JP2003008403A - Oscillation circuit - Google Patents

Abstract

(57) [Problem] A conventional oscillation circuit has a problem that since the feedback gain is constant, it takes a long time from power-on to stable operation when the feedback gain is low. SOLUTION: By increasing the gain of an amplifier circuit or a feedback circuit when power is turned on, the loop gain is increased, and after returning to a stable oscillation state, the original loop gain is restored. Can quickly start up to the oscillation steady state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oscillator circuit used in a wireless communication device such as a mobile phone and satellite communication.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to the drawings.

FIG. 12 is a circuit diagram of a conventional oscillator circuit.

In FIG. 12, 1 and 2 are oscillation transistors, 3 is a constant current source, 4 and 5 are feedback capacitors, 6 is a resonance capacitor,
7 is a resonance inductor, 8 is a bias choke, 9 and 1
0, 11, 12 are bias resistors, 13 is a power supply, 14, 1
Reference numeral 5 is an oscillation circuit output coupling capacitance, and 16 and 17 are oscillation circuit differential output terminals.

Parallel resonance occurs at the oscillation frequency by the resonance capacitor 6 and the resonance inductor 7, and the impedance seen from the collectors of the oscillation transistors 1 and 2 toward the power supply 13 becomes infinite.

Signals having an oscillation frequency amplified by thermal noise are oscillated by the feedback capacitors 4 and 5, respectively.
It is fed back to and maintains the oscillation state.

In the conventional oscillator circuit, the constants of the feedback capacitors 4 and 5 are fixed in order to stably oscillate at a desired frequency, and the loop gain of the oscillator circuit at a specific oscillation frequency is constant.

[0008]

However, the above-mentioned structure has a problem that the time from power-on to the stable state becomes long in the oscillation circuit having a low loop gain.

The present invention has been made in view of the above problems, and an object thereof is to provide an oscillation circuit having a short starting time.

[0010]

To solve this problem, the present invention increases the loop gain of the oscillation circuit when the power is turned on, and then returns the loop gain to reduce the startup time from power-on to stable oscillation. A short oscillation circuit can be obtained.

That is, the first aspect of the present invention (corresponding to claim 1) is that the gain of all or a part of the amplifier circuit, the feedback circuit, and the amplifier circuit and / or the feedback circuit is turned on when the power is turned on. A gain controller that sets a predetermined value and a gain of all or part of the amplification circuit and / or the feedback circuit to a second predetermined value after oscillation stabilization, and the amplification circuit and the feedback circuit form a loop circuit. Therefore, the first predetermined value is an oscillation circuit larger than the second predetermined value.

The second invention (corresponding to claim 2)
Is the oscillator circuit according to the first aspect of the present invention, wherein the amplifier circuit is a ring oscillator having N amplifier circuits 1 to N.

A third aspect of the present invention (corresponding to claim 3)
, The amplifier circuit has first to Nth amplifier circuits, the feedback circuit has first to Nth feedback circuits, and the first to Nth feedback circuits are provided. Of the circuits, the Nth feedback circuit feeds back an output of the Nth amplification circuit among the Nth amplification circuits of the first to Nths to an input of the first amplification circuit, When i is an arbitrary integer satisfying 1 <= i <= N−1, the i-th feedback circuit feeds back the output of the i-th amplification circuit to the input of the i + 1-th amplification circuit. An oscillation circuit according to a first aspect of the present invention.

A fourth invention (corresponding to claim 4)
Is the oscillation circuit according to the second or third aspect of the present invention, wherein N is an even number, and each of the first to Nth amplification circuits is an inverting amplification circuit.

A fifth aspect of the present invention (corresponding to claim 5)
Is the third amplification circuit in which the N is 2 and the N first to Nth amplification circuits are oscillation transistors, and an oscillation signal is differentially extracted from the first amplification circuit and the second amplification circuit. Is an oscillator circuit according to the present invention.

A sixth aspect of the present invention (corresponding to claim 6)
Is composed of a variable capacitance diode, a MOS capacitance, or a plurality of capacitors and a switchable switch connected in series to the capacitors. 1st
5 is an oscillation circuit according to any one of the present inventions.

A seventh aspect of the present invention (corresponding to claim 7)
Is the oscillation circuit according to the sixth aspect of the present invention, wherein the switch is a MOS switch.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment of an oscillator circuit of the present invention.

In FIG. 1, 1 is an amplifier circuit, 2 is a feedback circuit, and 3 is a gain controller. The operation is shown below.

