TWI325231B - Automatic switching phase-locked loop - Google Patents

Description

于 u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u u A phase-locked loop of a multi-band voltage controlled oscillator (Muiti band Voltage Control Oscillator). [Prior Art] The voltage-controlled vibrator must still be able to modulate or adjust the frequency to a sufficient range to cover a specific operating frequency L in the worst case expected. Voltage-controlled vibration 1:11 is commonly used in phase-locked loops. According to the phase-locked loop, the operating range of this limb can be used for riding or solving multiple frequencies. The worst conditions can be caused by factors such as supply voltage variations, process variations, and component tolerance changes. Traditionally, most phase-locked loops use a single-band voltage-controlled oscillator to provide a single-bright range (ie, single-operating frequency band). For a traditional phase-locked loop with a single-band voltage-controlled oscillator, the voltage-controlled oscillator's modulation range must cover the specific operating frequency range under the worst-case conditions. The voltage controlled oscillator must have a gain of phase tA in order to achieve a sufficiently large modulation equation. However, the large gain will cause the sensitivity of the voltage-controlled vibrating noise and the output jitter to be inferior. The multi-band voltage controlled oscillator provides a plurality of frequency ranges (i.e., a plurality of operating frequency bands) that collectively represent the complete modulation of the voltage controlled oscillator. The multi-band voltage-controlled oscillator cuts the variable frequency band into a complex operating frequency band, and the control signal received by the voltage controlled oscillator is P2005-040/0697-A40700-TW/^ 1325231, y clumsy: Λ4 The corresponding frequency range is only a small one of the operating bands, so the gain of the multi-band voltage controlled oscillator can be reduced. Multi-band voltage controlled oscillators can thus improve many of the shortcomings of single-band voltage controlled oscillators. Since the multi-band voltage controlled oscillator can operate in any of a plurality of operating frequency bands, the appropriate operating frequency band must be selected at any given time. Therefore, there is a need for a phase locked loop that utilizes a multi-band voltage controlled oscillator and has an automatic switching mechanism to properly switch the operating frequency band. SUMMARY OF THE INVENTION In a first embodiment of the present invention, an automatic switching phase locked loop includes a phase extractor, a charge pump, a band selector, a filter, and a band selector. The phase detector has a first input terminal for receiving a reference signal and a second input terminal for receiving a feedback signal, and outputs a phase detection signal corresponding to a phase difference between the reference signal and the feedback signal. The charge is received by the phase "[detection signal and based on the phase detection signal to generate a pump current. The band selector receives a control voltage and generates a band selection signal and a voltage setting signal according to the control voltage. The filter generates the control voltage based on the pump current and sets a signal according to the voltage to reset the control voltage. The multi-band voltage controlled oscillator is coupled to the control voltage and the frequency band selection signal for selecting one of a plurality of operating frequency bands according to the frequency band selection signal, and providing an output signal according to the control voltage, the output signal The frequency is within the frequency range of the selected operating band. The band selector detects whether the control voltage falls within a reference voltage range, and if so, neither the band selection signal is generated to convert the multi-frequency P2005-040/0697-A40700-TW/no 7 ϋ8·12. η, with voltage controlled oscillation II The control voltage, with a voltage controlled oscillator, the control voltage. *·The operating band of the monthly correction replacement page does not generate the voltage setting signal to set otherwise, then the band selection signal is generated to convert the multi-frequency operating band and generate the voltage slave number to set the other embodiment of the phase circuit. In one embodiment, the embodiment of the actual crying is only to increase or lock the debt test, whether the more active switching circuit is locked, and the frequency band selection 2, the k-lock signal, and more according to the locking signal to generate the frequency.

