CN111756371A - Temperature compensation method, auxiliary circuit and voltage-controlled oscillation device - Google Patents
Temperature compensation method, auxiliary circuit and voltage-controlled oscillation device Download PDFInfo
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- CN111756371A CN111756371A CN202010632043.7A CN202010632043A CN111756371A CN 111756371 A CN111756371 A CN 111756371A CN 202010632043 A CN202010632043 A CN 202010632043A CN 111756371 A CN111756371 A CN 111756371A
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L7/00—Automatic control of frequency or phase; Synchronisation
- H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
- H03L7/08—Details of the phase-locked loop
- H03L7/099—Details of the phase-locked loop concerning mainly the controlled oscillator of the loop
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L7/00—Automatic control of frequency or phase; Synchronisation
- H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
- H03L7/08—Details of the phase-locked loop
- H03L7/099—Details of the phase-locked loop concerning mainly the controlled oscillator of the loop
- H03L7/0995—Details of the phase-locked loop concerning mainly the controlled oscillator of the loop the oscillator comprising a ring oscillator
Abstract
The invention provides a temperature compensation method, an auxiliary circuit and a voltage-controlled oscillation device, aiming at improving the performance of a voltage-controlled oscillator. Wherein the temperature compensation auxiliary circuit comprises: the temperature control circuit comprises a conversion module and a voltage selection module, wherein the input end of the conversion module is used for inputting temperature information, and the conversion module is used for converting the temperature information into a control signal and outputting the control signal; the voltage selection module is coupled to the conversion module, and selects a voltage under the action of the control signal output by the conversion module, and outputs the selected voltage.
Description
Technical Field
The present invention relates to the field of integrated circuit technology, and in particular, to a temperature compensation method, an auxiliary circuit, and a voltage-controlled oscillation device.
Background
A Voltage Controlled Oscillator (VCO) is an oscillating circuit whose output frequency is controlled by an input voltage, the output frequency of the VCO being a function of the input signal voltage. Voltage-controlled oscillators are used in a wide variety of applications, such as for generating clocks in various types of communication systems, oscillating circuits in various high-speed data transmission systems, oscillating circuits in phase-locked loops (PLLs), and the like.
Voltage controlled oscillators are important circuit blocks in the above applications, whose main performance requirements are a wide frequency tuning range and low phase noise. In addition, the stability of the output frequency of the voltage-controlled oscillator with temperature change is also an extremely important index, and the decrease of the index can cause the performance of the circuit or system applied by the voltage-controlled oscillator to decrease and even cause the function to lose. For example, when the output frequency of the voltage-controlled oscillator varies greatly due to the ambient temperature, the pll frequency may lose lock for a short time or for a long time. Although the phase locked loop may be detected after losing lock and automatically restart the locking process, this period of loss of lock is generally unacceptable for communication systems.
Therefore, in the prior art, a method for compensating the temperature of the voltage-controlled oscillator is adopted, for example, a temperature compensation circuit is added in the voltage-controlled oscillator, however, the introduction of the temperature compensation circuit deteriorates the phase noise performance of the voltage-controlled oscillator, increases the complexity of the oscillation loop of the voltage-controlled oscillator, and simultaneously reduces the highest tunable frequency range of the voltage-controlled oscillator.
Disclosure of Invention
In view of the above, the present invention provides a temperature compensation method, an auxiliary circuit, and a voltage controlled oscillator to improve the performance of the voltage controlled oscillator.
The temperature compensation auxiliary circuit comprises: the temperature control circuit comprises a conversion module and a voltage selection module, wherein the input end of the conversion module is used for inputting temperature information, and the conversion module is used for converting the temperature information into a control signal and outputting the control signal; the voltage selection module is coupled to the conversion module, and selects a voltage under the action of the control signal output by the conversion module, and outputs the selected voltage.
Further, different temperature ranges correspond to different voltages, and the voltage selection module selects the voltage corresponding to the temperature range in which the temperature indicated by the temperature information is located under the action of the control signal.
