CN115021746A - Ring oscillator compensation circuit, CDR control loop and receiver - Google Patents
Ring oscillator compensation circuit, CDR control loop and receiver Download PDFInfo
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- H—ELECTRICITY
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- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L1/00—Stabilisation of generator output against variations of physical values, e.g. power supply
- H03L1/02—Stabilisation of generator output against variations of physical values, e.g. power supply against variations of temperature only
- H03L1/022—Stabilisation of generator output against variations of physical values, e.g. power supply against variations of temperature only by indirect stabilisation, i.e. by generating an electrical correction signal which is a function of the temperature
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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
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Abstract
The application relates to a ring oscillator compensation circuit, a CDR control loop and a receiver, the circuit comprising: the positive temperature current module is used for connecting the power supply source and the reference current source and outputting compensation current with positive temperature characteristics. The current-voltage conversion module is connected with the positive temperature current module and is used for converting the compensation current into compensation voltage with positive temperature characteristic. The voltage stabilizer is connected with the current-voltage conversion module and is used for being respectively connected with the power supply source and the ring oscillator, converting the power supply voltage of the ring oscillator without compensation into the ring oscillator power supply voltage changing along with the compensation voltage and outputting the ring oscillator power supply voltage to the power supply end of the ring oscillator. The process detection module is respectively connected with the positive temperature current module and the current-voltage conversion module and is used for detecting a process angle of the circuit and performing process compensation on the ring oscillator power supply voltage according to the process angle; the process corner includes a fast process corner or a slow process corner. The effect of compensating PVT variation on the oscillation frequency of the ring oscillator directly in a chip is realized.
Description
Technical Field
The invention belongs to the technical field of interface circuits, and relates to a ring oscillator compensation circuit, a CDR control loop and a receiver.
Background
The high-speed interface circuit comprises a transmitter part and a receiver part and is widely applied to various data transmission scenes. In a receiver chip using an on-chip reference clock, the on-chip clock circuit is greatly affected by PVT (Process, Voltage, Temperature), and usually has a frequency deviation of ± 20% or more. Such a large frequency deviation exceeds the operating range of the Clock Data Recovery (CDR) in the receiver, which may result in the CDR not operating properly. To compensate for the effect of PVT variations on the oscillation frequency, it is common to use the good PVT characteristics of the off-chip resistance to generate a reference current for the on-chip oscillator. However, in the process of implementing the present invention, the inventors found that in the practical application environment where the above off-chip reference current cannot be used, there is still a technical problem that the influence of PVT variation on the oscillation frequency cannot be directly compensated on-chip.
Disclosure of Invention
In view of the above problems in the conventional methods, the present invention provides a ring oscillator compensation circuit, a CDR control loop and a receiver, which can directly compensate the influence of PVT variation on oscillation frequency in chip.
In order to achieve the above purpose, the embodiment of the invention adopts the following technical scheme:
in one aspect, a ring oscillator compensation circuit is provided, comprising:
the positive temperature current module is used for connecting the power supply source and the reference current source and outputting compensation current with positive temperature characteristics;
the current-voltage conversion module is connected with the positive temperature current module and is used for converting the compensation current into compensation voltage with positive temperature characteristic;
the voltage stabilizer is connected with the current-voltage conversion module and is used for respectively connecting the power supply source and the ring oscillator, converting the power supply voltage of the ring oscillator without compensation into the ring oscillator power supply voltage changing along with the compensation voltage and outputting the ring oscillator power supply voltage to the power supply end of the ring oscillator;
the process detection module is respectively connected with the positive temperature current module and the current-voltage conversion module and is used for detecting a process angle of the circuit and performing process compensation on the ring oscillation power supply voltage according to the process angle; the process corner includes a fast process corner or a slow process corner.
In one embodiment, the positive temperature current module comprises a PTAT module and a current proportion control module, the PTAT module is used for being connected with a power supply source, the PTAT module is respectively connected with the current proportion control module, the current-voltage conversion module and the process detection module, and the current proportion control module is used for being connected with a reference current source;
the current proportion control module is used for converting the zero temperature drift current of the reference current source into proportion mirror current, and the PTAT module is used for generating compensation current under the control of the proportion mirror current.
In one embodiment, the PTAT module includes a transistor M0, a transistor M1, and a resistor R0, one end of the resistor R0 is used for connecting a power supply, a source of the transistor M0 is connected to the other end of the resistor R0, a drain of the transistor M0 is connected to the current-voltage conversion module and the process detection module, a gate of the transistor M0 is connected to a gate of the transistor M1, a source of the transistor M1 is used for connecting the power supply, and a drain of the transistor M1 is connected to an output end of the current ratio control module.
