Clock source with temperature process voltage compensation

Abstract

The present application relates to the field of integrated circuit design, in particular to a clock source with temperature process voltage compensation. The present application improves the existing temperature process compensation module, so that the temperature process compensation module can compensate the voltage variation of temperature and process at the same time; a selection module is added between the temperature process compensation module and the voltage controlled oscillator, the four variation voltages output by the temperature process compensation module are compared, the largest variation voltage under the current temperature condition is selected as the compensation voltage Vctrl and output to the voltage controlled oscillator; at this time, the control voltage obtained is a curve fitted by straight lines with different slopes, which can be applied to the case of large frequency and large temperature variation, the fitting is very good, and the output frequency error is very small.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit design, and more specifically to a clock source with temperature-process voltage compensation. Background Technology

[0002] Frequency generators are an essential component of most electronic systems and a core component of wireless communication systems. Since their inception, oscillators have played a vital role in equipment and instrumentation in fields such as communications, electronics, aerospace, and medicine. Clock sources are used in the design of many integrated circuit chips due to their simple structure, but their oscillation frequency is greatly affected by temperature changes, voltage changes, and uncertainties in the manufacturing process. Process, voltage, and temperature (PTT) factors cause significant deviations in the oscillator's output frequency.

[0003] The existing approach to temperature process compensation involves simulating the control voltage curve when the clock source output frequency is stable, and then designing a temperature process compensation circuit based on the control voltage curve. However, the voltage output by the existing temperature process compensation circuit changes linearly with temperature and cannot fit the control voltage curve well. When the clock source output frequency is too high or the arc of the control voltage curve is too large, the clock source output frequency of the existing temperature process compensation has a large deviation. Summary of the Invention

[0004] To address the aforementioned problems or shortcomings, and to resolve the issue that the voltage output by the bias circuit is linear and cannot well fit the control voltage curve, this invention provides a clock source with temperature-process voltage compensation.

[0005] A clock source with temperature process voltage compensation includes: a voltage regulator module, a temperature process compensation module, a selection module, and a voltage-controlled oscillator.

[0006] The voltage regulator module takes a power supply voltage Vdd as input and outputs a stable voltage Vref, which is used to provide a stable voltage for the temperature process compensation module, the selection module, and the voltage-controlled oscillator.

[0007] The temperature process compensation module includes a bias module and four temperature process compensation sub-units. The input of the bias module is connected to the stable voltage Vref output by the voltage regulator module, providing bias voltage for the four temperature process compensation sub-units. The four temperature process compensation sub-units output four varying voltages Vout1, Vout2, Vout3, and Vout4 that change with the temperature process, respectively. The rate of change of the four varying voltages Vout1, Vout2, Vout3, and Vout4 increases sequentially with temperature. At the lowest temperature, the voltage with the smaller rate of change is larger.

[0008] The selection module is used to select the largest change voltage under the current temperature condition based on the four change voltage signals output by the temperature process compensation module, and use it as the compensation voltage Vctrl and output it to the voltage-controlled oscillator.

[0009] Because the four variable voltages Vout1, Vout2, Vout3, and Vout4 vary with temperature, their different rates of change cause their relative values ​​to change at different temperatures. A selection module selects the voltage with the largest change rate among the four as the compensation voltage. At lower temperatures, the voltage with the lowest rate of change has the largest value, and the selection module outputs Vout1. As the temperature increases, the voltages with larger rates of change grow faster and their values ​​gradually exceed Vout1. At this point, the selection module outputs Vout2 as the compensation voltage. Similarly, as the temperature increases, the voltage with the largest rate of change grows more rapidly and its value is also larger. This means that as the temperature increases, the selection module outputs the voltage with the largest rate of change. This allows for a wider range of temperature compensation, with the selection module sequentially outputting Vout1, Vout2, Vout3, and Vout4, rather than a linearly changing compensation voltage, thus better aligning with the curvature for temperature-related process compensation.

[0010] The voltage-controlled oscillator has two input terminals: one input terminal is connected to the stable voltage Vref, and the other input terminal, the voltage control terminal, is connected to the compensation voltage Vctrl, which is used to output a frequency signal based on the stable voltage Vref and the compensation voltage Vctrl.

[0011] Furthermore, the selection module includes comparator op1, comparator op2, comparator op3, inverter inv1, inverter inv2, inverter inv3, transmission gate tra1, transmission gate tra2, transmission gate tra3, transmission gate tra4, transmission gate tra5, and transmission gate tra6.

