Frequency adjustment circuit and method for voltage controlled oscillator with temperature compensation function

Abstract

The frequency adjustment circuit and method for a voltage-controlled oscillator (VCO) with temperature compensation function according to this application embodiment first generates a voltage signal through a control voltage generation branch and transmits it to the second signal control terminal of the VCO. The output signal of the VCO is divided by a phase-locked loop (PLL) branch and input to the frequency calibration branch along with a reference clock. A temperature sensor collects temperature data from the chip and sends the temperature data to the frequency calibration branch. The frequency calibration branch outputs a control signal to the first control signal terminal of the VCO based on the divided clock of the VCO's output signal, the reference clock, and the temperature data, so that the operating frequency of the VCO is the target frequency. The PLL branch locks the VCO operating at the target frequency. This solution avoids the PTAT voltage generation circuit and corresponding varactor diodes involved in traditional temperature compensation circuits, reduces phase noise, effectively achieves temperature compensation adjustment of the VCO, and realizes frequency locking.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit technology, and more specifically to a frequency adjustment circuit and method for a voltage-controlled oscillator with temperature compensation function. Background Technology

[0002] A voltage-controlled oscillator (VCO) is an oscillating circuit whose output frequency corresponds to the input control voltage. The frequency of the VCO is a function of the input signal voltage, and the operating state of the oscillator or the component parameters of the oscillation circuit are controlled by the input control voltage. Types of VCOs include LC VCOs, RC VCOs, and crystal VCOs. The main technical requirements for VCOs include: good frequency stability, high control sensitivity, wide frequency range, linear frequency deviation with control voltage, and ease of integration. LC VCOs, due to their excellent low-noise performance, are widely used in radio frequency and communication systems. VCOs typically operate in a phase-locked loop (PLL) to provide a high-frequency, low-noise clock signal. To meet the needs of various applications, VCOs need to cover a wide frequency range. Generally, a VCO contains multiple discrete frequency bands with overlapping frequencies in adjacent bands. Within a single frequency band, the frequency increases with the increase of the control voltage. The phase-locked loop selects a suitable frequency band through a frequency calibration circuit, so that the voltage-controlled oscillator operates at the target frequency. During normal operation, the phase-locked loop is always locked to this frequency band.

[0003] Changes in the ambient temperature of the chip cause changes in the frequency of the voltage-controlled oscillator (VCO). Typically, the frequency of the VCO decreases as the temperature rises. When the temperature rises, the phase-locked loop (PLL) must increase the control voltage of the VCO to ensure that the VCO remains stable at the same target frequency. This can cause the control voltage to exceed the reasonable operating range, ultimately causing the PLL to lose lock. Summary of the Invention

[0004] In view of this, embodiments of this application provide a frequency adjustment circuit and method for a voltage-controlled oscillator with temperature compensation function, which at least partially solves the problems existing in the prior art.

[0005] In a first aspect, embodiments of this application provide a frequency adjustment circuit for a voltage-controlled oscillator (VCO) with temperature compensation function, used to adjust the operating frequency of the VCO to achieve temperature compensation. The VCO includes: an inductor, a switched capacitor circuit, a varactor circuit, a first NMOS transistor, and a second NMOS transistor. The switched capacitor circuit is connected to a first control signal terminal, the varactor circuit is connected to a second control signal terminal, the gate of the first NMOS transistor is connected to the drain of the second NMOS transistor, the gate of the second NMOS transistor is connected to the drain of the first NMOS transistor, and the sources of both the first and second NMOS transistors are grounded. The frequency adjustment circuit includes:

[0006] The circuit includes a frequency calibration branch, a control voltage generation branch, a temperature sensor, a phase-locked loop branch, and a reference clock; among which...

[0007] The output terminal of the temperature sensor is connected to the input terminal of the frequency calibration branch. The frequency calibration branch outputs a control signal to the first control signal terminal. The output terminals of the control voltage generation branch and the phase-locked loop branch are both connected to the second control signal terminal. The output terminal of the voltage-controlled oscillator is divided by the phase-locked loop branch and input to the frequency calibration branch along with the reference clock.

[0008] According to a specific implementation of this application, the control voltage generating branch is a fixed voltage generating branch, which is used to output a fixed voltage signal to the second control signal terminal.

[0009] According to a specific implementation of an embodiment of this application, the fixed voltage generating branch includes a first resistor and a second resistor. One end of the first resistor is connected to the power supply voltage, and the other end of the first resistor is connected to the equal voltage dividing node. One end of the second resistor is connected to the equal voltage dividing node, and the other end of the second resistor is grounded. The equal voltage dividing node is connected to the second control signal terminal.