In one embodiment, the current ratio control module includes a transistor M2 and a transistor M3, a drain of the transistor M2 is connected to a drain and a gate of the transistor M1, a gate of the transistor M2 is connected to a gate and a drain of the transistor M3, a source of the transistor M2 is connected to a source of the transistor M3, and a drain of the transistor M3 is connected to the reference current source.
In one embodiment, the current-voltage conversion module comprises a resistor R1 and a resistor R2 which are connected in series, one end of the resistor R1 is connected with the PTAT module, the other end of the resistor R2 is connected with the process detection module, and a connecting terminal led out between the resistor R1 and the resistor R2 is connected with the voltage stabilizer.
In one embodiment, the process detection module comprises a transistor M4, a transistor M5, a resistor R3 and a resistor R4, wherein the drain of the transistor M4 is connected with the PTAT module, the source of the transistor M4 is connected with one end of the resistor R3, the gate and the drain of the transistor M4 are connected, and the other end of the resistor R3 is connected with the other end of the resistor R2;
the source of the transistor M5 is connected with the PTAT module, the drain of the transistor M5 is connected with one end of the resistor R4, the gate and the drain of the transistor M4 are connected, and the other end of the resistor R4 is connected with the other end of the resistor R2.
In one embodiment, the voltage regulator comprises an operational amplifier OP, a transistor M6, a resistor R5 and a resistor R6, wherein the non-inverting input end of the operational amplifier OP is connected with a connecting terminal led out between the resistor R1 and the resistor R2, the inverting input end of the operational amplifier OP is connected with a connecting terminal led out between the resistor R5 and the resistor R6, and the output end of the operational amplifier OP is connected with the grid electrode of the transistor M6;
the drain of the transistor M6 is used for connecting a power supply source, the source of the transistor M6 is used for connecting the power supply end of the ring oscillator, the resistor R5 is connected with the resistor R6 in series, one end of the resistor R5 is connected with the source of the transistor M6, and the other end of the resistor R6 is connected with the other end of the resistor R2.
In another aspect, a CDR control loop is also provided, including a ring oscillator and the above ring oscillator compensation circuit.
In one embodiment, the ring oscillator is an N-stage ring oscillator, and N is an odd number not less than 3.
In yet another aspect, a receiver is also provided, which includes the CDR control loop described above.
One of the above technical solutions has the following advantages and beneficial effects:
according to the annular oscillator compensation circuit, the annular oscillator compensation device and the annular oscillator receiver, the positive temperature current module, the current-voltage conversion module, the voltage stabilizer and the process detection module are arranged in the chip, and the power supply voltage of the annular oscillator is controlled by the compensation voltage, so that the power supply voltage V is from the power supply voltage CC The disturbance of (2) has negligible influence on the oscillation frequency of the ring oscillator. The voltage of the output end of the voltage stabilizer is in direct proportion to the input compensation voltage with the positive temperature characteristic, namely the power supply voltage of the ring oscillator is adjusted by the voltage stabilizer and can strictly follow the variation of the compensation voltage with the positive temperature characteristic, so that the ring oscillation power supply voltage output by the voltage stabilizer is also the voltage with the positive temperature characteristic.
When the ring oscillator is not compensated, the oscillation frequency of the ring oscillator is reduced along with the increase of the temperature (negative temperature characteristic), and the supply voltage of the ring oscillator is adjusted by the voltage stabilizer, so that the supply voltage of the ring oscillator becomes a controlled positive temperature characteristic voltage which can be increased along with the increase of the temperature, and the oscillation frequency of the ring oscillator is in direct proportion to the supply voltage of the ring oscillator, so that the supply voltage of the ring oscillator is increased, the oscillation frequency of the ring oscillator is also increased, the ring oscillator is supplied by the controlled supply voltage of the ring oscillator, and the influence of the temperature factor on the oscillation frequency of the ring oscillator can be counteracted. In addition, the process detection module can automatically adjust the power supply voltage of the ring oscillator according to the process angle of the ring oscillator, so that the process compensation of the ring oscillator is realized, and the influence of process factors on the oscillation frequency of the ring oscillator is compensated. In conclusion, the influence of PVT change on the oscillation frequency of the ring oscillator is directly compensated in a chip, so that the oscillation frequency of the ring oscillator can be kept stable under the influence of the PVT change, and the normal working requirement of the CDR is met.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of a ring oscillator compensation circuit according to one embodiment;
FIG. 2 is a schematic diagram of the variation of the oscillation frequency of the ring oscillator with temperature when uncompensated;
FIG. 3 shows an exemplary voltage V ctrl Schematic diagram of variation with temperature;
FIG. 4 is a schematic diagram of the variation of the oscillation frequency of the compensated ring oscillator with temperature in one embodiment;
FIG. 5 is a schematic diagram of a ring oscillator compensation circuit according to another embodiment;
FIG. 6 is a schematic diagram of a ring oscillator compensation circuit according to yet another embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It should be noted that reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
One skilled in the art will appreciate that the embodiments described herein can be combined with other embodiments. The term "and/or" as used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.