Further, the conversion module includes a decoder, an input end of the decoder is used for inputting the temperature information, the decoder decodes the temperature information into the control signal, the decoder includes N output ends, and one of the N output ends is enabled at the same time; and, the voltage selection circuit includes a resistor array and a switch array, wherein the resistor array includes a plurality of resistors connected in series between a voltage source and a ground terminal, the switch array includes N switches respectively controlled by signals output by N output terminals of the decoder, one end of each switch is used for the output terminal of the selected voltage, the other end is coupled between two resistors in the resistor array, and the coupling positions of each switch in the resistor array are different, where N is a positive integer greater than 1.
Further, the circuit further comprises: the first switch and the second switch are respectively controlled by a first signal and a second signal which are opposite to each other, the first switch is controlled by the first signal to be switched on, the output voltage of the temperature compensation auxiliary circuit is the selected voltage, the second switch is controlled by the second signal to be switched on, and the output voltage of the temperature compensation auxiliary circuit is the voltage of a phase-locked loop PLL loop filter.
The invention also provides a temperature compensation method, which comprises the following steps: converting the temperature information of the circuit to be compensated into a control signal; selecting a voltage using the control signal; and using the selected voltage as a control voltage of the circuit to be compensated.
Further, different temperature ranges correspond to different voltages, and the control signal converted by the temperature information is used for selecting the voltage corresponding to the temperature range in which the temperature indicated by the temperature information is located.
Further, the step of using the selected voltage as the control voltage of the circuit to be compensated includes: and taking the selected voltage as a control voltage of the voltage-controlled oscillator in an automatic frequency calibration stage.
The present invention also provides a voltage controlled oscillation device comprising: a temperature compensation auxiliary circuit as described in any one of the above; and the output voltage of the temperature compensation auxiliary circuit is used for the control voltage of the automatic frequency calibration stage of the LC oscillating circuit.
Further, the device further comprises: a negative resistance generating circuit.
Further, the device further comprises: and the temperature detection circuit is used for detecting to acquire the temperature information.
In conclusion, the temperature compensation scheme can greatly improve the temperature compensation effect. In most cases, the frequency of the LC tank tends to decrease due to the temperature increase, and similar temperature compensation effects can be achieved by using the same concept and method for the case that the frequency of the LC tank tends to increase due to the extremely small temperature increase.
The embodiments of the present invention are designed and described by taking an LC oscillator as an example, but the above methods and circuits are not limited to an LC oscillator, and are equally applicable to other types of oscillators, such as a ring oscillator.
Drawings
The following description of the embodiments of the present invention will be made with reference to the accompanying drawings.
Fig. 1 is a schematic diagram of a conventional voltage-controlled oscillator;
FIG. 2 is a schematic diagram of a temperature compensation method according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of an auxiliary circuit for temperature compensation according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of another temperature compensation auxiliary circuit according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a voltage-controlled oscillation device according to an embodiment of the present invention;
fig. 6 is a schematic diagram of a variation curve of a frequency of a voltage-controlled oscillator with a control voltage Vtune according to an embodiment of the present invention.
Detailed Description
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description will be made with reference to the accompanying drawings. It is obvious that the drawings in the following description are only some examples of the invention, and that for a person skilled in the art, other drawings and embodiments can be derived from them without inventive effort. For the sake of simplicity, the drawings only schematically show the parts relevant to the present invention, and they do not represent the actual structure as a product.
Temperature compensation is very important for voltage controlled oscillators because large amplitude variations in temperature may cause Phase Locked Loops (PLLs) to lose lock. In order to realize temperature compensation of the voltage-controlled oscillator and improve the stability of the output frequency of the voltage-controlled oscillator along with the temperature change, a temperature compensation circuit is added in the voltage-controlled oscillator in the prior art.