[0010] According to a specific implementation of this application, the control voltage generating branch is a variable voltage generating branch, the input terminal of the control voltage generating branch is connected to the output terminal of the frequency calibration branch, and the variable voltage generating branch is connected to the second control signal terminal.

[0011] According to a specific implementation of an embodiment of this application, the variable voltage generating branch includes a plurality of equivalent resistors connected in series, and the voltage node between two adjacent equivalent resistors is selected and connected to the second control signal terminal.

[0012] According to a specific implementation of an embodiment of this application, the frequency adjustment circuit further includes a first switch and a second switch; wherein...

[0013] The control voltage generation branch is connected to the second control signal terminal of the voltage-controlled oscillator through the first switch, and the output terminal of the phase-locked loop branch is connected to the second control signal terminal through the second switch.

[0014] According to a specific implementation of an embodiment of this application, the phase-locked loop branch includes a frequency and phase detector, a charge pump, a filter, and a frequency divider; wherein...

[0015] The input terminal of the frequency and phase detector is connected to the output terminal of the reference clock. The frequency and phase detector, the charge pump, and the filter are connected in series. The filter is connected to the second control signal terminal. The input terminal of the frequency divider is connected to the output terminal of the voltage-controlled oscillator. The output terminal of the frequency divider is connected to the input terminal of the frequency calibration branch.

[0016] Secondly, embodiments of this application provide a frequency adjustment method for a voltage-controlled oscillator (VCO) with temperature compensation function, applied to the frequency adjustment circuit of the VCO with temperature compensation function as described in the first aspect, used to adjust the operating frequency of the VCO to achieve temperature compensation. The frequency adjustment circuit includes a frequency calibration branch, a control voltage generation branch, a temperature sensor, a phase-locked loop branch, and a reference clock. The frequency adjustment circuit is used to adjust the operating frequency of the VCO. The VCO includes an inductor, a switched capacitor circuit, a varactor circuit, a first NMOS transistor, and a second NMOS transistor. The switched capacitor circuit is connected to a first control signal terminal, the varactor circuit is connected to a second control signal terminal, the gate of the first NMOS transistor is connected to the drain of the second NMOS transistor, the gate of the second NMOS transistor is connected to the drain of the first NMOS transistor, and the sources of both the first and second NMOS transistors are grounded. The method includes:

[0017] The control voltage generating branch generates a voltage signal and transmits it to the second signal control terminal of the voltage-controlled oscillator.

[0018] The output signal of the voltage-controlled oscillator is divided by the phase-locked loop branch and input to the frequency calibration branch along with the reference clock;

[0019] The temperature sensor collects temperature data from the chip and sends the temperature data to the frequency calibration branch;

[0020] The frequency calibration branch outputs a control signal to the first control signal terminal of the voltage-controlled oscillator based on the frequency division clock of the output signal of the voltage-controlled oscillator, the reference clock, and the temperature data, so as to make the operating frequency of the voltage-controlled oscillator the target frequency;

[0021] The phase-locked loop branch locks the voltage-controlled oscillator to operate at the target frequency.

[0022] According to a specific implementation of an embodiment of this application, the control voltage generating branch is a fixed voltage generating branch; the step of the control voltage generating branch generating a voltage signal and transmitting it to the second signal control terminal of the voltage-controlled oscillator includes:

[0023] The fixed voltage generating branch outputs a fixed voltage signal to the second control signal terminal.

[0024] According to a specific implementation of an embodiment of this application, the control voltage generation branch is a variable voltage generation branch, the input terminal of the adjustable variable generation circuit is connected to the output terminal of the frequency calibration branch, and the variable voltage generation branch is connected to the second control signal terminal.

[0025] The step of generating a voltage signal in the control voltage generation branch and transmitting it to the second signal control terminal of the voltage-controlled oscillator includes:

[0026] The frequency calibration branch controls the variable voltage generation branch to output a corresponding voltage signal based on the temperature data.

