CN103731140B - High-frequency voltage-controlled oscillator with low phase noise - Google Patents
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- CN103731140B CN103731140B CN201210387643.7A CN201210387643A CN103731140B CN 103731140 B CN103731140 B CN 103731140B CN 201210387643 A CN201210387643 A CN 201210387643A CN 103731140 B CN103731140 B CN 103731140B
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Abstract
The invention provides a high-frequency voltage-controlled oscillator with low phase noise, comprising: the circuit comprises a resonant circuit, a negative resistance circuit, a current source circuit and a buffer circuit; the current source circuit is used for generating current for the voltage-controlled oscillator to work; the resonance circuit is used for generating an oscillation signal; the negative resistance circuit generates a negative resistance to counteract a positive resistance generated by the resonant circuit; the buffer circuit is used for buffering the oscillation signal generated by the resonance circuit and then outputting the buffered oscillation signal so as to isolate the buffered oscillation signal from an external signal. The oscillation signal generated by the resonant circuit in the high-frequency voltage-controlled oscillator provided by the invention is output after being buffered by the buffer circuit, so that the interference of an external signal to the oscillation circuit can be avoided, and the noise is reduced. And the current source adopts a heterojunction bipolar transistor, and the heterojunction bipolar transistor has lower flicker noise, so that the phase noise of the whole voltage-controlled oscillator can be improved. Meanwhile, the reverse diode is adopted in the resonant circuit, so that the voltage-controlled oscillator has better phase noise performance.
Description
Technical Field
The invention relates to the technical field of integrated circuits, in particular to a high-frequency voltage-controlled oscillator with low phase noise.
Background
A voltage-controlled oscillator (VCO) refers to an oscillating circuit in which an output frequency corresponds to an input control voltage.
The voltage-controlled oscillator is one of the most important basic circuits in an integrated circuit, and the circuit implementation modes of the voltage-controlled oscillator are mainly two, namely a Ring voltage-controlled oscillator (Ring VCO) and an inductance-capacitance voltage-controlled oscillator (LC VCO). Voltage controlled oscillators are widely used in Clock Synchronization (Clock Synchronization) circuits in microprocessors; a Frequency Synthesizer (Frequency Synthesizer) in a wireless communication transceiver; clock Recovery Circuit (CRC) and Multi-phase Sampling (Multi-phase Sampling) circuits in optical fiber communications.
The oscillation frequency is one of the main parameters for the performance of a balanced voltage controlled oscillator. In most cases, the oscillation frequency of the voltage-controlled oscillator is determined by the inductance and capacitance in the resonant circuit, but the parasitic capacitance of the voltage-controlled oscillator, particularly the parasitic capacitance connected to the resonant circuit, is also a major factor affecting the voltage-controlled oscillator to obtain a higher oscillation frequency.
Referring to fig. 1, a schematic diagram of a prior art voltage controlled oscillator is shown.
The resonant circuit of the voltage controlled oscillator shown in fig. 1 includes: the circuit comprises a differential inductor L0, a first variable capacitor C1, a second variable capacitor C2, a third capacitor C3, a fourth capacitor C4, a first resistor R1 and a second resistor R2;
one end of the differential inductor L0 is connected with the negative output end of the voltage-controlled oscillator, and the other end of the differential inductor L0 is connected with the positive output end of the voltage-controlled oscillator;
one end of the first variable capacitor C1 is connected to a first node a, and the other end is connected to a first control voltage ATUNE;
one end of the second variable capacitor C2 is connected to a second node B, and the other end is connected to the first control voltage ATUNE;
one end of the first resistor R1 is connected with the first node A, and the other end is grounded;
one end of the second resistor R2 is connected with the second node B, and the other end is grounded;
two ends of the third capacitor C3 are respectively connected to the first node a and the negative output end of the voltage-controlled oscillator, and two ends of the fourth capacitor C4 are respectively connected to the second node B and the positive output end of the voltage-controlled oscillator.
As can be seen from the above analysis, the oscillation signal generated by the resonant circuit in the voltage-controlled oscillator in the prior art is directly output without any isolation from the external signal, so that the external signal is liable to interfere with the oscillation circuit, thereby increasing the noise of the voltage-controlled oscillator.
Disclosure of Invention
The invention aims to provide a high-frequency voltage-controlled oscillator with low phase noise, which can improve the noise performance of the high-frequency voltage-controlled oscillator. .
