KR20110011512A - Voltage controlled oscillator - Google Patents

Abstract

The present technology relates to a transformer based voltage controlled oscillator suitable for multiband frequency oscillation. The present invention provides a voltage controlled oscillator, comprising: a transformer-based resonator including a primary coil and a secondary coil corresponding to the primary coil; And a complementary active element independently connected to both ends of the resonator. According to the present technology, by independently connecting the complementary active elements to both ends of the resonator, it is possible to provide a voltage controlled oscillator operating in a differential or common mode depending on the phase of the resonator. In addition, by independently connecting the complementary active elements constituting the multi-band oscillation loop to both ends of the resonator, and selecting the oscillation loop of at least one band of the multi-band oscillation loop through the switch unit, the resonant frequency of the multi-band A voltage controlled oscillator suitable for oscillation can be provided.

Description

Voltage Controlled Oscillators {VOLTAGE CONTROL OSCILLATOR}

The present invention relates to a transformer based voltage controlled oscillator, and more particularly, to a transformer based voltage controlled oscillator suitable for multiband frequency oscillation.

The present invention is derived from the research conducted as part of the IT growth engine technology development project of the Ministry of Knowledge Economy [Task management number: 2008-S-015-02, the task name: 45nm hybrid SoC analog circuit].

Voltage Control Oscillator (VCO) is an oscillator that adjusts frequency by changing the capacitance of a variable capacitor by adjusting the voltage, and is widely used in a transceiver for wired and wireless communication.

Recently, with the development of tuners, SDRs, and multi-band receivers, researches on voltage-controlled oscillators to improve phase noise performance while being wide-band have been actively conducted. ought.

Conventionally, LC-tank voltage controlled oscillators have been mainly used, which has the disadvantage that the noise performance is low and the amount of capacitors or variable capacitors in the tanks cannot increase widely at a fixed frequency. That is, the conventional LC-tank voltage generator has a problem that it is inappropriate for outputting a wideband frequency.

In order to solve the above problems, the prior art proposes a switch inductor technique and a technique using a switch capacitor array. For details regarding switch capacitor array technology and inductor technology, see Zhenbiao Li and Kenneth KO, "A Low-Phase-Noise and Low-Power Multiband CMOS Voltage-Controlled Oscillator," IEEE J. Solid-State Circuits, vol. 40. , no. 6, pp. 1296-1302, June. 2005. and Murat Demirkan, P. Brus, Richard R. Spencer, "Design of wide Tuning-Range CMOS VCOs Using Switched Coupled-Inductors," IEEE J. Solid-State Circuits, vol. 43, no. 5, pp. 1156-1163, May. 2008.], which are described in detail as follows.

Switch-controlled inductor technology connects the switch to the inductor to adjust the overall inductance through the switch, thereby increasing the resonant frequency output range of the voltage controlled oscillator. In addition, the switch capacitor array technology outputs a wide frequency frequency with a fixed capacitance that is variable with a number of binary controls with a variable capacitor.

However, since the inductor technology controlled by the switch adjusts the inductance through the switch, the switch deteriorates the characteristics of the inductor, thereby degrading the performance of the voltage controlled oscillator. In addition, the switch capacitor array technology has a problem in that the capacitor controlled by the switch has a parasitic component in the control element and the Q-factor of the resonant portion is reduced by the channel resistance of the switch transistor, thereby degrading the phase noise characteristic. There is this.

The present invention has been proposed to solve the above problems, and includes a complementary active element independently connected to both ends of the resonator, and through this, to provide a voltage controlled oscillator suitable for oscillating a multi-band resonant frequency do.

In order to achieve the above object, the present invention provides a voltage controlled oscillator comprising: a transformer-based resonator including a primary coil and a secondary coil corresponding to the primary coil; And a complementary active element independently connected to both ends of the resonator.

The present invention also provides a voltage controlled oscillator comprising: a transformer-based resonator including a primary coil and a secondary coil corresponding to the primary coil; A complementary active element connected to both ends of the resonator unit to form a multi-band oscillation loop; And a switch unit for selecting an oscillation loop of at least one band among the multi-band oscillation loops.