The amplifier circuit 1 is an amplifier circuit having a gain at the oscillation frequency. The output of the amplifier circuit 1 is fed back to the input by the feedback circuit 2. Amplifier circuit 1 and feedback circuit 2
In the closed loop circuit, the oscillator has a loop gain of 1 or more at the oscillation frequency.

In the above configuration, the gain controller 3
Thus, when the power is turned on, the gain of the feedback circuit 2 at the oscillation frequency is increased (or the loss is decreased) and the total loop gain is increased, so that the oscillation is stably started at a high speed, and after the rise, the gain controller 3 Thus, the gain of the feedback circuit 2 is lowered (or the loss is increased) to return to the optimum state of oscillation.

That is, when the power is turned on by the gain controller 3, the gain of the feedback circuit 2 at the oscillation frequency is set to the first predetermined value, and after the oscillation is stabilized, the gain of the feedback circuit 2 is set to the second predetermined value smaller than the first predetermined value. Value.

Specifically, when the power is turned on, the gain controller 3 increases the gain of the feedback circuit 2 at the oscillation frequency by, for example, about 1.5 times to several times, and after the oscillation is stabilized, the gain of the feedback circuit 2 is set to, for example, 1. Approximately 5 to several times lower.

According to the above configuration, even in an oscillation circuit having a low loop gain, it is possible to quickly start up to a stable state when the power is turned on.

(Second Embodiment) FIG. 2 shows a second embodiment of the oscillator circuit of the present invention.

In FIG. 2, 1 is an amplifier circuit, 2 is a feedback circuit, and 3 is a gain controller. The operation is shown below.

The amplifier circuit 1 is an amplifier circuit having a gain at the oscillation frequency. The output of the amplifier circuit 1 is fed back to the input by the feedback circuit 2. Amplifier circuit 1 and feedback circuit 2
In the closed loop circuit, the oscillator has a loop gain of 1 or more at the oscillation frequency.

When the power is turned on by the gain controller 3, the gain of the amplifier circuit 1 at the oscillation frequency is increased and the total loop gain is increased.
The oscillation is started up to a stable state at high speed, and after rising, the gain of the amplifier circuit 1 is lowered by the gain controller 3 to return to the optimum state of oscillation.

That is, when the power is turned on by the gain controller 3, the gain of the amplification circuit 1 at the oscillation frequency is set to the first predetermined value, and after the oscillation is stabilized, the gain of the amplification circuit 1 is set to the second predetermined value smaller than the first predetermined value. Value.

Specifically, when the power is turned on, the gain controller 3 increases the gain of the amplifier circuit 1 at the oscillation frequency by, for example, about 1.5 times to several times, and after the oscillation is stabilized, the gain of the amplifier circuit 1 is set to, for example, 1. Approximately 5 to several times lower.

According to the above configuration, even in an oscillation circuit having a low loop gain, it is possible to quickly start up to a stable state when the power is turned on.

(Third Embodiment) FIGS. 3 and 4 show a third embodiment of the oscillator circuit according to the present invention.

In FIG. 3, 1 to 3 are amplifier circuits and 4 is a gain controller. 4 is a circuit diagram of one amplifier circuit of FIG. 3, 6 is a transistor, 7 is a choke inductor, 8 is an output coupling capacitor, 9 is a signal output terminal, 10 is a variable emitter resistor, and 11 and 13 are bias. A resistor, 12 is an input coupling capacitor, 14 is a power supply, and 15 is a signal input terminal. The operation is shown below.

The amplifier circuits 1 to 3 are amplifier circuits having a gain at the oscillation frequency. The output of the amplifier circuit 3 is fed back to the input of the amplifier circuit 1. A ring oscillator is configured with a loop gain of 1 or more at the oscillation frequency.

When the power is turned on, the gain controller 4 reduces the value of the variable emitter resistor, increases the gains of the amplifier circuits 1 to 3 at the oscillation frequency, increases the total loop gain, and speeds up to the stable oscillation state. After the start-up and start-up, the gain controller 4 restores the emitter resistance value to the original value, so that the amplifier circuits 1 to
Lower the gain of 3 to return to the optimum state of oscillation.

According to the above configuration, even in an oscillation circuit having a low loop gain, it is possible to quickly start up to a stable state when the power is turned on.

(Fourth Embodiment) FIGS. 5 and 6 show a fourth embodiment of the oscillator circuit of the present invention.