The embodiment of the invention provides a high-frequency voltage-controlled oscillator with low phase noise, which comprises: the circuit comprises a resonant circuit, a negative resistance circuit, a current source circuit and a buffer circuit;
the resonant circuit is used for generating an oscillation signal of the voltage-controlled oscillator, and is an inductance-capacitance resonant circuit, wherein a capacitor adopts a reverse diode;
the negative resistance circuit is used for generating negative resistance so as to counteract positive resistance generated by the resonance circuit;
the current source circuit is used for generating a current for the voltage-controlled oscillator to work; the current source circuit comprises a seventh heterojunction bipolar transistor; an emitter electrode of the seventh heterojunction bipolar transistor is grounded, and a collector electrode of the seventh heterojunction bipolar transistor is connected with the first end and the second end of the negative resistance circuit; the base electrode of the seventh heterojunction bipolar transistor is connected with a third control voltage;
and the buffer circuit is used for buffering the oscillation signal generated by the resonance circuit and then outputting the buffered oscillation signal so as to isolate the buffered oscillation signal from an external signal.
Preferably, the resonance circuit includes: the circuit comprises a differential inductor, a first backward diode, a second backward diode, a third capacitor, a fourth capacitor, a first resistor and a second resistor;
one end of the differential inductor is connected with the first node, and the other end of the differential inductor is connected with the second node; a tap of the differential inductor is connected with a power supply;
the anode of the first reverse diode is connected with the first node, the cathode of the first reverse diode is connected with a first control voltage, the anode of the second reverse diode is connected with a second node, and the cathode of the second reverse diode is connected with the first control voltage;
two ends of the first resistor are respectively connected with the first node and the ground; two ends of the second resistor are respectively connected with the second node and the ground;
two ends of the third capacitor are respectively connected with the first node and the third node, and two ends of the fourth capacitor are respectively connected with the second node and the fourth node;
the third node is a first phase connection point of the resonance circuit and the buffer circuit and outputs a first resonance signal; the fourth node is a second connection point of the resonant circuit and the buffer circuit, and outputs a second resonant signal.
Preferably, the buffer circuit includes: the third bipolar transistor, the fourth bipolar transistor, the fifth bipolar transistor, the sixth bipolar transistor, the seventh capacitor, the eighth capacitor, the fifth resistor and the sixth resistor;
the base electrode of the third bipolar transistor is connected with the third node, the collector electrode of the third bipolar transistor is connected with the power supply, and the emitter electrode of the third bipolar transistor is connected with the fifth node;
a base electrode of the fourth bipolar transistor is connected with the fourth node, a collector electrode of the fourth bipolar transistor is connected with the power supply, and an emitter electrode of the fourth bipolar transistor is connected with the sixth node;
one end of the seventh capacitor is connected with the fifth node, and the other end of the seventh capacitor is connected with the base electrode of the fifth bipolar transistor;
a collector of the fifth bipolar transistor is connected with the power supply, and an emitter of the fifth bipolar transistor is grounded through the fifth resistor;
one end of the eighth capacitor is connected with the sixth node, and the other end of the eighth capacitor is connected with the base electrode of the sixth bipolar transistor;
a collector of the sixth bipolar transistor is connected with the power supply, and an emitter of the sixth bipolar transistor is grounded through the sixth resistor;
an emitter electrode of the fifth bipolar transistor is a first output end of the voltage-controlled oscillator, and an emitter electrode of the sixth bipolar transistor is a second output end of the voltage-controlled oscillator;
the third node is a first phase connection point of the resonance circuit and the buffer circuit; the fourth node is a second connection point of the resonance circuit and the buffer circuit;
the fifth node is a first phase connection point of the buffer circuit and the negative resistance circuit; and the sixth node is a second connection point of the buffer circuit and the negative resistance circuit.
Preferably, the negative resistance circuit includes: the first bipolar transistor, the second bipolar transistor, the fifth capacitor, the sixth capacitor, the third resistor, the fourth resistor and the ninth capacitor;
the collector of the first bipolar transistor is connected with a fifth node, the emitter of the first bipolar transistor is connected with the current source circuit, and the base of the first bipolar transistor is connected with a second control voltage through the third resistor;
the collector of the second bipolar transistor is connected with a sixth node, the emitter of the second bipolar transistor is connected with the current source, and the base of the second bipolar transistor is connected with the second control voltage through the fourth resistor;
two ends of the ninth capacitor are respectively connected with the second control voltage and the ground;
one end of the fifth capacitor is connected with the fifth node, and the other end of the fifth capacitor is connected with the base electrode of the second bipolar transistor;
one end of the sixth capacitor is connected with the sixth node, and the other end of the sixth capacitor is connected with the base electrode of the first bipolar transistor; wherein,
the fifth node is a first phase connection point of the buffer circuit and the negative resistance circuit; and the sixth node is a second connection point of the buffer circuit and the negative resistance circuit.