[0027] The frequency adjustment circuit and method for a voltage-controlled oscillator (VCO) with temperature compensation function in this application embodiment are used to adjust the output frequency of the VCO to achieve temperature compensation. The VCO includes an inductor, a switched capacitor circuit, a varactor circuit, a first NMOS transistor, and a second NMOS transistor. The frequency adjustment circuit includes a frequency calibration branch, a control voltage generation branch, a temperature sensor, a phase-locked loop (PLL) branch, and a reference clock. First, a voltage signal is generated by the control voltage generation branch and transmitted to the second signal control terminal of the VCO. The output signal of the VCO is divided by the PLL branch and input to the frequency calibration branch along with the reference clock. The temperature sensor collects temperature data from the chip and sends the temperature data to the frequency calibration branch. The frequency calibration branch outputs a control signal to the first control signal terminal of the VCO based on the divided clock of the VCO's output signal, the reference clock, and the temperature data, so that the operating frequency of the VCO is the target frequency. The PLL branch locks the VCO's operation at the target frequency. The solution disclosed herein avoids the PTAT voltage generation circuit and corresponding varactor tube involved in traditional temperature compensation circuits, reduces the phase noise of the voltage-controlled oscillator, effectively achieves compensation adjustment of the output frequency of the voltage-controlled oscillator as the temperature changes, and realizes output frequency locking. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the temperature compensation circuit for an existing voltage-controlled oscillator.

[0030] Figure 2A schematic diagram of the frequency adjustment circuit of a voltage-controlled oscillator with temperature compensation function provided in this application embodiment;

[0031] Figure 3 A schematic diagram of the structure of the voltage-controlled oscillator used in the frequency adjustment circuit of the voltage-controlled oscillator with temperature compensation function provided in the embodiments of this application;

[0032] Figure 4 A schematic diagram of the fixed voltage generation branch of the frequency adjustment circuit of a voltage-controlled oscillator with temperature compensation function provided in an embodiment of this application;

[0033] Figure 5 A frequency band schematic diagram of the frequency adjustment circuit of a voltage-controlled oscillator with temperature compensation function provided in the embodiments of this application;

[0034] Figure 6 A connection diagram of the control voltage generation branch of the frequency adjustment circuit of the voltage-controlled oscillator with temperature compensation function provided in the embodiments of this application when the control voltage generation branch is a variable voltage generation branch;

[0035] Figure 7 A schematic diagram of the control voltage generation branch of the frequency adjustment circuit of the voltage-controlled oscillator with temperature compensation function provided in the embodiment of this application, which is a variable voltage generation branch.

[0036] Figure 8 A flowchart illustrating a frequency adjustment method for a voltage-controlled oscillator with temperature compensation function, provided in an embodiment of this application;

[0037] Figure 9 A flowchart illustrating another frequency adjustment method for a voltage-controlled oscillator with temperature compensation function provided in this application embodiment. Detailed Implementation

[0038] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0039] The following specific examples illustrate the implementation of this disclosure. Those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. This disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0040] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0041] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this disclosure. The drawings only show the components related to this disclosure and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0042] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0043] like Figure 1 The diagram shows a conventional circuit for addressing temperature compensation in voltage-controlled oscillators (VCOs). It adds a second set of varactor transistors to the existing main varactor transistor. The main varactor transistor is controlled by a loop control voltage Vctrl, while the second set is controlled by a PTAT voltage generation circuit. This PTAT circuit generates a voltage proportional to absolute temperature; as the temperature rises, this voltage increases, reducing the capacitance of the varactor transistors and increasing the VCO frequency. This compensates for the VCO frequency decreasing with increasing temperature, keeping the loop control voltage Vctrl constant. However, the introduction of the second set of varactor transistors lowers the quality factor of the resonant unit, worsening phase noise performance. Typically, the PTAT voltage generation circuit includes a bandgap reference, current mirror, operational amplifier, etc. The noise generated by these circuits directly affects the phase of the VCO through the second set of varactor transistors, further deteriorating phase noise. Therefore, this application provides a frequency adjustment circuit and method for a VCO with temperature compensation to address the technical problem of frequency changes in a VCO caused by temperature. The specific solution is as follows.

[0044] Example 1

[0045] See Figure 2This is a schematic diagram of the structure of a frequency adjustment circuit 200 (hereinafter referred to as frequency adjustment circuit 200) for a voltage-controlled oscillator with temperature compensation function, provided in an embodiment of this application, used to adjust the operating frequency of the voltage-controlled oscillator. Figure 3 As shown, the voltage-controlled oscillator 300 includes: an inductor 310, a switched capacitor circuit 320, a varactor circuit 330, a first NMOS transistor 340, and a second NMOS transistor 350. The switched capacitor circuit 320 is connected to a first control signal terminal P1, and the varactor circuit is connected to a second control signal terminal P2. The gate of the first NMOS transistor 340 is connected to the drain of the second NMOS transistor 350, and the gate of the second NMOS transistor 350 is connected to the drain of the first NMOS transistor 340. The sources of both the first NMOS transistor 340 and the second NMOS transistor 350 are grounded. Figure 2 As shown, the frequency adjustment circuit 200 includes:

[0046] The circuit includes a frequency calibration branch 210, a control voltage generation branch 220, a temperature sensor 230, a phase-locked loop branch 240, and a reference clock 250; among which...

