KR100422505B1 - LC tank Voltage Controlled Push-Push Oscillator with Differential Configuration - Google Patents

Abstract

The present invention relates to an LC resonant voltage controlled push-push oscillator using a differential form, which does not directly generate an oscillation signal having a frequency of fo, but generates a differential type LC resonance that generates a signal having a frequency of fo / 2 and a phase difference of 180 °. The two output signals of the voltage controlled oscillator have the advantage of generating a frequency of fo having low phase noise in a push-push manner.

Description

LC tank Voltage Controlled Push-Push Oscillator with Differential Configuration}

The present invention relates to an LC resonant voltage controlled push-push oscillator using a differential type, and more particularly, two output signals of a differential type LC resonant voltage controlled oscillator generating a signal having a frequency of fo / 2 and a phase difference of 180 °. The present invention relates to an LC resonant voltage controlled push-push oscillator using a differential form that generates a frequency of fo having low phase noise in a push-push manner.

Recently, due to the explosive growth of the mobile communication market, many companies are forming their markets by releasing various mobile communication terminals using different frequency bands or having different functions.

However, the future prospects, both at home and abroad, are expected to not only operate in various frequency bands, but also to form a mobile communication terminal market in which various functions are integrated.

In addition, miniaturization must be accompanied for this purpose, and mobile communication terminals are also miniaturizing components used in many parts for miniaturization, and in the case of RF (Radio Frequency) systems, miniaturization is being performed at various parts.

Part of the present invention also deals with an RF system, and more particularly, a voltage controlled oscillator.

Currently, voltage controlled oscillators for mobile communication use voltage controlled oscillators using LC resonators. Inductors use off-chip devices. Integrating the inductor into on-chip can facilitate the miniaturization of mobile communication terminals. However, integrating the inductor results in a very low inductance (Q) of the inductor, which degrades the phase noise performance of the voltage controlled oscillator.

Therefore, there are two major research trends to overcome this problem.

The first is to improve the performance of the device itself, and the second is to solve the circuit.

That is, in the case of the former, a method of increasing the resonance degree (Q) of the inductor has been actively studied. For example, several Micro Electro-Mechanical System (MEMS) inductors have been developed.

In the latter case, accurate modeling of the phase noise ensures good phase noise performance even with low inductance (Q) of the inductor. In addition, the unique oscillation method has a low resonance degree (Q) and has a good phase noise performance. Such a method is a push-push method.

Push-push is a method of generating an oscillation signal having a frequency of fo by using two output signals of an oscillator generating a signal having a frequency of fo / 2 and a phase difference of 180 °.

This results in lower phase noise performance than directly generating an oscillating signal with a frequency of fo.

The present invention has been made to solve the above problems, and an object of the present invention is to use two output signals of a LC resonant voltage controlled oscillator of differential type to generate a signal having a frequency of fo / 2 and a phase difference of 180 °. The present invention provides an LC resonant voltage controlled push-push oscillator using a differential form that generates a frequency of fo having low phase noise in a push-push manner.

1 is a circuit diagram using a MOSFET as an embodiment of an LC resonant voltage controlled push-push oscillator using a differential form according to the present invention.

Figure 2 is a circuit diagram using a MESFET as another embodiment of the LC resonant voltage controlled push-push oscillator using the differential form according to the present invention.

-Explanation of symbols for the main parts of the drawings-

10: differential amplifier 20: LC resonator

30: output buffer unit 40: current supply unit

Q1 to Q7: First to Seventh MOSFETs

Q11 to Q17: 1st to 7th MESFET

L1: first inductor L2: second inductor

L11: 11th inductor L12: 12th inductor

C1: first capacitor C2: second capacitor

C11 to C16: 11th to 16th capacitors

VC1: first variable capacitor VC2: second variable capacitor

VC11: 11th variable capacitor VC12: 12th variable capacitor

R11 to R14: 11th to 14th resistors

N1 to N4: first to fourth nodes

N11 to N14: 11th to 14th nodes

The present invention for realizing the above object is a differential amplifier for implementing a voice resistance, an LC resonator formed by connecting an inductor and a capacitor symmetrically to the differential output terminal of each of the differential amplifier, and the differential output terminal of each differential amplifier And an output buffer for receiving the output value and outputting the harmonic component to the common output stage, and a current supply for variably controlling the current supplied to the differential amplifier and the output buffer according to the control voltage. do.

The symmetrical elements constituting the differential amplifier, the LC resonator, the output buffer, and the current supply source may be symmetrical by the same device.