[0012] The changing voltages Vout1 and Vout2 are input to the negative and positive terminals of comparator op1, respectively. The output of comparator op1 is connected to the input of inverter inv1, the disable terminal of transmission gate tra1, and the enable terminal of transmission gate tra2.

[0013] The variable voltages Vout3 and Vout4 are input to the negative and positive terminals of comparator op2, respectively. The output of comparator op2 is connected to the input of inverter inv2, the disable terminal of transmission gate tra3, and the enable terminal of transmission gate tra4.

[0014] The output of inverter inv1 is connected to the enable terminal of transmission gate tra1 and the disable terminal of transmission gate tra2; the output of inverter inv2 is connected to the enable terminal of transmission gate tra3 and the disable terminal of transmission gate tra4.

[0015] The changing voltage Vout1 is connected to the transmission gate tra1; the changing voltage Vout2 is connected to the transmission gate tra2; the changing voltage Vout3 is connected to the transmission gate tra3; and the changing voltage Vout4 is connected to the transmission gate tra4.

[0016] The outputs of transmission gate tra1 and tra2 are connected together, and then connected to the negative terminal of comparator op3 and the input terminal of transmission gate tra5; the outputs of transmission gate tra3 and tra4 are connected together, and then connected to the positive terminal of comparator op3 and the input terminal of transmission gate tra6.

[0017] The output of comparator op3 is connected to the input of inverter inv3, the disable terminal of transmission gate tra5, and the enable terminal of transmission gate tra6; the output of inverter inv3 is connected to the enable terminal of transmission gate tra5 and the disable terminal of transmission gate tra6; the output of transmission gate tra5 and the input of transmission gate tra6 are connected to the voltage control terminal of voltage-controlled oscillator.

[0018] Furthermore, the four temperature process compensation sub-units have the same architecture. Each temperature process compensation sub-unit includes resistors R1 and R2, NMOS transistors M2, M3, and M5, PMOS transistor M4, and BJT1, wherein:

[0019] One end of resistor R1 is used to connect the stable voltage Vref, and the other end of resistor R1 is connected to the source of PMOS transistor M2 and the collector of BJT transistor BJT1; the gate and drain of NMOS transistor M3 are connected, and the gate and drain of PMOS transistor M4 are connected; the drains of NMOS transistor M3 and PMOS transistor M4 are connected; NMOS transistor M2 is used to receive the bias voltage output from the bias circuit, and its drain is connected to the source of NMOS transistor M3; the source of NMOS transistor M2 is grounded; the collector of BJT transistor BJT1 is connected to one end of resistor R1, its base and emitter are connected, and its emitter is connected to one end of resistor R2; the other end of resistor R2 is connected to the drain of NMOS transistor M5; the gate and drain of NMOS transistor M5 are connected, and its source is grounded.

[0020] Furthermore, by changing the width-to-length ratio and number of MOS transistors and the length and number of resistors in each temperature process compensation subunit, different voltages are output. By adjusting the width-to-length ratio and number of MOS transistors and the length and number of resistors, the rate of change of the output voltage with temperature is adjusted.

[0021] Furthermore, the clock source with temperature process voltage compensation described in this invention can be used as a clock source for SOC (System on Chip) chips and SIP (System in Package) chips.

[0022] In summary, this invention improves upon existing temperature process compensation modules, enabling them to simultaneously compensate for both temperature and voltage variations in the process. A selection module is added between the temperature process compensation module and the voltage-controlled oscillator (VCO) to compare the magnitudes of the four varying voltages output by the temperature process compensation module, selecting the largest varying voltage under the current temperature conditions as the compensation voltage Vctrl, which is then output to the VCO. The resulting control voltage is a curve fitted by straight lines with different slopes, applicable to situations with high frequencies and large temperature variations, exhibiting excellent fitting and minimal output frequency error. Attached Figure Description

[0023] Figure 1 This is a schematic block diagram of the clock source structure with temperature process voltage compensation according to the present invention;

[0024] Figure 2 The circuit diagram of the temperature process compensation module is shown in the embodiment.

[0025] Figure 3 A schematic diagram of the structure of the selected module in the embodiment;

[0026] Figure 4 This is a schematic diagram of the voltage regulator module in the embodiment;

[0027] Figure 5 The circuit diagram of the voltage-controlled oscillator is shown in the example.

[0028] Figure 6 The graph shows the variation of compensation voltage with temperature process in the example.

[0029] Figure 7 This is a graph showing the change in compensation voltage with temperature and process parameters for a traditional non-selection module. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0031] This embodiment provides a clock source 100 with temperature process voltage compensation, such as... Figure 1 As shown, the clock source 100 with temperature process voltage compensation includes: a voltage regulator module 110, a temperature process compensation module 120, a selection module 130, and a voltage-controlled oscillator 140. One output terminal of the voltage regulator module 110 is connected to the voltage source terminal of the voltage-controlled oscillator module 140 and the voltage source terminal of the selection module 130, and another output terminal is connected to the voltage source terminal of the temperature process compensation module 120.