In FIG. 5, 1-4 are inverter circuits,
Reference numeral 5 is a gain controller. 6 shows the internal circuit of one inverter, 6 is a transistor,
7, 11 and 13 are bias resistors, 8 is an output coupling capacitor, 9 is a signal output terminal, 10 is an emitter variable resistor, 12
Is an input coupling capacitor, 14 is a power supply, and 15 is a signal input terminal. The operation is shown below.

The inverter circuits 1 to 4 are inverting amplifier circuits having a gain at the oscillation frequency. The output of the inverter circuit 4 is fed back to the input of the inverter circuit 1. The loop gain is 1 or more at the oscillation frequency and constitutes a ring oscillator.

When the power source is turned on by the gain controller 5, the resistance value of the variable emitter resistor 10 is reduced to increase the gain of the inverter circuits 1 to 4 at the oscillation frequency and increase the total loop gain to stabilize the oscillation. Up to a high speed, and after the rise, the gain controller 5 restores the emitter variable resistor 10 to the original value to lower the gain of the inverter circuits 1 to 4 and restore the optimum state of oscillation.

According to the above configuration, even in an oscillation circuit having a low loop gain, it is possible to quickly start up to a stable state when the power is turned on.

Although it has been described that the oscillator circuit of this embodiment uses four inverter circuits, the present invention is not limited to this, and any even number of inverter circuits may be used.

(Fifth Embodiment) FIG. 7 shows an oscillator circuit according to a fifth embodiment of the present invention.

In FIG. 7, 1 and 3 are amplifier circuits, 2 and 4
Is a feedback circuit, and 5 is a gain controller. The operation is shown below.

The amplifier circuits 1 and 3 are inverting amplifier circuits having a gain at the oscillation frequency. The output of the amplifier circuit 1 is input to the amplifier circuit 3 via the feedback circuit 2. Then, the output of the amplifier circuit 3 is fed back to the input of the amplifier circuit 1 via the feedback circuit 4. The loop gain is 1 or more at the oscillation frequency, and constitutes the oscillation circuit.

When the power is turned on, the gain controller 5 increases the gain of the feedback circuits 2 and 4 (or reduces the loss) at the oscillation frequency to increase the total loop gain. Start up to the stable state of oscillation at high speed,
After rising, the gain controller 5 lowers the gain of the feedback circuits 2 and 4 (increased loss) to return to the optimum state of oscillation.

According to the above configuration, even in an oscillation circuit having a low loop gain, it is possible to quickly start up to a stable state when the power is turned on.

Although the oscillation circuit of this embodiment has been described as being composed of the two amplifier circuits 1 and 3 and the two feedback circuits 2 and 4, the present invention is not limited to this, and N may be any number. It may be composed of N amplifier circuits and N feedback circuits as integers.

Further, the amplifier circuits 1 and 3 may be inverting amplifier circuits. In this case, the oscillator circuit
It may be composed of 2N amplifier circuits and 2N feedback circuits, where N is an arbitrary integer.

(Sixth Embodiment) FIG. 8 shows an oscillator circuit according to a sixth embodiment of the present invention.

In FIG. 8, 1 and 2 are oscillation transistors, 3 is a constant current source, 4 and 5 are variable capacitance diodes, 6 is a resonance capacitance, 7 is a resonance inductor, 8 is a bias choke, 9, 10, 11 and 12. Is a bias resistor, 13 is a power supply, 14 and 15 are oscillator circuit output coupling capacitors, 16 and 17 are oscillator circuit differential output terminals, 18 and 19 are feedback capacitors, 20,
Reference numeral 21 is a feedback capacitance control bias resistor, and 22 is a feedback capacitance control voltage. The operation is shown below.

Parallel resonance occurs at the oscillation frequency by the resonance capacitor 6 and the resonance inductor 7, and the impedance seen from the collectors of the oscillation transistors 1 and 2 toward the power supply 13 becomes infinite.

The signals of the oscillation frequency amplified by the thermal noise are respectively generated by the variable capacitance diodes 4 and 5 and the feedback capacitors 18 and 19 connected in series to the oscillation transistors 1 and 5, respectively.
It is fed back to 2 and maintains the oscillation state.

In such a multivibrator oscillator circuit, when the power is turned on, the feedback capacitance control voltage 22 is controlled to increase the capacitance values of the variable capacitance diodes 4 and 5 to increase the feedback signal.

After the oscillation reaches a steady state, the capacitance value of the variable capacitance diodes 4 and 5 is reduced by the feedback capacitance control voltage 22 to reduce the feedback signal (return to the original).

