阅读说明：本技术 一种超宽频段晶体驱动电路 (Ultra-wide frequency band crystal driving circuit ) 是由 宋登明 于 2021-09-09 设计创作，主要内容包括：本发明公开了一种超宽频段晶体驱动电路,涉及集成电路技术领域,尤其涉及一种晶体驱动电路。该超宽频段晶体驱动电路包括反馈电阻模块、起振电路模块和第一选择器；反馈电阻模块连接于起振电路模块,起振电路模块连接于第一选择器、外部晶体和外部负载端；第一选择器连接于起振电路模块；起振电路模块还包括低频起振子电路和中高频起振子电路；当需要启动外部晶体时,驱动电路根据所需频率连接对应晶体；发送控制信号至反馈电阻模块,以将反馈电阻模块的阻值配置到启动晶体所需的阻值；发送选择信号至起振电路模块,以接通起振电路模块；第一选择器根据选择信号将选择后的晶体振荡信号输出至后续电路。本发明的晶体驱动电路减小了芯片面积和成本。(The invention discloses an ultra-wide frequency band crystal driving circuit, relates to the technical field of integrated circuits, and particularly relates to a crystal driving circuit. The ultra-wide frequency band crystal driving circuit comprises a feedback resistor module, a starting oscillation circuit module and a first selector; the feedback resistance module is connected with the oscillation starting circuit module, and the oscillation starting circuit module is connected with the first selector, the external crystal and the external load end; the first selector is connected with the oscillation starting circuit module; the oscillation starting circuit module also comprises a low-frequency oscillation starting circuit and a medium-high frequency oscillation starting sub-circuit; when the external crystal needs to be started, the driving circuit is connected with the corresponding crystal according to the required frequency; sending a control signal to the feedback resistance module to configure the resistance value of the feedback resistance module to the resistance value required by starting the crystal; sending a selection signal to the oscillation starting circuit module to switch on the oscillation starting circuit module; the first selector outputs the selected crystal oscillation signal to a subsequent circuit according to the selection signal. The crystal driving circuit reduces the chip area and the cost.)

1. The ultra-wide frequency band crystal driving circuit is characterized by being used for driving a low-frequency crystal or a medium-high frequency crystal and outputting a low-frequency or medium-high frequency crystal oscillation signal; the crystal driving circuit comprises a feedback resistance module, an oscillation starting circuit module and a first selector;

the feedback resistance module is connected with the oscillation starting circuit module, and the oscillation starting circuit module is connected with the first selector, the external crystal and the external load end; the first selector is connected to the oscillation starting circuit module; the oscillation starting circuit module also comprises a low-frequency oscillation starting circuit and a medium-high frequency oscillation starting sub-circuit which are respectively used for starting the low-frequency crystal and the medium-high frequency crystal;

when the external crystal needs to be started, the driving circuit is connected with the corresponding crystal according to the required clock frequency; sending a control signal to the feedback resistance module to configure the resistance value of the feedback resistance module to the resistance value required by starting the crystal; sending a selection signal to the oscillation starting circuit module to switch on one oscillator circuit in the oscillation starting circuit module and simultaneously close the other oscillator circuit; the first selector outputs the selected crystal oscillation signal to a subsequent circuit according to the selection signal.

2. The ultra-wide band crystal driving circuit of claim 1, further comprising an output module, connected to the first selector, for increasing a driving capability of the crystal oscillation signal and outputting the crystal oscillation signal.

3. The ultra-wide band crystal driving circuit of claim 2, wherein said driving circuit further comprises a flip-flop module, said flip-flop module being connected to said output module and said external load terminal for sending an externally input clock signal to said output module.

4. The ultra-wide band crystal drive circuit of claim 3, wherein said trigger module is a Schmitt trigger.

5. The ultra-wideband crystal drive circuit according to claim 3, further comprising a second selector connected to said flip-flop module and said first selector for outputting a signal of said flip-flop module or said first selector.

