CN108933594B - Voltage controlled oscillator and phase locked loop - Google Patents

Voltage controlled oscillator and phase locked loop Download PDF

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Publication number
CN108933594B
CN108933594B CN201710365839.9A CN201710365839A CN108933594B CN 108933594 B CN108933594 B CN 108933594B CN 201710365839 A CN201710365839 A CN 201710365839A CN 108933594 B CN108933594 B CN 108933594B
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circuit
input end
control
coupled
ring
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CN108933594A (en
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邱星福
陈先敏
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Semiconductor Manufacturing International Shanghai Corp
Semiconductor Manufacturing International Beijing Corp
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Semiconductor Manufacturing International Shanghai Corp
Semiconductor Manufacturing International Beijing Corp
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
    • H03L7/00—Automatic control of frequency or phase; Synchronisation
    • H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
    • H03L7/08—Details of the phase-locked loop
    • H03L7/099—Details of the phase-locked loop concerning mainly the controlled oscillator of the loop
    • H03L7/0995—Details of the phase-locked loop concerning mainly the controlled oscillator of the loop the oscillator comprising a ring oscillator

Abstract

A voltage controlled oscillator and a phase locked loop. The voltage controlled oscillator includes: the current supply circuit is suitable for outputting a current signal with a preset current value under the control of the control voltage input by the control voltage input end; the ring oscillation circuit is suitable for outputting periodic signals of corresponding frequencies based on the current signals output by the current supply circuit under the control of the control voltage output by the control voltage input end; and the latch circuit is coupled with the starting signal input end of the voltage-controlled oscillator and the ring-shaped oscillation circuit, is suitable for starting based on a control signal input by the starting signal input end before the ring-shaped oscillation circuit starts oscillation, increases the gain of the ring-shaped oscillation circuit, and is closed based on the control signal input by the starting signal input end after the ring-shaped oscillation circuit starts oscillation and the frequency of the periodic signal reaches a preset frequency. By applying the scheme, the situation that the working speed of the VCO is reduced after Latch is introduced can be avoided.