With a selection signal and the voltage setting signal. V The band selector measures whether the control voltage { falls within a range or at least one of the additional reference voltage ranges, and the reference voltage range of 1 is adjacent to the reference money range. When the control 5 electric power is pressed within the reference voltage range, the money band selection ϋ neither generates the frequency band selection signal to convert the operating frequency band of the multi-band voltage controlled oscillator: the voltage setting signal is used to set the Control voltage. When the control voltage falls in one of the at least one additional reference voltage range, the frequency band selector generates the frequency band selection signal and generates the voltage after receiving the lock signal indicating that the automatic switching phase locked loop is in a locked state. Set the signal. When the control voltage does not fall within the reference voltage range or fall within the additional reference voltage, the (four) converter may generate the fresh selection signal to convert the operating band of the multi-band residual oscillator and generate the (4) Set the signal to set the control voltage. [Embodiment] FIG. 1 is a P2005-040/0697-A40700-TW/therapy using a multi-band voltage controlled oscillator provided by the present invention.

W: 'iSTT3 I Year Month Correction Replacement Page I: Block Diagram of Dynamic Switching PLL 100 - Embodiment. As shown, the automatic switching PLL 100 includes a phase detector 1 , a charge pump 11 , a filter 12 , a multi-band voltage controlled oscillator ( vc 〇 ) 13 , and a programmable frequency divider 14 . And a band selector 15. The phase detector 10 receives a reference signal CLKr and a feedback signal CLKF' to detect the instantaneous phase difference between the two, and outputs a phase detection signal SpD corresponding to the detected phase difference to the charge pump u. The charge ^ Η then generates a pump current lCP ′ whose on-time is determined by the phase difference represented by the phase detection signal SPD and transmits the pump current Icp to the filtered state 12 . The filter 12 in turn generates a control voltage Vctrl corresponding to the pump current Icp. When receiving the voltage setting signal svs from the band selector 15, the filter 12 sets the control voltage Vctrl to at least one of the voltages. The multi-band VCO 13 system has a complex (N) operating band, each operating band covering a particular frequency range. The multi-band vc 〇 13 is selected based on one of the band selection signals sB from the band selector 15 and operates in one of the operating bands. The multi-band VC〇 13 is coupled to the control voltage VCTRL from the filter and outputs an output signal CLK〇. The frequency of the round-trip signal CLK〇 falls within the individual frequency range of the selected frequency band and is controlled by the control voltage VCTRL. The output signal CLK is divided by the programmable amplifier 14 into a feedback signal CLKF. It is noted that, as is well known in the art, the programmable frequency divider 14 can be removed and the output signal coupled as the feedback signal CLKF.

2A and 2B diagrams show the conversion of a typical multi-band VCO. P2005-040/0697-A40700-TW/& 1325231 ^ϊΠ正狮

The example diagram of the number is used to display the change of the frequency of the output signal CLK〇 relative to the control voltage VCTRL. Referring first to Figure 2A, the multi-band VCO 13 system has a plurality of operating bands B1 through BN, each band having its own gain transfer function. The operating band B1 covers the frequency range from the frequency fl to f3, the operating band B2 covers the frequency range of the frequencies f3 to f5, ..., and the operating band BN covers the frequency range of the frequencies fM to fN. Therefore, the multi-band VCO 13 as a whole has a modulation range from the lowest frequency fl to the highest frequency fN. The multi-band VCO 13 selects one of the operating bands B1 to BN according to the band selection signal SB, and outputs the output signal CLK〇. The frequency of the output signal CLK 系 falls within the individual frequency range of the selected frequency band and is controlled by the control voltage VCTRL. The difference between Fig. 2B and Fig. 2A is only that the frequency of the output signal CLK〇 increases as the control voltage V CTRL rises and does not decrease. The frequency selector 15 is for providing the frequency selection signal SB to switch the operating frequency band of the multi-band VCO 13, and to provide the voltage setting signal Svs to control the filter 12 to set the control voltage VCTRL to one of the predetermined voltages. In the present invention, the band selector 15 generates the frequency selection signal SB and the voltage setting signal Svs based on the control voltage VCTRL supplied from the filter 12. When the frequency selector 15 provides the frequency selection signal SB to switch the operating band of the multi-band VCO 13, the voltage setting signal Svs is also provided to control the filter 12 to set the control voltage VCTRLS into a predetermined voltage - 〇 in the present invention. In one embodiment, the band selector 15 detects whether the control voltage VCTRL falls within a reference voltage range to determine whether to provide the frequency P2005-040/0697-A40700-TW/f7 10 1325231, __-!