6. The ultra-wide band crystal driving circuit according to claim 5, wherein the driving circuit further comprises a register module, the register module configures the control signal to adjust the resistance of the feedback resistor module, and configures the selection signal to selectively switch on the low-frequency oscillator starting sub-circuit or the medium-high frequency oscillator starting sub-circuit; the register module is also configured with a first starting signal or a second starting signal to respectively start the low-frequency oscillator starting sub-circuit or the medium-high frequency oscillator starting sub-circuit.

7. The ultra-wide band crystal driving circuit of claim 6, wherein the register module further sends a bypass control signal to the flip-flop module, the oscillation starting circuit module and the second selector, so as to turn on the external load terminals of the flip-flop module and the crystal driving circuit, turn off the oscillation starting circuit module, and enable the second selector to selectively output an external clock signal.

8. The ultra-wide band crystal driving circuit according to claim 1, wherein the feedback resistor module comprises a plurality of resistors connected in series, the plurality of resistors connected in series are respectively connected in parallel with a switch, and the control signal controls the on/off of the switch to adjust the resistance of the feedback resistor module.

9. The ultra-wide band crystal driving circuit of claim 8, wherein the resistance of the feedback resistor module is in a range of 500Kohm to 10 Mohm.

Technical Field

The invention relates to the technical field of integrated circuits, in particular to a crystal driving circuit, and particularly relates to an ultra-wide frequency band crystal driving circuit.

Background

Since the 20 th generation of the last century, the theoretical research and manufacturing level of the crystal driver are rapidly developed, and all performance indexes are remarkably improved. As a clock frequency source, crystal oscillators are widely used in military and consumer electronics fields because of their superior Q values, frequency accuracies, stability, and the like, as compared to other types of oscillators. In the field of integrated circuits, the role of an IO interface integrated circuit is crucial in order to effectively and reasonably transmit a crystal frequency signal to a chip core.

With the increasing requirements on the performance of the crystal driving circuit, the crystal driving circuit with 32.768KHz (low frequency) or several MHz to several tens MHz (medium-high frequency) is the direction of the research of designers. However, in the conventional crystal driving circuit, both the low frequency 32.768K and the medium-high frequency are independent from each other in different chips. If the same chip needs to support the low-frequency crystal oscillator and the medium-high frequency crystal oscillator at the same time, even if the two frequencies cannot exist in the chip system at the same time, the two crystal oscillators need to be provided with a crystal driving circuit, packaging pins and an external resistor respectively in the chip, so that the area of the chip is increased, the available packaging pins are reduced, and the cost is greatly increased.

Disclosure of Invention

The invention mainly aims to provide a crystal driving circuit with an ultra-wide frequency band, aiming at simultaneously supporting a low-frequency crystal oscillator and a medium-high frequency crystal oscillator by the same chip.

In order to achieve the above object, the present invention provides an ultra-wide frequency band crystal driving circuit, for driving a low frequency crystal or a middle or high frequency crystal and outputting a low frequency or middle or high frequency crystal oscillation signal; the crystal driving circuit comprises a feedback resistance module, an oscillation starting circuit module and a first selector; the feedback resistance module is connected with the oscillation starting circuit module, and the oscillation starting circuit module is connected with the first selector, the external crystal and the external load end; the first selector is connected to the oscillation starting circuit module; the oscillation starting circuit module also comprises a low-frequency oscillation starting circuit and a medium-high frequency oscillation starting sub-circuit which are respectively used for starting the low-frequency crystal and the medium-high frequency crystal; when the external crystal needs to be started, the driving circuit is connected with the corresponding crystal according to the required frequency; sending a control signal to the feedback resistance module to configure the resistance value of the feedback resistance module to the resistance value required by starting the crystal; sending a selection signal to the oscillation starting circuit module to switch on one oscillator circuit in the oscillation starting circuit module and simultaneously close the other oscillator circuit; the first selector outputs the selected crystal oscillation signal to a subsequent circuit according to the selection signal.

Preferably, the driving circuit further includes an output module, connected to the first selector, for increasing the driving capability of the crystal oscillation signal and outputting the increased driving capability.

Preferably, the driving circuit further includes a flip-flop module, connected to the output module and the external load terminal, for sending an externally input clock signal to the output module.

Preferably, the trigger module is a schmitt trigger.

