Negative feedback high frequency oscillator circuit

Abstract

The utility model embodiment provides a kind of negative feedback high frequency oscillation circuit, provides second voltage to the input of operational amplifier using charge-discharge module, to compare with the first voltage as reference voltage, the voltage control signal generated by comparison is used to drive oscillation module to generate corresponding clock signal, then using clock control module according to the switching frequency of two switches in charge-discharge module controlled by clock signal, to adjust the charge-discharge frequency of two capacitors, and then adjust the size of second voltage, finally make the frequency of clock signal adjust to target frequency, so through the above negative feedback architecture, the low cost and high stability of high frequency oscillation circuit are considered.

Description

Technical Field

[0001] This application relates to the field of clock frequency control technology, and in particular to the design of a negative feedback high-frequency oscillation circuit. Background Technology

[0002] In modern integrated circuit design, high-frequency clock sources are core modules of digital and mixed-signal systems, and their frequency stability directly affects the overall system performance. Currently, the implementation of high-frequency clock sources mainly relies on ring oscillators or phase-locked loops (PLLs), but both have technical limitations.

[0003] When using a ring oscillator as a high-frequency clock source, the clock frequency is susceptible to process variations, temperature fluctuations, and power supply voltage or current source disturbances. Although process adjustment circuits can compensate for these variations to some extent, the frequency remains significantly sensitive to temperature and power supply voltage or current sources. In some scenarios, clock frequency deviations may exceed system tolerances, leading to timing errors or functional failures. While phase-locked loop (PLL) circuits can provide stable high-frequency clocks, they are large in scale, complex in design, and significantly increase cost. For systems that do not require high frequency stability, such solutions clearly suffer from resource redundancy and insufficient cost-effectiveness.

[0004] Therefore, in view of the shortcomings of ring oscillators in meeting the requirements of medium and high precision, and the shortcomings of phase-locked loop circuits in high cost, there is an urgent need to develop an oscillation circuit that is low in cost and can provide a relatively stable frequency. Utility Model Content

[0005] This application provides a low-cost and highly stable negative feedback high-frequency oscillation circuit.

[0006] A negative feedback high-frequency oscillation circuit, characterized in that it comprises:

[0007] An operational amplifier, wherein the first input terminal of the operational amplifier is used to receive a first voltage;

[0008] A charging / discharging module includes a first capacitor, a second capacitor, a first switch, and a second switch. A first terminal of the first switch, a first terminal of the second capacitor, and a second input terminal of the operational amplifier are used to receive charging current. The second terminal of the first switch is connected to both the first terminal of the first capacitor and the first terminal of the second switch. The second terminals of the first capacitor, the second switch, and the second capacitor are connected to ground. The first capacitor and the second capacitor generate a second voltage based on the received charging current and output it to the second input terminal of the operational amplifier.

[0009] The operational amplifier is also used to compare the first voltage and the second voltage to obtain a voltage control signal;

[0010] An oscillation module, connected to the operational amplifier, is used to output a clock signal according to the voltage control signal;

[0011] The clock control module is connected to the oscillation module, the first switch, and the second switch respectively. It is used to control the first switch and the second switch to switch on and off, and to adjust the switching frequency of the first switch and the second switch according to the clock signal to adjust the second voltage until the clock signal reaches the target frequency.

[0012] In one embodiment, the clock control module is further configured to:

[0013] If the frequency of the clock signal is less than the target frequency, the switching frequency of the first switch and the second switch is reduced to increase the second voltage, thereby increasing the frequency of the clock signal.

[0014] In one embodiment, the clock control module is further configured to:

[0015] If the frequency of the clock signal is greater than the target frequency, the switching frequency of the first switch and the second switch is increased to reduce the second voltage, thereby reducing the frequency of the clock signal.

[0016] In one embodiment, the oscillation module includes:

[0017] Transistor PM1, the control terminal of transistor PM1 is connected to the operational amplifier, and the first connection terminal of transistor PM1 is used to receive the power supply voltage;

[0018] A ring oscillator is connected to the second connection terminal of the transistor PM1 and the clock control module, respectively.