The L_-J rate select signal SB switches the operating band of the multi-band VCO 13 and the voltage setting signal SVS to control the filter 12 to set the control voltage VcTRL. If the control voltage VCTRL falls outside the reference voltage range, the band selector 15 provides the frequency selection signal SB and the voltage setting signal Svs. Otherwise, the band selector 15 provides neither the frequency selection signal SB nor the voltage setting signal Svs. Fig. 3 is a block diagram showing an embodiment of the block diagram of the band selector 15 of Fig. 1 provided by the present invention. As shown, in the band selector 15, a reference voltage generator 31 generates at least one reference voltage VREF, wherein the at least one reference voltage VREF corresponds to a reference voltage range, and then the reference voltage VREF is supplied to Comparator 32. The comparator 32 compares the control voltage VCTRL with the at least one reference voltage VREF to determine whether the control voltage falls within the reference voltage range, and then generates a comparison signal Sc corresponding to the comparison result. The comparison signal Sc is transmitted to the control module 33. The control module 33 then outputs the frequency band selection signal SB and the voltage setting signal Svs based on the comparison signal Sc. If the control power M VcTRL is outside the reference voltage range, the control module 33 generates the band selection signal SB to switch the operating band of the multi-band VCO 13, and outputs the voltage setting signal Svs to control the filter 12 to set the control voltage. V CTRL is one of at least one predetermined voltage. Otherwise, the control module 33 neither generates the band selection signal SB to convert the operating band of the multi-band VCO 13 nor generates the voltage setting signal Svs to control the filter 12 to set the control voltage VCTRL. In one embodiment, the control module 33 determines which frequency band the multi-band VCO 13 is switched to and the control voltage VCTRL is set to which of the predetermined voltages. P2005-040/0697-A40700-TW/None 11 1325231 m7X27T^ Year Month Renovation Replacement Page 4A is a reference voltage distribution diagram showing an embodiment of the present invention, respectively. Figure 4B-4C shows the operating band switching mechanism of the multi-band VCO of Figure 2A-2B when the reference voltage is as shown in Figure 4A. In FIG. 4A, the reference voltage VREF includes first and second reference voltages Vref1 and Vref2. The comparator 32 compares the control voltage VCTRL with the first and second reference voltages VreH and Vref2 to determine which of the voltage regions A, B, and C the control voltage VCTRL falls in, and transmits the comparison result to the comparison signal Sc to Control module 33. Referring to Fig. 4B, if the control voltage Vctrl is within the voltage range A, the control module 3 3 generates a band selection signal SB to switch the multi-band VCO 13 to the next higher frequency band. At the same time, the control module 3 3 outputs the voltage setting signal Sys to control the filter 12 to pull the control voltage VCTRL to a first predetermined voltage. Similarly, if the control voltage VCTRL falls within the voltage range C, the control module 33 generates a band selection signal SB to switch the multi-band VCO 13 to the next lower frequency band, and simultaneously outputs the voltage setting signal Svs to control Filter 12 pulls control voltage VCTRL low to a second predetermined voltage. However, if the control voltage VCTRL falls within the voltage range B, the control module 33 neither generates the band selection signal SB to change the operating band of the multi-band VCO 13, nor generates the voltage setting signal Svs to control the filter 12 to set the control. Voltage Vctrl. In one embodiment, the first and second predetermined voltages are the first and second reference voltages Vref1 and Vref2, respectively. The difference between FIG. 4C and FIG. 4B is only that if the control voltage Vctrl falls in the area A », the control module 33 generates the band selection signal SB to switch the multi-band VCO to a lower rather than a higher operating band; If the control voltage VCTRL& enters the area C, P2005-040/0697-A40700-TW/no 12

