KR20140139829A - Low-power oscillator using triangular wave - Google Patents

Abstract

The present invention relates to a low power oscillator using a triangular wave. The oscillator according to the present invention comprises: a pulse generating unit which generates a pulse signal according to a predetermined period; a square wave generating unit which is connected to the pulse generating unit and outputs a square wave signal, which is generated to correspond to the pulse signal inputted through a clock terminal and a clear signal inputted through a clear terminal, through an output terminal; a triangular wave generating unit which generates a triangular wave signal by outputting a first signal, which increases from a low level to a high level at a predetermined slope, and a second signal, which decreases from the high level to the low level at a predetermined slope, corresponding to an on/off switching operation which is controlled by the square wave signal outputted from the square wave generating unit; and an oscillating unit which compares a voltage of the triangular wave signal outputted from the triangular wave generating unit with an oscillation reference voltage, and outputs a square wave oscillation signal which has the high level, when the voltage of the triangular wave signal is greater than or equal to the oscillation reference voltage, and the low level, when the voltage of the triangular wave signal is smaller than or equal to the oscillation reference voltage. According to the present invention, the oscillation signal can be provided at low power, and a pulsewidth and an oscillation frequency of the oscillation signal can be simply adjusted.

Description

[0001] LOW-POWER OSCILLATOR USING TRIANGULAR WAVE USING TRIANGLE WAVE [0002]

The present invention relates to an oscillator, and more particularly, to an oscillator capable of outputting a rectangular wave oscillation signal with a small power.

An oscillator is a device for generating a signal of a predetermined period and is used not only for an analog sound synthesizer but also for a variety of applications ranging from a mobile communication terminal to a wireless communication system including a satellite and radar communication device, It is widely used in devices.

When designing an oscillator, it is necessary to consider the amount of power consumed in the oscillator itself as well as characteristics related to signals generated from the oscillator, such as a quality factor, an output power, and a phase noise. The greater the amount of power the oscillator itself consumes when the oscillator is built into the device, the less the amount of available power available to other components.

As a kind of conventional oscillator, a ring oscillator, which is implemented by connecting an LC oscillator constituted by an amplifier and an LC tuning circuit and a plurality of inverters in a loop circulation form, consumes a large amount of current from the elements constituting the oscillator, . Accordingly, there has been a great difficulty in applying a conventional oscillator in a situation where oscillation has to be performed with a small power.

For example, in the case of a receiver that receives wireless power, the wireless power reaches a very small power in the receiver when the transmission distance is drastically reduced according to the transmission distance and the transmission distance is relatively large. Accordingly, the receiver amplifies the power using the DC-DC booster, and at this time, the driving of the DC-DC booster is controlled through the oscillation signal of the oscillator. In this case, it is directly related to the performance of the wireless power receiver that the oscillator outputs the oscillation signal while consuming the power which is reached to the receiver as much as possible. As shown in the above example, the amount of power consumed by the oscillator when performing the oscillation is one of the major issues in the design of the oscillator.

Therefore, the present applicant has newly proposed an oscillator capable of operating with low power while maintaining the oscillation performance of the conventional oscillator.

Korean Patent No. 10-0424952 Korean Patent No. 10-0297241

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide an oscillator capable of operating at low power.

The above object is achieved by an oscillator according to an aspect of the present invention, comprising: a pulse generator for generating a pulse signal according to a predetermined period; A square wave generator connected to the pulse generator and outputting a square wave signal generated corresponding to the pulse signal inputted through the clock terminal and the clear signal inputted through the clear terminal through the output terminal; A first signal rising from a low level to a high level with a predetermined slope corresponding to an on-off switching operation controlled by the square wave signal outputted from the square wave generating unit, and a second signal rising from a high level to a low level with a predetermined slope A triangular wave generator for generating a triangular wave signal by outputting a second signal; And a comparator for comparing the voltage of the triangle wave signal output from the triangle wave generator with the magnitude of the oscillation reference voltage and having a high level when the voltage of the triangle wave signal is equal to or higher than the oscillation reference voltage, And outputting a rectangular wave oscillation signal having a low level when the oscillation frequency is equal to or less than a predetermined value.