The present invention made as described above by the push-push method using two output signals having a phase difference of 180 ° and a half frequency of the output frequency generated from the LC resonant voltage controlled oscillator of the differential type by the LC resonator and the differential amplifier. By outputting the second harmonic component from the output buffer part installed in the differential output stage of the differential amplifier to the common output stage, the desired output frequency is obtained by cancellation and superposition, and low phase noise due to the increase of the output signal and the cancellation of external noise. To get the output frequency.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In addition, this embodiment is not intended to limit the scope of the present invention, but is presented by way of example only.

1 is a circuit diagram using a metal-oxide semiconductor field effect transistor (MOSFET) as an embodiment of an LC resonant voltage controlled push-push oscillator using a differential form according to the present invention.

As shown here, the drain of the first MOSFET Q1 is fed back to the gate of the second MOSFET Q2 and the drain of the 2 MOSFE Q2T is fed to the gate of the first MOSFET Q1 to implement the negative resistance. There is provided a differential amplifier 10 configured to be fed back.

In addition, an LC resonator 20 formed by connecting an inductor and a capacitor symmetrically to each of the differential output terminals of the differential amplifier 10 has a medium between the output terminal and the power supply terminal of the first MOSFET Q1 of the differential amplifier 10. The first inductor L1, the second inductor L2 interposed between the output terminal of the second MOSFET Q2 and the power supply terminal Vdd of the differential amplifier 10, and the output terminal of the first MOSFET Q1. The first to second variable capacitors VC1 and VC2 are formed to be symmetrical on both sides of the capacitance control terminal CTRL_C between the output terminals of the second MOSFET Q2.

In addition, an output buffer unit 30 connected symmetrically to each differential output terminal of the differential amplifier 10 and receiving an output value to output a second harmonic component to the common output terminal OUT, has a first MOSFET Q1. The output terminal and the gate are connected, the power supply terminal (Vdd) and the drain are connected, the source is connected between the third MOSFET (Q3) connected to the current supply unit 40, the source and the common output terminal (OUT) of the third MOSFET (Q3) The fourth capacitor Q1 connected to the first capacitor C1, the output terminal of the second MOSFET Q2 and the gate, the power terminal Vdd and the drain, and the source connected to the current supply unit 40; 4 is composed of a second capacitor C2 mediated between the source of the MOSFET Q4 and the common output terminal OUT.

At this time, the operating points of the third to fourth MOSFETs Q3 and Q4 are set to nonlinear regions.

On the other hand, the current supply unit 40 for supplying the current supplied to the differential amplifier 10 and the output buffer unit 30 is controlled in accordance with the control voltage, the gate is connected to the current control terminal (CTRL_I) source Is connected to the ground terminal and the drain is connected to the fifth MOSFET Q5 and the source of the third MOSFET Q3, the gate is connected to the current control terminal CTRL_I, the source is connected to the ground terminal, and the drain is connected to the differential amplifier 10. A sixth MOSFET Q6 connected to the sources of the first to second MOSFETs Q1 and Q2, a gate is connected to the current control terminal CTRL_I, a source is connected to the ground terminal, and a drain is connected to the source of the fourth MOSFET Q4. And a seventh MOSFET Q7 connected thereto.

The first MOSFET Q1, the second MOSFET Q2, the third MOSFET Q3, the fourth MOSFET Q4, the first variable capacitor VC1, the second variable capacitor VR2, The first inductor L1, the second inductor L2, the first capacitor C1, and the second capacitor C2 are composed of the same element.

Meanwhile, one node of each of the first to seventh MOSFETs Q1 to Q7 and one node of each of the first and second capacitors C1 and C2 serving as the common output terminal OUT are connected as closely as possible on the layout. It is desirable to be.

In addition, the arrangement of all the elements constituting the LC resonance voltage controlled push-push oscillator using the differential form according to the present invention is preferably arranged symmetrically.

Referring to the operation of one embodiment according to the present invention made as described above are as follows.

The voltage is applied to the current control terminal CTRL_I of the current supply unit 40 to control the operation of the fifth to seventh MOSFETs Q5 to Q7 to control the operating current to the differential amplifier 10 and the output buffer unit 30. Is authorized.

In the differential amplifier 10, the first to second MOSFETs Q1 and Q2 are fed back to each other to implement a negative type of negative resistance.

Therefore, when a voltage is applied to the capacitor redundancy control stage CTRL_C to adjust the frequency oscillated by the LC resonator 20, the first to second variable capacitors VC1 and VC2 may be changed while changing the capacitance. The first and second nodes N1 and N2, which are output terminals of the differential amplifier 10, which are LC-resonated by the inductors L1 and L2 to implement the differential type negative resistance, respectively, have a frequency of fo / 2 at 180 °. Generate a signal with a phase difference.