[0019] In one embodiment, the negative feedback high-frequency oscillation circuit further includes:

[0020] The level conversion module is connected to the ring oscillator and the clock control module respectively, and is used to convert the voltage value of the clock signal into the target voltage value.

[0021] In one embodiment, the negative feedback high-frequency oscillation circuit further includes a power supply module, the power supply module being used to provide the first voltage, the power supply module comprising:

[0022] A first current source is connected to the first input terminal of the operational amplifier to provide loop current;

[0023] A resistor R is provided, with its first end connected to the first current source and the first input terminal of the operational amplifier, and its second end connected to the ground terminal.

[0024] In one embodiment, the current value of the loop current is equal to the current value of the charging current, and the target frequency is equal to the conduction switching frequency.

[0025] In one embodiment, the negative feedback high-frequency oscillation circuit further includes:

[0026] The second current source is connected to the first terminal of the first switch, the first terminal of the second capacitor, and the second input terminal of the operational amplifier, respectively, to provide the charging current.

[0027] In one embodiment, the negative feedback high-frequency oscillation circuit further includes:

[0028] The filter is connected to the first terminal of the first switch, the first terminal of the second capacitor, and the second input terminal of the operational amplifier, respectively, and is used to filter the second voltage.

[0029] In one embodiment, the clock control module is a non-overlapping clock circuit.

[0030] The aforementioned negative feedback high-frequency oscillation circuit utilizes a charging / discharging module to provide a second voltage to one input terminal of an operational amplifier, which is compared with a first voltage serving as a reference voltage. The voltage control signal generated by the comparison is used to drive the oscillation module to generate a corresponding clock signal. Then, the clock control module controls the switching frequency of the two switches in the charging / discharging module according to the clock signal, thereby adjusting the charging / discharging frequency of the two capacitors, and thus adjusting the magnitude of the second voltage. Ultimately, the frequency of the clock signal is adjusted to the target frequency. In this way, the negative feedback architecture achieves both low cost and high stability of the high-frequency oscillation circuit. Attached Figure Description

[0031] Figure 1 This is a circuit structure diagram of a negative feedback high-frequency oscillation circuit according to an embodiment of this application;

[0032] Figure 2 This is a circuit structure diagram of a negative feedback high-frequency oscillation circuit according to another embodiment of this application;

[0033] Figure 3 This is a circuit structure diagram of a negative feedback high-frequency oscillation circuit according to another embodiment of this application;

[0034] Figure 4 This is a circuit diagram of a negative feedback high-frequency oscillation circuit according to another embodiment of this application. Detailed Implementation

[0035] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0036] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0037] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly. The connection can be a direct connection or an indirect connection.

[0038] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0039] Figure 1 This is a structural diagram of a negative feedback high-frequency oscillation circuit according to an embodiment of the present invention, as shown below. Figure 1As shown, the negative feedback high-frequency oscillation circuit includes: an operational amplifier 110, a charging / discharging module 120, an oscillation module 130, and a clock control module 140; the first input terminal of the operational amplifier 110 is used to receive a first voltage; the charging / discharging module 120 includes a first capacitor C1, a second capacitor C2, a first switch CK, and a second switch CKB, the first terminal of the first switch CK, the first terminal of the second capacitor C2, and the second input terminal of the operational amplifier 110 are respectively used to receive a charging current i2, the second terminal of the first switch CK is connected to the first terminal of the first capacitor C1 and the first terminal of the second switch CKB; the second terminal of the first capacitor C1, the second terminal of the second switch CKB, and the second terminal of the second capacitor C2 are respectively connected to ground. The first capacitor C1 and the second capacitor C2 are used to generate a second voltage based on the received charging current i2 and output it to the second input terminal of the operational amplifier 110. The operational amplifier 110 is also used to compare the first voltage and the second voltage to obtain a voltage control signal. The oscillation module 130 is connected to the operational amplifier 110 and is used to output a clock signal based on the voltage control signal. The clock control module 140 is connected to the oscillation module 130, the first switch CK, and the second switch CKB, respectively, and is used to control the switching of the first switch CK and the second switch CKB, and adjust the switching frequency of the first switch CK and the second switch CKB according to the clock signal to adjust the second voltage until the clock signal reaches the target frequency.