Please refer to fig. 1, which is a schematic structural diagram of a conventional Voltage Controlled Oscillator (VCO). In the voltage-controlled oscillator shown in fig. 1, the voltage Vtune is applied to the analog voltage control fine tuning capacitor element, and the output signal frequency of the voltage-controlled oscillator is controlled by the voltage Vtune fed back by a phase-locked loop (PLL) loop. In the following description, voltages may be replaced by voltage values, and different voltages refer to voltages with different values.
As shown in fig. 1, the voltage-controlled oscillator 100 is an inductance-capacitance (LC) voltage-controlled oscillator, and its circuit structure mainly includes a negative resistance (-Gm) generating circuit (or cell) 110 and an LC tank (LC tank) 120. The negative resistance generation circuit 110 uses a metal oxide semiconductor field effect (MOS) transistor as an active device to provide the energy required by the oscillator to sustain oscillation. In fig. 1, a cross-coupled structure of an N-type metal-oxide-semiconductor field effect (NMOS) transistor and a P-type metal-oxide-semiconductor field effect (PMOS) transistor is taken as an example, and the cross-coupled structure is formed by cross-coupling a PMOS pair (M1, M2) and an NMOS pair (M3, M4). The lc tank 120 is a passive energy storage device, which may also be referred to as a resonant circuit or resonator, and includes an inductive element 121 and a capacitive element, the inductance and capacitance values of which substantially determine the output signal frequency of the oscillator. The inductive element 121 may be an inductor or an inductor array, and belongs to a passive energy storage element. The capacitor element may be a capacitor or a capacitor array, and the structure of the capacitor is relatively complex, and mainly includes a digitally controlled coarse tuning capacitor element 122 and an analog voltage controlled fine tuning capacitor element 123, which may be referred to as a coarse tuning capacitor and a fine tuning capacitor, respectively. The digitally controlled coarse tuning capacitor 122 may be a digital binary code controlled coarse tuning capacitor array, and the analog voltage controlled fine tuning capacitor 123 may also be referred to as an analog voltage controlled fine tuning capacitor 123, and may be an analog voltage controlled fine tuning (or called "fine tuning") capacitor array. The voltage-controlled oscillator generally has a wide adjustable frequency range, the coarse tuning capacitor array controlled by a multi-bit digital binary code can enable the LC oscillating circuit to realize frequency coverage of a wider frequency range, and binary code control word search corresponding to specific frequency is generally realized through phase-locked loop Automatic Frequency Calibration (AFC). The final accurate frequency locking is realized by a fine tuning capacitor array controlled by an analog voltage (Vtune) generated by a phase-locked loop closed-loop feedback loop after the phase-locked loop AFC process is finished.
The temperature compensation technique shown in fig. 1 mainly utilizes the property that the parasitic capacitance of the device changes with temperature and with voltage to perform complementary compensation, so as to ensure that the capacitance value of the resonator is basically stable and unchanged when the temperature changes. As shown in fig. 1, a temperature compensation circuit 130 is added to the vco 100, and the temperature compensation circuit 130 at least includes a variable capacitance element (e.g., a temperature compensation voltage control capacitor or a capacitor array), and the main principle of the temperature compensation circuit is to generate a temperature-dependent voltage with a specific temperature coefficient, apply the temperature-dependent voltage to the variable capacitance element, and generate a temperature-dependent equivalent capacitance value, which is exactly complementary to and offset from the temperature-dependent coefficient of the resonator capacitance itself, so that the resonator capacitance value is substantially stable and constant during temperature variation.
However, the above temperature compensation method requires a more complex resonator circuit structure, and increases the total capacitance of the resonator, thereby reducing the maximum tunable frequency range of the resonator, and more importantly, the added temperature compensation circuit may affect the phase noise performance of the vco, resulting in performance degradation.