According to the present invention, by independently connecting the complementary active elements to both ends of the resonator, it is possible to provide a voltage controlled oscillator operating in a differential or common mode depending on the phase of the resonator.

In addition, by independently connecting the complementary active elements constituting the multi-band oscillation loop to both ends of the resonator, and selecting the oscillation loop of at least one band of the multi-band oscillation loop through the switch unit, the resonant frequency of the multi-band A voltage controlled oscillator suitable for oscillation can be provided. In particular, by independently connecting a complementary active element to one resonator unit to form a high frequency oscillation loop and a low frequency oscillation loop, it is possible to simultaneously generate a high frequency band and a low frequency band, and to reduce the chip size. Thus, it is possible to improve the wideband frequency performance of the system, reduce power consumption and reduce implementation costs.

1 is a circuit diagram showing a transformer-based resonator according to an embodiment of the present invention
2A to 2C are diagrams illustrating the configuration of a voltage controlled oscillator using a transformer-based resonator according to an embodiment of the present invention.
3A to 3C are diagrams illustrating the configuration of a complementary voltage controlled oscillator according to an embodiment of the present invention.
4A to 4C are diagrams illustrating the configuration of a voltage controlled oscillator according to an embodiment of the present invention.
5A and 5B are diagrams illustrating the configuration of a voltage controlled oscillator according to an embodiment of the present invention.
6 and 7 are diagrams showing the configuration of a multi-band voltage controlled oscillator according to an embodiment of the present invention.

Hereinafter, the most preferred embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention.

1 is a circuit diagram illustrating a transformer-based resonator according to an embodiment of the present invention.

As shown, the transformer-based resonator includes an inductor L1, a capacitor C1, and a parasitic resistor R1 of a first port, and an inductor L2, a capacitor C2, and a parasitic resistor of a second port. (R2).

Here, two inductors L1 and L2 for determining the resonance frequency of the resonator are coupled with a coupling constant k to generate mutual inductance M. If the inductor L1 and the capacitor C1 of the first port and the inductor L2 and the capacitor C2 of the second port have the same value, the resonator may be two types in two stable states. It has a phase value of mode.

Here, the oscillation frequency generated in each phase mode is determined by Equation 1 below.

는 오드 모드에서 생성되는 발진 주파수를 나타내고,

는 이븐 모드에서 생성되는 발진 주파수를 나타낸다. 이를 통해, 두 가지 위상 모드에서 상호 인덕턴스 M의 크기만큼 인덕터의 값이 변화하며, 발진 주파수 또한 두 모드에서 서로 다른 밴드에의 값을 가짐을 알 수 있다. In Equation 1

Represents the oscillation frequency generated in the odd mode,

Denotes the oscillation frequency generated in the even mode. Through this, it can be seen that the value of the inductor changes by the size of mutual inductance M in two phase modes, and the oscillation frequency also has values in different bands in both modes.

That is, the transformer-based resonator generates a resonant frequency of a relatively high frequency band in an odd mode, and generates a resonant frequency of a relatively low frequency band in an even mode. As described above, when the transformer-based resonator having two phase modes is used, two types are possible according to the shape of the feedback loop of the active element connected to the resonator.

2A to 2C are diagrams illustrating a configuration of a voltage controlled oscillator using a transformer-based resonator according to an embodiment of the present invention. However, some components are omitted or illustrated as blocks for the convenience of description.

2A shows the configuration of a voltage controlled generator using a negative resistance. As shown, the voltage controlled oscillator may be configured to include a transformer-based resonator 20 and an active element 21 to which a negative resistance is applied.

Figure 2b shows the configuration of a voltage controlled oscillator operating in odd mode to produce a relatively high frequency band resonant frequency. As shown, the voltage controlled oscillator may be configured to include a transformer based resonator 22 and an active element 23.