Preferably, the first and second backward diodes operate in a backward operation region.
Preferably, the capacitance values of the third and fourth capacitors are at least ten times greater than the capacitance values of the first and second backward diodes.
Preferably, the first and second bipolar transistors operate in a forward operating region.
Preferably, the seventh heterojunction bipolar transistor operates in a forward operating region.
Preferably, the third bipolar transistor, the fourth bipolar transistor, the fifth bipolar transistor and the sixth bipolar transistor operate in the forward operating region.
Preferably, the buffer circuit includes: the third MOS tube, the fourth MOS tube, the fifth MOS tube, the sixth MOS tube, the seventh capacitor, the eighth capacitor, the fifth resistor and the sixth resistor;
the grid electrode of the third MOS tube is connected with the third node, the drain electrode of the third MOS tube is connected with the power supply, and the source electrode of the third MOS tube is connected with the fifth node;
the grid electrode of the fourth MOS tube is connected with the fourth node, the drain electrode of the fourth MOS tube is connected with the power supply, and the source electrode of the fourth MOS tube is connected with the sixth node;
one end of the seventh capacitor is connected with the fifth node, and the other end of the seventh capacitor is connected with the base electrode of the fifth bipolar transistor;
the drain electrode of the fifth MOS tube is connected with the power supply, and the source electrode of the fifth MOS tube is grounded through the fifth resistor;
one end of the eighth capacitor is connected with the sixth node, and the other end of the eighth capacitor is connected with the base electrode of the sixth MOS tube;
the drain electrode of the sixth MOS tube is connected with the power supply, and the source electrode of the sixth MOS tube is grounded through the sixth resistor;
the source electrode of the fifth MOS transistor is a first output end of the voltage-controlled oscillator, and the source electrode of the sixth MOS transistor is a second output end of the voltage-controlled oscillator;
the third node is a first phase connection point of the resonance circuit and the buffer circuit; the fourth node is a second connection point of the resonance circuit and the buffer circuit;
the fifth node is a first phase connection point of the buffer circuit and the negative resistance circuit; and the sixth node is a second connection point of the buffer circuit and the negative resistance circuit.
Compared with the prior art, the invention has the following advantages:
in the high-frequency voltage-controlled oscillator with low phase noise, the current source circuit is used for generating the working current of the voltage-controlled oscillator; the resonance circuit is used for generating an oscillation signal; the negative resistance circuit generates a negative resistance to counteract a positive resistance generated by the resonant circuit; the buffer circuit is used for buffering the oscillation signal generated by the resonance circuit and then outputting the buffered oscillation signal so as to isolate the buffered oscillation signal from an external signal. The oscillation signal generated by the resonant circuit in the high-frequency voltage-controlled oscillator provided by the invention is output after being buffered by the buffer circuit, so that the interference of an external signal to the oscillation circuit can be avoided, and the noise is reduced. And the current source adopts a heterojunction bipolar transistor, and the heterojunction bipolar transistor has lower flicker noise, so that the phase noise of the whole voltage-controlled oscillator can be improved. Meanwhile, the reverse diode is adopted in the resonant circuit, so that the voltage-controlled oscillator has better phase noise performance.
Drawings
Fig. 1 is a schematic diagram of a prior art voltage controlled oscillator;
FIG. 2 is a schematic diagram of an embodiment of a high frequency voltage controlled oscillator with low phase noise according to the present invention;
FIG. 3 is a second circuit diagram of an embodiment of a high frequency voltage controlled oscillator with low phase noise according to the present invention;
fig. 4 is a circuit diagram of a high frequency voltage-controlled oscillator with low phase noise according to an embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
Referring to fig. 2, a schematic diagram of an embodiment of a high-frequency voltage-controlled oscillator with a large tuning range according to the present invention is provided.