The square wave generator may output a high level signal in response to the pulse signal and may transition the high level signal to a low level in response to the clear signal.

The triangle wave generator may further include: a first PMOS transistor having a source connected to a power supply; A capacitor connected to a drain of the first PMOS transistor and operated as a variable of a frequency of the triangular wave signal; And an on-off switching operation is performed through a square wave signal output from the rectangular wave generating unit, and the discharge path of the charge charged in the capacitor is connected to the drain of the first PMOS transistor NMOS transistors; A second PMOS transistor having a source connected to a power source and a gate connected to a gate of the first PMOS transistor with a drain and a gate connected to each other; And a resistor connected to the drain of the second PMOS transistor and operated as a variable of the frequency of the triangular wave signal.

The pulse generator may further include: a comparison circuit for comparing magnitudes of the voltage of the triangular wave signal fed back from the triangle wave generator and the pulse generation reference voltage; And a buffer circuit for buffering an output signal output from the comparison circuit. In this case, the buffer circuit receives the output signal output from the comparison circuit, inverts the output signal, and outputs a first inverting signal And a second inverter outputting a second inverting signal by inverting the first inverting signal.

The oscillation reference voltage of the oscillation unit is determined by a voltage output from the output terminal of the voltage divider circuit. The voltage divider circuit includes a first resistor and a second resistor serially connected in series between the power supply and the ground The output terminal may output a voltage applied to the second resistor. The second resistance of the voltage divider circuit may be varied to adjust a pulse width of the rectangular wave oscillation signal output from the oscillation section.

As described above, according to the present invention, it is possible to operate with low power. Further, according to the present invention, it is easy to adjust the pulse width and the oscillation frequency of the oscillation signal.

1 is a block diagram of an oscillator according to an embodiment of the present invention;
FIG. 2 is a circuit diagram of the oscillator of FIG. 1; FIG.
3 is a schematic circuit diagram of a pulse generating unit;
4 is an example of a pulse signal output from the pulse generator;
5 illustrates an example of a triangular wave signal output from the triangle wave generator;
6 is an example of an oscillation signal output from the oscillation unit; And
7 is a graph showing a change in the pulse width of the oscillation signal according to the oscillation reference voltage of the oscillation portion.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

1 is a block diagram of an oscillator 100 according to an embodiment of the present invention.

1, an oscillator 100 according to an embodiment of the present invention includes a pulse generating unit 110, a square wave generating unit 130, a triangle wave generating unit 150, and an oscillating unit 170.

The pulse generating unit 110 generates a pulse signal according to a predetermined period. A pulse signal is a signal in which a pulse having a predetermined pulse width (W) is repeated with a predetermined period.

The square wave generating unit 130 is connected to the pulse generating unit 110 and generates a square wave signal in response to the pulse signal input from the pulse generating unit 110. The square wave generating unit 130 outputs a rectangular wave signal generated by shifting the low level signal to the high level in response to the pulse signal and transiting the high level signal to the low level in response to the clear signal through the output terminal Q .

The triangular wave generator 150 is connected to the rectangular wave generator 130 and performs an ON / OFF switching operation according to the square wave signal output from the rectangular wave generator 130 to generate a triangular wave . The triangle wave generator 150 includes a switch element controlled by a square wave signal and outputs a first signal rising from a low level to a high level with a predetermined slope when the switch is turned off and the switch is turned on ON), a triangular wave signal TW is generated by outputting a second signal falling from a high level to a low level with a predetermined slope. Meanwhile, the generated triangular wave signal TW is fed back to the pulse generating unit 110 so that a pulse signal of a constant period can be continuously output.

The oscillating unit 170 is connected to the triangle wave generating unit 150 to compare the amplitude of the triangle wave signal TW output from the triangle wave generating unit 150 with a predetermined reference oscillation reference voltage Vref, And outputs the oscillation signal.

Hereinafter, the configuration of the oscillator 100 described above with reference to the circuit diagram of FIG. 2 will be described in further detail.