The circuit scheme provided by the application can be applied to a receiver chip. Due to the limitation of practical application scenes, the scheme of compensating PVT by using an off-chip element is abandoned, and an innovative compensation circuit scheme is provided by adopting an on-chip design, so that the influence of PVT of a transistor on the oscillation frequency is compensated. If the supply voltage of the ring oscillator changes, the oscillation frequency output of the ring oscillator will be affected and will deviate from the internal reference frequency required by the CDR control loop. In addition, the process angle (for example, the process angles of chips of different batches cannot be completely consistent) during the production of the chip also affects the oscillation frequency output of the ring oscillator, so that the design of the ring oscillator cannot be considered, and a certain compensation needs to be set for the ring oscillator so that the oscillation frequency output of the ring oscillator under different working conditions is stable and controllable. The scheme of this application can design the front end at on-chip ring oscillator to the influence of PVT to the oscillation frequency of compensation transistor guarantees that ring oscillator oscillation frequency output under different operating modes is all stable controllable.
The following detailed description of embodiments of the invention will be made with reference to the accompanying drawings.
Referring to fig. 1, in one embodiment, a ring oscillator compensation circuit 100 is provided, which includes a positive temperature current module 12, a current-to-voltage conversion module 14, a voltage regulator 16, and a process detection module 18. The positive temperature current module 12 is used for connecting the power supply source and the reference current source 102 and outputting a compensation current with positive temperature characteristics. The current-voltage conversion module 14 is connected to the positive temperature current module 12 for converting the compensation current into a compensation voltage with a positive temperature characteristic. The voltage stabilizer 16 is connected to the current-voltage conversion module 14, and is configured to be connected to the power supply and the ring oscillator 101, respectively, convert the power supply voltage of the ring oscillator 101 without compensation into a ring oscillation power supply voltage varying with the compensation voltage, and output the ring oscillation power supply voltage to the power supply terminal of the ring oscillator 101. The process detection module 18 is respectively connected with the positive temperature current module 12 and the current-voltage conversion module 14 and is used for detecting a process angle of the circuit and performing process compensation on the ring oscillator power supply voltage according to the process angle; the process corner includes a fast process corner or a slow process corner.
It will be appreciated that in this design the supply of ring oscillator 101 is no longer directly supplied, but rather ring oscillator 101 is supplied by voltage regulator 16, which supplies supply voltage V CC The variation will not reach the ring oscillator 101, so the effect of the supply voltage on the ring oscillator 101 becomes very small, compensating for the effect of the supply voltage of the ring oscillator 101 on its oscillation frequency. The power supply source and the reference current source 102 are both on-chip existing modules, and in this embodiment, they can be used directly.
In some embodiments, ring oscillator 101 is an N-stage ring oscillator 101, with N being an odd number not less than 3. It can be understood that the number of ring oscillators 101 used in CDR control loops in different receiver chips is different, and some ring oscillators 101 are 3-stage ring oscillators 101, some ring oscillators 101 are 5-stage ring oscillators 101, some ring oscillators 101 are 7-stage ring oscillators 101, and some ring oscillators oscillate more than 7 stages, and the above ring oscillator compensation circuit 100 can be applied to compensate the influence of PVT of transistors on oscillation frequency.
The positive temperature current module 12 is a circuit module for generating a current with positive temperature characteristics by using the reference current provided by the reference current source 102 and the current of the power supply source, that is, generating the compensation current I with the required positive temperature characteristics C . The positive temperature current module 12 may be designed by using transistors and resistors. The current-voltage conversion module 14 may be a circuit module formed by connecting resistive elements in series, in parallel, or by a combination of the two, as long as the required current-to-voltage conversion function can be realized.