The voltage controlled oscillator having such a configuration adds 180 ° of the phase delay of the active element 23 and 180 ° of the odd mode phase delay of the transformer to form a positive feed-back loop.

2C shows the configuration of a voltage controller operating in an even mode to generate a resonant frequency in a relatively low frequency band. As shown, the voltage controlled oscillator may be configured to include a transformer based resonator 24 and an active element 25.

The voltage controlled oscillator having such a configuration combines 180 ° of the phase delay of the active element 25 with 180 ° through the cross connection of the transformer differential stage to form a positive feedback loop.

3A to 3C are diagrams illustrating the configuration of a complementary voltage controlled oscillator according to an embodiment of the present invention. In particular, FIGS. 3A to 3C illustrate embodiments of the negative resistance generator and the LC resonator. However, some components are omitted or illustrated as blocks for convenience of description.

3A shows the configuration of a complementary voltage controlled oscillator having an N-PMOS cross-connected structure.

As shown, the complementary voltage controlled oscillator includes a resonator 30 and complementary transistors M _P and M _N , and a positive feedback loop combining the NMOS transistor M _N and the PMOS transistor M _P. It may be configured in the form of connecting one inductor (L1). The complementary voltage controlled oscillator having such a configuration oscillates at a relatively low frequency.

3b shows the configuration of a complementary voltage controlled oscillator having a gate inversely-coupled structure.

As shown, the complementary voltage controlled oscillator includes a resonator 32 and complementary transistors M _P and M _N. Here, a positive feedback loop is formed by connecting a drain and a gate of the NMOS transistor M _N and the PMOS transistor M _{P to} the first and second ports of the resonator 32, in particular, the NMOS transistor M _N. ) and is applied by inverting the phase applied to the gate of the PMOS transistor _(P M). The complementary voltage controlled oscillator having such a configuration oscillates in a relatively low frequency band.

FIG. 3C shows the configuration of a complementary voltage controlled oscillator having a gate-coupled structure.

As shown, the complementary voltage controlled oscillator includes a resonator 34 and complementary transistors M _P and M _N. Here, a positive feedback loop is formed by connecting the drain and the gate of the NMOS transistor M _N and the PMOS transistor M _{P to} the first and second ports of the resonator 34, in particular, the NMOS transistor M _N. ) and it is applied without inversion to the phase to be applied to the gate of the PMOS transistor _(P M). The complementary voltage controlled oscillator having such a configuration oscillates at a relatively high frequency.

4A to 4C are diagrams illustrating the configuration of a voltage controlled oscillator according to an embodiment of the present invention. In particular, FIGS. 4A to 4C show an embodiment in which active elements are independently connected to both ends of a transformer-based resonator. However, for convenience of description, some configurations are omitted.

As shown, the voltage controlled oscillator according to an embodiment of the present invention includes a transformer-based resonator 40 including a primary coil L1 and a secondary coil L2 corresponding to the primary coil L1. 42 and 44 and complementary active elements M _P and M _N independently connected to both ends of the resonators 40, 42 and 44. In addition, the current source 45 for supplying current to the complementary active elements (M _P , M _N ), the variable capacitor 46 for varying the frequency output of the voltage controlled oscillator and the noise in the operation of the voltage controlled oscillator and filter the noise It is preferable to further include a capacitor (C _by ) for increasing the gain of the active elements (M _P , M _N ).

In particular, in the present embodiment, the complementary active elements M _P and M _N are independently connected to both ends of the resonator parts 40, 42, 44, but have the same structure at the primary end (①) and the secondary end (②). A case of connecting the complementary active elements M _P and M _N will be described.

4A illustrates a voltage controlled oscillator connecting complementary active devices M _P and M _N in an N-PMOS cross connection structure across both transformer-based resonators 40.

FIG. 4B illustrates a voltage controlled oscillator connecting complementary active elements M _P and M _N in a gate reversed phase coupling structure across the transformer-based resonator 42.