1325231 The control module 33 then generates a frequency to be selected signal SB to switch the multi-band VCO to a higher, rather than lower, operating band. The relevant details are quite similar to those described in Figure 4B, and will not be repeated here for the sake of brevity. Figure 5 is another embodiment of a block diagram of the automatic switching PLL 500 provided by the present invention. The difference between this figure and the automatic switching PLL 100 of Fig. 1 is only the addition of a lock detector 51. The lock detector 51 receives the reference signal CLKr and the feedback signal CLKF, detects whether the automatic switching PLL 500 is locked, and transmits a lock signal SL corresponding to the detection result to the band selector 12. The band selector 12 receives the lock signal SL in addition to the control voltage VCTRL, and generates the band selection signal SB and the voltage setting signal Svs according to both the control voltage VCTRL and the lock signal SL. It should be noted that the connection between the lock detector 51 and the remaining blocks in Fig. 5 is only an example. For example, the lock detector 51 can separately receive the output signal S〇 to detect whether the automatic switching PLL 500 is locked. Figure 6 is an embodiment of a block diagram of the band selector 15 of Figure 5 of the present invention. The difference between this figure and FIG. 3 is that the control module 33 receives the lock signal SL in addition to the comparison signal Sc, and outputs the band selection signal SB and the voltage setting signal Svs according to both the comparison signal Sc and the lock signal SL. The detailed description of each block is omitted here for brevity. In this embodiment, the reference voltage generator 31 generates at least one reference voltage Vref, wherein the at least one reference voltage Vref corresponds to a reference voltage range and at least one additional reference voltage range, wherein the additional reference voltage range is adjacent to The reference voltage range, and the reference voltage generator 31 P2005-040/0697-A40700-TW/£/ 13 1325231

This reference voltage VREF is supplied to the comparator 32. The comparator 32 compares the control voltage VcTRL with the at least one reference voltage VreF to determine whether the control voltage vCTRL falls within the reference voltage range or one of the at least one additional reference voltage range, and then generates a corresponding The comparison signal Sc of the comparison result. The comparison signal Sc is transmitted to the control module 33. After receiving the comparison signal Sc, the control module 33 outputs the band selection signal SB and the voltage setting signal Svs according to both the comparison signal Sc and the lock signal SL. Similar to FIG. 4, if the comparison signal Sc indicates that the control voltage VCTRL falls outside the reference voltage range, the control module 33 generates the band selection signal SB to switch the operating band of the multi-band VCO 13, and outputs the voltage setting signal Svs. The control filter and the wave filter 12 are used to set the control voltage VcTRL to be one of at least one predetermined voltage. Otherwise, the control module 33 neither generates the band selection signal SB to convert the operating band of the multi-band VCO 13 nor generates the voltage setting signal Svs to control the filter 12 to set the control voltage VcTRL. However, there is a slight difference between Figure 6 and Figure 3. In this embodiment, if the comparison signal Sc indicates that the control voltage VcTRL is outside the reference voltage range, the two cases are distinguished. In the first case, controlling the electric dust