The invention provides a high-frequency voltage-controlled oscillator with a large tuning range, which comprises: the resonant circuit 100, the negative resistance circuit 200, the current source circuit 300 and the buffer circuit 400;
the resonant circuit 100 is configured to generate an oscillation signal of a voltage controlled oscillator, and the resonant circuit 100 is an inductance-capacitance resonant circuit, where a capacitor employs a reverse diode;
the negative resistance circuit 200 is used for generating a negative resistance to counteract the positive resistance generated by the resonant circuit 100;
the current source circuit 300 is used for generating a current for operating the voltage-controlled oscillator; the current source circuit 300 includes a seventh Heterojunction Bipolar Transistor (HBT); the emitter of the seventh heterojunction bipolar transistor is grounded, and the collector of the seventh heterojunction bipolar transistor is connected with the negative resistance circuit 200; the base electrode of the seventh heterojunction bipolar transistor is connected with a third control voltage;
the buffer circuit 400 is configured to buffer the oscillation signal generated by the resonant circuit 100 and then output the buffered oscillation signal to be isolated from an external signal.
In the high frequency voltage controlled oscillator with a large tuning range provided by the invention, the current source circuit 300 is used for generating the current for the voltage controlled oscillator to work; the resonant circuit 100 is used for generating an oscillating signal; the negative resistance circuit 200 generates a negative resistance to cancel the positive resistance generated by the resonant circuit 100; the buffer circuit 400 is configured to buffer the oscillation signal generated by the resonant circuit and then output the buffered oscillation signal to be isolated from the external signal. The oscillation signal generated by the resonant circuit 100 in the high-frequency voltage-controlled oscillator provided by the invention is buffered by the buffer circuit 400 and then output, so that the interference of an external signal to the oscillation circuit can be avoided. And the current source circuit 300 employs a heterojunction bipolar transistor, which has low flicker noise, so that the phase noise of the whole voltage-controlled oscillator can be improved. Meanwhile, the reverse diode is adopted in the resonant circuit, so that the voltage-controlled oscillator has better phase noise performance.
Referring to fig. 3, a circuit diagram of an embodiment of a high frequency voltage controlled oscillator with low phase noise is shown.
The current source circuit comprises a collector electrode of a seventh heterojunction bipolar transistor Q7 connected with the negative resistance circuit, and specifically comprises:
the collector of the seventh MOS transistor Q7 is connected to the emitter of the second bipolar transistor Q2 and the emitter of the first bipolar transistor Q1.
The base of the seventh MOS transistor Q7 is connected to the third control voltage VBIAS.
By adjusting the magnitude of the third control voltage VBIAS, the seventh heterojunction bipolar transistor Q7 is guaranteed to operate in the forward region.
Flicker noise of the current source, which is generated by traps in the active device randomly trapping and releasing carriers, is one of the factors affecting the phase noise performance of the voltage controlled oscillator. Since the HBT does not belong to a surface device, has fewer traps, and generates less flicker noise, Q7 may improve the phase noise performance of the voltage controlled oscillator.
The resonance circuit includes: the circuit comprises a differential inductor L0, a first reverse diode C1, a second reverse diode C2, a third capacitor C3, a fourth capacitor C4, a first resistor R1 and a second resistor R2;
one end of the differential inductor L0 is connected with a third node C, and the other end of the differential inductor L0 is connected with a fourth node D; a tap of the differential inductor L0 is connected with a power supply;
the cathode of the first backward diode C1 is connected with a first control voltage ATUNE, and the anode of C1 is connected with a first node A; the cathode of the second backward diode C2 is connected to the first control voltage ATUNE, and the anode of C2 is connected to a second node B;
the first reverse diode C1 and the second reverse diode C2 operate in a reverse operation region.
The capacitance values of the third capacitor C3 and the fourth capacitor C4 are at least ten times larger than the capacitance values of the first backward diode C1 and the second backward diode C2. This ensures that the voltage controlled oscillator has a wide frequency tuning range.
The operating frequency of the voltage-controlled oscillator can be adjusted by adjusting the magnitude of the first control voltage ATUNE.
Two ends of the first resistor R1 are respectively connected with the first node A and the ground; two ends of the second resistor R2 are respectively connected with the second node B and the ground;
two ends of the third capacitor C3 are connected to the first node a and the third node C, respectively, and two ends of the fourth capacitor C4 are connected to the second node B and the fourth node D, respectively;
the third node C is a first phase connection point of the resonance circuit and the buffer circuit and outputs a first resonance signal; the fourth node D is a second connection point of the resonance circuit and the buffer circuit, and outputs a second resonance signal.