Here, the complementary active elements M _P and M _N may be composed of an NMOS transistor M _N and a PMOS transistor. A primary coil L1 is connected to a drain of the transistors M _P and M _N. The secondary coil L2 is connected to the gates of the transistors M _P and M _N in reverse phase. That is, the resonator 42 has an even mode at both ends, that is, the voltage phases of the first and second ends ① and ② are the same.

FIG. 4C illustrates a voltage controlled oscillator connecting complementary active elements M _P and M _N in a gate coupling structure to both ends of the transformer-based resonator 44.

Here, the complementary active elements M _P and M _N may be composed of an NMOS transistor M _N and a PMOS transistor. A primary coil L1 is connected to a drain of the transistors M _P and M _N. The secondary coil L2 is connected to the gates of the transistors M _P and M _N in the same phase. That is, the resonator 42 has an odd mode in which the voltage phases of both ends, that is, the first and second ends ① and ② are reversed.

5A and 5B are diagrams illustrating the configuration of a voltage controlled oscillator according to an embodiment of the present invention. In particular, FIGS. 5A and 5B show an embodiment in which active elements are independently connected to both ends of a transformer-based resonator. However, for convenience of description, some configurations are omitted.

As shown, the voltage controlled oscillator according to an embodiment of the present invention includes a transformer-based resonator 50 including a primary coil L1 and a secondary coil L2 corresponding to the primary coil L1. 52 and complementary active elements M _P and M _N independently connected to both ends of the resonators 50 and 52. In addition, the current source 55 for supplying current to the complementary active elements (M _P , M _N ), the variable capacitor 56 for varying the frequency output of the voltage controlled oscillator and the noise in the operation of the voltage controlled oscillator and filter the noise It is preferable to further include a capacitor (C _by ) for increasing the gain of the active elements (M _P , M _N ).

Particularly, in the present embodiment, the complementary active elements M _P and M _N are independently connected to both ends of the resonator parts 50 and 52, but the complementary types are different from the primary end and the secondary end. A case in which the active elements M _P and M _N are connected will be described.

FIG. 5A shows a transistor (M _P , M _N ), which is a complementary active element, connected to the first end (①) of the transformer-based resonator unit 50 in a gate reversed phase coupling structure, and an N-PMOS at the second end ②. A cross connect structure shows a structure in which transistors M _P and M _N , which are complementary active elements, are connected. Of course, it is also possible to change the structure of the primary stage (①) and the secondary stage (②).

According to such a structure, when the voltage controlled oscillator operates, the voltage of the first stage (①) and the second stage (②) of the transformer-based resonator 50 is operated in the even mode.

Figure 5b N-PMOS cross to one block (①) connected to the transistor (M _P, M _N) the complementary active elements with gate coupling structure, and the second stage (②) to the transformer based on the resonator portion 52 of the A structure in which transistors M _P and M _N , which are complementary active elements, is connected as a connection structure. Of course, it is also possible to change the structure of the primary stage (①) and the secondary stage (②).

According to such a structure, when the voltage controlled oscillator operates, the voltage of the first stage (①) and the second stage (②) of the transformer-based resonator 50 is operated in an odd mode.

According to an embodiment of the present invention as described above, by independently connecting the complementary active element to both ends of the transformer-based resonator, the voltage controlled oscillator can operate in a differential mode or a common mode depending on the phase of the resonator.

6 and 7 are diagrams illustrating the configuration of a multi-band voltage controlled oscillator according to an embodiment of the present invention. In particular, FIGS.

Multi-band voltage controlled oscillator according to an embodiment of the present invention transformer-based resonator (60, 70) including a primary coil (L1) and a secondary coil (L2) corresponding to the primary coil (L1), Selecting the oscillation loop of at least one band of the complementary active elements (M ₁ to M ₈ ) and the multi-band oscillation loop independently connected to both ends of the resonator (60, 70) to form a multi-band oscillation loop Switch sections 67 and 77; In addition, noise in the operation of the current source (65,75) for supplying current to the complementary active elements (M ₁ ~ M ₈ ), the variable capacitor (66, 76) for varying the frequency output of the voltage controlled oscillator and the voltage controlled oscillator It is preferable to further include a capacitor C _{by for} filtering and increasing the gain of the active elements M ₁ to M ₈ .