The two signals generated in this way pass through the third MOSFET Q3 and the fourth MOSFET Q4 operating in the nonlinear region located in the output buffer unit 30, respectively, and are the second at the third to fourth nodes N3 and N4. The signal component having the frequency of fo, which is a harmonic component, is made large.

This signal is passed through the first to second capacitors C1 and C2 and summed to the common output terminal OUT. The odd mode signal is canceled and the even mode signal is superimposed so that the signal component having a frequency of fo / 2 is canceled. Signal components having a frequency of fo are superimposed and external noise is canceled out.

Therefore, the oscillation signal having low phase noise can be obtained at the common output terminal OUT.

FIG. 2 is a circuit diagram using a MESFET (Metal SEmiconductor Field Effect Transistor) as another embodiment of an LC resonance voltage controlled push-push oscillator using a differential form according to the present invention.

As shown here, the drain of the first MESFET Q11 is fed back to the gate of the second MESFET Q12 via the eleventh capacitor C11 and the drain of the second MESFET Q12 is formed to implement the negative resistance. It is fed back to the gate of the first MESFET Q11 via the 12 capacitor C12, and the first bias voltage terminal V1bias is formed between the gate of the first MESFET Q11 and the gate of the second MESFET Q12. The differential amplifier 10 is configured by an eleventh resistor R11 and a twelfth resistor R12 formed to be symmetrical to both sides.

In addition, an LC resonator 20 formed by connecting an inductor and a capacitor symmetrically to each of the differential output terminals of the differential amplifier 10 includes an output terminal and a power supply terminal Vdd of the first MESFET Q11 of the differential amplifier 10. The twelfth inductor L12 interposed between the twelfth inductor L12 and the output terminal of the second MESFET Q12 and the power supply terminal Vdd of the differential amplifier 10, and the first MESFET Q11. And an eleventh through twelfth variable capacitors VR11 and VR12 formed to be symmetrical on both sides with respect to the capacitance control stage CTRL_C between the output terminal of the output terminal and the output terminal of the second MESFET Q12.

In addition, the output buffer unit 30 is connected symmetrically to each of the differential output terminals of the differential amplifier 10 to receive the output value and output the second harmonic component to the common output terminal OUT. A source of the third MESFET Q13 and a source connected to the gate through the output terminal and the thirteenth capacitor C13, the power supply terminal Vdd and the drain, and the source connected to the current supply unit 40, and the source of the third MESFET Q13. Is connected to the gate through the fifteenth capacitor V15 and the output terminal of the second MESFET Q12 and the fourteenth capacitor C14 interposed between the common output terminal OUT and the common output terminal OUT, and the power supply terminal Vdd and the drain are connected. The source of the fourth MESFET Q14 connected to the current supply unit 40, the sixteenth capacitor C16 interposed between the source of the fourth MESFET Q14 and the common output terminal OUT, and the thirteenth capacitor C13. A thirteenth connected between one side and a gate of the third MESFET Q13 and mediated with the second bias voltage terminal V2bias; The resistor R13 is connected between one end of the fourteenth capacitor C14 and the gate of the fourth MESFET Q14 to constitute the fourteenth resistor R14 mediated with the third bias voltage terminal V3bias.

At this time, the operating points of the third to fourth MESFETs Q13 and Q14 are set to nonlinear regions.

On the other hand, the current supply unit 40 for supplying the current supplied to the differential amplifier 10 and the output buffer unit 30 is controlled in accordance with the control voltage, the gate is connected to the current control terminal (CTRL_I) source Is connected to the ground terminal, the drain is connected to the source of the third MESFET Q13, the fifth MESFET Q15, the current control terminal CTRL_I is connected to the gate, the source is connected to the ground terminal, and the drain of the differential amplifier 10 A sixth MESFET Q16 connected to the sources of the first to second MESFETs Q11 and Q12, a gate connected to the current control terminal CTRL_I, a source connected to the ground terminal, and a drain connected to the source of the fourth MESFET Q14. And a seventh MESFET Q17 connected thereto.

The first MESFET Q11 and the second MESFET Q12, the third MESFET Q13 and the fourth MESFET Q14, the eleventh variable capacitor VC11 and the twelfth variable capacitor VC12, and the symmetrical symmetric above, 11 Inductor L11 and second inductor L12, 11th capacitor C11 and 12th capacitor L12, 13th capacitor C13 and 14th capacitor C14, 15th capacitor C15 and 16th The capacitor C16 is composed of the same elements.