The buffer circuit includes: a third bipolar transistor Q3, a fourth bipolar transistor Q4, a fifth bipolar transistor Q5, a sixth bipolar transistor Q6, a seventh capacitor C7, an eighth capacitor C8, a fifth resistor R5, and a sixth resistor R6;
the base electrode of the third bipolar transistor Q3 is connected with the third node C, the collector electrode of the third bipolar transistor Q3 is connected with the power supply, and the emitter electrode of the third bipolar transistor Q3 is connected with the fifth node M;
the base of the fourth bipolar transistor Q4 is connected with the fourth node D, the collector is connected with the power supply, and the emitter is connected with the sixth node N;
one end of the seventh capacitor C7 is connected to the fifth node M, and the other end is connected to the base of the fifth bipolar transistor Q5;
the collector of the fifth bipolar transistor Q5 is connected with the power supply, and the emitter is grounded through the fifth resistor R5;
one end of the eighth capacitor C8 is connected to the sixth node N, and the other end is connected to the base of the sixth bipolar transistor Q6;
the collector of the sixth bipolar transistor Q6 is connected with the power supply, and the emitter is grounded through the sixth resistor R6;
an emitter of the fifth bipolar transistor Q5 is a first output terminal NOUT of the voltage-controlled oscillator, and an emitter of the sixth bipolar transistor Q6 is a second output terminal POUT of the voltage-controlled oscillator;
the third node C is a first phase connection point of the resonance circuit and the buffer circuit; the fourth node D is a second connection point of the resonance circuit and the snubber circuit;
the fifth node M is a first phase connection point of the buffer circuit and the negative resistance circuit; and the sixth node N is a second connection point of the buffer circuit and the negative resistance circuit.
The functions of the C7 and the C8 are to isolate the direct current signal and enable the alternating current signal to pass through.
The buffer circuit buffers the oscillation signal output by the resonance circuit and then outputs the buffered oscillation signal, so that the working frequency of the voltage-controlled oscillator is not influenced by an external signal.
Wherein Q5 and R5 form a follower, and Q6 and R6 form a follower.
The third bipolar transistor Q3, the fourth bipolar transistor Q4, the fifth bipolar transistor Q5, and the sixth bipolar transistor Q6 operate in the forward operating region.
In the high frequency voltage controlled oscillator provided by the present invention, the negative resistance circuit includes: a first bipolar transistor Q1, a second bipolar transistor Q2, a third resistor R3, a fourth resistor R4, a ninth capacitor C9, a fifth capacitor C5, and a sixth capacitor C6;
a collector of the first bipolar transistor Q1 is connected to the fifth node M, an emitter thereof is connected to the current source circuit, and a base thereof is connected to a second control voltage CDC through the third resistor R3;
a collector of the second bipolar transistor Q2 is connected to the sixth node N, an emitter thereof is connected to the current source, and a base thereof is connected to the second control voltage CDC through the fourth resistor R4;
both ends of the ninth capacitor C9 are connected to the second control voltage CDC and ground, respectively.
One end of the fifth capacitor C5 is connected to the fifth node M, and the other end is connected to the base of the second bipolar transistor Q2;
one end of the sixth capacitor C6 is connected to the sixth node N, and the other end is connected to the base of the first bipolar transistor Q1.
The emitter of the first bipolar transistor Q1 is a first terminal of a negative resistance circuit, and the emitter of the second bipolar transistor Q2 is a second terminal of the negative resistance circuit.
By adjusting the magnitude of the second control voltage CDC, Q1 and Q2 are guaranteed to be in the forward operating region.
In the high-frequency voltage-controlled oscillator according to the present invention, the first bipolar transistor Q1 and the second bipolar transistor Q2 may be heterojunction bipolar transistors.
The capacitance values of the fifth capacitor C5 and the sixth capacitor C6 are one tenth of the capacitance values of the first MOS capacitive reactance tube C1 and the second MOS capacitive reactance tube C2. This ensures a wide frequency tuning range of the voltage controlled oscillator.
The oscillation frequency of the voltage controlled oscillator may be expressed as:
wherein L is the inductance of the differential inductor L0; cpEquivalent parallel capacitance of the resonance circuit. The equivalent parallel capacitance of the voltage-controlled oscillator shown in fig. 1 of the prior art includes not only the capacitances (C1, C2, C3, C4), but also the fifth capacitance C5 and the sixth capacitance C6 connected to the resonant circuit, and the base capacitances of the first transistor Q1 and the second transistor Q2. In summary, FIG. 1 showsThe voltage-controlled oscillator has larger equivalent parallel capacitance of the resonant circuit, and the oscillation frequency is inversely proportional to the equivalent parallel capacitance. Therefore, the voltage-controlled oscillator has a low oscillation frequency.
