CN118399891B - Crystal oscillator circuit for improving phase noise - Google Patents
Crystal oscillator circuit for improving phase noise Download PDFInfo
- Publication number
- CN118399891B CN118399891B CN202410865176.7A CN202410865176A CN118399891B CN 118399891 B CN118399891 B CN 118399891B CN 202410865176 A CN202410865176 A CN 202410865176A CN 118399891 B CN118399891 B CN 118399891B
- Authority
- CN
- China
- Prior art keywords
- circuit
- resistor
- capacitor
- inductor
- radio frequency
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000013078 crystal Substances 0.000 title claims abstract description 53
- 230000008878 coupling Effects 0.000 claims abstract description 17
- 238000010168 coupling process Methods 0.000 claims abstract description 17
- 238000005859 coupling reaction Methods 0.000 claims abstract description 17
- 239000003990 capacitor Substances 0.000 claims description 107
- 230000000903 blocking effect Effects 0.000 claims description 9
- 230000005284 excitation Effects 0.000 claims description 9
- 230000010355 oscillation Effects 0.000 abstract description 20
- 239000010453 quartz Substances 0.000 description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 8
- 238000013461 design Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 3
- 230000003321 amplification Effects 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 230000032683 aging Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000002860 competitive effect Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
- H03B5/02—Details
- H03B5/04—Modifications of generator to compensate for variations in physical values, e.g. power supply, load, temperature
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
- H03B5/30—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator
- H03B5/32—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator
Landscapes
- Oscillators With Electromechanical Resonators (AREA)
Abstract
The invention discloses a crystal oscillator circuit for improving phase noise, which mainly solves the problem that the existing parallel resonance circuit is difficult to realize lower phase noise index. The circuit comprises a main vibration exciting circuit, a feedback circuit and an impedance matching circuit which are connected with the main vibration exciting circuit, a frequency modulation circuit which is connected with the feedback circuit, an emitter coupling amplifying circuit which is connected with the frequency modulation circuit, an output matching filter circuit which is connected with the emitter coupling amplifying circuit, and a first power supply circuit and a second power supply circuit which respectively supply power for the main vibration exciting circuit and the emitter coupling amplifying circuit. The crystal resonator in the circuit is equivalent to a high-Q inductor, works in a parallel resonance area with wider frequency range, can excite more reliable stable oscillation, and meanwhile, the oscillation circuit has wider frequency adjustment range.
Description
Technical Field
The invention belongs to the technical field of radio frequency oscillators, and particularly relates to a crystal oscillator circuit for improving phase noise.
Background
As is well known, low noise quartz crystal oscillators are widely used in the fields of test measurement, radio communication, navigation positioning, radar, fire control, electronic countermeasure, etc., and are the "heart" of these electronic information devices, and their index performance determines the performance of electronic star devices. Increasing crystal oscillator performance, particularly the phase noise index, has been a direction of effort by practitioners in the industry.
Existing low phase noise crystal oscillators generally employ series resonant circuits in which a quartz crystal resonator operates in a series resonant mode, which can be equivalently a resistor. A typical circuit of a series resonant crystal oscillator is shown as a Butler circuit (CN 202713232U) in FIG. 2, wherein a 'pi' -type phase shifting network 201 is adopted in the circuit structure to realize 180 DEG phase shifting, and the phase condition and the gain condition required by oscillation are met together with a transistor Q200. With high Q quartz crystal resonators and appropriate increases in resonator excitation power, a phase noise floor better than-175 dBc/Hz is typically obtained. The ultralow phase noise oscillator circuits disclosed in patent CN115498962B all use similar series resonant schemes, and the quartz resonators all operate at the series resonant frequency (Fs in fig. 3) in the circuit, which is equivalent to a pure resistance characteristic.
In order to achieve a lower phase noise index, a series resonant circuit generally needs stronger excitation power, and in order to ensure frequency stability indexes such as aging and the like, a double-rotation cut type SC cut quartz crystal resonator with stress compensation characteristic is generally adopted in engineering practice. Because of the process and processing difficulty of the SC cut crystal resonator, the cost is always high and is far higher than that of the AT cut crystal resonator which is conventionally used.