[0040] It is understood that the non-inverting and inverting input terminals of operational amplifier 110 are used to receive a first voltage and a second voltage, respectively. Taking the example of the non-inverting input terminal of operational amplifier 110 receiving the first voltage and the inverting input terminal receiving the second voltage, the first voltage can be provided by an internal or external power supply; the second voltage can be generated jointly by the first capacitor C1, the second capacitor C2, the first switch CK, and the second switch CKB under the action of the charging current i2, wherein one of the first switch CK and the second switch CKB is selectively turned on to realize the charging and discharging of the first capacitor C1. Specifically, in the initial stage, when the first switch CK is closed and the second switch CKB is open, the first capacitor C1 is in a charging state, and the charging current i2 charges the first capacitor C1 and the second capacitor C2 respectively, thereby generating the second voltage; initially, the second voltage is less than the first voltage, and operational amplifier 110 outputs a high level, thereby driving the oscillation module 130 to output a clock signal of the corresponding frequency.

[0041] The clock control module 140 can be used to switch the first switch CK and the second switch CKB on and off. When the first switch CK is off and the second switch CKB is closed, the first capacitor C1 discharges to ground and the second capacitor C2 continues to charge. When the switch is switched back to the state where the first switch CK is closed and the second switch CKB is off, in addition to the charging current i2 charging the first capacitor C1, the charge on the second capacitor C2 is also transferred to the first capacitor C1, resulting in a decrease in the second voltage at the second capacitor C2. When the switching frequency of the first switch CK and the second switch CKB is low, the number of charging and discharging cycles of the first capacitor C1 per unit time is low, the second voltage gradually increases, and thus exceeds the first voltage. The voltage control signal output by the operational amplifier 110 is at a low level, causing the frequency of the clock signal to change towards the first trend. When the switching frequency of the first switch CK and the second switch CKB increases, the number of charging and discharging cycles of the first capacitor C1 per unit time increases, the average current of the first capacitor C1 increases and exceeds the charging current i2, the second voltage gradually decreases, and thus falls below the first voltage. The voltage control signal output by the operational amplifier 110 is at a high level, causing the frequency of the clock signal to change towards the second trend. The first trend and the second trend are opposite, and they are one of the increasing trend and the decreasing trend, respectively.

[0042] The switching frequency of the first switch CK and the second switch CKB can be determined by the clock control module 140 based on the frequency of the clock signal output by the oscillation module 130. When the frequency of the clock signal is higher or lower than the target frequency, the clock control module 140 can adjust the switching frequency of the two switches according to the clock signal to adjust the second voltage, and then adjust the voltage control signal so that the frequency of the clock signal continuously approaches the target frequency, eventually reaching the target frequency. In some embodiments, the voltage levels of the first switch CK and the second switch CKB when they are turned on can be the same. The driving clock control module 140 can generate two driving signals according to the clock signal to drive the first switch CK and the second switch CKB respectively, so that only one of the first switch CK and the second switch CKB is turned on at the same time. In some embodiments, the voltage levels of the first switch CK and the second switch CKB when they are turned on can be opposite. The driving clock control module 140 can generate one driving signal according to the clock signal, thereby realizing selective turning of the first switch CK and the second switch CKB.

[0043] The aforementioned negative feedback high-frequency oscillation circuit utilizes the charging / discharging module 120 to provide a second voltage to one input terminal of the operational amplifier 110, which is compared with a first voltage used as a reference voltage. The voltage control signal generated by the comparison is used to drive the oscillation module 130 to generate a corresponding clock signal. Then, the clock control module 140 controls the switching frequency of the two switches in the charging / discharging module 120 according to the clock signal to adjust the charging / discharging frequency of the two capacitors, thereby adjusting the magnitude of the second voltage. Ultimately, the frequency of the clock signal is adjusted to the target frequency. Thus, through the aforementioned negative feedback architecture, both the low cost and high stability of the high-frequency oscillation circuit are achieved.