Preferably, the crystal driving circuit further comprises a second selector connected to the flip-flop module and the first selector, for outputting a signal of the flip-flop module or the first selector.

Preferably, the driving circuit further comprises a register module, and the register module configures the control signal to adjust the resistance value of the feedback resistance module and configures the selection signal to selectively switch on the low-frequency oscillator starting sub-circuit or the medium-high frequency oscillator starting sub-circuit; the register module is also configured with a first starting signal or a second starting signal to respectively start the low-frequency oscillator starting sub-circuit or the medium-high frequency oscillator starting sub-circuit.

Preferably, the register module further sends a bypass control signal to the flip-flop module, the oscillation starting circuit module and the second selector, so as to turn on the external load terminals of the flip-flop module and the crystal driving circuit, turn off the oscillation starting circuit module, and enable the second selector to selectively output an external clock signal.

Preferably, the feedback resistor module includes a plurality of resistors connected in series, the plurality of resistors connected in series are respectively connected in parallel with a switch, and the control signal controls the on or off of the switch to adjust the resistance value of the feedback resistor module.

Preferably, the resistance value range of the feedback resistance module is 500 Kohm-10 Mohm.

According to the technical scheme, the low-frequency oscillator starting sub-circuit and the medium-high frequency oscillator starting sub-circuit are integrated in the same chip, the feedback resistance required by the oscillator starting circuit module is met by adjusting the resistance value of the feedback resistance module, the low-frequency oscillator starting sub-circuit or the medium-high frequency oscillator starting sub-circuit is respectively connected through the selection signal, the low-frequency crystal or the medium-high frequency crystal is respectively started, the requirements of a chip system on different clocks are met, the circuit design area is reduced, the use of pins and external resistors are reduced, and the chip area and the chip cost are greatly reduced.

Drawings

FIG. 1 is a schematic circuit diagram of an ultra-wide band transistor driving circuit according to the present invention;

FIG. 2 is a circuit diagram of an ultra-wide band transistor driving circuit according to the present invention;

fig. 3 is a circuit diagram of a feedback resistor module in the ultra-wide band crystal driving circuit according to the present invention.

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention is further described below with reference to the accompanying drawings.

The embodiment of the invention provides an ultra-wide frequency band crystal driving circuit, which supports the driving of a low-frequency crystal and a medium-high frequency crystal and is used for providing clock signals with different frequencies for a chip system.

As shown in fig. 1 and fig. 2, the ultra-wide band crystal driving circuit is used for driving a low-frequency crystal or a middle-high frequency crystal and outputting a low-frequency or middle-high frequency crystal oscillation signal, and includes a feedback resistance module, an oscillation starting circuit module, and a first selector MUX 1; the feedback resistance module is connected to the oscillation starting circuit module, and the oscillation starting circuit module is connected to the first selector MUX1, an external crystal and external load terminals X0 and X1; the first selector MUX1 is connected to the oscillation circuit module; the oscillation starting circuit module also comprises a low-frequency oscillation starting circuit and a medium-high frequency oscillation starting sub-circuit which are respectively used for starting the low-frequency crystal and the medium-high frequency crystal; when the external crystal needs to be started, the driving circuit is connected with the corresponding crystal according to the required clock frequency; sending a control signal RF _ SEL to the feedback resistor module to configure the resistance value of the feedback resistor module to the resistance value required by starting the crystal; sending a selection signal REG _ SEL to the oscillation starting circuit module to switch on one oscillator circuit in the oscillation starting circuit module and simultaneously close the other oscillator circuit; the first selector MUX1 outputs the selected crystal oscillation signal to the subsequent circuit according to the selection signal REG _ SEL.

According to the embodiment of the invention, the low-frequency oscillator starting circuit and the medium-high frequency oscillator starting sub-circuit are integrated in the same chip, the feedback resistance required by the oscillator starting circuit module is met by adjusting the resistance value of the feedback resistance module, the low-frequency or medium-high frequency oscillator starting sub-circuit is respectively connected through the selection signal REG _ SEL, the low-frequency or medium-high frequency crystal is respectively started, the requirements of a chip system on different clocks are met, the circuit design area is reduced, the use of pins and external resistors are reduced, and the chip area and the chip cost are greatly reduced.