Parallel resonant circuits such as Pierce and Colpitts oscillator circuits are widely used in conventional low cost crystal oscillator circuits. In this type of circuit, the crystal resonator operates in parallel resonant mode (Fp in fig. 3), which is equivalent to a high Q inductance in the circuit. Fig. 1 is a typical pierce oscillating circuit. The whole parallel resonance area in the circuit can excite stable oscillation, and an SC cut crystal resonator capable of bearing strong excitation can be selected, and an AT cut crystal resonator with lower cost can also be selected. The circuit has simple overall design and reliable oscillation, and can realize lower cost. However, the circuit topology is limited, and it is difficult to achieve a lower phase noise index by using a conventional parallel resonant circuit, such as the classic pierce circuit, theoretical simulation and practical test, which are adopted in the document "design of a high-frequency low-phase noise crystal oscillator circuit (piezoelectric and acousto-optic, volume 28, 3 rd phase, 2006, P256-P259)", and it is difficult to achieve a background phase noise index superior to-170 dBc/Hz by using the conventional pierce parallel resonant circuit.
Disclosure of Invention
The invention aims to provide a crystal oscillator circuit for improving phase noise, which mainly solves the problem that the existing parallel resonance circuit is difficult to realize lower phase noise index.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
A crystal oscillator circuit for improving phase noise comprises a main vibration exciting circuit, a feedback circuit and an impedance matching circuit which are connected with the main vibration exciting circuit, a frequency modulation circuit which is connected with the feedback circuit, an emitter coupling amplifying circuit which is connected with the frequency modulation circuit, an output matching filter circuit which is connected with the emitter coupling amplifying circuit, and a first power supply circuit and a second power supply circuit which respectively supply power for the main vibration exciting circuit and the emitter coupling amplifying circuit.
Further, in the present invention, the main vibration exciting circuit includes a rf transistor Q400, a resistor R401, and a bypass capacitor C402, wherein one end of the resistor R400 is connected with the emitter of the rf transistor Q400 after being connected in series, and the other end of the resistor R401 is grounded; the collector of the radio frequency transistor Q400 is connected with the impedance matching circuit, and the base of the radio frequency transistor Q400 is connected with the first power supply circuit and the feedback circuit.
Further, in the present invention, the feedback circuit includes a crystal resonator Y400 having one end connected to the base of the rf transistor Q400 via a capacitor C405, and a capacitor C403 having one end connected to the base of the rf transistor Q400 and the other end grounded; wherein the other end of the crystal resonator Y400 is connected to a frequency modulation circuit.
Further, in the present invention, the frequency modulation circuit includes a frequency modulation inductor L403 connected to the other end of the crystal resonator Y400, a varactor D400 whose negative electrode is connected to the other end of the frequency modulation inductor L403, a resistor R407, a capacitor C408, a resistor R405, and a resistor R408, wherein one end of the resistor R407 is connected to a common terminal of the resistor R407 and the capacitor C408, and the other end of the resistor R405 is connected to an external voltage control terminal EFC, and one end of the resistor R408 is connected to an anode of the varactor D400, and the other end of the resistor R408 is grounded; the positive electrode of the varactor diode D400 is also connected to an emitter-coupled amplifying circuit.
Further, in the present invention, the emitter-coupled amplifying circuit includes a rf transistor Q401 having an emitter connected to the anode of the diode D400 via a capacitor C409, a resistor R409, an inductor L404, and a bypass capacitor C410 connected in parallel to both ends of the inductor L404, wherein one end of the resistor R409 is connected to the emitter of the rf transistor Q401 and the other end of the resistor R is grounded after the resistor R is connected in series; the collector of the radio frequency transistor Q401 is connected with the output matching filter circuit and the second power supply circuit; the base of the RF transistor Q401 is connected to an impedance matching circuit.