The regulator 16 may be a conventional regulator 16 circuit design, and the output ring supply voltage may utilize the characteristics of the regulator 16 and the compensation voltage V with positive temperature characteristics ref Proportional relation is formed, so that the ring oscillator power supply voltage is ensured to follow the compensation voltage V with positive temperature characteristic ref Variation, i.e. compensation voltage V of positive temperature characteristic of ring supply voltage ref And controlling so that the ring oscillator power supply voltage is also the voltage with positive temperature characteristic.
The principle of temperature compensation implemented by the ring oscillator compensation circuit 100 is as follows: as shown in fig. 2 to 4, fig. 2 shows the oscillation frequency f of the uncompensated ring oscillator 101 0 Decreases as the temperature T increases. FIG. 3 shows the output ring supply voltage V of the ring oscillator compensation circuit 100 ctrl Which increases with increasing temperature T. Oscillation frequency f of ring oscillator 101 and ring oscillator supply voltage V thereof ctrl Proportional ratio, V ctrl The larger the oscillation frequency f is. Therefore, the influence of the temperature factor on the oscillation frequency f and the influence of the ring oscillator power supply voltage factor on the oscillation frequency f are balanced out, and finally the compensated oscillation frequency f is obtained 1 Remains stable with temperature as shown in figure 4.
The carrier mobility of a CMOS (Complementary Metal Oxide Semiconductor) transistor has a negative temperature characteristic, i.e., the temperature T increases the carrier mobilityThe rate of shift decreases. Since the on-resistance of the transistor increases due to the decrease in the mobility of carriers, the oscillation frequency f decreases, and the ring oscillator 101 also has negative temperature characteristics. The supply voltage of the ring oscillator 101 is set to a controlled voltage source V in this design ctrl I.e. the ring supply voltage, the frequency f of the ring oscillator 101 and the ring supply voltage V ctrl In direct proportion. In order to compensate for the negative temperature characteristic of the oscillation frequency, a ring supply voltage V is required ctrl Having a positive temperature characteristic, V ctrl Increasing with increasing temperature T.
In addition, the oscillation frequency f of the uncompensated ring oscillator 101 varies with the process angle at the rated temperature, and therefore, the process angle of the ring oscillator 101 also needs to be compensated. The process corner variations are mainly caused by variations in the gate oxide thickness and doping concentration of the transistors. Gate oxide thickness and doping concentration influence threshold voltage V of transistor T And the mobility of carriers, a process corner with a thin gate oxide layer and a heavy doping concentration is generally defined as a fast process corner, and vice versa as a slow process corner. After the chips are produced, the process corners of the chips are determined, and the chips produced in the same batch are in a fast process corner, some chips are in a slow process corner, and some chips belong to a standard process corner.
The ring oscillator 101 has the greatest oscillation frequency at fast process corners because the threshold voltage V is the greatest at fast process corners where the carrier mobility of the CMOS transistors within the ring oscillator 101 is greatest T And is minimum, the on-resistance is also minimum. In contrast, the ring oscillator 101 oscillates at a minimum frequency at slow process corners. Therefore, to compensate for the deviation of the oscillation frequency due to the process corner difference, the ring oscillator compensation circuit 100 should reduce the voltage V (relative to the standard process corner) when the circuit is in the fast process corner ctrl While in the slow process corner the voltage V needs to be increased (relative to the standard process corner) ctrl . Therefore, the process monitor module 18 can be designed with transistors and resistive devices such that when the process monitor module is in the fast process corner, the current flowing through the process monitor module increases (relative to the current flowing in the normal process corner), and then the current flowing through the process monitor module increasesCompensation voltage V ref Decrease, correspondingly, V ctrl The voltage is reduced accordingly, thereby turning the oscillation frequency low. In the slow process corner, the compensation voltage V is reduced when the current flowing through the process detection module 18 is reduced (relative to the normal process corner) ref And voltage V ctrl And in turn, increases, thereby tuning the oscillation frequency higher. Through the adjustment, the process detection module 18 automatically detects the process angle and compensates the process angle, so that the compensation of the oscillation frequency deviation under different process angles is finally realized.