[0044] In one embodiment, the clock control module 140 is further configured to reduce the switching frequency of the first switch CK and the second switch CKB if the frequency of the clock signal is less than the target frequency, so as to increase the second voltage and increase the frequency of the clock signal.

[0045] It is understandable that if the frequency of the clock signal is less than the target frequency, the clock control module 140 can reduce the frequency of the driving signal used to drive the first switch CK and the second switch CKB, thereby reducing the number of charging and discharging cycles of the first capacitor C1, increasing the second voltage, and thus exceeding the first voltage, so that the operational amplifier 110 outputs a voltage control signal that can increase the frequency of the clock signal.

[0046] In one embodiment, the clock control module 140 is further configured to increase the switching frequency of the first switch CK and the second switch CKB if the frequency of the clock signal is greater than the target frequency, so as to reduce the second voltage and reduce the frequency of the clock signal.

[0047] It is understood that if the frequency of the clock signal is greater than the target frequency, the clock control module 140 can increase the frequency of the driving signal used to drive the first switch CK and the second switch CKB, thereby increasing the number of charging and discharging cycles of the first capacitor C1, causing the second voltage to decrease and thus fall below the first voltage, so that the operational amplifier 110 outputs a voltage control signal that can reduce the frequency of the clock signal.

[0048] In one embodiment, such as Figure 2 As shown, the oscillation module 130 includes a transistor PM1 and a ring oscillator 131. The control terminal of the transistor PM1 is connected to the operational amplifier 110, and the first connection terminal of the transistor PM1 is used to receive the power supply voltage VDD. The ring oscillator 131 is connected to the second connection terminal of the transistor PM1 and the clock control module 140.

[0049] The ring oscillator 131 can generate a high-frequency clock signal. It can be understood that the voltage control signal output by the operational amplifier 110 controls the on / off state of transistor PM1, which can be a PMOS transistor. Thus, when the clock signal frequency is greater than the target frequency, and the clock control module 140 increases the switching frequency of the first switch CK and the second switch CKB, the voltage control signal is high, transistor PM1 is off, the current flowing through the ring oscillator 131 decreases, and the frequency of the output clock signal also decreases. When the clock signal frequency is less than the target frequency, and the clock control module 140 decreases the switching frequency of the first switch CK and the second switch CKB, the voltage control signal is low, transistor PM1 is on, the current flowing through the ring oscillator 131 increases, and the frequency of the output clock signal also increases. The ground terminal of the ring oscillator 131 is connected to ground.

[0050] Thus, by combining negative feedback to regulate the clock signal, and using a combination of transistor and ring oscillator 131 as the oscillation module 130 for generating the clock signal, the circuit frequency stability is ensured, while the overall circuit structure complexity is reduced and circuit cost is saved.

[0051] In one embodiment, such as Figure 3 As shown, the negative feedback high-frequency oscillation circuit also includes a level conversion module 150, which is connected to the ring oscillator 131 and the clock control module 140 respectively, and is used to convert the voltage value of the clock signal into the target voltage value.

[0052] It is understandable that, since the voltage value of the clock signal output by the ring oscillator 131 may not reach the desired target voltage value, the level conversion module 150 can be configured to boost the clock signal. In some embodiments, the target voltage value can be equal to the supply voltage value. In this case, the power supply terminal of the level conversion module 150 can be used to receive the supply voltage, and the ground terminal of the level conversion module 150 is connected to ground, such as... Figure 3 As shown.