According to the above configuration, even in an oscillation circuit having a low loop gain, it is possible to quickly start up to a stable state when the power is turned on.

(Seventh Embodiment) FIG. 9 shows a seventh embodiment of the oscillator circuit of the present invention.

In FIG. 9, 1 and 2 are oscillation transistors, 3 is a constant current source, 4 and 5 are MOS capacitors, 6 is a resonance capacitor, 7 is a resonance inductor, 8 is a bias choke, and 9,
10, 11, 12 are bias resistors, 13 is a power supply, 14,
Reference numeral 15 is an oscillation circuit output coupling capacitance, 16 and 17 are oscillation circuit differential output terminals, 18 and 19 are feedback capacitances, 20 and 21 are feedback capacitance control bias resistors, and 22 is a feedback capacitance control voltage. The operation is shown below.

Parallel resonance occurs at the oscillation frequency by the resonance capacitor 6 and the resonance inductor 7, and the impedance seen from the collectors of the oscillation transistors 1 and 2 toward the power supply 13 becomes infinite. The oscillation frequency signal amplified by the thermal noise is fed back to the oscillation transistors 1 and 2 by the MOS capacitors 4 and 5 and the feedback capacitors 18 and 19 connected in series to the MOS capacitors 4 and 5, respectively, to maintain the oscillation state.

In such a multivibrator oscillator circuit, when the power is turned on, the feedback capacitance control voltage 22 is controlled to increase the capacitance values of the MOS capacitances 4 and 5 to increase the feedback signal. Then, after the oscillation reaches a steady state, the capacitance values of the MOS capacitors 4 and 5 are reduced by the feedback capacitance control voltage 22 to reduce the feedback signal (restore).

According to the above configuration, even in an oscillation circuit having a low loop gain, it is possible to quickly start up to a stable state when the power is turned on.

(Embodiment 8) FIG. 10 shows an eighth embodiment of the oscillator circuit of the present invention.

In FIG. 10, 1 and 2 are oscillation transistors, 3 is a constant current source, 4, 5, 18 and 20 are feedback capacitors, and 6 is a feedback capacitor.
Is a resonance capacitance, 7 is a resonance inductor, 8 is a bias choke, 9, 10, 11, 12 are bias resistors, 13 is a power supply, 14 and 15 are oscillation circuit output coupling capacitances, 16 and 17 are oscillation circuit differential output terminals, 19, 21 are MOS switches,
22 is a feedback capacitance control voltage. The operation is shown below.

The resonance capacitance 6 and the resonance inductor 7 cause parallel resonance at the oscillation frequency, and the impedance seen from the collectors of the oscillation transistors 1 and 2 toward the power supply 13 becomes infinite. The oscillation frequency signal amplified by the thermal noise is fed back to the oscillation transistors 1 and 2 by the MOS capacitors 4 and 5 and the feedback capacitors 18 and 19 connected in series to the MOS capacitors 4 and 5, respectively, to maintain the oscillation state. In such a multivibrator oscillator circuit, when the power is turned on, the feedback capacitance control voltage 22 is controlled to increase the capacitance values of the MOS capacitances 4 and 5 to increase the feedback signal. Then, after the oscillation reaches a steady state, the capacitance values of the MOS capacitors 4 and 5 are reduced by the feedback capacitance control voltage 22 to reduce the feedback signal (restore).

According to the above configuration, even in an oscillation circuit having a low loop gain, it is possible to quickly start up to a stable state when the power is turned on.

(Ninth Embodiment) FIG. 11 shows an oscillator circuit according to a ninth embodiment of the present invention.

In FIG. 11, 1 and 2 are oscillation transistors, 3 is a constant current source, 4 and 5 are feedback transistors, 6 is a resonance capacitance, 7 is a resonance inductor, 8 is a bias choke,
9, 10, 11, 12, 20, 21, 24, 25 are bias resistors, 13 is a power supply, 14 and 15 are oscillator circuit output coupling capacitors, 16 and 17 are oscillator circuit differential output terminals, 18 and 19.
Is a feedback capacitance, and 22 and 23 are feedback gain control voltages.
The operation is shown below.

Parallel resonance occurs at the oscillation frequency by the resonance capacitor 6 and the resonance inductor 7, and the impedance seen from the collectors of the oscillation transistors 1 and 2 toward the power supply 13 becomes infinite. The signal of the oscillation frequency amplified by the thermal noise is fed back to the oscillation transistors 1 and 2 through the feedback capacitors 18 and 19 and the feedback transistors 4 and 5, respectively, and the oscillation state is maintained. In such a multivibrator oscillator circuit, when the power is turned on, the feedback gain control voltage 22, 2
Adjust 3 to increase the feedback signal. Then, after the oscillation has reached a steady state, the feedback capacitance control voltages 22 and 23 are restored.