Further, in the present invention, the impedance matching circuit includes an inductor L402, a capacitor C401, an inductor L401, and a capacitor C407, wherein one end of the inductor L402 is connected to the collector of the rf transistor Q400, the other end of the inductor L401 is connected to the other end of the capacitor C401, the inductor L400 and the capacitor C400 are connected in series, one end of the inductor L400 is connected to the common end of the inductor L401 and the inductor L402, and the other end of the inductor C400 is grounded, and the capacitor C407 and the resistor R410 are connected in series, one end of the capacitor C407 is connected to the common end of the inductor L402, and the other end of the capacitor C410 is connected to the base of the rf transistor Q401.
Further, in the present invention, the output matching filter circuit includes a blocking capacitor C412, an inductor L407, a capacitor C416, an inductor L406, a capacitor C414, an inductor L408, and a capacitor C415; one end of the blocking capacitor C412 is connected to the collector of the rf transistor Q401, and one end of the blocking capacitor C is connected to the rf output terminal RFOUT through the inductor L407 and the capacitor C416 in sequence, and two ends of the inductor L407 are connected to the ground through parallel LC circuits formed by the inductor L406 and the capacitor C414 and the inductor L408 and the capacitor C415, respectively.
Further, in the present invention, the first power supply circuit includes a resistor R403, a resistor R404, a resistor R402, a capacitor C404, a capacitor C406, and a resistor R406, wherein one end of the resistor R403 is connected to the base of the rf transistor Q400, one end of the capacitor C406 is connected to the other end of the capacitor C404, the other end of the capacitor C406 is connected to one end of the resistor R402, and the other end of the resistor R406 is connected to the other end of the resistor R402, and the other end of the resistor R406 is terminated with VCC; the other end of the resistor R404 is grounded, the common ends of the capacitor C406 and the capacitor C404 are grounded, and the common ends of the resistor R406 and the resistor R402 are connected with the common ends of the inductor L401 and the capacitor C401.
Further, in the present invention, the second power supply circuit includes an inductor L405 with one end connected to the collector of the rf transistor Q401, a capacitor C411 connected in parallel to two ends of the inductor L405, a resistor R411 and a resistor R413 connected to the other end of the inductor L405, a resistor R412 with one end connected to the other end of the resistor R411 and the other end grounded, and a capacitor C413 with one end connected to the common end of the inductor L405 and the resistor R411 and the other end grounded; the non-grounded terminal of the resistor R412 is further connected to the common terminal of the C407 and the resistor R410, and the other terminal of the resistor R413 is connected to the power VCC.
Compared with the prior art, the invention has the following beneficial effects:
(1) The crystal resonator in the circuit is equivalent to a high-Q inductor, works in a parallel resonance area with wider frequency range, can excite more reliable stable oscillation, and meanwhile, the oscillation circuit has wider frequency adjustment range.
(2) The main vibration excitation circuit adopts the common-emitter amplifier with the emitter AC grounded, and the whole circuit design is simple.
(3) The resonator in the circuit works in a parallel resonance mode, is applicable to both SC cut quartz crystal resonators and AT cut quartz crystal resonators, and has wider circuit adaptability. The AT cut crystal resonator is adopted to realize low cost and has stronger competitive advantage.
(4) The oscillation signal in the circuit is directly taken out of the crystal resonator network, the high-Q narrow-band frequency selection characteristic of the crystal resonator can be fully utilized, the radio frequency signal with extremely low phase noise can be realized, and the circuit structure can realize more excellent phase noise index than the traditional low phase noise crystal oscillator.
(5) The signal output stage amplifying circuit adopts the emitter coupling amplifying circuit, the positive feedback signal required by oscillation is input by the emitter of the amplifying stage transistor, taken out from the base electrode and fed back to the collector electrode of the main vibration exciting transistor, so that the oscillation exciting power can be stabilized, a wide frequency adjusting range is realized while the low phase noise index is ensured, and the frequency stability is improved.
