CN111082802B - Crystal oscillator driving circuit - Google Patents
Crystal oscillator driving circuit Download PDFInfo
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- CN111082802B CN111082802B CN201911164284.7A CN201911164284A CN111082802B CN 111082802 B CN111082802 B CN 111082802B CN 201911164284 A CN201911164284 A CN 201911164284A CN 111082802 B CN111082802 B CN 111082802B
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- nmos
- pmos
- crystal oscillator
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- capacitor
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L3/00—Starting of generators
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L5/00—Automatic control of voltage, current, or power
Abstract
The invention discloses a crystal oscillator driving circuit, which comprises: first to fourth PMOS, first to fourth NMOS, first to third resistors, first and second switches, and capacitor; according to the crystal oscillator driving circuit, the switch capacitor is formed by the two switches and the capacitor, the switch capacitor does not work before the crystal oscillator starts to vibrate, the starting speed of the driving circuit is not affected, and after the crystal oscillator starts to vibrate, the switch capacitor works to enable the fourth PMOS to be turned off, so that the bias current is reduced to be an original value, and the power consumption of the bias current is not increased.
Description
Technical Field
The invention relates to the field of semiconductor device manufacturing, in particular to a crystal oscillator driving circuit.
Background
In the time sequence circuit, a crystal oscillator, for short, is the most basic electronic component and is widely used in integrated circuits. The crystal oscillator is characterized in that a slice (called a wafer for short) is cut from a quartz crystal according to a certain azimuth angle, silver layers are coated on two corresponding surfaces of the slice to serve as electrodes, a lead wire is welded on each electrode to be connected to a pin, and a packaging shell is added to form the quartz crystal resonator, called quartz crystal or crystal and crystal oscillator for short. And adding an IC inside the package constitutes a crystal element of the oscillating circuit called a crystal oscillator. The products are generally encapsulated with a metal shell, and also encapsulated with a glass shell, ceramic or plastic.
The crystal oscillator can be electrically equivalent to a two-end network of a capacitor and a resistor which are connected in parallel and then connected in series, the network has two resonance points in electroengineering, and the lower frequency is series resonance and the higher frequency is parallel resonance in the high-low frequency. Because the characteristics of the crystal itself cause the distance between the two frequencies to be quite close, in the extremely narrow frequency range, the crystal oscillator is equivalent to an inductor, so that the crystal oscillator can form a parallel resonant circuit as long as the two ends of the crystal oscillator are connected in parallel with proper capacitors. The parallel resonant circuit can be added into a negative feedback circuit to form a sine wave oscillating circuit, and the frequency of the oscillator does not change greatly even if the parameters of other elements change greatly because the frequency range of the crystal oscillator equivalent as an inductor is narrow.
The conventional crystal oscillator driving circuit is shown in fig. 1, and comprises 3 PMOS transistors (MP 1-MP 3), 3 NMOS transistors (MN 1-MN 3), MP2 and MN2 connected in series, MP3 and MN3 connected in series, the gates of MP1, MP2 and MP3 connected together and short-circuited with the drain of MP2, MP1 and MN1 connected in series through a resistor R1, the gate of MN1 connected with the drain of MP1, the gate of MN2 connected with the drain of MN1, and the gate of MN3 connected with the crystal oscillator and connected with the drain of MP3 through a resistor Rf.
The crystal oscillator oscillation signal outputs forward and reverse clock signals through an operational amplifier.
The driving circuit is characterized in that:
if the bias current is small, the circuit is started slowly; if the bias current is large, current waste is caused after the stabilization.
The aspect ratio of MN2 is N times that of MN1, and current I is generated on R1 B ＝(kT/q)*lnN/R1；
Wherein K is the Boltzmann constant T, and q is the temperature.
The amplifier AMP amplifies the signals of X1 and X2 to power supply ground.
Disclosure of Invention
The invention aims to provide a crystal oscillator driving circuit which has the characteristic of quick starting and does not increase power consumption.