In another temperature compensation method in the prior art, a temperature compensation circuit is also added to the voltage-controlled oscillator 100, except that the temperature compensation circuit is composed of a digitally controlled temperature compensation capacitive element, and reads the information of the temperature compensation control word pre-stored in the memory by means of a built-in lookup table on the chip. In specific application, after one frame is transmitted or received, the control voltage of the voltage-controlled oscillator is detected; and judging whether the control voltage is within a preset voltage range, if so, updating a control word of the temperature compensation capacitor corresponding to the frequency point in the lookup table to adjust the control voltage to be within the preset voltage range. The advantage of this approach over the approach shown in fig. 1 is that the digitally controlled temperature compensation capacitor does not significantly degrade the phase noise performance of the oscillator, but also increases the complexity of the resonator circuit and increases the total capacitance of the resonator, thus reducing the maximum tunable frequency range of the resonator. In addition, a read-write memory for the lookup table function with higher cost is introduced, increasing the chip cost. Moreover, after a frame is transmitted or received, the control voltage Vtune of the voltage-controlled oscillator needs to be detected to perform background parameter correction, which increases the use complexity of the system.
In view of the above drawbacks of the temperature compensation method, an embodiment of the present invention provides a temperature compensation method, which converts temperature information of a device to be compensated (e.g., a voltage-controlled oscillator) into a control signal through a simple logic circuit, selects a control voltage according to the control signal, and replaces an original control voltage of the device to be compensated (e.g., a control voltage of a fine-tuning capacitor of the voltage-controlled oscillator) with the control voltage to achieve a temperature compensation effect. Thus, the temperature compensation circuit of the voltage-controlled oscillator shown in fig. 1 can be removed, thereby reducing the influence on the highest adjustable frequency range and the like of the voltage-controlled oscillator and improving the performance of the voltage-controlled oscillator.
Please refer to fig. 2, which is a schematic diagram of a temperature compensation method according to an embodiment of the present invention. As shown in fig. 2, the method includes:
s210: converting the temperature information of the circuit to be compensated into a control signal;
s220: selecting a voltage using the control signal;
s230: and using the selected voltage as a control voltage of the circuit to be compensated.
The control signal converted by the temperature information is used for selecting the voltage corresponding to the temperature range in which the temperature represented by the temperature information is located. In this way, a selection of multi-level voltages can be achieved. Table 1 gives an example of the division of temperature ranges and voltages. It should be noted that table 1 only gives an example, and is not intended to limit the present invention, and in practical implementation, more or less ranges may be set as needed, and the range and voltage division may be different.
TABLE 1
The phase-locked loop can be divided into two stages, the first stage is an AFC stage, the PLL is in an open-loop state, a fixed voltage Vset is used as a control voltage Vtune in the prior art, the voltage Vset controlled by temperature information is used as the control voltage Vtune, and the value of the control voltage Vtune is a fixed value and cannot be changed in the AFC process. In the second phase, the PLL closed loop feedback loop starts to work, and the voltage Vset is used as the initial value of the control voltage Vtune. The above method provided by the embodiment of the present invention is mainly applied to the AFC stage, and the phase at which the PLL closed loop feedback loop starts to operate does not affect the essence of the embodiment of the present invention, and therefore, detailed description is not given, and reference may be specifically made to the prior art, and a corresponding manner may also be adopted to operate along with the technical evolution.
A temperature detection circuit is usually provided on the chip, and temperature information detected by the temperature detection circuit can be used as the above temperature information. The control voltage Vtune of the voltage-controlled oscillator in the AFC stage is selected, for example, by a control signal converted from temperature information provided by a temperature detection circuit of a chip on which the voltage-controlled oscillator is located.
The above temperature information can be processed by a simple logic circuit to realize conversion of the temperature information to the control signal and selection of the control voltage. An auxiliary circuit is described below in connection with the figures, which enables the selection of a control voltage using temperature information.
Please refer to fig. 3, which is a schematic diagram of a temperature compensation auxiliary circuit according to an embodiment of the present invention. As shown in fig. 3, the circuit 300 includes a conversion module 310 and a voltage selection module 320. The input terminal of the conversion module 310 is used for inputting the temperature information T _ info, and the conversion module 310 is used for converting the temperature information T _ info into a control signal (one of S0 to S8) and outputting the control signal; the voltage selecting module 320 is coupled to the converting module 310, and selects the voltage Vtune under the action of the control signal output by the converting module 310, and outputs the selected voltage Vtune.