The pulse generating unit 110 receives the triangular wave signal TW and the pulse generating reference voltage VCC 'fed back from the triangle wave generating unit 150 and generates a pulse signal corresponding to the comparison result of the magnitudes of the two voltages .

3 is a circuit diagram of the pulse generator 110 according to the embodiment of the present invention. 3, the pulse generating unit 110 includes a comparing circuit 113 for comparing the magnitude of the triangular wave signal TW fed from the triangle wave generating unit 150 and the pulse generating reference voltage VCC ' And a buffer circuit 115 for buffering an output signal outputted from the buffer circuit 113. [

The comparison circuit 113 includes a comparator. At this time, the feedback triangular wave signal TW and the pulse generation reference voltage VCC 'are respectively applied to the two input terminals of the comparator. 3, the OP-Amp (Operational Amplifier) is used to implement the comparator, but it is needless to say that the comparator can be designed by various known methods to compare the positive voltages.

At this time, the pulse generation reference voltage VCC 'may be determined through voltage division by resistors R5 and R6. This can be expressed as the following equation.

Assuming that the power supply voltage VCC is constant, the pulse generating reference voltage VCC 'having a desired magnitude can be obtained by appropriately changing the resistance values of the resistors R5 and R6. The comparing circuit 113 compares the voltage of the triangular wave signal TW with the magnitude of the pulse generating reference voltage VCC 'and has a high level when the voltage of the triangular wave signal TW is equal to or higher than the pulse generating reference voltage VCC' And outputs a pulse signal having a low level when the voltage of the triangular wave signal TW is smaller than the pulse generation reference voltage VCC '. Therefore, the pulse width W of the pulse signal varies depending on the magnitude of the pulse generation reference voltage VCC '. 4 is an example of a pulse signal output from the pulse generator 110. FIG. If the magnitude of the pulse generation reference voltage VCC 'is substantially similar to the maximum value of the triangular wave signal TW, a pulse signal having a very narrow pulse width W will be output as shown in FIG. On the other hand, when the pulse generation reference voltage VCC 'is small, a pulse signal having a relatively large pulse width W is generated.

The buffer circuit 115 is for buffering the output signal so that the output signal of the comparison circuit 113 is not attenuated and can be implemented using two inverters connected in series. That is, the buffer circuit 115 includes a first inverter INV1 receiving an output signal from the comparison circuit 113 and inverting an output signal to output a first inverting signal, And a second inverter INV2 that bucks and outputs a second inverting signal.

The square wave generating unit 130 receives the pulse signal of the pulse generating unit 110 and generates a square wave signal for controlling the switching operation of the triangle wave generating unit 150. For this purpose, the square wave generating unit 130 may include a D flip flop 133 as shown in FIG. The D flip-flop 133 includes an input terminal D, a clock terminal CK, an output terminal Q, and a clear terminal CLR.

The operation of the D flip-flop 133 is as follows. The power supply voltage VCC is applied to the input terminal D and the pulse signal output from the pulse generator 110 is applied to the clock terminal CK. Assuming that the D flip-flop 133 is a positive edge trigger, the edge at which the pulse signal rises from the low level to the high level becomes the trigger signal of the D flip-flop 133. The D flip-flop 133 outputs a high-level signal through the output terminal Q in response to the trigger signal. A clear signal is applied to the clear terminal CLR, and the D flip-flop 133 outputs the high level signal through the output terminal Q in response to the clear signal. As a result, the D flip-flop 133 outputs the square wave signal in response to the pulse signal and the clear signal.

The triangle wave generator 150 is connected to the square wave generator 130 and generates a triangle wave signal TW corresponding to the square wave signal output from the square wave generator 130. 2, the triangular wave generator 150 includes PMOS transistors PMOS1 and PMOS2 arranged as opposed to each other as a component of a current mirror for supplying current, a square wave output from the square wave generator 130, An NMOS transistor for performing a switching operation in response to a signal, and a capacitor C3 and a resistor R7 operating as frequency variables of the triangular wave signal TW.