According to such a structure, the complementary active elements M ₁ to M ₈ are independently connected to both ends of the resonators 60 and 70, and the complementary active elements M ₁ to M ₈ are multi-band oscillation loops. Is connected to configure. Accordingly, the oscillation loop of the desired band can be selected from the oscillation loops of the multi band through the switch units 67 and 77, thereby realizing a wideband frequency output. In addition, since a wideband voltage controlled oscillator is implemented using one resonator 60, power consumption may be reduced and implementation costs may be reduced.

6 illustrates an example of a multi-band voltage controlled oscillator according to an embodiment of the present invention, in which complementary active devices M ₁ to M _{8 form a} high frequency oscillation loop and a low frequency oscillation loop.

As shown, an oscillator and a transformer-based resonator connecting transistors M ₅ , M ₆ , M ₇ , and M ₈ , which are complementary active elements, with an N-PMOS cross-connect structure at both ends of the transformer-based resonator 60, respectively. A dual band voltage controlled oscillator may be configured by combining an oscillator coupled to transistors M ₁ , M ₂ , M ₃ , and M ₄ , which are complementary active elements, in a gate coupling structure at both ends of the unit 60.

Here, the transistors M ₅ , M ₆ , M ₇ , and M ₈ , which are complementary active elements connected by an N-PMOS cross-connect structure, operate in an even mode by forming a low frequency oscillation loop, and are complementary types connected by a gate coupling structure. The active elements transistors M ₁ , M ₂ , M ₃ and M _{4 form} a high frequency oscillation loop and operate in odd mode. Thus, the voltage controlled oscillator is operable in the eve mode and the odd mode, and thus has a dual frequency band.

Here, the two oscillation modes can be selected by selecting the high frequency oscillation mode or the low frequency oscillation loop using the switch unit 67. For example, the high frequency oscillation loop may be selected by activating the switch M _H , or the low frequency oscillation loop may be selected by activating the switch M _L.

7 illustrates an example of a multi-band voltage controlled oscillator according to an embodiment of the present invention, in which complementary active devices M ₁ to M _{8 form a} high frequency oscillation loop and a low frequency oscillation loop.

As shown, the transistors M ₅ , M ₆ , M ₇ , and M ₈ , which are complementary active elements, are connected to the first end of the transformer-based resonator 70 with a gate reversed phase coupling structure, and the N− at the second end. Complementary active device with gate coupling structure at the first stage of the oscillator and transformer-based resonator 70 connecting transistors M ₅ , M ₆ , M ₇ , and M ₈ , which are complementary active devices, with a PMOS cross-connect structure a transistor _{(M 1, M 2, M} 3, M 4) connected to and connecting the N-PMOS intersection complementary active elements in connection structure transistors _{(M 1, M 2, M} 3, M 4) in the second-stage Oscillators can be combined to form dual band voltage controlled oscillators.

Here, the complementary active elements (M ₅ , M ₆ , M ₇ , M ₈ ) connected to the first end of the resonator unit 70 by the gate reversed-phase coupling structure and connected to the second end by the N-PMOS cross-connect structure have low frequency oscillation. The loop is configured to operate in even mode. In addition, the complementary active elements M ₁ , M ₂ , M ₃ , and M ₄ connected to the first end of the resonator unit 70 by the gate coupling structure and the second end by the N-PMOS cross connection structure have high parking oscillation. The loop is configured to operate in odd mode. Thus, the voltage controlled oscillator can operate in an even mode and an odd mode, and thus have a dual frequency band.

Here, the two oscillation modes can be selected by selecting the high frequency oscillation mode or the low frequency oscillation loop using the switch unit 77. For example, the high frequency oscillation loop may be selected by activating the switch M _H , or the low frequency oscillation loop may be selected by activating the switch M _L.