Drawings
FIG. 1 is a schematic diagram of a typical Pierce crystal oscillator circuit;
FIG. 2 is a schematic diagram of a prior art ultralow phase noise crystal oscillator;
FIG. 3 is a schematic diagram of the frequency characteristics of a quartz crystal resonator;
FIG. 4 is a complete circuit diagram of the present invention;
fig. 5 is a simulated comparison of the phase noise of a conventional parallel resonant tank circuit and the phase noise indicator of the present invention.
Detailed Description
The invention will be further illustrated by the following description and examples, which include but are not limited to the following examples.
As shown in fig. 4, the crystal oscillator circuit for improving phase noise disclosed by the invention comprises a main vibration exciting circuit, a feedback circuit and an impedance matching circuit which are connected with the main vibration exciting circuit, a frequency modulation circuit which is connected with the feedback circuit, an emitter coupling amplifying circuit which is connected with the frequency modulation circuit, an output matching filter circuit which is connected with the emitter coupling amplifying circuit, and a first power supply circuit and a second power supply circuit which respectively supply power for the main vibration exciting circuit and the emitter coupling amplifying circuit.
In this embodiment, the main vibration exciting circuit includes a radio frequency transistor Q400, a resistor R401, and a bypass capacitor C402, wherein one end of the resistor R400 is connected with the emitter of the radio frequency transistor Q400 after being connected in series, and the other end of the resistor R401 is grounded; the collector of the radio frequency transistor Q400 is connected with the impedance matching circuit, and the base of the radio frequency transistor Q400 is connected with the first power supply circuit and the feedback circuit. R400 is an alternating current negative feedback resistor, and the gain of the amplifier is reduced in the circuit, so that the flicker noise coefficient of the main vibration excitation amplifier can be improved; the values of the resistors R401, R402, R403, R404 are adjusted to determine the quiescent operating point of the driver transistor Q400 to operate the transistor in a low noise figure linear amplification region. Bypass capacitor C402 has a sufficient capacitance to ensure that it is ac shorted to ground at the oscillator operating frequency; the RC low-pass filter structure formed by the bypass capacitor C404 and the resistor R402 can further improve the low-frequency noise of the bias circuit and improve the phase noise index of the oscillating signal.
In this embodiment, the feedback circuit includes a crystal resonator Y400 with one end connected to the base of the rf transistor Q400 via a capacitor C405, and a capacitor C403 with one end connected to the base of the rf transistor Q400 and the other end grounded; wherein the other end of the crystal resonator Y400 is connected to a frequency modulation circuit.
In this embodiment, the frequency modulation circuit includes a frequency modulation inductor L403 connected to the other end of the crystal resonator Y400, a varactor D400 whose negative electrode is connected to the other end of the frequency modulation inductor L403, a resistor R407 and a capacitor C408 connected in series with one end connected to the negative electrode of the varactor D400 and the other end grounded, a resistor R405 with one end connected to the common end of the resistor R407 and the capacitor C408 and the other end connected to the external voltage control end EFC, and a resistor R408 with one end connected to the positive electrode of the varactor D400 and the other end grounded; the positive electrode of the varactor diode D400 is also connected to an emitter-coupled amplifying circuit. The ground resistor R408 is connected to the positive electrode of the varactor diode D400 and provides a reference zero level, so that the varactor diode D400 is ensured to work in a reverse bias state. The voltage-controlled voltage EFC is connected to the negative electrode of the varactor diode through the resistors R405 and R407, the bypass capacitor C408 is arranged between the resistors R405 and R407 to the ground, the resistor R405 and the capacitor C408 form an RC filter, and noise introduced by the voltage-controlled terminal EFC can be filtered.
