A multi-core switch-switched octave tuning oscillator and tuning method

Abstract

The present invention discloses an octave tuning oscillator and a tuning method for multi-core switch switching, which includes N multi-core switch switching octave tuning oscillator components, each of which includes an oscillator VCO1 and an oscillator VCO5 with the same structure. The present invention adopts capacitive coupling and switch switching technology, and divides the oscillation mode into an odd mode or an even mode by enabling the switch, so that the two oscillators oscillate in phase or in anti-phase, and the oscillation frequency is extended to two frequency bands. The voltages at both ends of the switch are the same, and no current flows through the switch, so the loss of the switch will not affect the Q value of the resonant cavity, that is, it will not deteriorate the phase noise, and octave tuning is achieved. By adopting a multi-core cross-connection parallel mode, multi-core oscillation is achieved without affecting the switch switching, the parallel resonance resistance of the resonant cavity is reduced, and the phase noise is improved.

Description

Technical Field

[0001] The invention relates to the field of tuning oscillation, and in particular to an octave tuning oscillator switched by a multi-core switch and a tuning method. Background Art

[0002] The emergence of cellular technology, multi-mode wireless communication technology, and multi-standard communication equipment has led to the current pursuit of software-defined wireless transceivers. Software-defined wireless transceivers need to cover an extremely wide frequency range to provide all local oscillator signal frequencies for signal up-conversion and down-conversion in software-defined wireless transceivers, and need to meet stringent phase noise requirements to ensure communication quality. This requirement is difficult to achieve for traditional voltage-controlled oscillators using varactors and switched capacitor arrays.

[0003] A popular and practical method is to use multiple separate voltage-controlled oscillators operating at different frequencies, and use a multiplexer to select the frequency output to cover the octave tuning range, such as Figure 2 Another method is the switched inductor and switched capacitor technology, which adds MOS tube switches to the inductor and capacitor in the resonant cavity, and switches to the corresponding size of inductor in different frequency bands to achieve coverage of the octave tuning range, such as Figure 3 As shown. These two structures have the following disadvantages:

[0004] 1. Multiple inductors are used, which takes up a large area and is not desirable in integrated circuit applications;

[0005] 2. Only one of the voltage-controlled oscillators of the separated frequency bands is enabled at the same time, and the other voltage-controlled oscillators do not work, wasting area. At the same time, a high-frequency multiplexer must be designed to select the output frequency band, which introduces loss;

[0006] 3. The voltage-controlled oscillator with switched inductor and capacitor introduces a MOS tube switch in the resonant cavity. When the switch is turned on, it is equivalent to a small resistor, that is, it introduces loss in the resonant cavity, reduces the Q value of the resonant cavity, and deteriorates its phase noise performance. At the same time, when the switch is closed, it will introduce additional parasitic capacitance, limiting its tuning range. Summary of the invention

[0007] In view of the above-mentioned deficiencies in the prior art, the present invention provides an octave tuning oscillator and a tuning method for multi-core switch switching, which solves the problem that the prior tuning oscillator is difficult to achieve both wide tuning and low phase noise.

[0008] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0009] A multi-core switch-switched octave tuning oscillator is provided, which includes N multi-core switch-switched octave tuning oscillator components, each of which includes an oscillator VCO1 and an oscillator VCO5 with the same structure; in the same multi-core switch-switched octave tuning oscillator component:

[0010] One end of the oscillator VCO1 is respectively connected to one end of the switch S3, one end of the switch S1 and one end of the capacitor C1; the other end of the oscillator VCO1 is respectively connected to one end of the switch S4, one end of the switch S2 and one end of the capacitor C2; the other end of the capacitor C1, the other end of the switch S1 and the other end of the switch S4 are connected and connected to one end of the oscillator VCO5; the other end of the switch S3, the other end of the switch S2 and the other end of the capacitor C2 are connected and connected to the other end of the oscillator VCO5;

[0011] When the value of N is 1, the output ports of the octave tuning oscillator switched by the multi-core switch are the two ends of the oscillator VCO1 or the two ends of the oscillator VCO5;

[0012] When the value of N is greater than or equal to 2, N multi-core switch-switched octave tuning oscillator components are set in parallel, the parallel points are located at both ends of the oscillator, and the output ports of the multi-core switch-switched octave tuning oscillator are the two ends of any oscillator.

