CN116260394A - Octave tuning oscillator switched by multi-core switch and tuning method - Google Patents

Abstract

The invention discloses an octave tuning oscillator switched by a multi-core switch and a tuning method, wherein the octave tuning oscillator comprises N octave tuning oscillating components switched by the multi-core switch, and each octave tuning oscillating component switched by the multi-core switch comprises an oscillator VCO1 and an oscillator VCO5 which have the same structure. The invention adopts the capacitive coupling and switch switching technology, and enables the two oscillators to oscillate in phase or in opposite phase by enabling the switch to divide the oscillation mode into an odd mode or an even mode, so as to expand the oscillation frequency to two frequency bands. The voltages at the two ends of the switch are the same, no current flows through the switch, so that the loss of the switch does not influence the Q value of the resonant cavity, namely the phase noise is not deteriorated, and octave tuning is realized. The multi-core cross connection parallel connection mode is adopted, multi-core oscillation is realized on the premise of not influencing switching, the parallel resonance resistance of the resonant cavity is reduced, and the phase noise is improved.

Description

Multi-core switch switching octave tuned oscillator and tuning method

technical field

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

Background technique

The advent of cellular technology, multi-mode wireless communication technologies, and multi-standard communication devices 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 VCOs using varactors and switched capacitor arrays.

One of the more popular and practical methods is to use multiple independent voltage-controlled oscillators operating at different frequencies, and use a multiplexer to select the frequency output to cover the octave tuning range, as shown in Figure 2. Another method is the switched inductor and switched capacitor technology, adding a MOS tube switch to the inductor and capacitor in the resonant cavity, and switching to the corresponding inductance in different frequency bands to achieve the octave tuning range, as shown in Figure 3 . Both structures have the following disadvantages:

1. Multiple inductors are used, occupying a large area, which is not advisable in integrated circuit applications;

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

3. The voltage-controlled oscillator with switching inductance and capacitance introduces a MOS tube switch in the resonant cavity. When the switch is turned on, it is equivalent to a small resistance, that is, a loss is introduced in the resonant cavity, which reduces the Q value of the resonant cavity and deteriorates Its phase noise performance, meanwhile, introduces extra parasitic capacitance when the switch is off, limiting its tuning range.

Contents of the invention

In view of the above-mentioned shortcomings in the prior art, the present invention provides a multi-core switching octave tuning oscillator and a tuning method to solve the problem that the existing tuning oscillator is difficult to balance wide tuning and low phase noise.

In order to achieve the above-mentioned purpose of the invention, the technical scheme adopted in the present invention is:

An octave tuned oscillator switched by a multi-core switch is provided, which includes N octave tuned oscillation components switched by a multi-core switch, and each octave tuned oscillator switched by a multi-core switch includes an oscillator VCO1 and an oscillator with the same structure VCO5; in the octave-tuned oscillator part switched by the same multicore switch:

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 is connected to the other end of the switch S4 and connected to one end of the oscillator VCO5; the other end of the switch S3, the other end of the switch S2 is connected to the other end of the capacitor C2 and connected to the other end of the oscillator VCO5;

When the value of N is 1, the output port of the octave tuned oscillator switched by the multi-core switch is 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 multi-core switch-switched octave tuned oscillator components are set in parallel, the parallel point is located at both ends of the oscillator, and the output port of the multi-core switch switched octave tuned oscillator is any oscillation both ends of the device.

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

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 as an output terminal of the active core; the field effect transistor M1 The source of the field effect transistor M3 is connected to the source;

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 as another output terminal 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 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 and the other end of the resistor R2 One end, the drain of the field effect transistor M3 and the drain of the field effect transistor M4 are commonly grounded.

Further, each switched capacitor array includes 6 switched capacitor units, and each switched capacitor unit includes a field effect transistor M5, a field effect transistor M6 and a field effect transistor M7; in the same switched capacitor unit:

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 jointly 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 capacitor C+ The other end is used as an output end of the switched 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- is used as another output of the switched capacitor unit where it is located end.

Further, the value of N is 4.

A method for tuning an octave tuned oscillator based on multi-core switching is provided, comprising the following steps:

A1. Determine the tuning mode, if the tuning mode is even mode, then enter step A2; if the tuning mode is odd mode, then enter step A3;

A2. Close the switch S1 and the switch S2, open the switch S3 and the switch S4, and complete the even mode tuning;

A3, switch off switch S1 and switch S2, close switch S3 and switch S4, enter step A4;

A4. By adjusting the value of the capacitor C1 and the value of the capacitor C2, the oscillation frequency of the odd mode is distributed in different frequency bands, and the odd mode tuning is completed.

The beneficial effects of the present invention are: 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 the same phase or in the opposite phase, and expand the oscillation frequency to two frequency bands. The voltage at both ends of the switch is 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, the phase noise will not be deteriorated, and octave tuning is realized. The method of multi-core cross-connection and parallel connection is adopted to realize multi-core oscillation without affecting the switch switching, reduce the parallel resonance resistance of the resonant cavity, and improve the phase noise.