In order to solve the above problems, a crystal oscillator driving circuit according to the present invention includes:
first to fourth PMOS, first to fourth NMOS, first to third resistors, first and second switches, and capacitor;
the first PMOS is connected with the first NMOS in series through a first resistor, the source electrode of the first NMOS is grounded, and the source electrode of the first PMOS is connected with a power supply;
the second PMOS is connected in series with the second NMOS, the source electrode of the second NMOS is grounded, and the source electrode of the second PMOS is connected with a power supply;
the third PMOS is connected in series with the third NMOS, the source electrode of the third NMOS is grounded, and the source electrode of the third PMOS is connected with a power supply;
the fourth PMOS is connected in series with the fourth NMOS, the source electrode of the fourth NMOS is grounded, and the source electrode of the fourth PMOS is connected with the drain electrode of the second PMOS;
the grid electrodes of the first PMOS, the second PMOS and the third PMOS are connected and then connected with the drain electrode of the second PMOS;
the grid electrode of the first NMOS is connected with the drain electrode of the first PMOS, and the grid electrode of the second NMOS is connected with the drain electrode of the first NMOS and the grid electrode of the fourth NMOS;
the grid electrode of the fourth PMOS is connected with a DET control signal;
the first end of the first switch is connected with a power supply, the second section of the first switch is connected with the first end of the second switch, the second end of the second switch is grounded through a third resistor, and the second section of the second switch is a DET control signal;
the first end of the capacitor is connected with the first end of the first switch, and the second end of the capacitor is grounded;
and the crystal oscillator is connected with the grid electrode of the third NMOS and the drain electrode of the third NMOS through a second resistor.
The further improvement is that the first switch, the second switch and the capacitor form a switch capacitor, and the equivalent resistance is as follows:
wherein C is capacitance value, F is crystal oscillator frequency.
A further improvement is that the switched capacitor is not operated during the start-up.
When the DET control signal is at a low level, the fourth PMOS is conducted, the width-to-length ratio of the fourth NMOS is M times that of the first NMOS, M is more than or equal to 1, and M is an integer.
A further improvement is that the switched capacitor operates after the start of the oscillation.
The further improvement is that after the switch capacitor works, the equivalent resistance Req is far smaller than the third resistance, the DET control signal is at high level, and at this time, the fourth PMOS is turned off:
according to the crystal oscillator driving circuit, the switch capacitor is formed by the two switches and the capacitor, the switch capacitor does not work before the crystal oscillator starts to vibrate, the starting speed of the driving circuit is not affected, and after the crystal oscillator starts to vibrate, the switch capacitor works to enable the fourth PMOS to be turned off, so that the bias current is reduced to be an original value, and the power consumption of the bias current is not increased.
Drawings
Fig. 1 is a diagram of a conventional crystal oscillator driving circuit.
Fig. 2 is a diagram of the crystal oscillator driving circuit according to the present invention.
Detailed Description
As shown in fig. 2, the crystal oscillator driving circuit of the present invention includes first to fourth PMOS (corresponding to MP1 to MP 4), first to fourth NMOS (corresponding to MN1 to MN 4), first to third resistors (first resistor R1, second resistor Rf, third resistor Ra), first and second switches (SW 1, SW 2), and a capacitor Ca.
The first PMOS is connected with the first NMOS in series through a first resistor, the source electrode of the first NMOS is grounded, and the source electrode of the first PMOS is connected with a power supply.
The second PMOS is connected in series with the second NMOS, the source electrode of the second NMOS is grounded, and the source electrode of the second PMOS is connected with a power supply.
The third PMOS is connected with the third NMOS in series, the source electrode of the third NMOS is grounded, and the source electrode of the third PMOS is connected with a power supply.
The fourth PMOS is connected with the fourth NMOS in series, the source electrode of the fourth NMOS is grounded, and the source electrode of the fourth PMOS is connected with the drain electrode of the second PMOS.
And the grid electrodes of the first PMOS, the second PMOS and the third PMOS are connected and then connected with the drain electrode of the second PMOS.
The grid electrode of the first NMOS is connected with the drain electrode of the first PMOS, and the grid electrode of the second NMOS is connected with the drain electrode of the first NMOS and the grid electrode of the fourth NMOS.
And the grid electrode of the fourth PMOS is connected with a DET control signal.
The first end of the first switch is connected with a power supply, the second section of the first switch is connected with the first end of the second switch, the second end of the second switch is grounded through a third resistor, and the second section of the second switch is a DET control signal.
The first end of the capacitor is connected with the first end of the first switch, and the second end of the capacitor is grounded.
And the crystal oscillator is connected with the grid electrode of the third NMOS and the drain electrode of the third NMOS through a second resistor.