[0047] The output terminal of the temperature sensor 230 is connected to the input terminal of the frequency calibration branch 210. The frequency calibration branch 210 outputs a control signal to the first control signal terminal P1. The output terminals of the control voltage generation branch 220 and the phase-locked loop branch 240 are both connected to the second control signal terminal P2. The output terminal of the voltage-controlled oscillator is divided by the phase-locked loop branch 240 and input to the frequency calibration branch 210 along with the reference clock 250.

[0048] The frequency adjustment circuit 200 provided in this embodiment is used to adjust the operating frequency of the voltage-controlled oscillator 300 to avoid its influence from ambient temperature, thereby achieving temperature compensation for the voltage-controlled oscillator 300. Specifically, as shown... Figure 3 The diagram shows the structure of a voltage-controlled oscillator 300, which mainly includes an inductor 310, a switched capacitor circuit 320, a varactor circuit 330 composed of a set of varactor transistors, and two NMOS transistors. The switched capacitor circuit 320 includes a switched capacitor array, and its first control signal terminal P1 can be controlled by the control word sc<5:0>. The varactor circuit 330 includes variable capacitors C1 and C2, and its second control signal terminal P2 can be controlled by Vctrl. The two NMOS transistors are symmetrically connected, that is, the gate of the first NMOS transistor 340 is connected to the drain of the second NMOS transistor 350, and the gate of the second NMOS transistor 350 is connected to the drain of the first NMOS transistor 340. The sources of the first NMOS transistor 340 and the second NMOS transistor 350 are both grounded.

[0049] like Figure 2 As shown, the frequency adjustment circuit 200 is connected to the voltage-controlled oscillator 300 to achieve frequency control. Specifically, the temperature sensor 230 is placed in the environment where the voltage-controlled oscillator 300 is located to collect temperature data of the chip's environment and send the collected temperature data to the frequency calibration branch 210. The frequency calibration branch 210 generates a control signal based on the temperature data output by the temperature sensor 230 and sends it to the first control signal terminal P1 of the voltage-controlled oscillator 300, i.e., the control word sc<5:0>, to control the operation of the voltage-controlled oscillator 300. The output signal of the voltage-controlled oscillator 300 is divided by the phase-locked loop branch 240 and then input to the frequency calibration branch 210. The frequency calibration branch 210 adjusts the control word sc<5:0> output to the first control signal terminal P1 based on the difference between the reference clock 250 and the divided clock, so that the voltage-controlled oscillator 300 operates at the target frequency. The frequency calibration branch 210 shifts the selected frequency band up or down based on the temperature data collected by the temperature sensor 230. Then, the phase-locked loop branch 240 enters the fine-tuning locking stage, locking the voltage-controlled oscillator 300 to operate at the target frequency.

[0050] According to a specific implementation of an embodiment of this application, the frequency adjustment circuit 200 further includes a first switch 261 and a second switch 260; wherein...

[0051] The control voltage generating branch 220 is connected to the second control signal terminal P2 of the voltage-controlled oscillator 300 through the first switch 261, and the output terminal of the phase-locked loop branch 240 is connected to the second control signal terminal P2 through the second switch 262.

[0052] like Figure 2 As shown, in this embodiment, a first switch 261 and a second switch 262 are added to control the connection status of the control voltage generation branch 220 and the phase-locked loop branch 240 with the voltage-controlled oscillator 300, respectively, so as to realize the switching between coarse adjustment and fine adjustment.

[0053] Furthermore, according to a specific implementation of an embodiment of this application, such as Figure 2 As shown, the phase-locked loop branch 240 may include a frequency and phase detector 241, a charge pump 242, a filter 243, and a frequency divider 244; wherein,

[0054] The input terminal of the frequency and phase detector 241 is connected to the output terminal of the reference clock. The frequency and phase detector 241, the charge pump 242, and the filter 243 are connected in series. The filter 243 is connected to the second control signal terminal P2. The input terminal of the frequency divider 244 is connected to the output terminal of the voltage-controlled oscillator 300. The output terminal of the frequency divider 244 is connected to the input terminal of the frequency calibration branch 210.