Description of drawings

Fig. 1 is the structural block diagram of the octave tuned oscillator switched by the multi-core switch switched by four multi-core switches connected in parallel;

FIG. 2 is a schematic diagram of using a multiplexer to select frequency output in the prior art;

FIG. 3 is a schematic diagram of switching to an inductance of a corresponding size in different frequency bands in the prior art so as to cover an octave tuning range;

Fig. 4 is a schematic diagram of the structure of the active core of the present invention;

Fig. 5 is a schematic structural diagram of a switched capacitor array of the present invention;

Fig. 6 is the equivalent diagram of even mode in the embodiment;

Figure 7 is an equivalent diagram of an odd mode in an embodiment;

Figure 8 is an even mode tuning diagram;

Figure 9 is an odd mode tuning diagram;

Fig. 10 is a graph of offset frequency and phase noise data;

Figure 11 is a graph of oscillation frequency and current data.

Detailed ways

The specific embodiments of the present invention are described below so that those skilled in the art can understand the present invention, but it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes Within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are included in the protection list.

As shown in Figure 1, the octave tuned oscillator switched by the multi-core switch includes N octave tuned oscillation components switched by the multi-core switch, and each octave tuned oscillator switched by the multi-core switch includes an oscillator VCO1 with the same structure and oscillator VCO5; in the same octave-tuned oscillator part switched by the multicore switch:

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 is connected to the other end of the switch S4 and connected to one end of the oscillator VCO5; the other end of the switch S3, the other end of the switch S2 is connected to the other end of the capacitor C2 and connected to the other end of the oscillator VCO5;

When the value of N is 1, the output port of the octave tuned oscillator switched by the multi-core switch is 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 multi-core switch-switched octave tuned oscillator components are set in parallel, the parallel point is located at both ends of the oscillator, and the output port of the multi-core switch switched octave tuned oscillator is any oscillation both ends of the device.

Each oscillator includes a parallel connection of an active core, a switched capacitor array, and a center-tapped differential inductor; wherein the center tap of the center-tapped differential inductor is connected to an external voltage. In Fig. 1, both C3 and C4 are switched capacitor arrays, and both L1 and L2 are differential inductors with center taps.

As shown in Figure 4, each active core includes a field effect transistor M1, and 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 as an output terminal of the active core; The source of the 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 as another output terminal 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 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 and the other end of the resistor R2 One end, the drain of the field effect transistor M3 and the drain of the field effect transistor M4 are commonly grounded.

The active core in the present invention adopts a noise loop structure, outputs Vout+ and Vout- at the drain terminals of M1 and M2, M1 and M2 act as a cross-coupling pair as a negative resistance to compensate the loss of the resonant cavity, and M3 and M4 serve as tail current sources , C5 and C6 are AC coupling DC blocking capacitors, 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 tail current source M3 and M4 are turned on alternately, which shortens the working time of the tail current source, thus reducing the noise contribution of the tail current source.

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

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 jointly 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 capacitor C+ The other end is used as an output end of the switched 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- is used as another output of the switched capacitor unit where it is located end. The 6 switched capacitor units are controlled by 6bit digital codes EN1-EN6, C+ and C- are used as fixed capacitors, M5 is used as a MOS tube switch, M6 and M7 are used as inverters, and R3 and R4 are used as bias resistors.

The tuning method of the octave tuned oscillator based on multi-core switch switching includes the following steps:

A1. Determine the tuning mode, if the tuning mode is even mode, then enter step A2; if the tuning mode is odd mode, then enter step A3;

A2. Close the switch S1 and the switch S2, open the switch S3 and the switch S4, and complete the even mode tuning;

A3, switch off switch S1 and switch S2, close switch S3 and switch S4, enter step A4;

A4. By adjusting the value of the capacitor C1 and the value of the capacitor C2, the oscillation frequency of the odd mode is distributed in different frequency bands, and the odd mode tuning is completed.

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 same phase is oscillated, and the voltage at both ends of the two resonant cavities of the single multi-core switch is tuned by the octave tuning oscillation component. In the same phase, the equivalent effect diagram is shown in Figure 6. At this time, for capacitor C1 and capacitor 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, capacitor C1 and capacitor C2 lose their function. At this time, there is no C1 or C2 exists, as shown in formula (1).

For the odd mode, the switches S3 and S4 are closed, and the switches S1 and S2 are open. At this time, the anti-phase oscillation, the voltage across the two resonant cavities of the octave-tuned oscillation part switched by a single multi-core switch, etc. The effect diagram is shown in Figure 7. At this time, for capacitor C1 and capacitor C2, the voltage at both ends is a differential signal, so a virtual point will be equivalent to a virtual point in the middle, which is equivalent to twice the series connection of C1 or C2. At this time C1 or C2 exists in the calculation of the resonant frequency of the resonant cavity, as shown in formula (2).