In the ring oscillator compensation circuit 100, the positive temperature current module 12, the current-voltage conversion module 14, the voltage stabilizer 16 and the process detection module 18 are arranged in the chip, and the supply voltage of the ring oscillator 101 is compensated by the compensation voltage V ref Is controlled so as to be derived from the supply voltage V CC The disturbance of (a) has a negligible effect on the oscillation frequency of the ring oscillator 101. After the positive temperature current module 12 generates the current with positive temperature characteristic based on the reference current source 102 in the chip, the current is converted into the compensation voltage with positive temperature characteristic by the current-voltage conversion module 14 and is supplied to the voltage stabilizer 16, because the voltage at the output end of the voltage stabilizer 16 is in direct proportion to the input compensation voltage with positive temperature characteristic, that is, the power supply voltage of the ring oscillator 101 is adjusted by the voltage stabilizer 16 and can strictly follow the change of the compensation voltage with positive temperature characteristic, so that the ring oscillation power supply voltage output by the voltage stabilizer 16 is also the voltage with positive temperature characteristic.
Since the oscillation frequency of the ring oscillator 101 decreases with the increase of the temperature (negative temperature characteristic) when the ring oscillator 101 is not compensated, and the supply voltage of the ring oscillator 101 is adjusted by the voltage stabilizer 16, the supply voltage of the ring oscillator 101 becomes a controlled positive temperature characteristic voltage which can increase with the increase of the temperature, and the oscillation frequency of the ring oscillator 101 is in direct proportion to the supply voltage of the ring oscillator 101, the supply voltage of the ring oscillator increases, the oscillation frequency of the ring oscillator 101 also increases, and therefore the ring oscillator 101 is supplied by the controlled supply voltage of the ring oscillator, and the influence of the temperature factor on the oscillation frequency of the ring oscillator 101 can be counteracted. In addition, the process detection module 18 can automatically adjust the ring oscillator supply voltage according to the process angle of the ring oscillator 101, so as to realize process compensation on the ring oscillator 101 and compensate the influence of process factors on the oscillation frequency of the ring oscillator 101. In conclusion, the influence of the PVT change on the oscillation frequency of the ring oscillator 101 is directly compensated in a chip, so that the oscillation frequency of the ring oscillator 101 can be kept stable under the influence of the PVT change, and the normal working requirement of the CDR is met.
In one embodiment, as shown in fig. 5, the positive temperature current module 12 includes a PTAT module 122 and a current proportional control module 124. The PTAT module 122 is used for connecting a power supply, and the PTAT module 122 is respectively connected to the current ratio control module 124, the current-voltage conversion module 14, and the process detection module 18. The current ratio control module 124 is used to connect the reference current source 102. The current proportional control module 124 is used for converting the zero temperature drift current of the reference current source 102 into a proportional mirror current, and the PTAT module 122 is used for generating a compensation current under the control of the proportional mirror current.
It is to be understood that in FIG. 5, I B The zero temperature drift current from the on-chip reference module (i.e., the aforementioned reference current source 102) does not change with temperature changes. PTAT, also known as the reporting to absolute temperature, is proportional to the absolute temperature; proportional mirror current I used on the aforementioned PTAT module 122 B1 Is from I B The mirror currents of (a) and (b) may be equal in magnitude or proportional, and may be specifically determined by the adjustment of the current proportional control module 124. Thus, proportional mirror current I B1 Also zero temperature drift current, the PTAT module 122 mirrors the current I at a ratio B1 Under the control of (2), the current of the power supply source is converted into the current I with positive temperature characteristic C I.e. the aforementioned compensation current I C 。
The PTAT module 122 may adopt various PTAT circuit structures, as long as it can implement the current conversion output in the above-mentioned chip, and the current conversion output of the required positive temperature characteristic can be effectively and reliably implemented through the PTAT module 122 and the current ratio control module 124, and the current regulation flexibility is high.
In one embodiment, as shown in fig. 6, the PTAT module 122 includes a transistor M0, a transistor M1, and a resistor R0. One end of the resistor R0 is used for connecting a power supply source, and the source of the transistor M0 is connected with the other end of the resistor R0. The drain of the transistor M0 is connected to the current-voltage conversion module 14 and the process detection module 18, respectively, and the gate of the transistor M0 is connected to the gate of the transistor M1. The source of the transistor M1 is used for connecting the power supply source, and the drain of the transistor M1 is connected to the output terminal of the current ratio control module 124.