The selected voltage Vtune is used for the control voltage of the circuit to be compensated, so that the initial value of the control voltage Vtune is related to the environmental temperature, a larger adjusting range of the control voltage Vtune is available when the temperature changes, and the temperature compensation is realized.
When the temperature compensation method and the temperature compensation auxiliary circuit are used for temperature compensation of the voltage-controlled oscillator, a core circuit (such as a resonator) of the original voltage-controlled oscillator is not required to be changed, so that the core circuit of the original voltage-controlled oscillator is not influenced, a simple auxiliary circuit structure is added to act on a voltage control end of the fine tuning capacitor, the initial value of the control voltage Vtune is related to the ambient temperature, a larger control voltage Vtune adjusting range can be used when the temperature changes, and the temperature compensation of the voltage-controlled oscillator is realized.
In addition, the temperature compensation method and the temperature compensation auxiliary circuit do not need to introduce larger system-level or chip-level cost, do not increase parasitic capacitance of the resonator to reduce the maximum frequency adjustable range, and have no influence on phase noise of the voltage-controlled oscillator. The voltage control curve (frequency vs Vtune) of the voltage-controlled oscillator can be greatly increased along with the stable range of temperature change by only utilizing the temperature information provided by the temperature detection circuit usually carried on the chip and processing the temperature information by a simple logic circuit, thereby achieving a more ideal temperature compensation effect.
The above voltage selection module 320 may implement the selection of the multi-level voltages, wherein each temperature information represents a temperature, the temperature may be within a temperature range, the temperature information within different temperature ranges may be converted into different control signals, such as one of the control signals S0 to S8, and the different control signals are used for controlling the voltage selection module 320 to select different voltages, so as to implement the selection of the multi-level voltages. Examples of temperature ranges and voltage divisions can also be seen in table 1 above.
In one implementation, the above conversion module 310 may be implemented by a decoder, and the voltage selection circuit 320 may be implemented by a resistor array and a switch array, which is simple and low-cost. The following description is made with reference to the accompanying drawings.
Please refer to fig. 4, which is a schematic diagram of another temperature compensation auxiliary circuit according to an embodiment of the present invention, and illustrates a specific implementation of the circuit structure shown in fig. 3, which is not intended to limit the present invention, and in other embodiments, other circuit elements may be used instead of the decoder, as long as the conversion of the temperature information into the control signal can be achieved. Instead of the switch array and the resistor array, other circuit elements may be used as long as the selection of the multilevel voltages is achieved.
As shown in fig. 4, the converting module 310 includes a decoder, an input end of the decoder is used for inputting temperature information, the decoder decodes the temperature information into a control signal, the decoder includes N output ends, one of the N output ends is enabled at a certain time, that is, one of the N output ends is enabled at the same time, and an output signal of the enabled output end is the above control signal. The voltage selection circuit 320 includes a resistor array and a switch array, wherein the resistor array includes a plurality of resistors connected in series between a voltage source and a ground terminal, the switch array includes N switches respectively controlled by signals S0-S8 output by N output terminals of the decoder, one terminal of each switch is used for the output terminal of the selected voltage, the other terminal of each switch is coupled between two resistors in the resistor array, and the coupling positions of each switch in the resistor array are different, where N is a positive integer greater than 1.
Further, the temperature compensation auxiliary circuit further includes a first switch and a second switch respectively controlled by a first signal and a second signal that are inverse to each other, for example, the first switch is controlled by the inverse SW _ B of the control signals SW and SW output by the PLL state machine. When the first switch is turned on under the control of the first signal, the output voltage of the temperature compensation auxiliary circuit is the voltage selected above, and when the second switch is turned on under the control of the second signal, the output voltage of the temperature compensation auxiliary circuit is the PLL loop filter voltage V _ LPF.