[0055] Based on this embodiment, the control voltage generation branch can be defined as a fixed voltage generation branch and a variable voltage generation branch, providing two different control schemes.

[0056] According to a specific implementation of an embodiment of this application, the control voltage generating branch 220 is a fixed voltage generating branch, which is used to output a fixed voltage signal to the second control signal terminal P2.

[0057] Specifically, such as Figure 4 As shown, the fixed voltage generating branch includes a first resistor R1 and a second resistor R2. One end of the first resistor R1 is connected to the power supply voltage, and the other end of the first resistor R1 is connected to the equal voltage dividing node P3. One end of the second resistor R2 is connected to the equal voltage dividing node P3, and the other end of the second resistor R2 is grounded. The equal voltage dividing node P3 is connected to the second control signal terminal P2 through the first switch 261.

[0058] In specific implementation, such as Figure 4 As shown, the fixed voltage generating circuit consists of two resistors of equal resistance connected in series, with one end of one resistor connected to the power supply V. DD The other end is connected to a second resistor, and the other end of the second resistor is grounded. Therefore, the output voltage of the fixed voltage generating circuit is V. DD / 2. When coarse adjustment begins, the first switch 261 closes, the second switch 262 opens, and Vctrl is connected to voltage V. DD / 2, the clock of the voltage-controlled oscillator 300 is divided by the frequency divider 244 and sent to the frequency calibration branch 210. The frequency calibration branch 210 compares the output clock of the reference clock 250 and the output clock of the frequency divider 244, selects the control word sc<5:0>, and finally selects a frequency band from the frequency band of the voltage-controlled oscillator 300. This frequency band covers the target frequency.

[0059] Figure 5 The diagram shows a 300-band frequency response of a voltage-controlled oscillator. Each band covers a continuous frequency range, and the frequency varies with V. ctrl As the voltage increases, the frequency increases, and the control voltage V... ctrl The working range is V L ~V H When V ctrl Less than V L Or greater than V H The phase-locked loop branch cannot function. The frequency calibration branch 210 ultimately selects frequency band 3. At this point, the frequency corresponding to the midpoint of the frequency band is the target frequency f. The frequency calibration branch reads the chip temperature value monitored by the temperature sensor 230. If the chip temperature value exceeds the limit value T... maxThen the frequency band shifts down by one band to frequency band 4. First switch 261 opens, second switch 262 closes, and phase-locked loop branch 240 begins fine-tuning the locking, ultimately V... ctrl It will stabilize at V high The output frequency is the target frequency f. If the chip temperature is lower than the limit value T... min Then the frequency band shifts up by one band to frequency band 2, then the first switch 261 opens, the second switch 262 closes, and the phase-locked loop begins fine-tuning and locking, ultimately V ctrl It will stabilize at V low The output frequency is the target frequency f.

[0060] As the chip temperature drops from high to low, the frequency of the voltage-controlled oscillator 300 increases, the bandwidth expands, and the fine-tuning of the phase-locked loop branch 240 adjusts V... ctrl From V high Reduce to a stable value, keep the target frequency constant, and control the voltage V. L ~V high The controlled frequency range is greater than the frequency change caused by temperature, so the phase-locked loop branch 240 remains locked in the same frequency band, achieving the effect of temperature compensation.

[0061] As the chip temperature rises from a low temperature to a high temperature, the frequency of the voltage-controlled oscillator decreases, the bandwidth drops, and the fine-tuning of the phase-locked loop branch makes V... ctrl From V low Increase to a stable value, keeping the target frequency constant, and control the voltage V. low ~V H The controlled frequency range is greater than the frequency change caused by temperature, so the phase-locked loop branch 240 remains locked in the same frequency band, achieving the effect of temperature compensation.

[0062] According to another specific implementation of the present application, the control voltage generating branch 220 is a variable voltage generating branch, the input terminal of the control voltage generating branch is connected to the output terminal of the frequency calibration branch 210, and the variable voltage generating branch is connected to the second control signal terminal P2 through the first switch 261.

[0063] Specifically, the variable voltage generating branch includes multiple equivalent resistors connected in series, and the voltage node between two adjacent equivalent resistors is connected to the second control signal terminal.