On the other hand, one node of each of the first to seventh MESFETs Q11 to Q17 and one node of each of the fifteenth capacitor C15 and the sixteenth capacitor C16 that are common output terminals OUT are connected as closely as possible on the layout. It is desirable to be.

In addition, the arrangement of all the elements constituting the LC resonance voltage controlled push-push oscillator using the differential form according to the present invention is preferably arranged symmetrically.

Referring to the operation of another embodiment according to the present invention made as described above are as follows.

The voltage is applied to the current control terminal CTRL_I of the current supply unit 40 to control the operation of the fifth to seventh MESFETs Q15 to Q17 to control the operating current to the differential amplifier 10 and the output buffer unit 30. Is authorized.

The first to second MESFETs Q11 and Q12 are positively fed through the eleventh to twelfth capacitors C11 and C12 in order to generate a negative resistance in the differential amplifier 10, and the eleventh to twelfth resistors. R11 and R12 are provided on both sides of the first bias voltage terminal V1bias so as to be symmetrical, and an operating point is obtained by applying a voltage to the first bias voltage terminal V1bias.

Therefore, when a voltage is applied to the capacitor redundancy control stage CTRL_C in order to adjust the frequency oscillated by the LC resonator 20, the eleventh through twelfth while changing the capacitances of the eleventh through twelfth variable capacitors VC11 and VC12. The first and second nodes N11 and N12, which are output stages of the differential amplifier 10, which are LC-resonated by the inductors L11 and L12 to implement the differential type voice resistance, have a frequency of fo / 2 at 180 °. Generate a signal with a phase difference.

The two signals generated in this way are input to the gates of the third MESFET Q13 and the fourth MESFET Q14 through the thirteenth through fourteenth capacitors C13 and C14, respectively, and the thirteenth through fourteenth resistors, which are bias resistors, are input to the gate. The third MESFET Q13 and the fourth MESFET Q14 operate in the nonlinear region by applying a voltage to the second to third bias voltage terminals V2bias and V3bias via the R13 and R14 to operate the third MESFET. While passing through Q13) and the fourth MESFET Q14, signal components having a frequency of fo, which is the second harmonic component, are made larger at the thirteenth through fourteenth nodes N13 and N14.

This signal is passed through the fifteenth to sixteenth capacitors Q15 and Q16 and summed to the common output terminal OUT. The odd mode signal is canceled and the even mode signal is superimposed so that the signal component having a frequency of fo / 2 is canceled. Signal components having a frequency of fo are superimposed and external noise is canceled out.

Therefore, the oscillation signal having low phase noise can be obtained at the common output terminal OUT.

As described above, the present invention utilizes two output signals of the LC resonant voltage controlled oscillator of differential type to generate a signal having a frequency of fo / 2 and a phase difference of 180 °. Branches have the advantage of generating a frequency of fo.

In addition, there is an advantage that the phase noise is lowered by maximizing the separation of the resonance portion and the portion where the push-push is implemented.

Also, even when oscillating only the frequency of fo / 2 in the LC resonator, the frequency of fo can be generated by the push-push method, thereby generating a frequency having a good phase noise performance even with a low resonance of the inductor. There is an advantage that can be miniaturized.

Claims (10)