For example, the first switch is controlled by the first signal, one end of the first switch is used as the input end of the voltage of the PLL loop filter, and the other end of the first switch is coupled to the second switch; and the second switch is controlled by a second signal, one end of the second switch is used as the output end of the selected voltage, and the other end of the second switch is coupled with one end of the output end of each switch in the switch array, which is used for the selected voltage. One end of the first switch and one end of the second switch which are coupled are used as the output end of the temperature compensation auxiliary circuit.
In the example shown in FIG. 4, the temperature information is a 4-bit binary digital temperature code T _ info [3:0] as an example. The decoder receives, for example, a 4-bit binary digital temperature code T _ info [3:0] supplied from an on-chip temperature detection circuit, decodes it into S0 to S8 as an enable signal of the Vset voltage value selection switch. SW is the control signal output by the PLL state machine, and SW _ B is the inverse of SW. In the AFC process, SW is set to 0, SW _ B is set to 1, and the control voltage Vtune is connected with Vset; after AFC is finished, SW is set to 1, SW _ B is set to 0, and Vtune is connected to PLL loop filter voltage V _ LPF.
In fig. 4, N output terminals of the decoder are respectively used for outputting S0 to S8, and the N output terminals respectively control N switches S0 to S8 in the switch array. The different values of the digital temperature code T _ info [3:0] enable one of signals S0-S8 output by N output ends of the decoder to be effective, correspondingly, one of N switches S0-S8 is controlled to be switched on, for example, the decoder outputs a signal S4 to be effective, so that the switch S4 is switched on, and the corresponding output voltage is 0.7V, namely, the selection of the control voltage Vtune is realized.
The application of the above temperature compensation method or the auxiliary circuit in a voltage controlled oscillator is described below with reference to the drawings.
Fig. 5 is a schematic structural diagram of a voltage-controlled oscillation device according to an embodiment of the present invention. Compared to the temperature compensation scheme of fig. 1, this embodiment removes the temperature compensation circuit 130, for example, removes the variable capacitance element of the temperature compensation circuit 130, and adds an auxiliary circuit for providing the control voltage Vtune of the voltage-controlled oscillator in the AFC stage, and thus may also be referred to as a control voltage Vtune initial bias circuit.
As shown in fig. 5, the voltage-controlled oscillation device 500 includes a negative resistance generation circuit 510, an inductance-capacitance (LC) oscillation circuit 520, and a Vtune (control voltage) initial bias circuit 530, where the Vtune initial bias circuit 530 may also be referred to as a temperature compensation auxiliary circuit, and has the structure of the auxiliary circuit described in the above embodiments, which may be referred to as the above description and is not described herein again. And the output voltage of Vtune initial bias circuit 530 is used for control voltage Vtune of LC tank 520.
Further, Vtune initial bias circuit 530 may receive signals from a Phase Locked Loop (PLL) state machine control signal SW and a PLL loop filter voltage V _ LPF in addition to temperature information T _ info.
When the PLL system is powered up and begins to enter a lock process, the PLL internal state machine, e.g., Finite State Machine (FSM), first enters the phase locked loop Automatic Frequency Calibration (AFC) state. In the AFC state, the state machine sets the PLL feedback loop in an off state, the digitally controlled coarse tuning capacitor element enters an automatic search frequency control word state, and an AFC algorithm obtains an optimal digital code frequency control word through related analog and digital circuit processing. As shown in fig. 6, each curve represents the frequency output of the voltage controlled oscillator for a digital control word, and the AFC algorithm selects the one of the curves that is closest to the target frequency. In this process, the control voltage Vtune is kept at a fixed voltage value Vset until AFC ends. When AFC is complete, the state machine places the PLL feedback loop in an engaged state, and the control voltage Vtune begins to be subject to the PLL negative feedback loop and eventually settles to a voltage value very close to Vset. At this point, the PLL completes the frequency locking process.
After the PLL is locked, if the ambient temperature changes, the value of the inductance element and/or the capacitance element in the LC tank of the vco tends to change slightly due to the temperature change, which results in a change in the output frequency of the vco. In most cases, the frequency of the LC tank itself tends to decrease due to the increase of temperature, and therefore, as shown in fig. 6, the value of the control voltage Vtune is increased to keep the output frequency of the vco constant.