In this embodiment, the emitter-coupled amplifying circuit includes a rf transistor Q401 with an emitter connected to the anode of the diode D400 via a capacitor C409, a resistor R409, an inductor L404, and a bypass capacitor C410 connected in parallel to two ends of the inductor L404, wherein one end of the resistor R409 is connected to the emitter of the rf transistor Q401 and the other end of the resistor R is grounded after the resistor R is connected in series; the collector of the radio frequency transistor Q401 is connected with the output matching filter circuit and the second power supply circuit; the base of the RF transistor Q401 is connected to an impedance matching circuit. An oscillation feedback signal is input from the emitter of the transistor Q401, the feedback signal is led out from the base of the transistor Q401, and is fed back to the main oscillation amplifying circuit through the resistor R401 and the capacitor C407 in sequence, and the amplified oscillation signal is taken out from the collector of the transistor Q401; one end of a resistor R409 is connected to the emitter of the transistor Q401, and the other end is connected to the ground through a parallel resonance network consisting of an inductor L404 and a capacitor C410. In particular, the inductance L404, the capacitance C410 parallel resonance frequency is at the target oscillation frequency. The resistor R413 and the bypass capacitor C413 form a simple RC filter circuit, the power supply VCC supplies power to the emitter coupling amplifier through the R413, the voltage dividing resistors R411 and R412 supply direct current bias voltage to the transistor Q401 through the resistor R410, and the feedback signal power can be adjusted by adjusting the resistance value of the resistor R410. Inductor L405 provides a dc bias voltage to the collector of transistor Q401 and resonates tuned with capacitor C411 to improve the output signal spectral quality.
In this embodiment, the impedance matching circuit includes an inductor L402, a capacitor C401, and an inductor L401, one end of which is connected to the collector of the rf transistor Q400, and the other end of which is connected to the other end of the inductor L402, an inductor L400, a capacitor C400, and a capacitor C407, and a resistor R410, wherein one end of the inductor L401 is connected to the common end of the inductor L402 and the other end of which is grounded, after being connected in series, the other end of which is connected to the common end of the inductor L401 and the common end of the inductor L402, and the other end of which is connected to the base of the rf transistor Q401. In other embodiments, the configuration of the inductor L400 and the capacitor C400 may be series, parallel or series-parallel, where it is necessary to ensure that the inductor is capacitive near the oscillation frequency, equivalent to a capacitor, and inductive at other unwanted frequencies of the oscillation modes (e.g., the low harmonic mode of the reactive crystal resonator and the B mode of the SC-cut crystal resonator). The inductor L400 and the capacitor C400 are equivalent capacitors, the capacitor C403 and the crystal resonator Y400, and the serially connected capacitors C405, C409 and C407, the inductor L403 and the varactor D400 resistor R410 are connected together to form a pi positive feedback loop, so that the base electrode and the emitter electrode of the radio-frequency transistor Q400 are connected together to provide a phase condition for starting oscillation.
The matching circuit formed by the inductor L401, the inductor L402 and the capacitor C401 matches the high impedance of the collector of the transistor Q400 with the low impedance of the base of the transistor Q401 so as to ensure the necessary gain and phase condition of oscillation and ensure the smooth starting of the circuit.
In this embodiment, the output matching filter circuit includes a blocking capacitor C412, an inductor L407, a capacitor C416, an inductor L406, a capacitor C414, and an inductor L408, a capacitor C415; one end of the blocking capacitor C412 is connected to the collector of the rf transistor Q401, and one end of the blocking capacitor C is connected to the rf output terminal RFOUT through the inductor L407 and the capacitor C416 in sequence, and two ends of the inductor L407 are connected to the ground through parallel LC circuits formed by the inductor L406 and the capacitor C414 and the inductor L408 and the capacitor C415, respectively.
In this embodiment, the first power supply circuit includes a resistor R403, a resistor R404, a resistor R402, a capacitor C404, a capacitor C406, and a resistor R406, wherein one end of the resistor R403 is connected to the base of the rf transistor Q400, one end of the capacitor C406 is connected to the other end of the capacitor C404, the other end of the capacitor C406 is connected to one end of the resistor R402, and the other end of the resistor R406 is connected to the other end of the resistor R402, and the other end of the resistor R406 is connected to VCC; the other end of the resistor R404 is grounded, the common ends of the capacitor C406 and the capacitor C404 are grounded, and the common ends of the resistor R406 and the resistor R402 are connected with the common ends of the inductor L401 and the capacitor C401. In the circuit, R406 is a current limiting resistor and forms a simple RC filter circuit with a filter capacitor C406 to supply power for the main vibration excitation circuit.