[0064] like Figure 6 As shown, the frequency adjustment circuit provided in this embodiment includes a frequency calibration branch 210, a variable voltage generation branch 220, a temperature sensor 230, and a phase-locked loop branch 240. The phase-locked loop branch 240 includes a frequency and phase detector 241, a charge pump 242, a filter 243, and a frequency divider 244. Figure 7As shown, the variable voltage generating branch 220 is composed of multiple resistors R0 of equal value connected in series, with one end of the first resistor connected to V. DD The other end is connected to the second resistor. The output voltage V1 is between the first and second resistors, and so on. One end of the last resistor is connected to GND, and the other end is connected to the second-to-last resistor. The output voltage V is between the two resistors. n The frequency calibration branch 210 reads the chip temperature value monitored by the temperature sensor 230, and controls the variable voltage generation branch 220 to output a corresponding voltage based on the temperature value. Different temperature values ​​result in different output voltage values ​​from the variable voltage generation branch 220. For example, a higher temperature value results in a higher output voltage, such as V2, while a lower temperature value results in a lower output voltage, such as V. n-1 Then, coarse adjustment begins. First switch 261 is closed, second switch 262 is open, V ctrl The output voltage V2 or V connected to the variable voltage generation branch 220 n-1 The frequency calibration branch 210 compares the reference clock and the frequency of the divider output clock, selects sc<5:0>, and finally selects a frequency band from the frequency band of the voltage-controlled oscillator 300 that covers the target frequency. Then, the first switch 261 opens, the second switch 262 closes, and the phase-locked loop branch 230 begins fine-tuning the lock, ultimately V ctrl It will stabilize at the same level as V2 / V n-1 Similar voltage values ​​V 2' / V n-1' The output frequency is the target frequency f.

[0065] As the chip temperature decreases from high to low, the frequency of the voltage-controlled oscillator 300 increases, the bandwidth expands, and the fine-tuning of the phase-locked loop branch 240 adjusts V... ctrl From V 2' Reduce to a stable value, keep the target frequency constant, and control the voltage V. L ~V 2' The controlled frequency range is greater than the frequency change caused by temperature, so the phase-locked loop remains locked in the same frequency band, achieving the effect of temperature compensation.

[0066] As the chip temperature rises from a low temperature to a high temperature, the frequency of the voltage-controlled oscillator decreases, the bandwidth drops, and the phase-locked loop (PLL) is fine-tuned to adjust V... ctrl From V n-1' Increase to a stable value, keeping the target frequency constant, and control the voltage V. n-1' ~V H The controlled frequency range is greater than the frequency change caused by temperature, so the phase-locked loop remains locked in the same frequency band, achieving the effect of temperature compensation.

[0067] Example 2

[0068] This application provides a frequency adjustment method for a voltage-controlled oscillator with temperature compensation function, applied to the frequency adjustment circuit (hereinafter referred to as the frequency adjustment circuit) of the voltage-controlled oscillator with temperature compensation function provided in the above embodiment. Figure 2 and Figure 3 As shown, the frequency adjustment circuit 200 includes a frequency calibration branch 210, a control voltage generation branch 220, a temperature sensor 230, a phase-locked loop branch 240, and a reference clock 250. The frequency adjustment circuit 200 is used to adjust the operating frequency of the voltage-controlled oscillator 300. The voltage-controlled oscillator 300 includes an inductor 310, a switched capacitor circuit 320, a varactor circuit 330, a first NMOS transistor 340, and a second NMOS transistor 350. The switched capacitor circuit 320 is connected to a first control signal terminal P1, and the varactor circuit 330 is connected to a second control signal terminal P2. The gate of the first NMOS transistor 340 is connected to the drain of the second NMOS transistor 350, and the gate of the second NMOS transistor 350 is connected to the drain of the first NMOS transistor 340. The sources of both the first NMOS transistor 340 and the second NMOS transistor 350 are grounded. The frequency adjustment method of the voltage-controlled oscillator with temperature compensation mainly includes the following steps:

[0069] The control voltage generating branch generates a voltage signal and transmits it to the second signal control terminal of the voltage-controlled oscillator.

[0070] The output signal of the voltage-controlled oscillator is divided by the phase-locked loop branch and input to the frequency calibration branch along with the reference clock;

[0071] The temperature sensor collects temperature data from the chip and sends the temperature data to the frequency calibration branch;

[0072] The frequency calibration branch outputs a control signal to the first control signal terminal of the voltage-controlled oscillator based on the frequency division clock of the output signal of the voltage-controlled oscillator, the reference clock, and the temperature data, so as to make the operating frequency of the voltage-controlled oscillator the target frequency;

[0073] The phase-locked loop branch locks the voltage-controlled oscillator to operate at the target frequency.