The control voltage Vtune has a more ideal working interval, and when the value of the control voltage Vtune is in the interval, the working state of a loop and the quality of an output signal are stable; when the value of the control voltage Vtune exceeds the interval, the PLL may lose lock. In the example shown in fig. 6, the ideal operating range of the control voltage Vtune is 0.2V to 1.2V.
In the AFC state, the control voltage Vtune needs to be maintained at a fixed voltage value Vset until the AFC is finished. In the prior art, Vset is connected to a fixed potential, and Vset is typically half of the ideal operating voltage interval of Vtune, which is 0.7V in fig. 6. After AFC is completed, the state machine places the PLL analog feedback loop in an engaged state and the control voltage Vtune eventually settles to a voltage value very close to 0.7V. If the ambient temperature variation range of the chip required to work normally is-40 deg.C-100 deg.C, the maximum possible variation of 140 deg.C is total, and the middle value is 30 deg.C. If the temperature for starting locking when the PLL is electrified is 30 ℃, after locking, if the maximum value of temperature rise or fall is 70 ℃, and the control voltage Vtune has a 1V change range for offsetting the influence of temperature change; if the temperature for starting locking when the PLL is electrified is-40 ℃, after locking, if the temperature rises to the maximum value of 140 ℃, the control voltage Vtune still has a variation range of 0.5V for offsetting the influence of temperature variation; if the temperature at which the PLL starts to lock after power-up is 100 ℃, the temperature after locking is 140 ℃ at the maximum, and the control voltage Vtune still has a variation range of 0.5V to offset the effect of temperature variation. At this time, if the PLL power-on start locking time temperature is not 30 ℃, an ideal operating interval of the control voltage Vtune cannot be used to compensate for the temperature variation and is "wasted".
Based on this, in an embodiment of the present invention, Vtune initial bias circuit for controlling voltage is shown in fig. 4, and the value of Vset is no longer set to a fixed value, but is a value associated with temperature. The temperature information may be "free" information provided to the system by a temperature detection circuit (e.g., a temperature diode) built in the chip, and may not be at the cost of an additional temperature detection circuit. Taking 0.2V to 1.2V in FIG. 6 as an example, the step value of one Vset is taken every 0.1V, corresponding on average to-40 ℃ to 100 ℃. If the value of Vset is set to 0.3V when the ambient temperature is detected to be-30 ℃ when the PLL is initially locked, the control voltage Vtune has a variation range of 0.9V for offsetting the influence of temperature variation when the maximum temperature rises by 130 ℃; if Vset is set to 1.1V when the ambient temperature is detected to be 90 c when the PLL is initially locked, then the control voltage Vtune also has a variation range of 0.9V to offset the effects of temperature variations when the maximum temperature is decreased by 130 c.
Therefore, the temperature compensation scheme can greatly improve the temperature compensation effect. And the corresponding relationship between the temperature variation range and the Vset value can be referred to the table 1.
In most cases, the frequency of the LC tank tends to decrease due to the temperature increase, and similar temperature compensation effects can be achieved by using the same concept and method for the case that the frequency of the LC tank tends to increase due to the extremely small temperature increase.
The embodiments of the present invention are designed and described by taking an LC oscillator as an example, but the above methods and circuits are not limited to an LC oscillator, and are equally applicable to other types of oscillators, such as a ring oscillator.
In addition, the negative resistance generating circuit according to the embodiment of the present invention is described by taking an NMOS-PMOS cross-coupled circuit as an example, but the above method and circuit do not limit the structure of the negative resistance generating circuit, and for example, an NMOS cross-coupled circuit or a PMOS cross-coupled circuit may also be used.
The foregoing is only a partial embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A temperature compensation assist circuit, comprising: a conversion module and a voltage selection module, wherein,
the input end of the conversion module is used for inputting temperature information, and the conversion module is used for converting the temperature information into a control signal and outputting the control signal;
the voltage selection module is coupled to the conversion module, and selects a voltage under the action of the control signal output by the conversion module, and outputs the selected voltage.