In this embodiment, the second power supply circuit includes an inductor L405 with one end connected to the collector of the rf transistor Q401, a capacitor C411 connected in parallel to two ends of the inductor L405, a resistor R411 and a resistor R413 connected to the other end of the inductor L405, a resistor R412 with one end connected to the other end of the resistor R411 and the other end grounded, and a capacitor C413 with one end connected to the common end of the inductor L405 and the resistor R411 and the other end grounded; the non-grounded terminal of the resistor R412 is further connected to the common terminal of the C407 and the resistor R410, and the other terminal of the resistor R413 is connected to the power VCC. The output matching filter circuit is a typical LC chebyshev band-pass filter, and matches the collector output impedance of the amplifier transistor Q401 to the impedance (e.g., 50 ohms) required by the output signal, and simultaneously filters the output signal to improve the harmonic clutter suppression index of the output signal.
The main vibration excitation adopts the common emitter amplifier circuit, the crystal resonator in the circuit works in the parallel resonance area, the radio frequency signal is directly taken out from the feedback circuit of the crystal resonator, and the high Q characteristic of the crystal resonator can be utilized separately, so that extremely low phase noise index is obtained; the emitter coupling amplifying circuit performs signal amplification and also participates in the feedback of an oscillation signal, and can compensate loop gain when external load impedance changes or the junction capacitance of the varactor changes in a large range, so that the excitation power of the resonator is stabilized, and the output frequency is stabilized. In fig. 5, curve a is the phase noise prediction of the traditional pierce parallel oscillating circuit when the output signal is 100MHz, and curve B is the phase noise index prediction of the invention when the output signal is 100MHz, and it can be seen that the phase noise index of the oscillator output signal is obviously improved, the oscillation is more reliable, and a larger frequency adjustment range and frequency stability can be provided under the condition that the same crystal resonator parallel resonance mode is adopted in the circuit scheme. In addition, the invention allows the use of the AT cut-type crystal resonator with lower cost, ensures excellent phase noise index, has the characteristics of simple overall circuit design and more obvious cost advantage, and can be widely applied to high-performance electronic information equipment such as test measurement equipment, communication systems, radar systems, time synchronization systems and the like.
The above embodiment is only one of the preferred embodiments of the present invention, and should not be used to limit the scope of the present invention, but all the insubstantial modifications or color changes made in the main design concept and spirit of the present invention are still consistent with the present invention, and all the technical problems to be solved are included in the scope of the present invention.
Claims (4)
1. The crystal oscillator circuit for improving phase noise is characterized by comprising a main vibration exciting circuit, a feedback circuit and an impedance matching circuit which are connected with the main vibration exciting circuit, a frequency modulation circuit which is connected with the feedback circuit, an emitter coupling amplifying circuit which is connected with the frequency modulation circuit, an output matching filter circuit which is connected with the emitter coupling amplifying circuit, and a first power supply circuit and a second power supply circuit which respectively supply power for the main vibration exciting circuit and the emitter coupling amplifying circuit;
The main vibration excitation circuit comprises a radio frequency transistor Q400, a resistor R401 and a bypass capacitor C402, wherein one end of the resistor R400 is connected with the emitter of the radio frequency transistor Q400 after being connected in series, and the other end of the resistor R401 is grounded; the collector of the radio frequency transistor Q400 is connected with the impedance matching circuit, and the base of the radio frequency transistor Q400 is connected with the first power supply circuit and the feedback circuit;