[0074] According to a specific implementation of an embodiment of this application, the control voltage generating branch is a fixed voltage generating branch; the step of the control voltage generating branch generating a voltage signal and transmitting it to the second signal control terminal of the voltage-controlled oscillator includes:

[0075] The fixed voltage generating branch outputs a fixed voltage signal to the second control signal terminal.

[0076] like Figure 8As shown, the frequency adjustment process for limiting the control voltage generation branch to a fixed voltage generation branch mainly includes the following steps:

[0077] Step S801, coarse adjustment begins: close the first switch and open the second switch;

[0078] Step S802: Compare the speed of the reference clock and the output clock of the frequency divider, and select a suitable frequency band;

[0079] Step S803: Read the temperature data from the temperature sensor and shift the selected frequency band up or down;

[0080] Step S804: Disconnect the first switch, close the second switch, and enter fine-tuning lock.

[0081] According to another specific implementation of the present application, the control voltage generation branch is a variable voltage generation branch, the input terminal of the adjustable variable generation circuit is connected to the output terminal of the frequency calibration branch, and the variable voltage generation branch is connected to the second control signal terminal.

[0082] The step of generating a voltage signal in the control voltage generation branch and transmitting it to the second signal control terminal of the voltage-controlled oscillator includes:

[0083] The frequency calibration branch controls the variable voltage generation branch to output a corresponding voltage signal based on the temperature data.

[0084] like Figure 9 As shown, the frequency adjustment process for limiting the control voltage generation branch to a fixed voltage generation branch mainly includes the following steps:

[0085] Step S901: Read the temperature data from the temperature sensor, and the variable voltage generation branch generates a corresponding voltage value.

[0086] Step S901, coarse adjustment begins: close the first switch and open the second switch;

[0087] Step S903: Compare the speed of the reference clock and the output clock of the frequency divider, and select a suitable frequency band;

[0088] Step S904: Disconnect the first switch, close the second switch, and enter fine-tuning lock.

[0089] The frequency adjustment method in this embodiment is used to adjust the output frequency of a voltage-controlled oscillator (VCO). The VCO includes an inductor, a switched capacitor circuit, a varactor circuit, a first NMOS transistor, and a second NMOS transistor. The frequency adjustment circuit includes a frequency calibration branch, a control voltage generation branch, a temperature sensor, a phase-locked loop (PLL) branch, and a reference clock. First, a voltage signal is generated by the control voltage generation branch and transmitted to the second signal control terminal of the VCO. The output signal of the VCO is divided by the PLL branch and input to the frequency calibration branch along with the reference clock. The temperature sensor collects temperature data from the chip and sends the temperature data to the frequency calibration branch. The frequency calibration branch outputs a control signal to the first control signal terminal of the VCO based on the divided clock of the VCO's output signal, the reference clock, and the temperature data, so that the operating frequency of the VCO is the target frequency. The PLL branch locks the VCO's operation at the target frequency. The solution disclosed herein avoids the PTAT voltage generation circuit and corresponding varactor transistor involved in traditional temperature compensation circuits, reduces the phase noise of the voltage-controlled oscillator, effectively compensates for and adjusts the output frequency of the voltage-controlled oscillator as it changes with temperature, and achieves output frequency locking. The specific implementation process of the frequency adjustment method can be found in the specific implementation process of the frequency adjustment circuit provided in the above embodiments, and will not be repeated here.

[0090] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A frequency adjustment circuit for a voltage-controlled oscillator with temperature compensation function, characterized in that, For adjusting the operating frequency of a voltage-controlled oscillator (VCO) to achieve temperature compensation, the VCO includes: an inductor, a switched capacitor circuit, a varactor circuit, a first NMOS transistor, and a second NMOS transistor. The switched capacitor circuit is connected to a first control signal terminal, and the varactor circuit is connected to a second control signal terminal. The gate of the first NMOS transistor is connected to the drain of the second NMOS transistor, and the gate of the second NMOS transistor is connected to the drain of the first NMOS transistor. The sources of both the first and second NMOS transistors are grounded. The frequency adjustment circuit includes: The circuit includes a frequency calibration branch, a control voltage generation branch, a temperature sensor, a phase-locked loop branch, and a reference clock; among which... The output terminal of the temperature sensor is connected to the input terminal of the frequency calibration branch. The frequency calibration branch outputs a control signal to the first control signal terminal. The output terminals of the control voltage generation branch and the phase-locked loop branch are both connected to the second control signal terminal. The output terminal of the voltage-controlled oscillator is divided by the phase-locked loop branch and input to the frequency calibration branch along with the reference clock.

