are crystal oscillators. Crystal oscillators have a high Q value, making them a highly stable oscillation source, but on the other hand, they have the disadvantage of a slow oscillation start-up. In the case of a crystal oscillator, the noise level oscillation state continues for a certain period of time before returning to the original oscillation state.

The inventors have considered the time required for oscillation at this noise level, i.e., the time required for the first operation, which is a preliminary oscillation, and have found that, for example, it is as follows: Figures 4(A) and (B) are explanatory diagrams for this purpose, where Figure 4(A) is a model diagram of a crystal oscillator using an inverter circuit, and Figure 4(B) is its equivalent circuit.
The time required for the first operation actually depends on the mutual conductance and amplification factor of the crystal oscillator shown in Figure 4(B), but even so, it can be said to be roughly 3τ to 6τ. Here, τ is given by the following equation 1, and r' in equation 1 is given by r' = r/((ω Cds r)2 + 1), where ω is the angular frequency of the oscillation frequency, r is the resistance value of the amplifier shown in Figure 4(A), and Cds, R1, and L1 are the equivalent circuit constants shown in Figure 4(B).
Furthermore, the time required for the second operation is actually influenced by the mutual conductance and amplification factor in the crystal oscillator shown in FIG. 4B, but is still roughly about 3τ.

On the other hand, methods for speeding up the rise of oscillation in a crystal oscillator include a method of setting the amplification of the oscillation circuit at its maximum when driving the crystal oscillation circuit, monitoring the oscillation amplitude, and lowering the amplification when the desired amplitude is reached, or a method of predetermining a period during which the amplification of the oscillation circuit is at its maximum and lowering the amplification after a certain period of time has elapsed, which is called an AGC (Auto Gain Control) method. These methods can shorten the oscillation state of the noise level and the time required for oscillation growth, but on the other hand, they have the disadvantage of increasing power consumption.
In contrast to this, in the present invention, in a communication algorithm for a predetermined communication system, the minimum necessary preliminary oscillation as a first operation at a predetermined first time is set to a suitable time according to the circuit, such as 3τ to 6τ, and based on this preliminary oscillation, a main oscillation is induced with the minimum necessary power at the next second time, completing the reference clock at the arrival of the predetermined period T. This makes it possible to provide an oscillator device with a novel configuration that can achieve low power consumption and a short rise time.

3. Example of operation of the oscillator of the present invention (example of operation of the control unit 17)
Next, to deepen understanding of the present invention, an example of the operation of the oscillator device of the embodiment will be described with reference to Figures 5 and 6. Here, Figure 5 is a flowchart showing the operation of the master 11 shown in Figure 2(A), and Figure 6 is a flowchart showing the operation of the slave 13 shown in Figure 2(A).

The master waits (step S1 in FIG. 5), starts the reference clock (step S2 in FIG. 5), and monitors (step S3 in FIG. 5) a connection request from the slave (step S52 in FIG. 6). Meanwhile, the slave also starts the reference clock (step S51 in FIG. 6), and when it wants to make a connection request, it sends the connection request to the master (step S52 in FIG. 6).
When a connection request is received from a slave, the master performs authentication, and if authentication is successful, it transmits to the slave communication specifications, such as the data size to be transmitted and received, the number of communications (e.g., the number of packets), the communication cycle T, and the third time t3 at which transmission and reception will end (step S4 in FIG. 5). This establishes a link between the master and the slave (step S5 in FIG. 5, step S53 in FIG. 6).

Once the link is established, the master and slave stop the reference clock that was running as an initial operation (step S6 in FIG. 5, step S54 in FIG. 6). Also, once the link is established, the timer 17a of the control unit 17 (see FIG. 2B) starts time monitoring (step S7 in FIG. 5, step S55 in FIG. 6).
Next, timer 17a monitors the arrival of first time t1 (step S8 in FIG. 5, step S56 in FIG. 6), and when first time t1 arrives, control unit 17 outputs a control signal Sc to oscillator 15 to cause it to operate in the first operation. In response to this control signal Sc, oscillator 15 shown in FIG. 3A or 3B, for example, performs the first operation corresponding to preliminary oscillation (step S9 in FIG. 5, step S57 in FIG. 6).