The source of the first PMOS transistor PMOS1 and the source of the second PMOS transistor PMOS2 are connected to the power source VCC and the second PMOS transistor PMOS1 and the second PMOS transistor PMOS2 are connected to each other. The gate of the transistor PMOS2 is connected to the gate of the first PMOS transistor PMOS1 while the drain and the gate are connected to each other. A capacitor C3 is connected to the drain of the first PMOS transistor PMOS1 and a resistor R7 is connected to the drain of the second PMOS transistor PMOS2. The gate of the NMOS transistor is connected to the output terminal Q of the square wave generator 130 to perform an on-off switching operation through the square wave signal output from the square wave generator 130, and the drain of the NMOS transistor is connected to the first PMOS transistor PMOS1 to provide the discharge path of the charge charged in the capacitor C3. The triangular wave generator 150 configured as described above includes a resistor R7 and a capacitor C3 and consequently operates as an RC integrator circuit to form a triangular wave signal TW.

5 shows an example of the triangular wave signal TW output from the triangular wave generator 150. As shown in FIG. 5, when the low-level signal is input to the square wave generator 130, the NMOS transistor is turned off, so that the first PMOS transistor PMOS1 supplies The capacitor C3 is charged by the current that flows from the low level to the high level and outputs a first signal rising at a predetermined slope. When the high level signal is input in the square wave generating unit 130, the NMOS transistor is turned on and the discharging path of the charge charged in the capacitor C3 is conducted. Thus, the triangle wave generating unit 150 generates the triangle wave from the high level to the low level Wave signal TW by outputting a second signal that falls with a predetermined slope.

On the other hand, in the RC integration circuit, the charging and discharging speeds are determined by the values of R and C, so that the resistor R7 and the capacitor C3 are operated with the frequency of the frequency of the triangular wave signal TW. Therefore, the frequency of the triangular wave signal TW output from the triangular wave generator 150 can be adjusted by changing the values of the resistor R7 and the capacitor C3. Since oscillation is performed using the triangular wave signal TW as described later, a change in the frequency of the triangular wave signal TW eventually leads to a change in the frequency of the oscillation signal.

The oscillating unit 170 compares the voltage of the triangle wave signal TW output from the triangle wave generator 150 with the magnitude of the oscillation reference voltage Vref and outputs the oscillation signal Vout.

6 shows an example of the oscillation signal Vout output from the oscillation unit 170. As shown in FIG. The oscillation section 170 outputs a high level signal when the voltage of the triangle wave signal TW is equal to or higher than the oscillation reference voltage Vref and outputs a low level signal when the voltage of the triangle wave signal TW is smaller than the oscillation threshold voltage Vref And outputs a rectangular wave oscillation signal Vout as shown in FIG. The oscillation unit 170 uses a comparator including an input terminal to which the oscillation reference voltage Vref and the triangle wave signal TW are respectively inputted to compare the oscillation reference voltage Vref with the voltage of the triangle wave signal TW . The comparator may be designed based on various known circuit configurations, including an OP-AMP comparator.

On the other hand, the oscillation reference voltage Vref can be determined through the voltage division by the resistors R3 and R4. The circuit for voltage distribution includes a first resistor R3 and a second resistor R4 that are serially connected in series between a power supply VCC and ground and the oscillation reference voltage Vref includes a second resistor R4, As shown in FIG. For reference, the relationship between the resistance and the voltage in the voltage distribution is as shown in Equation (1).

Therefore, when it is assumed that the power supply voltage VCC is constant, the oscillation reference voltage Vref of a desired magnitude can be obtained by appropriately changing the resistance values of the resistors R3 and R4. At this time, all of the resistance values of R3 and R4 may be changed, but the resistor R3 may be fixed and the oscillation reference voltage Vref may be changed while changing only R4. Here, the change in the oscillation reference voltage Vref means a change in the pulse width W of the oscillation signal Vout. Hereinafter, the change of the pulse width W of the oscillation signal according to the change of the oscillation reference voltage Vref will be described with reference to FIG.

7 (b) shows a case where the oscillation reference voltage Vref is larger than that in the case of (a). It can be confirmed that when the oscillation reference voltage Vref is increased, an oscillation signal having a relatively small pulse width W is outputted. Therefore, by appropriately changing the oscillation reference voltage Vref, that is, the voltage applied to the resistor R4, an oscillation signal corresponding to the desired pulse width W can be obtained.