The crystal oscillator also comprises an operational amplifier (op amp), the clock after the crystal oscillator is started generates a forward and reverse clock signal after the op amp, the forward clock signal is also provided for the first switch to control the opening and closing of the first switch, and the reverse clock signal is provided for the second switch to control the opening and closing of the second switch.
The circuit structure is the crystal oscillator driving circuit provided by the invention, and compared with the traditional structure, the circuit is added with a fourth PMOS, a fourth NMOS, two switches, a capacitor and a resistor to form a switch capacitor.
The working principle is as follows:
the first switch SW1, the second switch SW2 and the capacitor Ca form a switch capacitor, and the equivalent resistance of the switch capacitor is Req:
wherein C is the capacitance of the capacitor Ca, and F is the crystal oscillator frequency.
When the crystal oscillator does not start vibrating, the switch capacitor does not work, the DET control signal is at a low level, the fourth PMOS MP4 controlled by the DET signal is in a conducting state, because the width-to-length ratio of the fourth NMOS is M times that of the first NMOS, M is more than or equal to 1, M is an integer, and the current flowing through R1 at the moment is:
I B0 is the current value flowing through the bias circuit R1 when the crystal oscillator is not started, and has the bias current I generated by the traditional structure B The larger current value of = (kT/q) lnN/R1 can accelerate the start-up speed of the driving circuit.
After the crystal oscillator starts to vibrate, the switch capacitor starts to work, the equivalent resistance Req of the switch capacitor formed by the first switch SW1, the second switch SW2 and the capacitor Ca is far smaller than Ra, the DET control signal is at high level, the fourth PMOS MP4 is turned off, and at this moment, the current flowing through R1 is as follows:
from the above description, it can be seen that the bias current of the present invention is the same as that of the conventional structure after the crystal oscillator is started, that is, the circuit structure of the present invention does not increase the power consumption after the crystal oscillator is started.
The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Various modifications and variations of the present invention will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A crystal oscillator driving circuit is characterized in that: the driving circuit includes:
first to fourth PMOS, first to fourth NMOS, first to third resistors, first and second switches, and capacitor;
the first PMOS is connected with the first NMOS in series through a first resistor, the source electrode of the first NMOS is grounded, and the source electrode of the first PMOS is connected with a power supply;
the second PMOS is connected in series with the second NMOS, the source electrode of the second NMOS is grounded, and the source electrode of the second PMOS is connected with a power supply;
the third PMOS is connected in series with the third NMOS, the source electrode of the third NMOS is grounded, and the source electrode of the third PMOS is connected with a power supply;
the fourth PMOS is connected in series with the fourth NMOS, the source electrode of the fourth NMOS is grounded, and the source electrode of the fourth PMOS is connected with the drain electrode of the second PMOS;
the grid electrodes of the first PMOS, the second PMOS and the third PMOS are connected and then connected with the drain electrode of the second PMOS;
the grid electrode of the first NMOS is connected with the drain electrode of the first PMOS, and the grid electrode of the second NMOS is connected with the drain electrode of the first NMOS and the grid electrode of the fourth NMOS; the drain electrode of the second NMOS is connected with the drain electrode of the second PMOS;
the grid electrode of the fourth PMOS is connected with a DET control signal; the drain electrode of the fourth PMOS is connected with the drain electrode of the fourth NMOS;
the first end of the first switch is connected with a power supply, the second end of the first switch is connected with the first end of the second switch, the second end of the second switch is grounded through a third resistor, and the second end of the second switch is a DET control signal;
the first end of the capacitor is connected with the first end of the first switch, and the second end of the capacitor is grounded;
and the crystal oscillator is connected with the grid electrode of the third NMOS and the drain electrode of the third NMOS through a second resistor.
2. The crystal oscillator drive circuit of claim 1, wherein: the width-to-length ratio of the fourth NMOS is M times that of the first NMOS, M is more than or equal to 1, and M is an integer.
3. The crystal oscillator drive circuit of claim 1, wherein: the crystal oscillator driving circuit also comprises an operational amplifier, and the clock after the crystal oscillator starts to vibrate outputs forward and reverse clock signals after the operational amplifier.
4. The crystal oscillator drive circuit of claim 1, wherein: the first switch and the second switch are respectively controlled by clock signals output by the crystal oscillator.
5. The crystal oscillator drive circuit according to claim 3 or 4, characterized in that: the first switch is controlled by a forward clock of the operational amplifier, and the second switch is controlled by a reverse clock of the operational amplifier.