[0032] When the clock source 100 with temperature-controlled process voltage compensation starts working, the voltage regulator module 110 outputs a stable voltage. Figure 1 The stable voltage is represented by Vref.

[0033] The temperature process compensation module 120 receives a stable voltage Vref. The mobility and threshold voltage of the MOS transistor in the temperature process compensation module will have different values ​​depending on the temperature and process. The resistance will also have different resistance values ​​depending on the temperature and process. The current flowing through the BJT transistor will also change with the temperature. Therefore, when the temperature and process change, the voltage signal output by the temperature process compensation subunit will also change. This voltage that changes with the temperature and process is called the variable voltage, and Vout1, Vout2, Vout3 and Vout4 represent the variable voltage signal, respectively.

[0034] The selection circuit module 130 receives four variable voltage signals Vout1, Vout2, Vout3 and Vout4 output by the temperature process compensation module. It compares the magnitudes of the four variable voltages, selects the largest variable voltage under the current temperature condition, and outputs it as the compensation voltage to the voltage-controlled oscillator 140. The selected compensation voltage is represented by Vctrl.

[0035] After receiving the stable voltage Vref and the selected compensation voltage signal Vctrl, the voltage-controlled oscillator module 140 starts oscillation according to the stable voltage Vref and the selected compensation voltage Vctrl, and outputs the fundamental frequency signal.

[0036] The voltage regulator module 110 takes a power supply voltage Vdd as input and outputs a stable voltage Vref, which is used to provide a stable voltage for the temperature process compensation module 120, the selection module 130, and the voltage-controlled oscillator module 140.

[0037] like Figure 2 As shown, the temperature process compensation module 120 includes a bias module 121 and four temperature process compensation sub-units 122, 123, 124, and 125. The input terminal of the bias module 121 is connected to the stable voltage Vref output by the voltage regulator module 110, providing bias voltage for the four temperature process compensation sub-units. The four temperature process compensation sub-units output four varying voltages Vout1, Vout2, Vout3, and Vout4 that change with the temperature process, respectively. The rate of change of the four varying voltages Vout1, Vout2, Vout3, and Vout4 increases sequentially with temperature. At the lowest temperature, the voltage with the smaller rate of change is larger.

[0038] The four temperature process compensation sub-units have the same structure. By changing the width-to-length ratio and number of MOSFETs, and the length and number of resistors, different voltages are output. The output voltage changes with the temperature process at different rates depending on the width-to-length ratio and number of MOSFETs and the length and number of resistors.

[0039] In this embodiment of the invention, the bias circuit 121 includes an NMOS transistor M0 and a PMOS transistor M1. The connection method of the NMOS transistor M0 and the PMOS transistor M1 is described in [reference needed]. Figure 2 The gate and drain of a MOSFET are connected, which is similar to that of a diode. Temperature and process affect the threshold voltage and electron mobility of the MOSFET. The drain voltage will also be different depending on the width-to-length ratio of the PMOS and NMOS transistors. Therefore, the drain output voltage of the MOSFET changes with temperature and process.

[0040] The temperature compensation subunit 122 includes resistors R1 and R2, NMOS transistors M2, M3, M5, M4, and BJT1. The connection method is described in [reference needed]. Figure 2 ,in:

[0041] One end of resistor R1 is used to connect the stable voltage Vref, and the other end of resistor R1 is connected to the source of PMOS transistor M2 and the collector of BJT transistor BJT1; the gate and drain of NMOS transistor M3 are connected, and the gate and drain of PMOS transistor M4 are connected; the drains of NMOS transistor M3 and PMOS transistor M4 are connected; NMOS transistor M2 is used to receive the bias voltage output from the bias circuit, and its drain is connected to the source of NMOS transistor M3; the source of NMOS transistor M2 is grounded; the collector of BJT transistor BJT1 is connected to one end of resistor R1, its base and emitter are connected, and its emitter is connected to one end of resistor R2; the other end of resistor R2 is connected to the drain of NMOS transistor M5; the gate and drain of NMOS transistor M5 are connected, and its source is grounded.

[0042] In this embodiment of the invention, the structures of temperature process compensation subunits 123, 124 and 125 are the same as and similar to those of temperature process compensation subunit 122, except that the aspect ratio and number of MOS transistors and BJT transistors are different, as are the size and number of resistors. For example, two or more MOS transistors connected to diodes can be placed at NMOS transistor M3. The specific situation can be determined according to the actual situation, and this invention does not make specific limitations in this regard.