It will be appreciated that in the present embodiment, a preferred PTAT module 122 as described above is designed. According to current I B1 And the value of the resistor R0, and the sizes of the devices of the transistor M0 and the transistor M1 can directly deduce I through the circuit relation C Is inversely related to the carrier mobility and the value of the resistance R0. Since the carrier mobility and the resistance have negative temperature characteristics, I is obtained C Is a current with a positive temperature characteristic. In this design, although the resistance device has a negative temperature characteristic, the absolute value of the temperature coefficient of resistance is much smaller than the current I C Absolute value of the temperature coefficient of (a). Thus, V is finally obtained A Is a voltage with positive temperature characteristic, thereby compensating the voltage V ref Also a voltage with a positive temperature characteristic.
By adopting the circuit design of the PTAT module 122, the required current conversion output can be realized while saving the circuit scale and having higher reliability.
In one embodiment, as shown in FIG. 6, the current ratio control module 124 includes a transistor M2 and a transistor M3. The drain of the transistor M2 is connected to the drain and the gate of the transistor M1, respectively, the gate of the transistor M2 is connected to the gate and the drain of the transistor M3, respectively, and the source of the transistor M2 is connected to the source of the transistor M3. The drain of transistor M3 is used to connect to reference current source 102.
It is understood that in the present embodiment, a preferred current ratio control module 124 is designed, which is composed of a pair of transistors. Current I is passed through transistor M2 and transistor M3 B Is proportional mirror image to I of transistor M1 B1 The ratio may be selected to be 1, or may be selected to be other than 1 ratio, and the sizes of the transistor M2 and the transistor M3 may be specifically selected according to the actual application requirements.
By adopting the circuit design of the current proportion control module 124, the required current proportion mirror image output can be realized, the circuit scale is saved, and the reliability is higher.
In one embodiment, as shown in fig. 6, the current-voltage conversion module 14 includes a resistor R1 and a resistor R2 connected in series. One end of the resistor R1 is connected to the PTAT module 122, and the other end of the resistor R2 is connected to the process detection module 18. The connection terminal led out between the resistor R1 and the resistor R2 is connected with the voltage stabilizer 16.
It can be understood that, in the present embodiment, it is preferable that the current-voltage conversion module 14 is formed by using a series resistor, so that the flowing current is converted into a voltage output by using the resistor. In particular, a current I having a positive temperature characteristic C Will be shunted to the process detecting module 18 and the current-to-voltage converting module 14, where the positive temperature characteristic current flowing through the resistor R1 and the resistor R2 will generate a corresponding voltage drop, i.e. be converted into the compensation voltage V with positive temperature characteristic ref And output to the regulator 16.
Specifically, as shown in fig. 6, although the resistor has a negative temperature characteristic, the absolute value of the temperature coefficient of the resistor is much smaller than the current I C Absolute value of the temperature coefficient of (a). Thus, V is finally obtained A Is a voltage having a positive temperature characteristic. Due to V A And a compensation voltage V ref Proportional relation, voltage V ctrl And a compensation voltage V ref Is in direct proportion, so the voltage V ctrl A voltage of positive temperature characteristics. Because of the voltage V ctrl As temperature increases, the oscillation frequency will also increase accordingly, thereby compensating for the decreased frequency of the ring oscillator 101 due to the increased temperature.
By using the current-voltage conversion module 14 formed by the series resistors, it is possible to achieve a desired current-voltage conversion output while further saving the circuit scale and achieving higher reliability.
In one embodiment, as shown in fig. 6, the process detection module 18 includes a transistor M4, a transistor M5, a resistor R3, and a resistor R4. The drain of the transistor M4 is connected to the PTAT module 122, the source of the transistor M4 is connected to one end of the resistor R3, and the gate and drain of the transistor M4 are connected. The other end of the resistor R3 is connected to the other end of the resistor R2. The source of the transistor M5 is connected to the PTAT module 122, and the drain of the transistor M5 is connected to one end of the resistor R4. The gate and the drain of the transistor M4 are connected, and the other end of the resistor R4 is connected to the other end of the resistor R2.
It is to be understood that, in the present embodiment, preferably, the process detection module 18 adopts a circuit structure formed by the transistor and the resistor element. In particular, to compensate for the deviation of the oscillation frequency due to the process corner difference, the ring oscillator compensation circuit 100 should reduce the voltage V (relative to the standard process corner) when the circuit is in the fast process corner ctrl While in the slow process corner the voltage V needs to be increased (relative to the standard process corner) ctrl . Therefore, when the circuit is in the fast process corner, the current flowing through the transistor M4 and the transistor M5 increases (relative to the standard process corner), and the compensation voltage V ref Decrease, correspondingly, V ctrl The voltage is also reduced accordingly, thereby turning the oscillation frequency low. While in the slow process corner, the current flowing through the transistor M4 and the transistor M5 is reduced (relative to the normal process corner), and the compensation voltage V is reduced ref And voltage V ctrl And in turn, increases, thereby turning the oscillation frequency higher.