In the high-frequency voltage-controlled oscillator with low phase noise, capacitors in a resonant circuit, which are directly and indirectly connected with a differential inductor L0, comprise a third capacitor C3, a fourth capacitor C4, a capacitor of a first reverse diode C1, a capacitor of a second reverse diode C2 and equivalent capacitors of bases of a third bipolar transistor Q3 and a fourth bipolar transistor Q4; thus, compared with the voltage-controlled oscillator in the prior art, the equivalent parallel capacitance of the resonant circuit is reduced, and the oscillation frequency is inversely proportional to the equivalent parallel capacitance as can be seen from formula (1). Therefore, the voltage-controlled oscillator has a high oscillation frequency. And the current source adopts a heterojunction bipolar transistor, and the heterojunction bipolar transistor has lower flicker noise, so that the phase noise of the whole voltage-controlled oscillator can be improved.
It should be noted that the oscillation starting condition of the voltage-controlled oscillator can be expressed as:
gmRp≥2 (2)
wherein, gmIs the equivalent transconductance of a negative resistance circuit connected in parallel with the resonant circuit; rpIs an equivalent resistance in parallel with the resonant circuit. Because the HBT has larger transconductance under the same power consumption condition, the negative resistance circuit in the voltage-controlled oscillator adopts the HBT (Q1, Q2) to enable the voltage-controlled oscillator to start oscillating quickly.
The resonant circuit employs backward diodes (C1, C2). Because the control backward diode works in the backward working area, the capacitance of the backward diode is smaller than that of the MOS capacitive reactance tube, and the value of the capacitance of the backward diode is less along with the change of the control voltage ATUNE, so that the control backward diode has better phase noise.
The Q3, Q4, Q5 and Q6 in the buffer circuit in the embodiment shown in fig. 3 are implemented by transistors, it is understood that the transistor positions in the buffer circuit can also be implemented by MOS transistors, as shown in fig. 4, which is yet another embodiment of the high-frequency voltage-controlled oscillator provided by the present invention. The difference between fig. 4 and fig. 3 is that Q3, Q4, Q5 and Q6 in fig. 3 are changed to M3, M4, M5 and M6, respectively.
The buffer circuit includes: a third MOS transistor M3, a fourth MOS transistor M4, a fifth MOS transistor M5, a sixth MOS transistor M6, a seventh capacitor C7, an eighth capacitor C8, a fifth resistor R5, and a sixth resistor R6;
the grid electrode of the third MOS tube M3 is connected with the third node C, the drain electrode is connected with the power supply, and the source electrode is connected with the fifth node M;
the gate of the fourth MOS transistor M4 is connected to the fourth node D, the drain is connected to the power supply, and the source is connected to the sixth node N;
one end of the seventh capacitor C7 is connected to the fifth node M, and the other end is connected to the gate of the fifth MOS transistor M5;
the drain electrode of the fifth MOS transistor M5 is connected with the power supply, and the source electrode is grounded through the fifth resistor R5;
one end of the eighth capacitor C8 is connected to the sixth node N, and the other end is connected to the gate of the sixth MOS transistor M6;
the drain electrode of the sixth MOS transistor M6 is connected with the power supply, and the source electrode is grounded through the sixth resistor R6;
the source of the fifth MOS transistor M5 is a first output terminal NOUT of the voltage-controlled oscillator, and the source of the sixth MOS transistor M6 is a second output terminal POUT of the voltage-controlled oscillator;
the third node C is a first phase connection point of the resonance circuit and the buffer circuit; the fourth node D is a second connection point of the resonance circuit and the snubber circuit;
the fifth node M is a first phase connection point of the buffer circuit and the negative resistance circuit; and the sixth node N is a second connection point of the buffer circuit and the negative resistance circuit.
The working principle of fig. 4 is the same as that of fig. 3, and will not be described again.
In summary, compared with the voltage-controlled oscillator in the prior art, the voltage-controlled oscillator has the advantages that the oscillation frequency is improved, the oscillation can be started quickly, and the phase noise is low.
The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner. Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make numerous possible variations and modifications to the present teachings, or modify equivalent embodiments to equivalent variations, without departing from the scope of the present teachings, using the methods and techniques disclosed above. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the scope of the protection of the technical solution of the present invention, unless the contents of the technical solution of the present invention are departed.