[0013] Furthermore, each oscillator includes an active core, a switch capacitor array and a differential inductor with a center tap connected in parallel; wherein the center tap of the differential inductor with a center tap is connected to an external voltage.

[0014] Further, each active core includes a field effect transistor M1, the drain of the field effect transistor M1 is respectively connected to the gate of the field effect transistor M2 and one end of the capacitor C5 and serves as an output end of the active core; the source of the field effect transistor M1 is connected to the source of the field effect transistor M3;

[0015] The drain of the field effect transistor M2 is respectively connected to the gate of the field effect transistor M1 and one end of the capacitor C6 and serves as another output end of the active core; the source of the field effect transistor M2 is connected to the source of the field effect transistor M4;

[0016] The gate of the field effect transistor M3 is respectively connected to the other end of the capacitor C5 and one end of the resistor R1; the gate of the field effect transistor M4 is respectively connected to the other end of the capacitor C6 and one end of the resistor R2; the other end of the resistor R1, the other end of the resistor R2, the drain of the field effect transistor M3 and the drain of the field effect transistor M4 are commonly grounded.

[0017] Furthermore, each switch capacitor array includes 6 switch capacitor units, each switch capacitor unit includes a field effect transistor M5, a field effect transistor M6 and a field effect transistor M7; in the same switch capacitor unit:

[0018] The gate of the field effect transistor M6, the gate of the field effect transistor M7 and the gate of the field effect transistor M5 are commonly connected to an external control signal; the source of the field effect transistor M6 is grounded, and the source of the field effect transistor M7 is connected to an external voltage; the drain of the field effect transistor M6 is respectively connected to the drain of the field effect transistor M7, one end of the resistor R3 and one end of the resistor R4; the source of the field effect transistor M5 is respectively connected to the other end of the resistor R3 and one end of the capacitor C+, and the other end of the capacitor C+ serves as an output end of the switch capacitor unit where it is located; the drain of the field effect transistor M5 is respectively connected to the other end of the resistor R4 and one end of the capacitor C-, and the other end of the capacitor C- serves as another output end of the switch capacitor unit where it is located.

[0019] Furthermore, the value of N is 4.

[0020] A tuning method for an octave tuning oscillator based on multi-core switch switching is provided, which comprises the following steps:

[0021] A1. Determine the tuning working mode. If the tuning working mode is the even mode, proceed to step A2; if the tuning working mode is the odd mode, proceed to step A3;

[0022] A2, close switch S1 and switch S2, open switch S3 and switch S4, and complete even mode tuning;

[0023] A3, open switch S1 and switch S2, close switch S3 and switch S4, and go to step A4;

[0024] A4. The oscillation frequency of the odd mode is distributed in different frequency bands by adjusting the values ​​of capacitors C1 and C2, thereby completing odd mode tuning.

[0025] The beneficial effects of the present invention are as follows: the present invention adopts capacitive coupling and switch switching technology, and divides the oscillation mode into odd mode or even mode by enabling the switch, so that the two oscillators oscillate in phase or in anti-phase, and the oscillation frequency is extended to two frequency bands. The voltages at both ends of the switch are the same, and no current flows through the switch, so the loss of the switch will not affect the Q value of the resonant cavity, that is, it will not deteriorate the phase noise, and octave tuning is achieved. By adopting the method of multi-core cross-connection in parallel, multi-core oscillation is achieved without affecting the switch switching, the parallel resonance resistance of the resonant cavity is reduced, and the phase noise is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The structure block diagram is a multi-core switch-switched octave tuning oscillator formed by connecting four multi-core switch-switched octave tuning oscillator components in parallel;

[0027] Figure 2 A schematic diagram of using a multiplexer to select frequency output in the prior art;

[0028] Figure 3 A schematic diagram of switching to an inductor of corresponding size in different frequency bands to achieve coverage of an octave tuning range in the prior art;

[0029] Figure 4 It is a schematic diagram of the active core structure of the present invention;

[0030] Figure 5 This is a schematic diagram of the structure of the switched capacitor array of the present invention;

[0031] Figure 6 It is an even mode equivalent diagram in the embodiment;

[0032] Figure 7 It is an odd mode equivalent diagram in the embodiment;