[0053] In one embodiment, such as Figure 4 As shown, the negative feedback high-frequency oscillation circuit also includes a power supply module 160, which is used to provide a first voltage. The power supply module 160 includes a first current source I1 and a resistor R. The first current source I1 is connected to the first input terminal of the operational amplifier 110 and is used to provide a loop current i1. The first end of the resistor R is connected to the first current source I1 and the first input terminal of the operational amplifier 110 respectively, and the second end of the resistor R is connected to ground.

[0054] It is understood that the power supply module 160 can be either a voltage source or a current source paired with a load. It can provide a stable first voltage to form a reference voltage for the second voltage, which is then input to the operational amplifier 110 for comparison. Specifically, the power supply module 160 can employ a structure of a first current source I1 paired with a resistor R to generate the first voltage.

[0055] In one embodiment, the current value of the loop current i1 is equal to the current value of the charging current i2, and the target frequency is equal to the conduction switching frequency.

[0056] The following analysis examines the parameters that affect the clock signal frequency.

[0057] Let the first voltage be V+ and the second voltage be V-. When the circuit reaches a steady state, the input voltages at the non-inverting and inverting inputs of operational amplifier 110 are equal. Therefore:

[0058] V+=V- (1)

[0059] V+=R*i1 (2)

[0060] The first switch CK and the second switch CKB switch conduct at equal frequencies, both denoted by fck, with the corresponding period denoted by Tck. Within one Tck period, the first capacitor C1 charges and discharges once. Therefore, the average current Ic1 of the first capacitor C1 can be expressed as:

[0061] Ic1=(V-)*C1*fck (3)

[0062] At the same time:

[0063] Ic1=i2 (4)

[0064] From the above formulas (1) to (4), we can calculate:

[0065] fck=i2 / (i1*R*C1) (5)

[0066] Let i2 = a*i1, and the target frequency of the clock signal fclk_out = b*fck, then equation (5) can be rewritten as:

[0067] fclk_out=a*b / (R*C1) (6)

[0068] Since the current value of the loop current i1 is equal to the current value of the charging current i2, and the target frequency is equal to the switching frequency, i.e., a and b are both equal to 1, then equation 6 can be rewritten as:

[0069] fclk_out=1 / (R*C1) (7)

[0070] As can be seen from equation (7), by using the above-described oscillation circuit and combining the above-described current and frequency settings, the target frequency of the clock signal is only related to two parameters, namely the resistance value of resistor R and the capacitance value of the first capacitor C1. To obtain the desired frequency of fclk_out, it is only necessary to set the appropriate resistor R and the first capacitor C1. The method is simple and easy to implement.

[0071] In one embodiment, such as Figure 4 As shown, the negative feedback high-frequency oscillation circuit also includes a second current source I2, which is connected to the first terminal of the first switch CK, the first terminal of the second capacitor C2, and the second input terminal of the operational amplifier 110, respectively, to provide charging current.

[0072] It is understandable that a second current source I2 can be set in the negative feedback high-frequency oscillation circuit to provide charging current, thus achieving a high degree of overall circuit integration.

[0073] In one embodiment, the negative feedback high-frequency oscillation circuit further includes a filter 170, which is connected to the first terminal of the first switch CK, the first terminal of the second capacitor C2, and the second input terminal of the operational amplifier 110, respectively, for filtering the second voltage.

[0074] It is understandable that when the charging and discharging module 120 is working, there will be voltage ripple on the upper plate of the second capacitor C2. This ripple can be filtered out by setting the filter 170, so that the input terminal of the operational amplifier 110 can obtain a stable second voltage.

[0075] In one embodiment, the clock control module 140 is a non-overlapping clock circuit.

[0076] It is understood that the first switch CK and the second switch CKB can be controlled by different drive signals, and these two drive signals can be generated by non-overlapping clock circuits.

[0077] This utility model embodiment also provides a negative feedback high-frequency oscillation circuit, including an operational amplifier 110, a charging and discharging module 120, an oscillation module 130, a clock control module 140, a level conversion module 150, a power supply module 160, a second current source I2, and a filter 170. The charging and discharging module 120 includes a first capacitor C1, a second capacitor C2, a first switch CK, and a second switch CKB. The oscillation module 130 includes a transistor PM1 and a ring oscillator 131. The power supply module 160 includes a first current source I1 and a resistor R. The connection relationship and working principle of each component can be referred to the above-described negative feedback high-frequency oscillation circuit embodiment, and will not be repeated here.