2. The circuit of claim 1, wherein different temperature ranges correspond to different voltages, and the voltage selection module selects the voltage corresponding to the temperature range in which the temperature indicated by the temperature information is located under the action of the control signal.
3. The circuit of claim 1, wherein the conversion module includes a decoder having an input for the temperature information, the decoder decoding the temperature information into the control signal, the decoder including N outputs, one of the N outputs being active at a time; and the number of the first and second electrodes,
the voltage selection circuit comprises a resistor array and a switch array, wherein the resistor array comprises a plurality of resistors connected in series between a voltage source and a ground terminal, the switch array comprises N switches respectively controlled by signals output by N output ends of the decoder, one end of each switch is used for the output end of the selected voltage, the other end of each switch is coupled between two resistors in the resistor array, the coupling positions of each switch in the resistor array are different, and N is a positive integer greater than 1.
4. The circuit of claim 3, further comprising: the first switch and the second switch are respectively controlled by a first signal and a second signal which are opposite to each other, the first switch is controlled by the first signal to be switched on, the output voltage of the temperature compensation auxiliary circuit is the selected voltage, the second switch is controlled by the second signal to be switched on, and the output voltage of the temperature compensation auxiliary circuit is the voltage of a phase-locked loop PLL loop filter.
5. A method of temperature compensation, comprising:
converting the temperature information of the circuit to be compensated into a control signal;
selecting a voltage using the control signal;
and using the selected voltage as a control voltage of the circuit to be compensated.
6. The method according to claim 5, wherein different temperature ranges correspond to different voltages, and the control signal converted by the temperature information is used to select the voltage corresponding to the temperature range in which the temperature indicated by the temperature information is located.
7. The method of claim 5, wherein the circuit to be compensated is a voltage controlled oscillator, and wherein the using the selected voltage as the control voltage of the circuit to be compensated comprises: and taking the selected voltage as a control voltage of the voltage-controlled oscillator in an automatic frequency calibration stage.
8. A voltage controlled oscillation device, comprising:
a temperature compensation auxiliary circuit as claimed in any one of claims 1-4;
and the output voltage of the temperature compensation auxiliary circuit is used for the control voltage of the automatic frequency calibration stage of the LC oscillating circuit.
9. The apparatus of claim 8, further comprising:
a negative resistance generating circuit.
10. The apparatus of claim 8, further comprising:
and the temperature detection circuit is used for detecting to acquire the temperature information.
Priority Applications (1)
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| CN202010632043.7A CN111756371A (en) | 2020-07-03 | 2020-07-03 | Temperature compensation method, auxiliary circuit and voltage-controlled oscillation device |
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| CN202010632043.7A CN111756371A (en) | 2020-07-03 | 2020-07-03 | Temperature compensation method, auxiliary circuit and voltage-controlled oscillation device |
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Cited By (2)
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| CN114584073A (en) * | 2022-02-28 | 2022-06-03 | 微龛(广州)半导体有限公司 | LC oscillator circuit, application system and temperature drift compensation method |
| CN114879779A (en) * | 2022-05-31 | 2022-08-09 | 成都中远创视科技有限公司 | Temperature control circuit based on filter |
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| CN114584073A (en) * | 2022-02-28 | 2022-06-03 | 微龛(广州)半导体有限公司 | LC oscillator circuit, application system and temperature drift compensation method |
| CN114584073B (en) * | 2022-02-28 | 2022-12-20 | 微龛(广州)半导体有限公司 | LC oscillator circuit, application system and temperature drift compensation method |
| CN114879779A (en) * | 2022-05-31 | 2022-08-09 | 成都中远创视科技有限公司 | Temperature control circuit based on filter |
| CN114879779B (en) * | 2022-05-31 | 2023-09-01 | 成都中远创视科技有限公司 | Temperature control circuit based on filter |
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