6. The crystal oscillator drive circuit of claim 1, wherein: the first switch, the second switch and the capacitor form a switch capacitor, and the equivalent resistance is as follows:
wherein C is capacitance value, F is crystal oscillator frequency.
7. The crystal oscillator drive circuit of claim 1, wherein: before the crystal oscillator starts vibrating, the switch capacitor does not work.
8. The crystal oscillator drive circuit of claim 7, wherein: before the crystal oscillator starts vibrating, the DET control signal is in a low level, the fourth PMOS is conducted, and the width-to-length ratio of the fourth NMOS is M times that of the first NMOS:
I B0 the current value flowing through the bias resistor R1 when the crystal oscillator does not start to vibrate is K, K is a Boltzmann constant, T is temperature, q is a charge constant, N is a width-to-length ratio multiple of the second NMOS and the first NMOS, and R1 is the resistance value of the first resistor.
9. The crystal oscillator drive circuit of claim 1, wherein: after the crystal oscillator starts to vibrate, the switch capacitor works.
10. The crystal oscillator drive circuit according to claim 6 or 9, characterized in that: after the switched capacitor works, the equivalent resistance Req of the switched capacitor is far smaller than that of the third resistor, the DET control signal is at a high level, and at the moment, the fourth PMOS is turned off:
I B1 is the current flowing through the bias resistor R1 after the crystal oscillator is started to vibrate, K is the Boltzmann constant, T is the temperature, q is the charge constant, N is the width-to-length ratio multiple of the second NMOS and the first NMOS, R1 is the resistance value of the first resistor, I B Is the branch current through resistor R1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911164284.7A CN111082802B (en) | 2019-11-25 | 2019-11-25 | Crystal oscillator driving circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911164284.7A CN111082802B (en) | 2019-11-25 | 2019-11-25 | Crystal oscillator driving circuit |
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| CN111082802A CN111082802A (en) | 2020-04-28 |
| CN111082802B true CN111082802B (en) | 2023-04-28 |
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| CN114689964B (en) * | 2022-02-28 | 2023-11-24 | 深圳市造物工场科技有限公司 | Crystal oscillator starting stability testing circuit, testing and adjusting method |
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|---|---|---|---|---|
| JP2006019877A (en) * | 2004-06-30 | 2006-01-19 | Epson Toyocom Corp | Voltage-controlled crystal oscillator |
| CN102118131A (en) * | 2009-12-31 | 2011-07-06 | 意法-爱立信公司 | Method for shortening start time of crystal oscillator |
| CN103346782A (en) * | 2013-07-09 | 2013-10-09 | 东南大学 | Fast oscillation starting crystal oscillator |
| CN106100584A (en) * | 2016-06-23 | 2016-11-09 | 上海芯赫科技有限公司 | Voltage-Controlled oscillation circuit |
| CN107666314A (en) * | 2017-10-23 | 2018-02-06 | 上海华虹宏力半导体制造有限公司 | Crystal oscillator drive circuit |
| CN110113032A (en) * | 2019-05-17 | 2019-08-09 | 芯翼信息科技(南京)有限公司 | Crystal oscillation control circuit and its control method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB0220617D0 (en) * | 2002-09-05 | 2002-10-16 | Koninkl Philips Electronics Nv | Active matrix liquid crystal display devices |
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2019
- 2019-11-25 CN CN201911164284.7A patent/CN111082802B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006019877A (en) * | 2004-06-30 | 2006-01-19 | Epson Toyocom Corp | Voltage-controlled crystal oscillator |
| CN102118131A (en) * | 2009-12-31 | 2011-07-06 | 意法-爱立信公司 | Method for shortening start time of crystal oscillator |
| CN103346782A (en) * | 2013-07-09 | 2013-10-09 | 东南大学 | Fast oscillation starting crystal oscillator |
| CN106100584A (en) * | 2016-06-23 | 2016-11-09 | 上海芯赫科技有限公司 | Voltage-Controlled oscillation circuit |
| CN107666314A (en) * | 2017-10-23 | 2018-02-06 | 上海华虹宏力半导体制造有限公司 | Crystal oscillator drive circuit |
| CN110113032A (en) * | 2019-05-17 | 2019-08-09 | 芯翼信息科技(南京)有限公司 | Crystal oscillation control circuit and its control method |
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| CN111082802A (en) | 2020-04-28 |
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