[0043] The temperature process compensation module 120 is used to output four compensation voltage signals Vout1, Vout2, Vout3, and Vout4 based on the stable voltage Vref and the real-time temperature and process.

[0044] The selection module 130 includes comparators op1, op2, op3, inverters inv1, inv2, inv3, transmission gates tra1, tra2, tra3, tra4, tra5, and tra6; as shown. Figure 3 As shown.

[0045] The changing voltages Vout1 and Vout2 are input to the negative and positive terminals of comparator op1, respectively. The output of comparator op1 is connected to the input of inverter inv1, the disable terminal of transmission gate tra1, and the enable terminal of transmission gate tra2.

[0046] The variable voltages Vout3 and Vout4 are input to the negative and positive terminals of comparator op2, respectively. The output of comparator op2 is connected to the input of inverter inv2, the disable terminal of transmission gate tra3, and the enable terminal of transmission gate tra4.

[0047] The output of inverter inv1 is connected to the enable terminal of transmission gate tra1 and the disable terminal of transmission gate tra2; the output of inverter inv2 is connected to the enable terminal of transmission gate tra3 and the disable terminal of transmission gate tra4.

[0048] The changing voltage Vout1 is connected to the transmission gate tra1; the changing voltage Vout2 is connected to the transmission gate tra2; the changing voltage Vout3 is connected to the transmission gate tra3; and the changing voltage Vout4 is connected to the transmission gate tra4.

[0049] The outputs of transmission gate tra1 and tra2 are connected together, and then connected to the negative terminal of comparator op3 and the input terminal of transmission gate tra5; the outputs of transmission gate tra3 and tra4 are connected together, and then connected to the positive terminal of comparator op3 and the input terminal of transmission gate tra6.

[0050] The output of comparator op3 is connected to the input of inverter inv3, the disable terminal of transmission gate tra5, and the enable terminal of transmission gate tra6; the output of inverter inv3 is connected to the enable terminal of transmission gate tra5 and the disable terminal of transmission gate tra6; the output of transmission gate tra5 and the input of transmission gate tra6 are connected to the voltage control terminal of voltage-controlled oscillator.

[0051] The selection module has 4 input terminals and 1 output terminal. The 4 input terminals are used to input the 4 changing voltages output by the 4 temperature process compensation modules. The largest changing voltage under the current temperature condition is selected as the compensation voltage Vctrl and output to the voltage-controlled oscillator. The output terminal outputs the compensation voltage Vctrl and connects it to the voltage control terminal of the voltage-controlled oscillator.

[0052] In this embodiment, the structure of the voltage regulator module is as follows: Figure 4 As shown.

[0053] This embodiment provides a voltage-controlled oscillator module 140, such as Figure 5 As shown, the voltage-controlled oscillator module 140 includes a self-biasing circuit, a first inverter, a second inverter, and a third inverter.

[0054] The self-biasing circuit and the two current sources of the first inverter are connected. The output of the first inverter is connected to the input of the second inverter. The output of the second inverter is connected to the input of the third inverter. The output of the third inverter is connected to the input of the first inverter.

[0055] Temperature and process variations cause changes in the inverter's capacitance. The control voltage required to maintain a constant output frequency of the voltage-controlled oscillator under different temperatures and processes is provided by the selection circuit, while the voltage regulator module provides a stable voltage.

[0056] Figure 6 The graph shows the variation of compensation voltage with temperature process in this embodiment. Figure 7 To compare the compensation voltage variation with temperature and process parameters in a traditional non-selection module, it is evident that this invention improves upon existing temperature and process compensation modules, enabling them to simultaneously compensate for voltage variations related to both temperature and process parameters. Furthermore, a selection module is added between the temperature and process compensation module and the voltage-controlled oscillator (VCO). This module compares the magnitudes of the four varying voltages output by the temperature and process compensation module, selecting the largest variation voltage under the current temperature conditions as the compensation voltage Vctrl, which is then output to the VCO. The resulting control voltage is a curve fitted from straight lines with different slopes, achieving better fitting and smaller output frequency errors. This invention can be applied to situations with high frequencies and large temperature variations.