Specifically, the specific circuit structure of the low-frequency oscillator circuit and the medium-high frequency oscillator circuit in the oscillator circuit module can use any oscillator circuit disclosed in the prior art, and only needs to respectively and correspondingly meet the requirement of starting the low-frequency crystal or the medium-high frequency crystal.

In a specific embodiment, when the chip system requires a low frequency clock signal, the crystal driving circuit connects the low frequency crystal at its external load terminals X0, X1 and hangs up the load to ground. And sending a control signal RF _ SEL to the feedback resistor module so as to configure the resistance value of the feedback resistor module to the resistance value required for starting the low-frequency crystal. And sending a selection signal REG _ SEL to the low-frequency oscillator starting sub-circuit to switch on the low-frequency oscillator starting sub-circuit and simultaneously switch off the medium-high frequency oscillator starting sub-circuit. After the low frequency crystal is started, the first selector MUX1 outputs the low frequency crystal oscillation signal to the subsequent circuit according to the selection signal REG _ SEL.

In another embodiment, when the system-on-chip requires a mid-high frequency clock signal, the crystal driving circuit connects the mid-high frequency crystal at its external load terminals X0, X1 and puts the load on ground. And sending a control signal RF _ SEL to the feedback resistor module so as to configure the resistance value of the feedback resistor module to the resistance value required for starting the medium-high frequency crystal. And sending a selection signal REG _ SEL to the medium-high frequency oscillator starting sub-circuit to switch on the medium-high frequency oscillator starting sub-circuit and switch off the low-frequency oscillator starting sub-circuit. After the medium-high frequency crystal is started, the first selector MUX1 outputs the medium-high frequency crystal oscillation signal to the subsequent circuit according to the selection signal REG _ SEL.

In a preferred embodiment, as shown in fig. 2, the crystal driving circuit further includes a register module, where the register module configures the control signal RF _ SEL to adjust a resistance value of the feedback resistor module, and configures the selection signal REG _ SEL to selectively turn on the low-frequency oscillator starting sub-circuit or the middle-high-frequency oscillator starting sub-circuit; the register module also configures a first enable signal 32K _ IOPSEL or a second enable signal MF _ IOPSEL to enable the low frequency oscillator starting sub-circuit or the mid-high frequency oscillator starting sub-circuit, respectively. Specifically, the first start signal 32K _ IOPSEL is used to start the low frequency oscillator circuit, and the second start signal MF _ IOPSEL is used to start the middle-high frequency oscillator sub-circuit.

In a specific embodiment, when the chip system requires a low frequency clock signal, the crystal driving circuit connects the low frequency crystal at its external load terminals X0, X1 and hangs up the load to ground. The register module sends a control signal RF _ SEL to the feedback resistor module so as to configure the resistance value of the feedback resistor module to the resistance value required for starting the low-frequency crystal. The register module sends a selection signal REG _ SEL to the low-frequency oscillator starting sub-circuit to switch on the low-frequency oscillator starting sub-circuit and simultaneously close the medium-high frequency oscillator starting sub-circuit. The register module sends a first starting signal 32K _ IOPSEL to the low-frequency oscillator starting sub-circuit so that the low-frequency oscillator starting sub-circuit works normally and starts the low-frequency crystal. The register module sends a selection signal REG _ SEL to the first selector MUX1, and the first selection selectively outputs the low frequency crystal oscillation signal to the subsequent circuits. Specifically, the first enable signal 32K _ IOPSEL is a suitable low frequency crystal start-up current. The oscillation starting current can be set according to the specific frequency of the crystal, the actual circuit process and other conditions.