[0033] Figure 8 is the even mode tuning diagram;

[0034] Fig. 9 is the odd mode tuning diagram;

[0035] Fig.10 This is the graph of offset frequency and phase noise data;

[0036] Fig.11 This is a graph of oscillation frequency and current data. DETAILED DESCRIPTION

[0037] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0038] like Figure 1 As shown, the multi-core switch-switched octave tuning oscillator includes N multi-core switch-switched octave tuning oscillator components, each of which includes an oscillator VCO1 and an oscillator VCO5 having the same structure; in the same multi-core switch-switched octave tuning oscillator component:

[0039] One end of the oscillator VCO1 is respectively connected to one end of the switch S3, one end of the switch S1 and one end of the capacitor C1; the other end of the oscillator VCO1 is respectively connected to one end of the switch S4, one end of the switch S2 and one end of the capacitor C2; the other end of the capacitor C1, the other end of the switch S1 and the other end of the switch S4 are connected and connected to one end of the oscillator VCO5; the other end of the switch S3, the other end of the switch S2 and the other end of the capacitor C2 are connected and connected to the other end of the oscillator VCO5;

[0040] When the value of N is 1, the output ports of the octave tuning oscillator switched by the multi-core switch are the two ends of the oscillator VCO1 or the two ends of the oscillator VCO5;

[0041] When the value of N is greater than or equal to 2, N multi-core switch-switched octave tuning oscillator components are set in parallel, the parallel points are located at both ends of the oscillator, and the output ports of the multi-core switch-switched octave tuning oscillator are the two ends of any oscillator.

[0042] Each oscillator includes an active core, a switched capacitor array and a differential inductor with a center tap connected in parallel; wherein the center tap of the differential inductor with a center tap is connected to an external voltage. Figure 1 In the figure, C3 and C4 are both switched capacitor arrays, and L1 and L2 are both differential inductors with center taps.

[0043] like Figure 4 As shown, each active core includes a field effect transistor M1, the drain of the field effect transistor M1 is respectively connected to the gate of the field effect transistor M2 and one end of the capacitor C5 and serves as an output end of the active core; the source of the field effect transistor M1 is connected to the source of the field effect transistor M3;

[0044] The drain of the field effect transistor M2 is respectively connected to the gate of the field effect transistor M1 and one end of the capacitor C6 and serves as another output end of the active core; the source of the field effect transistor M2 is connected to the source of the field effect transistor M4;

[0045] The gate of the field effect transistor M3 is respectively connected to the other end of the capacitor C5 and one end of the resistor R1; the gate of the field effect transistor M4 is respectively connected to the other end of the capacitor C6 and one end of the resistor R2; the other end of the resistor R1, the other end of the resistor R2, the drain of the field effect transistor M3 and the drain of the field effect transistor M4 are commonly grounded.

[0046] The active core in the present invention adopts a noise circulation structure, outputs Vout+ and Vout- at the drain end of M1 and M2, M1 and M2 as a cross-coupling pair show negative resistance to compensate for the loss of the resonant cavity, M3 and M4 are tail current sources, C5 and C6 are AC coupling DC blocking capacitors, and R1 and R2 are bias resistors. Since the noise contributed by M1 and M3, M2 and M4 can degenerate each other, the total noise contributed is half of the traditional class-B structure, and the tail current source is divided into two, and the output signal of the VCO is used to control the alternating conduction of the tail current sources M3 and M4, which shortens the working time of the tail current source, so the noise contribution of the tail current source is reduced.

[0047] like Figure 5 As shown, each switch capacitor array includes 6 switch capacitor units, and each switch capacitor unit includes a field effect transistor M5, a field effect transistor M6 and a field effect transistor M7; in the same switch capacitor unit:

[0048] The gate of field effect tube M6, the gate of field effect tube M7 and the gate of field effect tube M5 are connected to an external control signal; the source of field effect tube M6 is grounded, and the source of field effect tube M7 is connected to an external voltage; the drain of field effect tube M6 is respectively connected to the drain of field effect tube M7, one end of resistor R3 and one end of resistor R4; the source of field effect tube M5 is respectively connected to the other end of resistor R3 and one end of capacitor C+, and the other end of capacitor C+ is used as an output end of the switch capacitor unit where it is located; the drain of field effect tube M5 is respectively connected to the other end of resistor R4 and one end of capacitor C-, and the other end of capacitor C- is used as another output end of the switch capacitor unit where it is located. The six switch capacitor units are controlled by 6-bit digital codes EN1-EN6, C+ and C- are used as fixed capacitors, M5 is used as a MOS tube switch, M6 and M7 form inverters, and R3 and R4 are used as bias resistors.