The VcTRL is within one of the at least one additional reference voltage range. In this case, the control module 33 will again refer to the lock signal SL to check if the automatic switching PLL is in the locked state. The control module 33 neither generates the band selection signal SB nor generates the voltage setting signal Svs until the lock signal SL is received to indicate that the automatic switching PLL 500 is in the locked state. In the second case, the control voltage VCTRL does not fall within any of the additional reference voltage ranges. In this case, the control module 33 does not check the lock signal SL to immediately generate the frequency band selection P2005-040/0697-A40700-TW/f/ 14 1325231 : 3⁄4 replacement page selection signal Sb and voltage setting signal Svs. In the conventional embodiment, the control module 33 determines which frequency band the multi-band VCO 13 is switched to and the control voltage VCTRL is set to which of the predetermined voltages, regardless of the first and second cases. Fig. 7A is a view showing a reference voltage distribution diagram of another embodiment of the present invention, respectively. The 7B-7C diagram shows the operating band switching mechanism of the multi-band VCO of the 2A-2B diagram when the reference voltage is as shown in FIG. 7A. The difference between the 7A and 4A is only that the voltage range A is divided into two sub-voltage regions A1 and A2 by a third reference voltage Vref3, and similarly, the voltage range C is divided into a fourth reference voltage Vref4. Two secondary voltage regions C1 and C2. This means that the reference voltage generator 31 generates the reference voltages Vref1 to Vref4. The voltage region B between the reference voltages Vref1 and Vref2 is used as the reference voltage region 'and the voltage range A is within the secondary voltage range A2 between the reference voltages Vref3 and Vref1, and the voltage range C is between the reference voltage Vref2 and The secondary voltage C1 between Vref4 is used as an additional voltage range. The comparator 32 then compares the control voltage VCTRL with the first to fourth reference voltages Vref1 to Vref4 to determine which of the voltage regions A1, A2, B, C1, and C2 the control voltage VCTRL falls in, and compares the comparison result through the comparison signal. Sc is transmitted to the control module 33. As shown in FIG. 7B, similar to FIG. 4B, if the control voltage VcTRL falls within the voltage range B, the control module 33 neither generates the band selection signal SB to convert the operating band of the multi-band VCO 13, nor generates a voltage setting. The signal Svs is controlled by the control filter 12 to set the control voltage VcTRL ° P2005-040/0697-A40700-TW/f/ 15 1325231, and similarly, if the control module 33 receives the comparison signal Sc, the control voltage VcTRL is at the voltage. In the range of A and C, the control panel group 33 generates a band selection signal SB to switch the multi-band VCO 13 to the next higher and lower lower frequency bands, respectively, and outputs a voltage setting signal Svs to control the filter 12. The control voltage VCTRL is pulled high to the first predetermined voltage and pulled low to the second predetermined voltage. In one embodiment, the first and second predetermined voltages are the first and second reference voltages Vref1 and Vref2, respectively. However, the difference between the 7B and 4B is that if the control voltage VCTRL is within the voltage range A2 of the voltage range A and the voltage C1 of the voltage range C, respectively, the control module 33 does not receive the lock signal SL. The band selection signal Sb and the voltage setting signal Svs are generated only when the automatic switching PLL is in the locked state. More specifically, if the control module 33 receives the comparison signal Sc indicating that the control voltage Vctrl is not connected to the power A1 and C2, the control phase: the group 33 generates the band selection signal SB to respectively respectively