By adopting the process compensation circuit structure, the required compensation of the oscillation frequency deviation under different process angles can be realized, the circuit scale is further saved, and the reliability is higher.
In one embodiment, as shown in FIG. 6, the voltage regulator 16 includes an operational amplifier OP, a transistor M6, a resistor R5, and a resistor R6. The non-inverting input end of the operational amplifier OP is connected with a connection terminal led out between the resistor R1 and the resistor R2, the inverting input end of the operational amplifier OP is connected with a connection terminal led out between the resistor R5 and the resistor R6, and the output end of the operational amplifier OP is connected with the grid electrode of the transistor M6. The drain of the transistor M6 is used for connecting the power supply source, and the source of the transistor M6 is used for connecting the power supply terminal of the ring oscillator 101. The resistor R5 and the resistor R6 are connected in series, one end of the resistor R5 is connected with the source of the transistor M6, and the other end of the resistor R6 is connected with the other end of the resistor R2.
It is to be understood that in the present embodiment, it is preferableThe above-described specific configuration of the regulator 16 is adopted. Specifically, the drain of the transistor M6 at the output of the regulator 16 is connected to the power supply voltage, and the compensation voltage V with positive temperature characteristic is used ref The control is carried out so that the power supply voltage connected to the power supply terminal of the ring oscillator 101 becomes a voltage V with positive temperature characteristic ctrl So that the oscillation frequency clk of the ring oscillator 101 is at the voltage V ctrl Is not influenced by PVT factors of the transistor.
By adopting the above-described structure of the voltage regulator 16, it is possible to further save the circuit scale and to achieve higher reliability while realizing a desired voltage control function.
It should be noted that the cmos transistor in each of the above embodiments may be an N-channel transistor or a P-channel transistor, and when a specific device is used, the device exchange may be achieved by performing adaptive adjustment according to the needs and the characteristics of the transistor. The ring oscillator 101 in fig. 6 is a schematic diagram illustrating an example of 3-stage ring oscillation, and other ring oscillations are controlled in the same manner.
In one embodiment, a CDR control loop is also provided that includes a ring oscillator 101 and the ring oscillator compensation circuit 100 described above.
It can be understood that, regarding the description limitations of the ring oscillator compensation circuit 100 and the ring oscillator 101 in the present embodiment, the same description and limitations in each embodiment of the ring oscillator compensation circuit 100 can be understood with reference to the above description, and are not repeated herein. Those skilled in the art can understand that the CDR control loop referred to herein may include other circuit structures besides the ring oscillator 101 and the ring oscillator compensation circuit 100, such as but not limited to PLL loop, FD/PD loop, and digital unit circuit, and the like, and it can be understood by referring to the structural components of the CDR control loop commonly known in the art, and the detailed description thereof is omitted here.
According to the CDR control loop, by applying the annular oscillator compensation circuit 100, the influence of PVT change on the oscillation frequency of the annular oscillator 101 is directly compensated in a chip, so that the oscillation frequency of the annular oscillator 101 can be kept stable under the influence of PVT change, the normal working requirement of the CDR control loop is met, and the working reliability is improved.
In one embodiment, there is also provided a receiver comprising the CDR control loop described above.
It is understood that the detailed explanation of the CDR control loop in the present embodiment can be understood by referring to the corresponding explanation of the CDR control loop embodiment described above, and the description is not repeated here. It should be noted that the receiver in this embodiment may include other existing components not described in this specification, in addition to the above-mentioned improved ring oscillator compensation circuit 100, and it can be understood by referring to the structure of the receiver chip existing in the art, and the detailed description is not listed in this specification.
By applying the CDR control loop, the receiver can ensure that the internal reference clock of the CDR control loop is not influenced by PVT changes, thereby effectively improving the working reliability of the receiver.
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above examples only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the spirit of the present application, and all of them fall within the scope of the present application. Therefore, the protection scope of the present patent should be subject to the appended claims.