2. The frequency adjustment circuit according to claim 1, characterized in that, The control voltage generation branch is a fixed voltage generation branch, which is used to output a fixed voltage signal to the second control signal terminal.

3. The frequency adjustment circuit according to claim 2, characterized in that, The fixed voltage generating branch includes a first resistor and a second resistor. One end of the first resistor is connected to the power supply voltage, and the other end of the first resistor is connected to the equal voltage dividing node. One end of the second resistor is connected to the equal voltage dividing node, and the other end of the second resistor is grounded. The equal voltage dividing node is connected to the second control signal terminal.

4. The frequency adjustment circuit according to claim 1, characterized in that, The control voltage generation branch is a variable voltage generation branch. The input terminal of the control voltage generation branch is connected to the output terminal of the frequency calibration branch, and the variable voltage generation branch is connected to the second control signal terminal.

5. The frequency adjustment circuit according to claim 4, characterized in that, The variable voltage generating branch includes multiple equivalent resistors connected in series, and the voltage node between two adjacent equivalent resistors is connected to the second control signal terminal.

6. The frequency adjustment circuit according to claim 1, characterized in that, The frequency adjustment circuit further includes a first switch and a second switch; wherein... The control voltage generation branch is connected to the second control signal terminal of the voltage-controlled oscillator through the first switch, and the output terminal of the phase-locked loop branch is connected to the second control signal terminal through the second switch.

7. The frequency adjustment circuit according to any one of claims 1 to 6, characterized in that, The phase-locked loop branch includes a frequency and phase detector, a charge pump, a filter, and a frequency divider; wherein... The input terminal of the frequency and phase detector is connected to the output terminal of the reference clock. The frequency and phase detector, the charge pump, and the filter are connected in series. The filter is connected to the second control signal terminal. The input terminal of the frequency divider is connected to the output terminal of the voltage-controlled oscillator. The output terminal of the frequency divider is connected to the input terminal of the frequency calibration branch.

8. A method for adjusting the frequency of a voltage-controlled oscillator with temperature compensation function, characterized in that, A frequency adjustment circuit for a voltage-controlled oscillator (VCO) with temperature compensation function, applied to any one of claims 1 to 7, is used to adjust the operating frequency of the VCO to achieve temperature compensation. The frequency adjustment circuit includes a frequency calibration branch, a control voltage generation branch, a temperature sensor, a phase-locked loop (PLL) branch, and a reference clock. The frequency adjustment circuit is used to adjust the operating frequency of the VCO. The VCO includes an inductor, a switched capacitor circuit, a varactor circuit, a first NMOS transistor, and a second NMOS transistor. The switched capacitor circuit is connected to a first control signal terminal, and the varactor circuit is connected to a second control signal terminal. The gate of the first NMOS transistor is connected to the drain of the second NMOS transistor, and the gate of the second NMOS transistor is connected to the drain of the first NMOS transistor. The sources of both the first and second NMOS transistors are grounded. The method includes: The control voltage generating branch generates a voltage signal and transmits it to the second signal control terminal of the voltage-controlled oscillator. The output signal of the voltage-controlled oscillator is divided by the phase-locked loop branch and input to the frequency calibration branch along with the reference clock; The temperature sensor collects temperature data from the chip and sends the temperature data to the frequency calibration branch; The frequency calibration branch outputs a control signal to the first control signal terminal of the voltage-controlled oscillator based on the frequency division clock of the output signal of the voltage-controlled oscillator, the reference clock, and the temperature data, so as to make the operating frequency of the voltage-controlled oscillator the target frequency; The phase-locked loop branch locks the voltage-controlled oscillator to operate at the target frequency.

9. The method according to claim 8, characterized in that, The control voltage generation branch is a fixed voltage generation branch; the step of the control voltage generation branch generating a voltage signal and transmitting it to the second signal control terminal of the voltage-controlled oscillator includes: The fixed voltage generating branch outputs a fixed voltage signal to the second control signal terminal.

10. The method according to claim 8, characterized in that, The control voltage generation branch is a variable voltage generation branch. The input terminal of the variable voltage generation branch is connected to the output terminal of the frequency calibration branch. The variable voltage generation branch is connected to the second control signal terminal. The step of generating a voltage signal in the control voltage generation branch and transmitting it to the second signal control terminal of the voltage-controlled oscillator includes: The frequency calibration branch controls the variable voltage generation branch to output a corresponding voltage signal based on the temperature data.

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