In the present specification, the dual band voltage controlled oscillator has been described as an example of the multi band voltage controlled oscillator, but the present invention is not limited thereto. In addition, a multi-band voltage controlled oscillator may be implemented by combining complementary active elements independently of both ends of the resonator by combining oscillators having various structures shown in FIGS. 4A to 5B.

Although the technical spirit of the present invention has been described in detail according to the above-described preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will recognize that various embodiments are possible within the scope of the technical idea of the present invention.

20, 22, 24: resonator 21, 23, 25: active element
30, 32, 34: resonator 40, 42, 44: resonator
50, 52: resonator 60, 70: resonator
65,75 Current source 66,76 Variable capacitor
67,77: switch section

Claims (17)

A transformer-based resonator including a primary coil and a secondary coil corresponding to the primary coil; And
Complementary active device independently connected to both ends of the resonator unit
Voltage controlled oscillator comprising
The method of claim 1,
The voltage controlled oscillator,
Operating in a differential mode or a common mode according to a feedback loop type of the complementary active element connected to both ends of the idler.
Voltage controlled oscillator.
The method of claim 1,
The voltage controlled oscillator,
The complementary active device operates in an even mode or an odd mode according to the voltage phases of the first and second ends of the resonator connected to each other.
Voltage controlled oscillator.
The method of claim 1,
The complementary active element,
N-PMOS cross connection structures are respectively connected to both ends of the resonator unit.
Voltage controlled oscillator
The method of claim 1,
The complementary active element,
Connected to both ends of the resonator in a gate inverse coupling structure, respectively.
Voltage controlled oscillator.
The method of claim 1,
The complementary active element,
Connected to both ends of the resonator in a gate coupling structure.
Voltage controlled oscillator.
The method of claim 1,
The complementary active element,
N-PMOS cross connection structure is connected to the first end of the resonator unit, and a gate inverse coupling structure is connected to the second end of the resonator unit.
Voltage controlled oscillator.
The method of claim 1,
The complementary active element,
N-PMOS cross connection structure is connected to the first end of the resonator unit, and a gate coupling structure is connected to the second end of the resonator unit.
Voltage controlled oscillator.
The method of claim 1,
Current source for supplying current to the complementary active element
Voltage controlled oscillator further comprising.
The method of claim 1,
A variable capacitor varying the frequency output of the voltage controlled oscillator
Voltage controlled oscillator further comprising.
A transformer-based resonator including a primary coil and a secondary coil corresponding to the primary coil; And
A complementary active element connected to both ends of the resonator unit to form a multi-band oscillation loop; And
A switch unit for selecting an oscillation loop of at least one band among the multi-band oscillation loops;
Voltage controlled oscillator comprising a.
The method of claim 11,
The complementary active element is independently connected to both ends of the resonator to form a high frequency oscillation loop and a low frequency oscillation loop,
The voltage controlled oscillator oscillates a resonant frequency of a dual band
Voltage controlled oscillator.
The method of claim 12,
The high frequency oscillation loop,
Complementary active elements are connected to both ends of the resonator in a gate coupling structure.
Voltage controlled oscillator.
The method of claim 12,
The high frequency oscillation loop,
The complementary active element is connected to the first end of the resonator with an N-PMOS cross connection structure, and the complementary active element is connected to the second end of the resonator with a gate coupling structure.
Voltage controlled oscillator.
The method of claim 12,
The low frequency oscillation loop,
Complementary active elements are connected to both ends of the resonator in an N-PMOS cross-connect structure.
Voltage controlled oscillator.
The method of claim 12,
The low frequency oscillation loop,
Complementary active elements are connected to both ends of the resonator in a gate inverse coupling structure.
Voltage controlled oscillator.
The method of claim 12,
The low frequency oscillation loop,
The complementary active element is connected to the first end of the resonator with an N-PMOS cross connection structure, and the complementary active element is connected to the second end of the resonator with a gate reverse phase coupling structure.
Voltage controlled oscillator.

Images