The feedback circuit comprises a crystal resonator Y400 with one end connected with the base electrode of the radio frequency transistor Q400 through a capacitor C405, and a capacitor C403 with one end connected with the base electrode of the radio frequency transistor Q400 and the other end grounded; the other end of the crystal resonator Y400 is connected with a frequency modulation circuit;
The frequency modulation circuit comprises a frequency modulation inductor L403 connected with the other end of the crystal resonator Y400, a varactor D400 with the negative electrode connected with the other end of the frequency modulation inductor L403, a resistor R407 and a capacitor C408, wherein one end of the resistor R407 is connected with the negative electrode of the varactor D400 and the other end of the resistor R408 is grounded after the series connection, a resistor R405 with one end connected with the common end of the resistor R407 and the capacitor C408 and the other end connected with an external voltage control end EFC, and a resistor R408 with one end connected with the positive electrode of the varactor D400 and the other end grounded; the positive electrode of the varactor diode D400 is also connected with an emitter coupling amplifying circuit;
The emitter coupling amplifying circuit comprises a radio frequency transistor Q401, an emitter of which is connected with the anode of a diode D400 through a capacitor C409, a resistor R409, an inductor L404 and a bypass capacitor C410, wherein one end of the resistor R409 is connected with the emitter of the radio frequency transistor Q401 after being connected in series, and the other end of the resistor R404 is grounded; the collector of the radio frequency transistor Q401 is connected with the output matching filter circuit and the second power supply circuit; the base electrode of the radio frequency transistor Q401 is connected with an impedance matching circuit;
The impedance matching circuit comprises an inductor L402 and a capacitor C401, wherein one end of the inductor L402 is connected with the collector of the radio frequency transistor Q400, one end of the inductor L401 is connected with the other end of the inductor L402, the other end of the inductor L401 is connected with the other end of the capacitor C401, the inductor L400 and the capacitor C400 are connected with the common end of the inductor L402 and the other end of the inductor L400 is grounded after being connected in series, and the capacitor C407 and the resistor R410 are connected with the common end of the inductor L401 and the common end of the inductor L402 and the other end of the capacitor C410 are connected with the base of the radio frequency transistor Q401 after being connected in series.
2. The crystal oscillator circuit for improving phase noise according to claim 1, wherein the output matching filter circuit comprises a blocking capacitor C412, an inductor L407, a capacitor C416, an inductor L406, a capacitor C414, an inductor L408, and a capacitor C415; one end of the blocking capacitor C412 is connected to the collector of the rf transistor Q401, and one end of the blocking capacitor C is connected to the rf output terminal RFOUT through the inductor L407 and the capacitor C416 in sequence, and two ends of the inductor L407 are connected to the ground through parallel LC circuits formed by the inductor L406 and the capacitor C414 and the inductor L408 and the capacitor C415, respectively.
3. The crystal oscillator circuit for improving phase noise according to claim 2, wherein the first power supply circuit comprises a resistor R403 connected at one end to the base of the radio frequency transistor Q400, a resistor R404, a resistor R402 connected at one end to the resistor R403, a capacitor C404, a capacitor C406 connected at one end to the other end of the capacitor C404 and connected at the other end to one end of the resistor R402, and a resistor R406 connected at one end to the other end of the resistor R402 and connected at the other end to VCC; the other end of the resistor R404 is grounded, the common ends of the capacitor C406 and the capacitor C404 are grounded, and the common ends of the resistor R406 and the resistor R402 are connected with the common ends of the inductor L401 and the capacitor C401.