Next, timer 17a monitors the arrival of second time t2 (step S10 in FIG. 5, step S58 in FIG. 6), and when second time t2 arrives, control unit 17 outputs a control signal Sc to oscillator 15 to cause it to operate in the second operation. In response to this control signal Sc, oscillator 15 shown in FIG. 3(A) or 3(B), for example, starts the second operation corresponding to the reference clock signal, i.e., the operation of raising the reference clock (step S11 in FIG. 5, step S59 in FIG. 6).
Next, the timer 17a monitors the arrival of the period T (step S12 in FIG. 5, step S60 in FIG. 6), and when the period T arrives, the master and slave perform the intended transmission and reception (step S13 in FIG. 5, step S61 in FIG. 6).
Next, the timer 17a monitors the arrival of the third time t3 (step S14 in FIG. 5, step S62 in FIG. 6), and when the third time t3 arrives, the master and slave stop the reference clock (step S15 in FIG. 5, step S63 in FIG. 6).
In monitoring the period T, when the period T arrives, the timer 17a simultaneously monitors the first time t1 for the next transmission/reception, the second time t2, the period T, and the third time t3.
The above-described series of operations performs the first and second operations of the present invention and transfers signals, thereby generating a reference clock signal with low power consumption and a short rise time.

In the above description, as explained with reference to Figures 2(A) and (B), an example has been described in which two devices, Device 1 and Device 2, are used, and each device is equipped with an oscillator device of the present invention, but the present invention is not limited to the above example.
For example, as shown in Fig. 7A, the present invention can be applied to a communication system 30 using three or more devices 31 to 31N. Specifically, the present invention can be applied to multi-pairing in the Bluetooth (registered trademark) standard. Furthermore, as shown in Fig. 7B, the present invention can be applied to a communication system 40 in which one oscillator 11a of the present invention is shared by multiple devices 41 to 41N.
Furthermore, in the above description, an example of applying the present invention to a Bluetooth (registered trademark) standard communication system has been shown, but the communication system to which the present invention can be applied is not limited to Bluetooth (registered trademark) standard communication systems, and may be various communication systems that implement the communication algorithm that is a prerequisite for the present invention.

10, 30, 40: Communication system of the embodiment 11, 13, 31, 31N, 41, 41N: Device (device used in the communication system)
11a, 13a: Oscillator device of the embodiment 15: Oscillator unit 17: Controller 17a: Timer

Claims (6)

1. An oscillator device for use in a communication system in which a link between a plurality of communication devices is established through authentication between the plurality of communication devices, and information is transmitted and received within a period T determined at the time of authentication, the oscillator device generating a reference clock signal for the transmission and reception,
a first operation of inducing a preliminary oscillation of the reference clock signal at a first time t1 before the period T arrives, the preliminary oscillation being lower than the level of the reference clock signal;
and a second operation of starting operation at a second time t2 after the first time t1 and before the period T arrives, using the preliminary oscillation as an oscillation source, and forming the reference clock signal at least when the period T arrives. The oscillator device described in claim 1, characterized in that during initial operation after the authentication, the reference clock signal is output, and the first operation and second operation are performed from the first time t1 before the first period T arrives. An oscillator device as described in claim 1 or 2, characterized in that, during the authentication, information regarding a third time t3 as the end time of the second operation is exchanged, and the second operation is terminated when time t3 arrives. The oscillator device described in any one of claims 1 to 3, characterized in that the communication system complies with the Bluetooth® Classic standard or the Bluetooth® Low Energy standard. a first-stage C-MOS inverter connected to a power supply;
a second-stage C-MOS inverter circuit connected to the power supply via a switching element, the switching element;
An oscillator unit including each of the inverter circuits and a crystal oscillator that forms a feedback loop,
The oscillator device according to any one of claims 1 to 4, characterized in that it comprises an oscillator unit in which the amplification degree is changed by enabling/disabling the second-stage C-MOS inverter circuit in accordance with an on/off control signal Sc for the switching element. a C-MOS inverter circuit connected to a power supply via a switching element;
the switching element varying an injection current from the power supply to the C-MOS inverter circuit in response to a control signal;
5. The oscillator device according to claim 1, further comprising an oscillation section in which the injection current is controlled to change the amplification factor in response to a control signal Sc for the switching element.