In another embodiment, when the system-on-chip requires a mid-high frequency clock signal, the crystal driving circuit connects the mid-high frequency crystal at its external load terminals X0, X1 and puts the load on ground. The register module sends a control signal RF _ SEL to the feedback resistor module so as to configure the resistance value of the feedback resistor module to the resistance value required by starting the medium-high frequency crystal. The register module sends a selection signal REG _ SEL to the medium-high frequency oscillator starting sub-circuit so as to switch on the medium-high frequency oscillator starting sub-circuit and switch off the low-frequency oscillator starting sub-circuit. The register module sends a second starting signal MF _ IOPSEL to the medium-high frequency oscillation starting sub-circuit so as to enable the medium-high frequency oscillation starting sub-circuit to work normally and start the medium-high frequency crystal. The register module sends a selection signal REG _ SEL to the first selector MUX1, and the first selector MUX1 selects and outputs the middle-high frequency crystal oscillation signal to the subsequent circuits. Specifically, the second enable signal MF _ IOPSEL is a suitable mid-high frequency crystal start-up current. The oscillation starting current can be set according to the specific frequency of the crystal, the actual circuit process and other conditions.

In a preferred embodiment, as shown in fig. 1 and fig. 2, the driving circuit further includes an output module VOUT, and the output module VOUT is connected to the first selector MUX1, and is configured to increase a driving capability of the crystal oscillation signal and output the crystal oscillation signal. The output module VOUT is used for outputting a crystal oscillation signal of the driving circuit and increasing the driving capability.

In a preferred embodiment, as shown in fig. 1 and fig. 2, the driving circuit further includes a flip-flop module BUFFER, which is connected to the output module VOUT and the external load terminals X0 and X1, and is configured to send an externally input clock signal to the output module VOUT. Clock signals input from outside are input through the external load ends X0 and X1, the crystal driving clock is replaced, the clock signals can be input according to actual needs, and flexibility is greatly improved. Specifically, the trigger module BUFFER is a schmitt trigger.

Further, as shown in fig. 1 and fig. 2, the crystal driving circuit further includes a second selector MUX2, and the second selector MUX2 is connected to the flip-flop module BUFFER and the first selector MUX1, and is configured to output a signal of the flip-flop module BUFFER or the first selector MUX 1.

Furthermore, the register module also sends a bypass control signal BYP to the flip-flop module BUFFER, the oscillation starting circuit module and the second selector MUX2, so as to turn on the external load terminals X0 and X1 of the flip-flop module BUFFER and the crystal driving circuit, turn off the oscillation starting circuit module, and enable the second selector MUX2 to selectively output the external clock signal.

When the chip system requires a clock signal other than the crystal driving clock, the clock signal can be selected to be inputted from the outside. Specifically, the register module inputs a bypass control signal BYP to the oscillation starting circuit module, the flip-flop module BUFFER and the second selector MUX2 to turn off the oscillation starting circuit module, the external clock signal is input to the flip-flop module BUFFER from the external load terminals X0 and X1, and then is sent to the second selector MUX2 from the flip-flop module BUFFER, and the second selector MUX2 selects the external clock signal to output. In an embodiment, the external clock signal may be input according to the specific clock requirements of the chip system.

In the embodiment of the invention, during actual use, an external crystal or an external clock signal can be selected according to the required frequency, the resistance value of the feedback resistance module is controlled by the register module, and then the register module is used for selecting whether the low-frequency oscillator circuit works or the medium-high frequency oscillator circuit works.

In a preferred embodiment, the feedback resistor module includes a plurality of resistors connected in series, each of the plurality of resistors connected in parallel has a switch, and the control signal RF _ SEL controls the on/off of the switch to adjust the resistance of the feedback resistor module.

Further, the resistance range of the feedback resistance module is 500 Kohm-10 Mohm. In the specific embodiment, the low-frequency crystal generally refers to a 32.768K crystal, and correspondingly, the feedback resistance value of the crystal during operation is generally 10 Mohm; the medium-high frequency crystal is generally 4-32M crystal, and correspondingly, the feedback resistance value of the crystal during working is generally 500 Kohm-2 Mohm. In other embodiments, the required crystal can be connected according to user requirements, and then the resistance range of the feedback resistance module is set according to the crystal, and the specific resistance can be preset according to actual use conditions.