4. A crystal oscillator circuit for improving phase noise according to claim 3, wherein the second power supply circuit comprises an inductor L405 with one end connected to the collector of the radio frequency transistor Q401, a capacitor C411 connected in parallel to both ends of the inductor L405, a resistor R411 and a resistor R413 connected to the other end of the inductor L405, a resistor R412 with one end connected to the other end of the resistor R411 and the other end grounded, and a capacitor C413 with one end connected to the common end of the inductor L405 and the resistor R411 and the other end grounded; the non-grounded terminal of the resistor R412 is further connected to the common terminal of the C407 and the resistor R410, and the other terminal of the resistor R413 is connected to the power VCC.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410865176.7A CN118399891B (en) | 2024-07-01 | 2024-07-01 | Crystal oscillator circuit for improving phase noise |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410865176.7A CN118399891B (en) | 2024-07-01 | 2024-07-01 | Crystal oscillator circuit for improving phase noise |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN118399891A CN118399891A (en) | 2024-07-26 |
| CN118399891B true CN118399891B (en) | 2024-09-20 |
Family
ID=91985497
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202410865176.7A Active CN118399891B (en) | 2024-07-01 | 2024-07-01 | Crystal oscillator circuit for improving phase noise |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN118399891B (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115498962A (en) * | 2022-11-16 | 2022-12-20 | 成都世源频控技术股份有限公司 | Low-phase-noise crystal oscillator circuit and implementation method |
| CN115955196A (en) * | 2023-03-14 | 2023-04-11 | 成都世源频控技术股份有限公司 | High-performance low-noise crystal oscillator circuit |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6909334B2 (en) * | 2001-03-08 | 2005-06-21 | Rf Monolithics, Inc. | Low phase noise, wide tune range saw oscillators and methods of operating the same |
| US6768389B2 (en) * | 2002-09-23 | 2004-07-27 | Ericsson Inc. | Integrated, digitally-controlled crystal oscillator |
| JP2020088706A (en) * | 2018-11-29 | 2020-06-04 | セイコーエプソン株式会社 | Oscillator, electronic apparatus and mobile body |
-
2024
- 2024-07-01 CN CN202410865176.7A patent/CN118399891B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115498962A (en) * | 2022-11-16 | 2022-12-20 | 成都世源频控技术股份有限公司 | Low-phase-noise crystal oscillator circuit and implementation method |
| CN115955196A (en) * | 2023-03-14 | 2023-04-11 | 成都世源频控技术股份有限公司 | High-performance low-noise crystal oscillator circuit |
Also Published As
| Publication number | Publication date |
|---|---|
| CN118399891A (en) | 2024-07-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN106877819B (en) | Voltage controlled oscillator based on composite resonator | |
| US6297704B1 (en) | Oscillation circuits featuring coaxial resonators | |
| US20010004225A1 (en) | Oscillation circuits featuring coaxial resonators | |
| EP1096665A2 (en) | Coaxial resonator and oscillation circuits featuring coaxial resonators | |
| CN115498962B (en) | Low-phase-noise crystal oscillator circuit and implementation method | |
| FI97925C (en) | A voltage controlled oscillator circuit with improved tuning linearity | |
| CN115955196B (en) | High-performance low-noise crystal oscillator circuit | |
| CN118399891B (en) | Crystal oscillator circuit for improving phase noise | |
| US6489853B1 (en) | Low phase noise oscillator | |
| US6486744B1 (en) | Low phase noise voltage-controlled oscillator and method of using the same | |
| US20070090889A1 (en) | High frequency colpitts oscillation circuit | |
| CN2299422Y (en) | Broadband Electronic Oscillator | |
| CN116886046B (en) | Voltage-controlled oscillating circuit | |
| Nick et al. | A very low phase-noise voltage-controlled-oscillator at X-band | |
| US7369007B2 (en) | Oscillating circuit for suppressing second harmonic wave | |
| CN113872527B (en) | Overtone temperature compensation crystal oscillator and electronic equipment | |
| CN115051650B (en) | S-band Octave Band Low Phase Noise Voltage Controlled Oscillator and Signal Generator | |
| CN113037217B (en) | 10MHZ crystal oscillator working at ultra-low phase noise | |
| CN111416576B (en) | Oscillator based on coaxial medium resonant cavity and design method | |
| CN115865026A (en) | Microwave voltage-controlled oscillator with low phase noise | |
| CN210297638U (en) | Stable constant-current bias CASCODE MMIC VCO | |
| CN217508714U (en) | Voltage-controlled oscillator and signal generating device of frequency doubling band low phase noise | |
| US4743865A (en) | Quartz-crystal microwave oscillator of the common-emitter transmission type with two transistors and a predetermined loaded Q factor | |
| US4843349A (en) | UHF crystal oscillator | |
| US3839685A (en) | Single-stage balanced oscillator/frequency multiplier |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |