CN114900130A - Novel differential crystal oscillator circuit - Google Patents
Novel differential crystal oscillator circuit Download PDFInfo
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- CN114900130A CN114900130A CN202210587463.7A CN202210587463A CN114900130A CN 114900130 A CN114900130 A CN 114900130A CN 202210587463 A CN202210587463 A CN 202210587463A CN 114900130 A CN114900130 A CN 114900130A
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- bipolar transistor
- resistor
- field effect
- effect transistor
- load
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- 239000013078 crystal Substances 0.000 title claims abstract description 27
- 230000010355 oscillation Effects 0.000 claims abstract description 13
- 230000005669 field effect Effects 0.000 claims description 52
- 238000010586 diagram Methods 0.000 description 4
- 239000002184 metal Substances 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000036039 immunity Effects 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- 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
- H03B5/36—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator active element in amplifier being semiconductor device
- H03B5/364—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator active element in amplifier being semiconductor device the amplifier comprising field effect transistors
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- 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
- H03B2200/00—Indexing scheme relating to details of oscillators covered by H03B
- H03B2200/006—Functional aspects of oscillators
- H03B2200/0088—Reduction of noise
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- Oscillators With Electromechanical Resonators (AREA)
Abstract
The invention discloses a novel differential crystal oscillator circuit, which comprises an oscillator, a first load, a second load, a fifth resistor, a sixth resistor, a first bipolar transistor, a second bipolar transistor and a low-resistance path for assisting the oscillator to start oscillation, wherein the first load is connected with the fifth resistor; one end of the oscillator is connected with a collector electrode of the first bipolar transistor, and the collector electrode of the first bipolar transistor is connected with an external power supply through a first load and is connected with a base electrode of the second bipolar transistor; the other end of the oscillator is connected with a collector electrode of a second bipolar transistor, and the collector electrode of the second bipolar transistor is connected to an external power supply through a second load and is connected with a base electrode of the first bipolar transistor; one end of a low-resistance path is connected with the oscillator in parallel, the other end of the low-resistance path is connected with the base electrode of the first bipolar transistor through a fifth resistor, and the other end of the low-resistance path is connected with the base electrode of the second bipolar transistor through a sixth resistor.
Description
Technical Field
The invention belongs to the technical field of electronic circuit design, and particularly relates to a novel differential crystal oscillator circuit.
Background
In wireless communication systems, oscillators are a very critical part, often used to generate a reference frequency, and therefore it is desirable that the frequency be adjustable within a certain range while maintaining good stability. LC oscillators can achieve frequency regulation but produce poor frequency stability. Therefore, in wireless communication systems, crystal oscillators are often used to generate frequencies with better stability. Crystals, such as quartz, are often easier to generate stable frequencies because of their higher Q values.
For different transceivers, the harmonics of the oscillator may be easily coupled to other radio frequency circuits via multiple paths and appear at the output. Compared with a single-ended structure, the differential crystal oscillator has better immunity to various interferences.
In a traditional common differential crystal oscillator circuit, a metal field effect transistor is often used as a gain tube, and because a current path does not exist in a grid electrode of the metal field effect transistor, a structure formed by two gain tubes in the oscillator cannot cause a starting problem due to mismatch. However, because the flicker noise of the mosfet is large, the lower the frequency is, the more obvious the mosfet is, the structure greatly deteriorates the near-end phase noise, and the output phase noise of the oscillator is poor. In order to solve the problem of poor output noise, bipolar transistors are often used in a traditional differential crystal oscillator circuit, but the gates of the bipolar transistors have current flowing, two bipolar transistors form a latch in the oscillator circuit in a differential mode, and the latch is easily locked in another abnormal state due to the positive feedback effect under the mismatch condition, so that the problem of oscillation starting is caused.
Disclosure of Invention
The purpose of the invention is as follows: in order to solve the noise problem of the traditional differential crystal oscillator and the starting vibration problem caused by the noise problem, the invention provides a novel differential crystal oscillator circuit.
The technical scheme is as follows: the invention discloses a novel differential crystal oscillator circuit, which comprises an oscillator, a first load, a second load, a fifth resistor, a sixth resistor, a first bipolar transistor, a second bipolar transistor and a low-resistance path for assisting the oscillator to start oscillation, wherein the first load is connected with the fifth resistor;
one end of the oscillator is connected with a collector of the first bipolar transistor, the collector of the first bipolar transistor is connected with an external power supply through the first load, the collector of the first bipolar transistor is connected with a base of the second bipolar transistor, and an emitter of the first bipolar transistor is grounded;
the other end of the oscillator is connected with a collector of a second bipolar transistor, the collector of the second bipolar transistor is connected to an external power supply through a second load, the collector of the second bipolar transistor is connected with a base of the first bipolar transistor, and an emitter of the second bipolar transistor is grounded;
one end of the low-resistance path is connected with the differential output end of the oscillator, the other end of the low-resistance path is connected with the base electrode of the first bipolar transistor through a fifth resistor, and the other end of the low-resistance path is connected with the base electrode of the second bipolar transistor through a sixth resistor.
Further, the low-resistance path comprises a third resistor, a fourth resistor, a first field effect transistor and a second field effect transistor;
the third resistor and the fourth resistor are connected in series and then connected with the differential output end of the oscillator, the grid electrode of the first field effect transistor is connected with the connection point of the third resistor and the fourth resistor, the drain electrode of the first field effect transistor is connected with an external power supply, the source electrode of the first field effect transistor is connected with the drain electrode of the second field effect transistor, the source electrode of the first field effect transistor is connected with the grid electrode of the second field effect transistor, and the source electrode of the second field effect transistor is grounded;
the base electrode of the first bipolar transistor is connected with the grid electrode of the second field effect transistor through a fifth resistor; the base of the second bipolar transistor is connected to the gate of the second field effect transistor via a sixth resistor.
Further, the first load is a first resistor, and the second load is a second resistor.
Further, the first load is a first current source, and the second load is a second current source.
Further, the first field effect transistor may be replaced by a third bipolar transistor.
Further, the second field effect transistor may be replaced by a fourth bipolar transistor.
Has the advantages that: the invention solves the problem of oscillation starting of the bipolar transistor under the mismatch condition by adding the auxiliary oscillation starting circuit, and greatly reduces the phase noise of the output end by adopting the bipolar transistor as the gain tube in the differential crystal oscillation circuit.
Drawings
FIG. 1 is a diagram of a novel differential crystal oscillator circuit using resistors as the load;
fig. 2 is a diagram of a novel differential crystal oscillator circuit employing a current source as a load.
Fig. 3 is a diagram of a novel differential crystal oscillator circuit using a field effect transistor as a load.
Fig. 4 is a diagram of a novel differential crystal oscillator circuit using an inductor as a load.
Detailed Description
The technical solution of the present invention will be further explained with reference to the accompanying drawings.
The invention relates to a novel differential crystal oscillating circuit, which mainly comprises: the circuit comprises an oscillator X1, a first load, a second load, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a first bipolar transistor M1, a second bipolar transistor M2, a first field effect transistor M3 and a second field effect transistor M4.
One end of the oscillator X1 is connected to the collector of the first bipolar transistor M1, the collector of the first bipolar transistor M1 is connected to an external power source through the first load at the same time, and the collector of the first bipolar transistor M1 is connected to the base of the second bipolar transistor M2. The emitter of the first bipolar transistor M1 is grounded.
The other end of the oscillator X1 is connected to the collector of the second bipolar transistor M2, the collector of the second bipolar transistor M2 is connected to an external power source through the second load at the same time, and the collector of the second bipolar transistor M2 is connected to the base of the first bipolar transistor M1. The emitter of the second bipolar transistor M2 is grounded.
The third resistor R3, the fourth resistor R4, the first field effect transistor M3 and the second field effect transistor M4 form a vibration auxiliary circuit, and the main functions of the vibration auxiliary circuit are as follows: by introducing a low-impedance path at low frequency, the loop gain of the two bipolar transistors at low frequency is low, and the problem of oscillation starting of the bipolar transistors M1 and M2 under mismatch conditions is solved. The specific circuit structure of the start-up auxiliary circuit will now be further described. The third resistor R3 is connected in series with the fourth resistor R4 and then connected in parallel with the oscillator X1, the gate of the first field effect transistor M3 is connected with the connection point of the third resistor R3 and the fourth resistor R4, the drain of the first field effect transistor M3 is connected with an external power supply, the source of the first field effect transistor M3 is connected with the drain of the second field effect transistor M4 and simultaneously connected with the gate of the second field effect transistor M4, and the source of the second field effect transistor M4 is grounded.
The base of the first bipolar transistor M1 is connected with the gate of the second field effect transistor M4 through a fifth resistor R5; the base of the second bipolar transistor M1 is connected to the gate of the second field effect transistor M4 via a sixth resistor R6.
The invention adopts the bipolar transistors M1 and M2 as gain tubes, and because the bipolar transistors have no flicker noise, the phase noise at the output end of the crystal oscillation circuit is greatly improved.
As shown in fig. 1, a resistor may be used as a load, that is, the novel differential crystal oscillation circuit mainly includes: the circuit comprises an oscillator X1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a first bipolar transistor M1, a second bipolar transistor M2, a first field effect transistor M3 and a second field effect transistor M4.
One end of the oscillator X1 is connected to the collector of the first bipolar transistor M1, the collector of the first bipolar transistor M1 is connected to the external power source through the first resistor R1, and the collector of the first bipolar transistor M1 is connected to the base of the second bipolar transistor M2. The emitter of the first bipolar transistor M1 is grounded.