multi-band VCO 13 Switching to the next higher and lower lower frequency band, and outputting the voltage setting signal Svs to control the filter 12 to pull the control voltage VcTRL respectively and pull it low. However, if the control module 33 receives the comparison signal Sc indicating that the control voltage VCTRL falls within the voltage ranges A2 and C1, the control module 33 further checks the lock signal SL to detect whether the automatic switching PLL 500 has been locked. If the lock signal SL indicates that the automatic switching PLL 500 is currently in the locked state, the control module 33 also generates the band selection signal SB to switch the multi-band VCO to the next higher and lower lower frequency bands, respectively, and output voltage. Set the signal Svs to control the chopper 12 to control the voltage Vctrl respectively P2005-040/0697-A40700-TW/f/16 1325231 9|:.1 day! The replacement page is pulled high and pulled low; otherwise, the control module 33 is up to The band selection signal SB and the voltage setting signal Svs are generated only when the lock signal SL is instructed to automatically switch the PLL 500 to the locked state. Similarly, the difference between the 7C and 4C is that if the control voltage VCTRL is within the voltage range A2 of the voltage range A and the voltage C1 of the voltage range C, the control module 33 does not receive the lock signal SL indication. The band selection signal SB and the voltage setting signal Svs are generated only when the automatic switching PLL is in the locked state. The difference between the 7C and 7B is only that if the control voltage VCTRL falls into the area A, the control module 33 generates the band selection signal SB to switch the multi-band VCO to the lower, rather than the south, operating band; If the control voltage VcTRL is in the zone C, the control module 33 generates a frequency to be selected signal SB to switch the multi-band VCO to a higher, rather than lower, operating band. The relevant details are quite similar to those described in Figure 7B and will not be repeated here for the sake of brevity. While the present invention has been described in its preferred embodiments, the present invention is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an embodiment of a block diagram of an automatic switching phase-locked loop using a multi-band voltage controlled oscillator according to the present invention; FIGS. 2A and 2B show typical multi-band voltage control Example diagram of the gain conversion function of the oscillator; Fig. 3 is a block diagram of the band selector P2005-040/0697-A40700-TW/f7 17 1325231 of the first figure provided by the present invention. Example 4A shows a reference voltage distribution diagram of an embodiment of the present invention; • 4B-4C shows the operation of the multi-band VCO of the 2A-2B diagram when the reference voltage is as shown in FIG. 4A. Band switching mechanism; FIG. 5 is another embodiment of a block diagram of an automatic switching phase-locked loop provided by the present invention; FIG. 6 is a block diagram of a block diagram of the band selector of FIG. 5 provided by the present invention. Example 7A shows a reference voltage distribution diagram of another embodiment of the present invention; and FIG. 7B-7C shows a multi-band VCO of the 2A-2B diagram when the reference voltage is as shown in FIG. 7A. Operating band switching mechanism. [Description of main component symbols] 11 to charge pump 13 to multi-band voltage controlled oscillator 15 to band selector 32 to comparator 51 to lock detector B to reference voltage range C, Cl, C2 to voltage range CLK 〇 ~ output Signal fl-f6, fM, fN~band 10~phase detector 12~filter 14~programmable frequency divider 31~reference voltage generator 33~control module A, Al, A2~voltage range B1- BN~band CLKf~receiving signal CLKR~reference signal boundary frequency P2005-040/0697-A40700-TW/f/ 18 1325231 98, 12. I 4 ~~ etc. 曰Correct replacement page Icp~ fruit current_sB~band Select signal Sc~ control signal Sl~ lock signal