From the Lesson formula (shown in formula (3)), it can be seen that the phase noise of the oscillator is inversely proportional to the power consumption, that is, it is directly proportional to the parallel resistance of the resonant cavity. Therefore, the present invention connects two identical oscillators in parallel, then their resonant cavities are equivalently connected in parallel, the inductance value is halved, the capacitance value is doubled, and the resonant frequency remains unchanged, but the total current is doubled, the parallel resistance is halved, and the output swing remains unchanged , the Q value of the resonator 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 N oscillators are connected in parallel, the phase noise will be optimized by 10log(N)dB. As shown in formula (4).

ζ _N {Δω}＝ζ ₁ {Δω}-10log(N) (4)

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

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 the same phase or in the opposite phase, and expand the oscillation frequency to two frequency bands . The voltage at both ends of the switch is 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, the phase noise will not be deteriorated, and octave tuning is realized. Using the 8-core cross-connection parallel method, multi-core oscillation is realized without affecting the switch switching, the parallel resonance resistance of the resonator is reduced by 8 times, the power consumption is increased by 8 times, but the phase noise is improved by 9dB.

Claims (6)

1. The octave tuning oscillator is characterized by comprising N octave tuning oscillating components switched by the multi-core switch, wherein each octave tuning oscillating component switched by the multi-core switch comprises an oscillator VCO1 and an oscillator VCO5 which have the same structure; in the octave tuning oscillation component switched by the same multi-core switch:

one end of the oscillator VCO1 is connected to one end of the switch S3, one end of the switch S1, and one end of the capacitor C1, respectively; the other end of the oscillator VCO1 is respectively connected with 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 with 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 with 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 two ends of the oscillator VCO1 or two ends of the oscillator VCO5;

when the value of N is more than or equal to 2, the octave tuning oscillating components switched by the N multi-core switches are arranged in parallel, the parallel points are positioned at two ends of the oscillator, and the output ports of the octave tuning oscillator switched by the multi-core switches are at two ends of any one oscillator.

2. The multi-core switched octave tuning oscillator of claim 1, wherein each oscillator comprises an active core, a switched capacitor array, and a center tapped differential inductor in parallel; wherein the center tap of the differential inductor with the center tap is connected to an external voltage.

3. The multi-core switched octave tuning oscillator according to claim 2, wherein each active core comprises a field effect transistor M1, and a drain electrode of the field effect transistor M1 is connected to a gate electrode of the field effect transistor M2 and one end of a capacitor C5 respectively and is used as an output end of the active core; the source electrode of the field effect transistor M1 is connected with the source electrode of the field effect transistor M3;

the drain electrode of the field effect tube M2 is respectively connected with the grid electrode of the field effect tube M1 and one end of the capacitor C6 and is used as the other output end of the active core; the source electrode of the field effect transistor M2 is connected with the source electrode of the field effect transistor M4;

the grid electrode of the field effect tube M3 is respectively connected with the other end of the capacitor C5 and one end of the resistor R1; the grid electrode of the field effect tube M4 is respectively connected with 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 electrode of the field effect transistor M3 and the drain electrode of the field effect transistor M4 are commonly grounded.

4. The multi-core switched octave tuning oscillator of claim 2, wherein each switched capacitor array comprises 6 switched capacitor units, each switched capacitor unit comprising a field effect transistor M5, a field effect transistor M6, and a field effect transistor M7; in the same switched capacitor unit:

the grid electrode of the field effect tube M6, the grid electrode of the field effect tube M7 and the grid electrode of the field effect tube M5 are commonly connected with an external control signal; the source electrode of the field effect tube M6 is grounded, and the source electrode of the field effect tube M7 is connected with external voltage; the drain electrode of the field effect tube M6 is respectively connected with the drain electrode of the field effect tube M7, one end of the resistor R3 and one end of the resistor R4; the source electrode of the field effect tube M5 is respectively connected with the other end of the resistor R3 and one end of the capacitor C+ and the other end of the capacitor C+ is used as an output end of a switch capacitor unit where the capacitor C+ is positioned; the drain electrode of the field effect tube M5 is respectively connected with the other end of the resistor R4 and one end of the capacitor C-and the other end of the capacitor C-is used as the other output end of the switch capacitor unit where the capacitor C-is located.

5. The multi-core switch-switched octave-tuned oscillator of claim 1, wherein the value of N is 4.

6. A tuning method of an octave tuning oscillator based on multi-core switching according to any one of claims 1 to 5, characterized by comprising the steps of:

a1, determining a tuning working mode, and if the tuning working mode is an even mode, entering a step A2; if the tuning working mode is an odd mode, entering a step A3;

a2, closing the switch S1 and the switch S2, and opening the switch S3 and the switch S4 to finish even mode tuning;

a3, opening the switch S1 and the switch S2, closing the switch S3 and the switch S4, and entering the step A4;

a4, the oscillation frequency of the odd mode is distributed on different frequency bands by adjusting the value of the capacitor C1 and the value of the capacitor C2, and the tuning of the odd mode is completed.

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