Claims

1. A clock source with temperature-process voltage compensation, characterized in that, include: Voltage regulator module, temperature and process compensation module, selection module, voltage-controlled oscillator; The voltage regulator module takes power supply voltage Vdd as input and outputs stable voltage Vref, which is used to provide stable voltage for the temperature process compensation module, the selection module and the voltage-controlled oscillator module. The temperature process compensation module includes a bias module and four temperature process compensation sub-units. The input of the bias module is connected to the stable voltage Vref output by the voltage regulator module, providing bias voltage for the four temperature process compensation sub-units. The four temperature process compensation sub-units output four varying voltages Vout1, Vout2, Vout3, and Vout4 that change with the temperature process, respectively. The rate of change of the four varying voltages Vout1, Vout2, Vout3, and Vout4 with temperature increases sequentially. At the lowest temperature, the voltage with the smaller rate of change is larger. The selection module is used to select the largest change voltage under the current temperature condition based on the four change voltage signals output by the temperature process compensation module, and use it as the compensation voltage Vctrl and output it to the voltage-controlled oscillator. The voltage-controlled oscillator has two input terminals: one input terminal is connected to the stable voltage Vref, and the other input terminal, the voltage control terminal, is connected to the compensation voltage Vctrl, which is used to output a frequency signal based on the stable voltage Vref and the compensation voltage Vctrl.

2. The clock source with temperature process voltage compensation as described in claim 1, characterized in that: The selection module includes comparator op1, comparator op2, comparator op3, inverter inv1, inverter inv2, inverter inv3, transmission gate tra1, transmission gate tra2, transmission gate tra3, transmission gate tra4, transmission gate tra5 and transmission gate tra6. The changing voltages Vout1 and Vout2 are input to the negative and positive terminals of comparator op1, respectively. The output of comparator op1 is connected to the input of inverter inv1, the disable terminal of transmission gate tra1, and the enable terminal of transmission gate tra2. The variable voltages Vout3 and Vout4 are input to the negative and positive terminals of comparator op2, respectively. The output of comparator op2 is connected to the input of inverter inv2, the disable terminal of transmission gate tra3, and the enable terminal of transmission gate tra4. The output of inverter inv1 is connected to the enable terminal of transmission gate tra1 and the disable terminal of transmission gate tra2; the output of inverter inv2 is connected to the enable terminal of transmission gate tra3 and the disable terminal of transmission gate tra4. The changing voltage Vout1 is connected to the transmission gate tra1; the changing voltage Vout2 is connected to the transmission gate tra2; the changing voltage Vout3 is connected to the transmission gate tra3; and the changing voltage Vout4 is connected to the transmission gate tra4. The outputs of transmission gate tra1 and tra2 are connected together, and then connected to the negative terminal of comparator op3 and the input terminal of transmission gate tra5; the outputs of transmission gate tra3 and tra4 are connected together, and then connected to the positive terminal of comparator op3 and the input terminal of transmission gate tra6. The output of comparator op3 is connected to the input of inverter inv3, the disable terminal of transmission gate tra5, and the enable terminal of transmission gate tra6; the output of inverter inv3 is connected to the enable terminal of transmission gate tra5 and the disable terminal of transmission gate tra6; the output of transmission gate tra5 and the input of transmission gate tra6 are connected to the voltage control terminal of voltage-controlled oscillator.

3. The clock source with temperature process voltage compensation as described in claim 1, characterized in that: The four temperature process compensation subunits have the same architecture. Each temperature process compensation subunit includes resistors R1 and R2, NMOS transistors M2, M3, and M5, PMOS transistor M4, and BJT1, wherein: One end of resistor R1 is used to connect the stable voltage Vref, and the other end of resistor R1 is connected to the source of PMOS transistor M2 and the collector of BJT transistor BJT1; the gate and drain of NMOS transistor M3 are connected, and the gate and drain of PMOS transistor M4 are connected; the drains of NMOS transistor M3 and PMOS transistor M4 are connected; NMOS transistor M2 is used to receive the bias voltage output from the bias circuit, and its drain is connected to the source of NMOS transistor M3; the source of NMOS transistor M2 is grounded; the collector of BJT transistor BJT1 is connected to one end of resistor R1, its base and emitter are connected, and its emitter is connected to one end of resistor R2; the other end of resistor R2 is connected to the drain of NMOS transistor M5; the gate and drain of NMOS transistor M5 are connected, and its source is grounded.

4. The clock source with temperature process voltage compensation as described in claim 3, characterized in that: By changing the width-to-length ratio and number of MOS transistors, and the length and number of resistors in each temperature process compensation subunit, different voltages are output. By adjusting the width-to-length ratio and number of MOS transistors, and the length and number of resistors, the rate of change of the output voltage with temperature is adjusted.

5. The clock source with temperature process voltage compensation as described in any one of claims 1-4, characterized in that: It is used as a clock source in SOC chips and SIP chips.

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