[0049] The tuning method of the octave tuning oscillator based on multi-core switch switching comprises the following steps:

[0050] A1. Determine the tuning working mode. If the tuning working mode is the even mode, proceed to step A2; if the tuning working mode is the odd mode, proceed to step A3;

[0051] A2, close switch S1 and switch S2, open switch S3 and switch S4, and complete even mode tuning;

[0052] A3, open switch S1 and switch S2, close switch S3 and switch S4, and go to step A4;

[0053] A4. The oscillation frequency of the odd mode is distributed in different frequency bands by adjusting the values ​​of capacitors C1 and C2, thereby completing odd mode tuning.

[0054] In the specific implementation process, for the even mode, the switches S1 and S2 are closed, and the switches S3 and S4 are opened. At this time, the oscillation is in phase, and the voltages at both ends of the two resonant cavities of the octave tuning oscillation component switched by a single multi-core switch are in phase. The equivalent effect diagram is shown in FIG. Figure 6 At this time, for capacitors C1 and C2, it is equivalent to being short-circuited by switches S1 and S2, the voltages at both ends are equal, and no current flows, that is, capacitors C1 and C2 lose their functions. At this time, there is no C1 or C2 in the calculation of the resonant frequency of the resonant cavity, as shown in formula (1).

[0055]

[0056] For the odd mode, the switches S3 and S4 are closed, and the switches S1 and S2 are opened. At this time, the oscillation is reversed, and the voltages at both ends of the two resonant cavities of the octave tuning oscillation component switched by a single multi-core switch are reversed. The equivalent effect diagram is shown in the figure below. Figure 7 As shown, at this time, for capacitors C1 and C2, the voltage across both ends is a differential signal, so a virtual ground point will be equivalent in the middle, which is equivalent to twice C1 or C2 in series. At this time, C1 or C2 exists in the calculation of the resonant frequency of the resonant cavity, as shown in formula (2).

[0057]

[0058] It can be seen from Lesson's formula (shown in formula (3)) that the phase noise of the oscillator is inversely proportional to the power consumption, that is, proportional to the parallel resistance of the resonant cavity. Therefore, the present invention connects two identical oscillators in parallel, and then their resonant cavities are equivalently connected in parallel, the inductance value is halved, the capacitance value is doubled, the resonant frequency remains unchanged, but the total current is doubled, the parallel resistance is halved, the output swing remains unchanged, the Q value of the resonant cavity remains unchanged, and its phase noise becomes half of that of a single oscillator, that is, the phase noise is optimized by 3dB. By analogy, when there are N oscillators in parallel, the phase noise will be optimized by 10log(N)dB, as shown in formula (4).

[0059]

[0060] ζ N {Δω}=ζ1{Δω}-10log(N) (4)

[0061] In one embodiment of the present invention, the value of N is 4, that is, four multi-core switch-switched octave tuning oscillator components are connected in parallel to form a multi-core switch-switched octave tuning oscillator, and its structure diagram is as follows Figure 1 As shown. Under 1V power supply, Figure 8 As shown, the current consumption of the multi-core switch-switched octave tuning oscillator formed by connecting four multi-core switch-switched octave tuning oscillators in parallel is 82mA, and the tuning range of the even mode is 5.36GHz to 8.41GHz; Fig. 9 As shown in the figure, the odd mode tuning range is 4.15GHz-5.84GHz, with a 500MHz margin in the middle, and finally an octave tuning range of 4.2GHz-8.4GHz is achieved. Fig.10 and Fig.11 As shown, the final phase noise achieved at 8 GHz is -127 dBc / Hz @ 1 MHz offset frequency.