[0078] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural changes made based on the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A negative feedback high-frequency oscillation circuit, characterized in that, include: An operational amplifier, wherein the first input terminal of the operational amplifier is used to receive a first voltage; A charging / discharging module includes a first capacitor, a second capacitor, a first switch, and a second switch. A first terminal of the first switch, a first terminal of the second capacitor, and a second input terminal of the operational amplifier are used to receive charging current. The second terminal of the first switch is connected to both the first terminal of the first capacitor and the first terminal of the second switch. The second terminals of the first capacitor, the second switch, and the second capacitor are connected to ground. The first capacitor and the second capacitor generate a second voltage based on the received charging current and output it to the second input terminal of the operational amplifier. The operational amplifier is also used to compare the first voltage and the second voltage to obtain a voltage control signal; An oscillation module, connected to the operational amplifier, is used to output a clock signal according to the voltage control signal; The clock control module is connected to the oscillation module, the first switch, and the second switch respectively. It is used to control the first switch and the second switch to switch on and off, and to adjust the switching frequency of the first switch and the second switch according to the clock signal to adjust the second voltage until the clock signal reaches the target frequency.

2. The negative feedback high-frequency oscillation circuit according to claim 1, characterized in that, The clock control module is also used for: If the frequency of the clock signal is less than the target frequency, the switching frequency of the first switch and the second switch is reduced to increase the second voltage, thereby increasing the frequency of the clock signal.

3. The negative feedback high-frequency oscillation circuit according to claim 1 or 2, characterized in that, The clock control module is also used for: If the frequency of the clock signal is greater than the target frequency, the switching frequency of the first switch and the second switch is increased to reduce the second voltage, thereby reducing the frequency of the clock signal.

4. The negative feedback high-frequency oscillation circuit according to claim 3, characterized in that, The oscillation module includes: Transistor PM1, the control terminal of transistor PM1 is connected to the operational amplifier, and the first connection terminal of transistor PM1 is used to receive the power supply voltage; A ring oscillator is connected to the second connection terminal of the transistor PM1 and the clock control module, respectively.

5. The negative feedback high-frequency oscillation circuit according to claim 4, characterized in that, The negative feedback high-frequency oscillation circuit also includes: The level conversion module is connected to the ring oscillator and the clock control module respectively, and is used to convert the voltage value of the clock signal into the target voltage value.

6. The negative feedback high-frequency oscillation circuit according to claim 1, characterized in that, The negative feedback high-frequency oscillation circuit further includes a power supply module, which provides the first voltage. The power supply module includes: A first current source is connected to the first input terminal of the operational amplifier to provide loop current; A resistor R is provided, with its first end connected to the first current source and the first input terminal of the operational amplifier, and its second end connected to the ground terminal.

7. The negative feedback high-frequency oscillation circuit according to claim 6, characterized in that, The current value of the loop current is equal to the current value of the charging current, and the target frequency is equal to the conduction switching frequency.

8. The negative feedback high-frequency oscillation circuit according to claim 1, characterized in that, The negative feedback high-frequency oscillation circuit also includes: The second current source is connected to the first terminal of the first switch, the first terminal of the second capacitor, and the second input terminal of the operational amplifier, respectively, to provide the charging current.

9. The negative feedback high-frequency oscillation circuit according to claim 1, characterized in that, The negative feedback high-frequency oscillation circuit also includes: The filter is connected to the first terminal of the first switch, the first terminal of the second capacitor, and the second input terminal of the operational amplifier, respectively, and is used to filter the second voltage.

10. The negative feedback high-frequency oscillation circuit according to claim 1, characterized in that, The clock control module consists of non-overlapping clock circuits.

Images