Claims (10)
1. A high frequency voltage controlled oscillator with low phase noise, comprising: the circuit comprises a resonant circuit, a negative resistance circuit, a current source circuit and a buffer circuit;
the resonant circuit is used for generating an oscillation signal of the voltage-controlled oscillator, and is an inductance-capacitance resonant circuit, wherein a capacitor adopts a reverse diode;
the negative resistance circuit is used for generating negative resistance so as to counteract positive resistance generated by the resonance circuit;
the current source circuit is used for generating a current for the voltage-controlled oscillator to work; the current source circuit comprises a seventh heterojunction bipolar transistor; an emitter electrode of the seventh heterojunction bipolar transistor is grounded, and a collector electrode of the seventh heterojunction bipolar transistor is connected with a negative resistance circuit; the base electrode of the seventh heterojunction bipolar transistor is connected with a third control voltage;
and the buffer circuit is used for buffering the oscillation signal generated by the resonance circuit and then outputting the buffered oscillation signal so as to isolate the buffered oscillation signal from an external signal.
2. The high frequency voltage controlled oscillator with low phase noise of claim 1, wherein the resonant circuit comprises: the circuit comprises a differential inductor, a first backward diode, a second backward diode, a third capacitor, a fourth capacitor, a first resistor and a second resistor;
one end of the differential inductor is connected with the third node, and the other end of the differential inductor is connected with the fourth node; a tap of the differential inductor is connected with a power supply;
the anode of the first reverse diode is connected with a first node, the cathode of the first reverse diode is connected with a first control voltage, the anode of the second reverse diode is connected with a second node, and the cathode of the second reverse diode is connected with the first control voltage;
two ends of the first resistor are respectively connected with the first node and the ground; two ends of the second resistor are respectively connected with the second node and the ground;
two ends of the third capacitor are respectively connected with the first node and the third node, and two ends of the fourth capacitor are respectively connected with the second node and the fourth node;
the third node is a first phase connection point of the resonance circuit and the buffer circuit and outputs a first resonance signal; the fourth node is a second connection point of the resonant circuit and the buffer circuit, and outputs a second resonant signal.
3. The high frequency voltage controlled oscillator with low phase noise of claim 1, wherein the buffer circuit comprises: the third bipolar transistor, the fourth bipolar transistor, the fifth bipolar transistor, the sixth bipolar transistor, the seventh capacitor, the eighth capacitor, the fifth resistor and the sixth resistor;
the base electrode of the third bipolar transistor is connected with the third node, the collector electrode of the third bipolar transistor is connected with the power supply, and the emitter electrode of the third bipolar transistor is connected with the fifth node;
the base electrode of the fourth bipolar transistor is connected with a fourth node, the collector electrode of the fourth bipolar transistor is connected with the power supply, and the emitter electrode of the fourth bipolar transistor is connected with a sixth node;
one end of the seventh capacitor is connected with the fifth node, and the other end of the seventh capacitor is connected with the base electrode of the fifth bipolar transistor;
a collector of the fifth bipolar transistor is connected with the power supply, and an emitter of the fifth bipolar transistor is grounded through the fifth resistor;
one end of the eighth capacitor is connected with the sixth node, and the other end of the eighth capacitor is connected with the base electrode of the sixth bipolar transistor;
a collector of the sixth bipolar transistor is connected with the power supply, and an emitter of the sixth bipolar transistor is grounded through the sixth resistor;
an emitter electrode of the fifth bipolar transistor is a first output end of the voltage-controlled oscillator, and an emitter electrode of the sixth bipolar transistor is a second output end of the voltage-controlled oscillator; wherein,
the third node is a first phase connection point of the resonance circuit and the buffer circuit; the fourth node is a second connection point of the resonance circuit and the buffer circuit;
the fifth node is a first phase connection point of the buffer circuit and the negative resistance circuit; and the sixth node is a second connection point of the buffer circuit and the negative resistance circuit.