A differential amplifier for implementing voice resistance, An LC resonator formed by connecting an inductor and a capacitor symmetrically to each of the differential output terminals of the differential amplifiers; An output buffer unit symmetrically connected to each differential output terminal of the differential amplifier and receiving an output value to output a harmonic component to a common output terminal; Current supply unit for controlling and supplying the current supplied to the differential amplifier and the output buffer unit in accordance with a control voltage LC resonant voltage controlled push-push oscillator using a differential form, characterized in that consisting of. The LC resonance voltage control using the differential type according to claim 1, wherein the symmetrical elements constituting the differential amplifier, the LC resonator, the output buffer unit, and the current supply source are symmetrical with each other. Push-push oscillator. A differential amplifier configured to drain the first MOSFET to the gate of the second MOSFET and the drain of the 2 MOSFET to the gate of the first MOSFET to implement the negative resistance; A first inductor interposed between an output terminal and a power supply terminal of the first MOSFET of the differential amplifier, a second inductor interposed between an output terminal and a power supply terminal of the second MOSFET of the differential amplifier, an output terminal of the first MOSFET and the An LC resonator including first to second variable capacitors formed on both sides of a capacitance control stage between output terminals of the second MOSFET; A third MOSFET having an output terminal and a gate connected to the first MOSFET, a power terminal and a drain connected, and a source connected to a current supply unit, a first capacitor interposed between the source and the common output terminal of the third MOSFET, and the second MOSFET An output buffer unit comprising a fourth MOSFET having an output terminal and a gate of which is connected, a power terminal and a drain connected, and a source connected to a current supply unit, and a second capacitor interposed between the source and the common output terminal of the fourth MOSFET; A current supply unit for supplying the current supplied to the differential amplifier and the output buffer by varying control according to a control voltage, A fifth MOSFET having a gate connected to a current control terminal, a source connected to a ground terminal, a drain connected to a source of the third MOSFET, a gate connected to the current control terminal, a source connected to the ground terminal, and a drain connected to the differential amplifier A current supply unit including a sixth MOSFET connected to the sources of the first to second MOSFETs, a seventh MOSFET connected to a gate of the current control terminal, a source connected to the ground terminal, and a drain connected to a source of the fourth MOSFET; LC resonant voltage controlled push-push oscillator using a differential form, characterized in that consisting of. 4. The LC resonant voltage controlled push-push oscillator according to claim 3, wherein the operating point of the third to fourth MOSFETs is set to a nonlinear region. 4. The LC according to claim 3, wherein one node of each of the first and second capacitors, which is a common output terminal with one node of each of the first to seventh MOSFETs, is connected as closely as possible on the layout. Resonant voltage controlled push-push oscillator. 4. The method of claim 3, wherein the first and second MOSFETs, the third and fourth MOSFETs, the first variable capacitor and the second variable capacitor, the first inductor and the second inductor, the first capacitor and the second capacitor are each other. LC resonant voltage controlled push-push oscillator using differential form, characterized by the same element. The drain of the first MESFET is fed back to the gate of the second MESFET via the eleventh capacitor to implement the negative resistance, the drain of the 2 MESFET is fed back to the gate of the first MESFET via the twelfth capacitor, A differential amplifier comprising an eleventh resistor and a twelfth resistor formed between the gate of the first MESFET and the gate of the second MESFET so as to be symmetrical on both sides of the first bias voltage terminal; An eleventh inductor interposed between an output terminal and a power supply terminal of the first MESFET of the differential amplifier, a twelfth inductor interposed between an output terminal and a power supply terminal of the second MESFET of the differential amplifier, an output terminal of the first MESFET and the An LC resonator configured of eleventh to twelfth variable capacitors formed symmetrically on both sides of the capacitance control stage between the output terminals of the second MESFET; A third MESFET connected to a gate through an output terminal and a thirteenth capacitor of the first MESFET, a power terminal and a drain connected to each other, and a source connected to a current supply unit; and a fifteenth capacitor interposed between the source and the common output terminal of the third MESFET. And a fourth MESFET connected to the gate through the output terminal of the second MESFET and the fourteen capacitor, the power supply terminal and the drain connected, and the source connected to the current supply unit, and the sixteenth mediated between the source and the common output terminal of the fourth MESFET. A thirteenth resistor connected between a capacitor, one side of a thirteenth capacitor, and a gate of the third MESFET and interposed with a second bias voltage terminal; and a third resistor connected between one end of the fourteenth capacitor and a gate of the fourth MESFET; An output buffer unit configured of a bias voltage terminal and an intermediated fourteenth resistor; A fifth MESFET having a gate connected to the current control terminal, a source connected to the ground terminal, a drain connected to the source of the third MESFET, a gate connected to the current control terminal, a source connected to the ground terminal, and a drain connected to the A sixth MESFET connected to sources of first to second MESFETs, and a seventh MESFET having a gate connected to the current control terminal, a source connected to a ground terminal, and a drain connected to a source of the fourth MESFET; LC resonant voltage controlled push-push oscillator using a differential form, characterized in that consisting of. 8. The LC resonant voltage controlled push-push oscillator according to claim 7, wherein the operating point of the third to fourth MESFETs is set to a nonlinear region. The method of claim 7, wherein the first MESFET and the second MESFET, the third MESFET and the fourth MESFET, the eleventh variable capacitor and the twelfth variable capacitor, the eleventh inductor and the twelfth inductor, the eleventh capacitor and the twelfth capacitor, 13. An LC resonant voltage controlled push-push oscillator using a differential form, wherein the thirteenth capacitor, the fourteenth capacitor, the fifteenth capacitor, and the sixteenth capacitor are composed of the same elements. 8. The differential form of claim 7, wherein one node of each of the fifteenth capacitor and the sixteenth capacitor, which is a common output terminal of one node of each of the first to seventh MESFETs, is connected as closely as possible on the layout. LC resonant voltage controlled push-push oscillator.