Specifically, as shown in fig. 3, the feedback resistance module includes a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4 connected in series in sequence, and the other end of the first resistor S1 and the other end of the fourth resistor S4 are further connected to the oscillation starting circuit module. The second resistor R2 is connected in parallel with a first switch S1, the third resistor R3 is connected in parallel with a second switch S2, the fourth resistor R4 is connected in parallel with a third switch S3, and the register module respectively sends control signals RF _ SEL to the first switch S1, the second switch S2 and the third switch S3 so as to respectively control the on or off of the first switch S1, the third switch R4 and the third switch S3. Specifically, the first control sub-signal RF _ SEL <1> is used to control the on or off of the first switch S1; the second control sub-signal RF _ SEL <2> is used to control the on or off of the second switch S2; the third control sub-signal RF _ SEL <3> is used to control the third switch S3 to be turned on or off. Presetting the resistance values of a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4 to be 500Kohm, 1.5Mohm, 3Mohm and 5Mohm in sequence; when the low-frequency 32.768K crystal needs to be driven, all resistors are switched on, and the resistance value of the resistor can be fed back when the low-frequency crystal works; when the medium-high frequency 4-32M crystal needs to be driven, the medium-high frequency crystal can work after the resistor with the corresponding resistance value is connected. In other embodiments, the number of resistors and switches may be preset according to actual requirements.

The specific embodiment is as follows:

as shown in fig. 2, in the first embodiment, when the crystal driving circuit is used for a 32.768K crystal driving circuit:

connecting 32.768K crystals between external load terminals X0 and X1 of the crystal drive circuit; the external load terminals X0 and X1 are used for hanging a load of 12pF to the ground; sending a control signal RF _ SEL through a register module to configure the resistance value of the feedback resistance module to 10 Mohm; let the bypass control signal BYP output by the register module be 0, select the crystal oscillation mode, that is: turning off the trigger module BUFFER, turning on the oscillation starting circuit module, and enabling the second selector MUX2 to select and output the oscillation signal of the oscillation starting circuit module;

the register module is used for sending a selection signal REG _ SEL to select the low-frequency oscillator starting circuit to work, simultaneously closing the medium-high frequency oscillator starting circuit, and then sending a first starting signal 32K _ IOPSEL to configure a proper 32.768K crystal oscillator starting current; at this time, the crystal oscillator starts to work, and the output module VOUT outputs a 32.768K clock signal.

As shown in fig. 2, in the second embodiment, when the transistor driving circuit is used in a middle-high frequency transistor driving circuit, 32M transistors are taken as an example:

connecting a 32M crystal between external load terminals X0 and X1 of the crystal driving circuit; the external load terminals X0 and X1 are used for hanging a load of 12pF to the ground; sending a control signal RF _ SEL through the register module to configure the resistance value of the feedback resistor module to be 500 Kohm; let the bypass control signal BYP output by the register module be 0, select the crystal oscillation mode, that is: turning off the trigger module BUFFER, turning on the oscillation starting circuit module, and enabling the second selector MUX2 to select and output the oscillation signal of the oscillation starting circuit module;

the register module is used for sending a selection signal REG _ SEL to select the medium-high frequency oscillator starting circuit to work, simultaneously close the low-frequency oscillator starting circuit, and then sending a second starting signal MF _ IOPSEL to configure proper 32M crystal oscillator starting current; at this time, the crystal oscillator starts to operate, and the output module VOUT outputs a 32M clock signal.

As shown in fig. 2, in the third embodiment, when the system-on-chip requires an external input clock signal, i.e. a crystal bypass mode:

the bypass control signal BYP output by the register module is set to be 1, the external clock input mode is selected, the priority of the bypass control signal BYP is very high, and when the priority of the bypass control signal BYP is set to be 1, the low-frequency oscillation starting sub-circuit or the medium-high frequency oscillation starting sub-circuit cannot work;

the clock signal is input from the external load terminal X0 of the crystal driving circuit, at this time, the crystal oscillator does not work, the clock output at the output module VOUT is equal to the clock input at the external load terminal X0, that is, at this time, the external load terminal X0 inputs the 10MHz clock, and the output module VOUT also outputs the 10MHz clock.

In the mode, clock signal input with any frequency can be supported, more clock frequency selections are provided for the chip system, and the flexibility of the chip system is improved.

It should be understood that the above is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent structures or equivalent flow transformations made by the present specification and drawings, or applied directly or indirectly to other related technical fields, are included in the scope of the present invention.