The other end of the oscillator X1 is connected to the collector of the second bipolar transistor M2, the collector of the second bipolar transistor M2 is connected to an external power source through the second resistor R2, and the collector of the second bipolar transistor M2 is connected to the base of the first bipolar transistor M1. The emitter of the second bipolar transistor M2 is grounded.
The third resistor R3, the fourth resistor R4, the first field effect transistor M3 and the second field effect transistor M4 form a low-resistance path for assisting oscillation starting.
As shown in fig. 2, a current source may be used as a load, that is, the novel differential crystal oscillation circuit mainly includes: the circuit comprises an oscillator X1, a first current source I1, a second current source I2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a first bipolar transistor M1, a second bipolar transistor M2, a first field effect transistor M3 and a second field effect transistor M4.
One end of the oscillator X1 is connected to the collector of the first bipolar transistor M1, the collector of the first bipolar transistor M1 is connected to the external power source through the first current source I1, and the collector of the first bipolar transistor M1 is connected to the base of the second bipolar transistor M2. The emitter of the first bipolar transistor M1 is grounded.
The other end of the oscillator X1 is connected to the collector of the second bipolar transistor M2, the collector of the second bipolar transistor M2 is connected to the external power source through the second current source I2, and the collector of the second bipolar transistor M2 is connected to the base of the first bipolar transistor M1. The emitter of the second bipolar transistor M2 is grounded.
The third resistor R3, the fourth resistor R4, the first field effect transistor M3 and the second field effect transistor M4 form a low-resistance path for assisting oscillation starting.
The first field effect transistor M3 and the second field effect transistor M4 may be replaced by bipolar transistors, or one of them may be a bipolar transistor and the other may be a field effect transistor.
The structure of the auxiliary circuit may be a circuit structure of a similar principle.
Claims (6)
1. A novel differential crystal oscillator circuit, characterized by: the oscillator comprises an oscillator, a first load, a second load, a fifth resistor, a sixth resistor, a first bipolar transistor, a second bipolar transistor and a low-resistance path for assisting the oscillator to start oscillation;
one end of the oscillator is connected with a collector of the first bipolar transistor, the collector of the first bipolar transistor is connected with an external power supply through the first load, the collector of the first bipolar transistor is connected with a base of the second bipolar transistor, and an emitter of the first bipolar transistor is grounded;
the other end of the oscillator is connected with a collector of a second bipolar transistor, the collector of the second bipolar transistor is connected to an external power supply through a second load, the collector of the second bipolar transistor is connected with a base of the first bipolar transistor, and an emitter of the second bipolar transistor is grounded;
one end of the low-resistance path is connected with the differential output end of the oscillator, the other end of the low-resistance path is connected with the base electrode of the first bipolar transistor through a fifth resistor, and the other end of the low-resistance path is connected with the base electrode of the second bipolar transistor through a sixth resistor.
2. The novel differential crystal oscillator circuit of claim 1, wherein: the low-resistance path comprises a third resistor, a fourth resistor, a first field effect transistor and a second field effect transistor;
the third resistor and the fourth resistor are connected in series and then connected with the differential output end of the oscillator, the grid electrode of the first field effect transistor is connected with the connection point of the third resistor and the fourth resistor, the drain electrode of the first field effect transistor is connected with an external power supply, the source electrode of the first field effect transistor is connected with the drain electrode of the second field effect transistor, the source electrode of the first field effect transistor is connected with the grid electrode of the second field effect transistor, and the source electrode of the second field effect transistor is grounded;
the base electrode of the first bipolar transistor is connected with the grid electrode of the second field effect transistor through a fifth resistor; the base of the second bipolar transistor is connected to the gate of the second field effect transistor via a sixth resistor.
3. A novel differential crystal oscillator circuit according to claim 1 or 2, characterized in that: the first load is a first resistor, and the second load is a second resistor.
4. A novel differential crystal oscillator circuit according to claim 1 or 2, characterized in that: the first load is a first current source, and the second load is a second current source.
5. The novel differential crystal oscillator circuit of claim 2, wherein: the first field effect transistor may be replaced by a third bipolar transistor.
6. A novel differential crystal oscillator circuit according to claim 2 or 5, wherein: the second field effect transistor may be replaced by a fourth bipolar transistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210587463.7A CN114900130A (en) | 2022-05-27 | 2022-05-27 | Novel differential crystal oscillator circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210587463.7A CN114900130A (en) | 2022-05-27 | 2022-05-27 | Novel differential crystal oscillator circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114900130A true CN114900130A (en) | 2022-08-12 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210587463.7A Pending CN114900130A (en) | 2022-05-27 | 2022-05-27 | Novel differential crystal oscillator circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114900130A (en) |
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2022
- 2022-05-27 CN CN202210587463.7A patent/CN114900130A/en active Pending
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