4. The high frequency voltage controlled oscillator with low phase noise of claim 1, wherein the negative resistance circuit comprises: the first bipolar transistor, the second bipolar transistor, the fifth capacitor, the sixth capacitor, the third resistor, the fourth resistor and the ninth capacitor;
the collector of the first bipolar transistor is connected with a fifth node, the emitter of the first bipolar transistor is connected with the current source circuit, and the base of the first bipolar transistor is connected with a second control voltage through the third resistor;
the collector of the second bipolar transistor is connected with a sixth node, the emitter of the second bipolar transistor is connected with the current source circuit, and the base of the second bipolar transistor is connected with the second control voltage through the fourth resistor;
two ends of the ninth capacitor are respectively connected with the second control voltage and the ground;
one end of the fifth capacitor is connected with the fifth node, and the other end of the fifth capacitor is connected with the base electrode of the second bipolar transistor;
one end of the sixth capacitor is connected with the sixth node, and the other end of the sixth capacitor is connected with the base electrode of the first bipolar transistor; wherein,
the fifth node is a first phase connection point of the buffer circuit and the negative resistance circuit; and the sixth node is a second connection point of the buffer circuit and the negative resistance circuit.
5. The high frequency voltage controlled oscillator with low phase noise of claim 2, wherein the first and second backward diodes operate in a backward operation region.
6. The high frequency voltage controlled oscillator with low phase noise of claim 2, wherein the third and fourth capacitors have a capacitance value at least ten times greater than the capacitance values of the first and second backward diodes.
7. The high frequency voltage controlled oscillator with low phase noise of claim 4, wherein the first bipolar transistor and the second bipolar transistor operate in a forward operating region.
8. The high frequency voltage controlled oscillator with low phase noise of claim 1, wherein the seventh heterojunction bipolar transistor operates in a forward operating region.
9. A high frequency voltage controlled oscillator with low phase noise according to claim 3 wherein the third bipolar transistor, the fourth bipolar transistor, the fifth bipolar transistor and the sixth bipolar transistor operate in the forward operating region.
10. The high frequency voltage controlled oscillator with low phase noise of claim 1, wherein the buffer circuit comprises: the third MOS tube, the fourth MOS tube, the fifth MOS tube, the sixth MOS tube, the seventh capacitor, the eighth capacitor, the fifth resistor and the sixth resistor;
the grid electrode of the third MOS tube is connected with a third node, the drain electrode of the third MOS tube is connected with a power supply, and the source electrode of the third MOS tube is connected with a fifth node;
the grid electrode of the fourth MOS tube is connected with a fourth node, the drain electrode of the fourth MOS tube is connected with the power supply, and the source electrode of the fourth MOS tube is connected with a sixth node;
one end of the seventh capacitor is connected with the fifth node, and the other end of the seventh capacitor is connected with the base electrode of the fifth MOS tube;
the drain electrode of the fifth MOS tube is connected with the power supply, and the source electrode of the fifth MOS tube is grounded through the fifth resistor;
one end of the eighth capacitor is connected with the sixth node, and the other end of the eighth capacitor is connected with the base electrode of the sixth MOS tube;
the drain electrode of the sixth MOS tube is connected with the power supply, and the source electrode of the sixth MOS tube is grounded through the sixth resistor;
the source electrode of the fifth MOS transistor is a first output end of the voltage-controlled oscillator, and the source electrode of the sixth MOS transistor is a second output end of the voltage-controlled oscillator;
the third node is a first phase connection point of the resonance circuit and the buffer circuit; the fourth node is a second connection point of the resonance circuit and the buffer circuit;
the fifth node is a first phase connection point of the buffer circuit and the negative resistance circuit; and the sixth node is a second connection point of the buffer circuit and the negative resistance circuit.
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| CN105281761B (en) * | 2015-11-07 | 2018-03-16 | 浙江大学 | The low voltage control CMOS LC oscillators for recalcitrating shake of 60GHz phaselocked loop low-power consumption |
| CN107623492A (en) * | 2017-10-31 | 2018-01-23 | 广西师范大学 | A kind of high-frequency wideband voltage controlled oscillator and its operation method |
| CN110113008A (en) * | 2019-05-31 | 2019-08-09 | 华讯方舟科技有限公司 | A kind of Voltage-Controlled oscillation circuit and voltage controlled oscillator |
| CN110708019A (en) * | 2019-12-13 | 2020-01-17 | 成都铱通科技有限公司 | Compact millimeter wave voltage-controlled oscillator |
| CN111628725B (en) * | 2020-06-19 | 2022-11-01 | 南京邮电大学 | LC voltage-controlled oscillator circuit with noise circulation |
| CN113395042B (en) * | 2021-06-05 | 2022-08-05 | 苏州瀚宸科技有限公司 | High-frequency low-power-consumption low-jitter voltage-controlled oscillator |
| CN116781014A (en) * | 2023-06-30 | 2023-09-19 | 重庆西南集成电路设计有限责任公司 | Voltage controlled oscillator |
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