[0062] In summary, the present invention adopts capacitive coupling and switch switching technology, and divides the oscillation mode into odd mode or even mode by enabling the switch, so that the two oscillators oscillate in phase or in anti-phase, and the oscillation frequency is extended to two frequency bands. The voltages at both ends of the switch are the same, and no current flows through the switch, so the loss of the switch will not affect the Q value of the resonant cavity, that is, it will not deteriorate the phase noise, and octave tuning is achieved. By adopting the method of 8-core cross-connection in parallel, multi-core oscillation is achieved without affecting the switch switching, and the parallel resonant resistance of the resonant cavity is reduced by 8 times, the power consumption is increased by 8 times, but the phase noise is improved by 9dB.

Claims

1. An octave tuning oscillator switched by a multi-core switch, characterized in that: It includes N multi-core switch-switched octave tuning oscillation components, each of which includes an oscillator VCO1 and an oscillator VCO5 with the same structure; In the same multicore switching octave tuned oscillator component: One end of the oscillator VCO1 is respectively connected to one end of the switch S3, one end of the switch S1 and one end of the capacitor C1; the other end of the oscillator VCO1 is respectively connected to one end of the switch S4, one end of the switch S2 and one end of the capacitor C2; the other end of the capacitor C1, the other end of the switch S1 and the other end of the switch S4 are connected and connected to one end of the oscillator VCO5; the other end of the switch S3, the other end of the switch S2 and the other end of the capacitor C2 are connected and connected to the other end of the oscillator VCO5; When the value of N is 1, the output ports of the octave tuning oscillator switched by the multi-core switch are the two ends of the oscillator VCO1 or the two ends of the oscillator VCO5; When the value of N is greater than or equal to 2, N octave tuning oscillator components switched by the multi-core switches are arranged in parallel, the parallel connection points are located at both ends of the oscillator, and the output ports of the octave tuning oscillator switched by the multi-core switches are the two ends of any oscillator; Each oscillator includes an active core, a switched capacitor array and a differential inductor with a center tap connected in parallel; wherein the center tap of the differential inductor with a center tap is connected to an external voltage; Each active core includes a field effect transistor M1, the drain of the field effect transistor M1 is respectively connected to the gate of the field effect transistor M2 and one end of the capacitor C5 and serves as an output end of the active core; the source of the field effect transistor M1 is connected to the source of the field effect transistor M3; The drain of the field effect transistor M2 is respectively connected to the gate of the field effect transistor M1 and one end of the capacitor C6 and serves as another output end of the active core; the source of the field effect transistor M2 is connected to the source of the field effect transistor M4; The gate of the field effect tube M3 is connected to the other end of the capacitor C5 and one end of the resistor R1 respectively; the gate of the field effect tube M4 is connected to the other end of the capacitor C6 and one end of the resistor R2 respectively; the other end of the resistor R1, the other end of the resistor R2, the drain of the field effect tube M3 and the drain of the field effect tube M4 are grounded together; Each switch capacitor array includes 6 switch capacitor units, and each switch capacitor unit includes a field effect transistor M5, a field effect transistor M6 and a field effect transistor M7; In the same switched capacitor cell: The gate of the field effect transistor M6, the gate of the field effect transistor M7 and the gate of the field effect transistor M5 are commonly connected to an external control signal; The source of the field effect tube M6 is grounded, and the source of the field effect tube M7 is connected to the external voltage; the drain of the field effect tube M6 is respectively connected to the drain of the field effect tube M7, one end of the resistor R3 and one end of the resistor R4; the source of the field effect tube M5 is respectively connected to the other end of the resistor R3 and one end of the capacitor C+, and the other end of the capacitor C+ serves as an output end of the switch capacitor unit where it is located; the drain of the field effect tube M5 is respectively connected to the other end of the resistor R4 and one end of the capacitor C-, and the other end of the capacitor C- serves as another output end of the switch capacitor unit where it is located; Among them, the value of N is 4; The tuning method of the octave tuning oscillator comprises the following steps: A1. Determine the tuning working mode. If the tuning working mode is the even mode, proceed to step A2; if the tuning working mode is the odd mode, proceed to step A3; A2, close switch S1 and switch S2, open switch S3 and switch S4, and complete even mode tuning; A3, open switch S1 and switch S2, close switch S3 and switch S4, and go to step A4; A4. The oscillation frequency of the odd mode is distributed in different frequency bands by adjusting the values ​​of capacitors C1 and C2, thereby completing odd mode tuning.

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