SpD ~ lock detection signal SVS ~ ink setting signal

VcTRL~ control voltage VreF~ reference voltage

Vrefl-Vref4~reference voltage P2005-040/0697-A40700-TW/i/ 19

Claims (1)

1325231 Case No. 095142799 Revised on December 14, 1998, this application scope: 1. An automatic switching phase-locked loop, comprising: a phase detector, receiving a reference signal and a feedback signal, and outputting a phase detection The signal signal corresponds to a phase difference between the reference signal and the feedback signal; a charge pump receives the phase detection signal and generates a pump current according to the phase detection signal; a frequency band selector receives a control voltage, And generating a frequency band selection signal and a voltage setting signal according to the control voltage; a filter, generating the control voltage according to the pump current, and setting the signal according to the voltage to reset the control voltage; a multi-band voltage controlled oscillation The controller is coupled to the control voltage and the frequency band selection signal for selecting a signal according to the frequency band to select one of a plurality of operating frequency bands, and providing an output signal according to the control voltage, wherein the frequency of the output signal is located Within the frequency range of the selected operating band; wherein the band selector detects the control voltage is Falling within a reference voltage range, if so, neither generating the band selection signal to convert the operating band of the multi-band voltage controlled oscillator nor generating the voltage setting signal to set the control voltage; if not, generating the frequency band Selecting a signal to convert an operating frequency band of the multi-band voltage controlled oscillator and generating the voltage setting signal to set the control voltage; a lock detector, detecting whether the automatic switching phase locked loop is locked, and outputting a locking signal Corresponding to the detection result; P2005-040/0697-A40700-TW/f7 20 1325231 wherein the band selector further receives the lock signal and further detects whether the control voltage falls within one of at least one additional reference voltage range, Wherein the additional reference voltage range is adjacent to the reference voltage range, and when detecting that the control voltage falls in one of the at least one additional reference voltage range, receiving the lock signal indicates that the automatic switching phase locked loop is After the locked state, the band selection signal and the voltage setting signal are generated. 2. The automatic switching phase-locked loop of claim 1, wherein the frequency band selector comprises: a reference voltage generator for providing at least one reference voltage, wherein the reference voltage corresponds to a reference voltage range a comparator that compares the control voltage with the at least one reference voltage to detect whether the control voltage falls within the reference voltage range, and generates a comparison signal corresponding to the detection result; a control module, Receiving the comparison signal, if the comparison signal indicates that the control voltage falls within the reference voltage range, neither the frequency band selection signal nor the voltage setting signal is generated; otherwise, the frequency band selection signal is generated to convert the multi-band voltage control The operating frequency band of the oscillator and the voltage setting signal are generated to set the control voltage. 3. The automatic switching phase-locked loop of claim 2, wherein the reference voltage generator generates a first reference voltage and a second reference voltage higher than the first reference voltage; wherein the comparator Comparing the control voltage with the first and second reference voltages to detect whether the control voltage falls between the first and second reference voltages P2005-040/0697-A40700-TW/f^21 1325231, and The comparison signal is generated corresponding to the detection result; wherein the control module receives the comparison signal to indicate that the control voltage is lower than the first reference voltage, 'if the frequency of the output signal increases or decreases with the voltage Generating the band selection signal to switch the dust-controlled vibrator to a lower or higher operating band, i, and generating a voltage control signal to control the filter to pull the control voltage higher. When the control module receives the comparison signal indicating that the control voltage is higher than the second reference voltage, 'if the frequency of the round-trip signal increases or decreases with the voltage, the frequency band is generated. Selecting a signal to switch the voltage controlled oscillator to a higher or lower operating frequency band, and generating a voltage control signal to control the filter to lower the control power $ wherein the control module receives The comparison signal indicates that the voltage is between the first and second reference voltages, and neither the power selection signal nor the voltage setting signal is generated. A. The automatic switching phase-locked loop of claim 3, wherein the control module receives the comparison signal and does not indicate the first reference voltage of the control voltage and is higher than the second reference voltage. The generation = lower than the set signal to control the filter to respectively set the control voltage to the voltage and the second reference voltage. Λ — Lock 5. The automatic switching lock circuit described in item 3 of the patent application scope includes: a lock detector, detecting whether the automatic switching phase locked loop is set, and outputting a lock signal corresponding to the detect a result of the measurement; and wherein the voltage generator further generates a reference voltage lower than the first reference voltage and a fourth higher than the second reference voltage > the electric house; P2005-040/0697- A40700-TW/f/ 22 1325231 wherein the comparator compares the control voltage with the third and fourth voltages to detect whether the control voltage falls between the third and first reference voltages or Between the second and fourth reference voltages, and the comparison signal is more corresponding to the comparison result; and wherein the control module further receives the lock signal, and when the control signal is received, the control voltage is indicated Falling between the third and first reference voltages and falling between the second and fourth reference voltages, the band selection is generated after receiving the lock signal indicating that the automatic switching phase-locked loop is in a locked state. Select the signal and the voltage setting signal. 6. The automatic switching phase-locked loop of claim 5, wherein the control module receives the comparison signal to indicate that the control voltage is lower than the first reference voltage and higher than the second reference voltage, The voltage setting signal is generated to control the filter to respectively set the control voltage to the first and second reference voltages. P2005-040/0697-A40700-TW/f7 23 1325231 001 2 Η Ϊ Η Η :slu 1325231 Figure 2A 1325231 Figure 2B 1325231 15 \ I------------------i------------------1 Figure 3 1325231 Vrefl B Vref2 Figure 4A ABC , -Λ-V-A-v-^ Figure 4B 1325231 Figure 4C 1325231 j 1—(to Y4 H-l J 1325231 15 \ I------------------------------------1 Figure 6 1325231 C A _A-_ Al, A2 + B I Cl , C2 Vref3 Vrefl Vref2 Vref4 Figure 7A Figure 7B 1325231 ABC A1 A2 Cl C2 Figure 7C