Claims (10)
1. A ring oscillator compensation circuit, comprising:
the positive temperature current module is used for connecting the power supply source and the reference current source and outputting compensation current with positive temperature characteristics;
the current-voltage conversion module is connected with the positive temperature current module and is used for converting the compensation current into compensation voltage with positive temperature characteristic;
the voltage stabilizer is connected with the current-voltage conversion module and is used for being respectively connected with the power supply source and the ring oscillator, converting the power supply voltage of the ring oscillator without compensation into the ring oscillator power supply voltage changing along with the compensation voltage and outputting the ring oscillator power supply voltage to the power supply end of the ring oscillator;
the process detection module is respectively connected with the positive temperature current module and the current-voltage conversion module and is used for detecting a process angle of a circuit and performing process compensation on the ring oscillator power supply voltage according to the process angle; the process corner includes a fast process corner or a slow process corner.
2. The ring oscillator compensation circuit of claim 1, wherein the positive temperature current module comprises a PTAT module and a current proportional control module, the PTAT module is configured to be connected to the power supply, the PTAT module is respectively connected to the current proportional control module, the current-voltage conversion module and the process detection module, and the current proportional control module is configured to be connected to the reference current source;
the current proportion control module is used for converting zero temperature drift current of the reference current source into proportion mirror current, and the PTAT module is used for generating the compensation current under the control of the proportion mirror current.
3. The ring oscillator compensation circuit of claim 3, wherein the PTAT module comprises a transistor M0, a transistor M1 and a resistor R0, one end of the resistor R0 is used for connecting the power supply, a source of the transistor M0 is connected to the other end of the resistor R0, a drain of the transistor M0 is respectively connected to the current-voltage conversion module and the process detection module, a gate of the transistor M0 is connected to a gate of the transistor M1, a source of the transistor M1 is used for connecting the power supply, and a drain of the transistor M1 is connected to an output end of the current ratio control module.
4. The ring oscillator compensation circuit of claim 3, wherein the current ratio control module comprises a transistor M2 and a transistor M3, the drain of the transistor M2 is connected to the drain and the gate of the transistor M1, respectively, the gate of the transistor M2 is connected to the gate and the drain of the transistor M3, respectively, the source of the transistor M2 is connected to the source of the transistor M3, and the drain of the transistor M3 is connected to the reference current source.
5. A ring oscillator compensation circuit according to any one of claims 2 to 4, wherein the current-voltage conversion module comprises a resistor R1 and a resistor R2 connected in series, one end of the resistor R1 is connected to the PTAT module, the other end of the resistor R2 is connected to the process detection module, and a connection terminal led out between the resistor R1 and the resistor R2 is connected to the voltage regulator.
6. A ring oscillator compensation circuit according to claim 5, characterized in that the process detection module comprises a transistor M4, a transistor M5, a resistor R3 and a resistor R4, the drain of the transistor M4 is connected with the PTAT module, the source of the transistor M4 is connected with one end of the resistor R3, the gate and the drain of the transistor M4 are connected, and the other end of the resistor R3 is connected with the other end of the resistor R2;
the source of the transistor M5 is connected to the PTAT module, the drain of the transistor M5 is connected to one end of the resistor R4, the gate and the drain of the transistor M4 are connected, and the other end of the resistor R4 is connected to the other end of the resistor R2.
7. A ring oscillator compensation circuit according to claim 5, wherein said voltage regulator comprises an operational amplifier OP, a transistor M6, a resistor R5 and a resistor R6, wherein a non-inverting input terminal of said operational amplifier OP is connected to a terminal leading out between said resistor R1 and said resistor R2, an inverting input terminal of said operational amplifier OP is connected to a terminal leading out between said resistor R5 and said resistor R6, and an output terminal of said operational amplifier OP is connected to a gate of said transistor M6;
the drain of the transistor M6 is used for connecting the power supply source, the source of the transistor M6 is used for connecting the power supply end of the ring oscillator, the resistor R5 is connected with the resistor R6 in series, one end of the resistor R5 is connected with the source of the transistor M6, and the other end of the resistor R6 is connected with the other end of the resistor R2.
8. A CDR control loop comprising a ring oscillator and the ring oscillator compensation circuit of any one of claims 1 to 7.
9. The CDR control loop of claim 8, wherein the ring oscillator is an N-stage ring oscillator, N being an odd number not less than 3.
10. A receiver comprising a CDR control loop according to claim 8 or 9.
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| CN202210686862.9A CN115021746A (en) | 2022-06-17 | 2022-06-17 | Ring oscillator compensation circuit, CDR control loop and receiver |
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| CN202210686862.9A CN115021746A (en) | 2022-06-17 | 2022-06-17 | Ring oscillator compensation circuit, CDR control loop and receiver |
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