According to the above configuration, even in an oscillation circuit having a low loop gain, it is possible to quickly start up to a stable state when the power is turned on.

Although the present embodiment has been described as controlling the gain of either the amplifier circuit or the feedback circuit, the present invention is not limited to this, and the gains of both the amplifier circuit and the feedback circuit may be controlled. I do not care. Further, the gains of all or part of the amplifier circuit and the feedback circuit may be controlled. Further, the gain of part of the amplifier circuit or part of the feedback circuit may be controlled.

As described above, according to the present embodiment, the loop gain is increased by increasing the gain of the amplifier circuit or the feedback circuit (or reducing the loss of the feedback circuit) when the power of the oscillator is turned on. By reducing the loop gain after the steady state, it is possible to obtain an oscillation circuit in which the rise is quick after power-on even when the loop gain in the steady state of oscillation is small.

[0073]

As is apparent from the above description, the present invention can provide an oscillation circuit having a short starting time.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing a third embodiment of the present invention.

FIG. 4 is an amplifier partial circuit diagram of a third embodiment of the present invention.

FIG. 5 is a circuit diagram showing a fourth embodiment of the present invention.

FIG. 6 is an inverter partial circuit diagram of a fourth embodiment of the present invention.

FIG. 7 is a circuit diagram showing a fifth embodiment of the present invention.

FIG. 8 is a circuit diagram showing a sixth embodiment of the present invention.

FIG. 9 is a circuit diagram showing a seventh embodiment of the present invention.

FIG. 10 is a circuit diagram showing an eighth embodiment of the present invention.

FIG. 11 is a circuit diagram showing a ninth embodiment of the present invention.

FIG. 12 is a circuit diagram of a conventional high frequency oscillator circuit.

[Explanation of symbols]

1 and 2 oscillation transistor 3 constant current source 4, 5 MOS capacity 6 Resonance capacity 7 Resonant inductor 8 bias chokes 9,10,11,12 Bias resistance 13 power supply 14, 15 Oscillator output coupling capacity 16, 17 Oscillation circuit differential output terminals 18, 19 Return capacitance 20,21 Feedback capacitance control bias resistor 22 Feedback capacitance control voltage

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hisashi Adachi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5J081 AA08 BB01 CC04 DD03 DD11                       FF25 GG09 KK09 KK16

Claims (7)

[Claims] 1. An amplifier circuit, a feedback circuit, and the gain of all or a part of the amplifier circuit and / or the feedback circuit at a first predetermined value when power is turned on, and after the oscillation is stabilized, the amplifier circuit and / or the gain. A gain controller for setting the gain of all or part of the feedback circuit to a second predetermined value, wherein the amplification circuit and the feedback circuit form a loop circuit, and the first predetermined value is the second value. Oscillation circuit larger than the predetermined value of. 2. The oscillator circuit according to claim 1, wherein the amplifier circuit is a ring oscillator having N amplifier circuits 1 to N. 3. The amplifier circuit includes N first to N amplifier circuits, the feedback circuit includes N first to N feedback circuits, and the first to Nth N feedback circuits are provided. Of the N feedback circuits, the Nth feedback circuit feeds back the output of the Nth amplification circuit among the N first to Nth amplification circuits to the input of the first amplification circuit. And i is an arbitrary integer satisfying 1 <= i <= N−1, the i-th feedback circuit is
2. The oscillator circuit according to claim 1, wherein the output of the amplifier circuit is fed back to the input of the (i + 1) th amplifier circuit. 4. The oscillator circuit according to claim 2, wherein N is an even number, and each of the first to Nth amplifier circuits is an inverting amplifier circuit. 5. The N is 2 and the N amplification circuits of the first to Nth are oscillation transistors, and an oscillation signal is differentially extracted from the first amplification circuit and the second amplification circuit. The oscillator circuit according to claim 3, wherein 6. A feedback switch comprising all or a part of a variable capacitance diode, a MOS capacitance, or a plurality of capacitors and a switchable switch connected in series to the capacitors. The oscillator circuit according to any one of claims 1 to 5, which is configured by. 7. The oscillator circuit according to claim 6, wherein the switch is a MOS switch.