In addition, the period of the oscillation signal also changes according to the period of the triangle wave signal TW. That is, if the period of the triangle wave signal TW is long, the period of the oscillation signal becomes long. If the period of the triangle wave signal TW is short, the period of the oscillation signal becomes short accordingly. Accordingly, when the period of the triangular wave signal TW is changed by changing the values of the capacitors C3 and the resistors R7 of the triangular wave generator 150, the frequency of the oscillation signal is changed.

As described above, according to the oscillator 100 according to the embodiment of the present invention, by using the elements consuming less current than the conventional LC oscillator or the ring oscillator consuming the current in the unit of mA at the oscillation, So that the oscillation can be performed. On the other hand, it is easy to adjust the pulse width and the oscillation frequency of the oscillation signal as compared with the conventional oscillator.

Although some embodiments of the present invention have been described above, those skilled in the art will appreciate that various modifications may be made without departing from the spirit of the present invention.

For example, the elements operating with the oscillation frequency and the pulse width variable including the capacitor C3 of the triangle wave generator 150 and the resistor R4 of the oscillator 170 may be implemented as variable capacitors and variable resistors, respectively, And the pulse width, so that a desired oscillation signal can be obtained.

Therefore, the scope of protection of the present invention should be determined by the appended claims and their equivalents.

100: Oscillator 110: Pulse generator
130: Square wave generator 150: Triangle wave generator
170:

Claims (7)

A pulse generator for generating a pulse signal according to a predetermined period;
A square wave generator connected to the pulse generator and outputting a square wave signal generated corresponding to the pulse signal inputted through the clock terminal and the clear signal inputted through the clear terminal through an output terminal;
A first signal rising from a low level to a high level with a predetermined slope corresponding to an on-off switching operation controlled by the square wave signal outputted from the square wave generating unit, and a second signal rising from a high level to a low level with a predetermined slope A triangular wave generator for generating a triangular wave signal by outputting a second signal; And
The triangular wave signal output from the triangular wave generator is compared with the oscillation reference voltage to determine whether the voltage of the triangle wave signal is higher than the oscillation reference voltage, And outputting a rectangular wave oscillation signal having a low level.
The method according to claim 1,
Wherein the rectangular wave generating unit outputs a high level signal in response to the pulse signal and transitions the high level signal to a low level in response to the clear signal.
The method according to claim 1,
Wherein the triangle wave generator comprises:
A first PMOS transistor having a source connected to a power supply;
A capacitor connected to a drain of the first PMOS transistor and operated as a variable of a frequency of the triangular wave signal;
And an on-off switching operation is performed through a square wave signal output from the rectangular wave generating unit, and the discharge path of the charge charged in the capacitor is connected to the drain of the first PMOS transistor NMOS transistors;
A second PMOS transistor having a source connected to a power source and a gate connected to a gate of the first PMOS transistor with a drain and a gate connected to each other; And
And a resistor coupled to a drain of the second PMOS transistor and operating as a variable of the frequency of the triangular wave signal.
The method according to claim 1,
Wherein the pulse generator comprises:
A comparison circuit for comparing the magnitude of the voltage of the triangular wave signal fed back from the triangle wave generator and the magnitude of the pulse generation reference voltage; And
And a buffer circuit for buffering an output signal output from said comparing circuit.
5. The method of claim 4,
The buffer circuit includes a first inverter receiving an output signal output from the comparison circuit, inverting the output signal to output a first inverting signal, inverting the first inverting signal to output a second inverting signal, And a second inverter for outputting an output signal of the second inverter.
The method according to claim 1,
The oscillation reference voltage of the oscillation unit is determined by the voltage output from the output terminal of the voltage distribution circuit,
Wherein the voltage divider circuit includes a first resistor and a second resistor serially connected in series between a power source and ground, and the output terminal outputs a voltage applied to the second resistor.
The method according to claim 6,
And a pulse width of the rectangular wave oscillation signal output from the oscillation section is adjusted by changing a value of a second resistance of the voltage divider circuit.

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