Description

Voltage controlled oscillator and phase locked loop
Technical Field
The invention relates to the technical field of phase-locked loops, in particular to a voltage-controlled oscillator and a phase-locked loop.
Background
A Voltage Controlled Oscillator (VCO) is a Voltage Controlled Oscillator whose oscillation frequency is adjustable, and is a core part of a phase-locked loop circuit.
In a conventional VCO, a Ring Oscillator (Ring Oscillator) is used as an oscillating circuit, an oscillating speed of the Ring Oscillator, i.e. so-called I to F, is controlled by an incoming current, and a control voltage determines a current value, i.e. V to I, to finally realize linear control of V to F.
However, the ring oscillator generally has a problem of oscillation starting, and in order to break a stable and non-oscillating degeneracy point, a sufficiently strong cross-coupled Latch circuit (Latch) needs to be coupled to the ring oscillator to ensure a sufficient differential gain.
However, the introduction of Latch will pull the speed of VCO operation down to some extent.
Disclosure of Invention
The invention solves the technical problem of how to avoid reducing the working speed of the VCO after Latch is introduced.
To solve the above technical problem, an embodiment of the present invention provides a voltage controlled oscillator, including: the current providing circuit is coupled with the control voltage input end of the voltage-controlled oscillator and is suitable for outputting a current signal with a preset current value under the control of the control voltage input by the control voltage input end; the ring oscillation circuit is coupled with the output end of the current providing circuit and the control voltage input end and is suitable for outputting periodic signals of corresponding frequencies based on the current signals output by the current providing circuit under the control of the control voltage output by the control voltage input end; and the latch circuit is coupled with the starting signal input end of the voltage-controlled oscillator and the ring-shaped oscillation circuit, is suitable for starting based on a control signal input by the starting signal input end before the ring-shaped oscillation circuit starts oscillation, increases the gain of the ring-shaped oscillation circuit, and is closed based on the control signal input by the starting signal input end after the ring-shaped oscillation circuit starts oscillation and the frequency of the periodic signal reaches a preset frequency.
Optionally, the latch circuit includes:
the first switch is coupled with the starting signal input end and is suitable for being switched on or switched off under the control of a control signal input by the starting signal input end;
a gain adjustment circuit coupled to the first switch and the ring oscillator circuit and adapted to increase a gain of the ring oscillator circuit when the first switch is turned on.
Optionally, the first switch comprises: and the grid electrode of the first PMOS tube is coupled with the starting signal input end, the drain electrode of the first PMOS tube is coupled with the gain adjusting circuit, and the source electrode of the first PMOS tube is coupled with the first power supply voltage input end.
Optionally, the gain adjustment circuit includes: and the source electrodes of the second PMOS tube and the third PMOS tube are coupled with the first switch, the drain electrodes of the second PMOS tube and the third PMOS tube are coupled with the ring oscillation circuit, and the substrate is coupled with the first power supply voltage input end.
Optionally, the ring oscillator circuit is a differential ring oscillator circuit.
Optionally, the differential ring oscillator circuit includes three inverters connected end to end in sequence.
Optionally, the current providing circuit comprises:
the bias current generating circuit is suitable for generating a current signal of the preset current value under the control of the control voltage input by the control voltage input end;
and the mirror image circuit is coupled with the bias current generating circuit and the ring oscillation circuit, is suitable for mirroring the current signal generated by the bias current generating circuit and outputting the current signal to the ring oscillation circuit.
Optionally, the voltage controlled oscillator further comprises:
and the starting signal generating circuit is coupled with the starting signal input end of the voltage-controlled oscillator and is suitable for generating a control signal of the starting signal input end.
Optionally, the control signal at the start signal input end is a digital signal.
The embodiment of the invention also provides a phase-locked loop, which comprises any one of the voltage-controlled oscillators.
Compared with the prior art, the technical scheme of the embodiment of the invention has the following beneficial effects:
by adopting the scheme, the latch circuit can be closed based on the control signal output by the starting signal input end after the ring-shaped oscillation circuit starts oscillation and the frequency of the periodic signal reaches the preset frequency, so that the working speed of the voltage-controlled oscillator can not be reduced continuously.
Drawings
Fig. 1 is a schematic circuit diagram of a voltage-controlled oscillator according to an embodiment of the present invention;
FIG. 2 is a circuit diagram of a latch circuit according to an embodiment of the present invention;
fig. 3 is a schematic circuit diagram of another voltage-controlled oscillator according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a simulation curve of the periodic signal output by the vco according to an embodiment of the present invention.
Detailed Description
In the conventional voltage-controlled oscillator, a latch circuit coupled to a ring oscillator is always in a working state during the working process of the voltage-controlled oscillator, so that the working speed of the voltage-controlled oscillator is increased after the ring oscillator starts oscillation.
In view of the above problem, an embodiment of the present invention provides a voltage-controlled oscillator, where a latch circuit may be turned off based on a control signal output by a start signal input end after a ring oscillator starts oscillation and a frequency of a periodic signal reaches a preset frequency, so that a working speed of the voltage-controlled oscillator may not be further reduced.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
Referring to fig. 1, an embodiment of the present invention provides a voltage controlled oscillator 1, where the voltage controlled oscillator 1 may include: a current supply circuit 11, a ring oscillation circuit 12, and a latch circuit 13, wherein:
the current providing circuit 11 is coupled to the control voltage input terminal T1 of the voltage-controlled oscillator 1, and is adapted to output a current signal with a preset current value under the control of the control voltage VC input from the control voltage input terminal T1;
the ring oscillator circuit 12, coupled to the output terminal of the current providing circuit 11 and the control voltage input terminal T1, is adapted to output a periodic signal of a corresponding frequency based on the current signal output by the current providing circuit 11 under the control of the control voltage VC output by the control voltage input terminal T1;
the latch circuit 13, coupled to the start signal input terminal T2 of the vco 1 and the ring oscillator circuit 12, is adapted to start based on the control signal ST input from the start signal input terminal T2 before the ring oscillator circuit 12 starts oscillation, increase the gain of the ring oscillator circuit 12, and turn off based on the control signal ST input from the start signal input terminal T2 after the ring oscillator circuit 12 starts oscillation and the frequency of the periodic signal reaches a predetermined frequency.
Since the latch circuit 13 can be turned off based on the control signal ST after the ring oscillator circuit 12 starts oscillating and the frequency of the periodic signal reaches the preset frequency, the operating speed of the vco may not be further reduced.
In an embodiment of the present invention, referring to fig. 2, the latch circuit 13 may include:
a first switch 131 coupled to the enable signal input terminal T2 and adapted to be turned on or off under the control of a control signal ST input from the enable signal input terminal T2;
a gain adjustment circuit 132, coupled to the first switch 131 and the ring oscillator circuit 12, adapted to increase the gain of the ring oscillator circuit 12 when the first switch 131 is turned on.
In specific implementation, the circuit structure of the first switch 131 may be varied as long as it can be turned on or off under the control of the control signal ST input from the start signal input terminal T2.
In an embodiment of the present invention, referring to fig. 2, the first switch 131 may include: a first PMOS transistor P1. The gate of the first PMOS transistor P1 is coupled to the enable signal input terminal T2, the drain is coupled to the gain adjustment circuit 132, and the source is coupled to a first power voltage input terminal VDD.
Of course, the first switch 131 may also be another type of switch, for example, the first switch 131 may also be a CMOS switch in parallel connection of PMOS and NMOS.
In a specific implementation, with continued reference to fig. 2, the gain adjustment circuit 132 may include: a second PMOS transistor P2 and a third PMOS transistor P3 are cross-coupled, i.e., the gate of the second PMOS transistor P2 is coupled to the drain of the third PMOS transistor P3, and the gate of the third PMOS transistor P3 is coupled to the drain of the second PMOS transistor P2. The sources of the second PMOS transistor P2 and the third PMOS transistor P3 are coupled to the first switch 131, the drains are coupled to the ring oscillator 12, and the substrate is coupled to the first power voltage input terminal VDD.
When the first switch 131 is turned on, the second PMOS transistor P2 and the third PMOS transistor P3 are turned on, and the second PMOS transistor P2 and the third PMOS transistor P3 are differentially coupled, so that one of the drain terminals of the output terminals of the second PMOS transistor P2 and the drain terminal of the output terminal of the third PMOS transistor P3 are pulled low, and the other is pulled high, which is equivalent to increasing the differential gain of the ring oscillator circuit 12, so that the ring oscillator circuit can rapidly start to vibrate. When the ring oscillator 12 starts oscillation and the frequency of the periodic signal reaches the predetermined frequency, the first switch 131 is turned off, so that the second PMOS transistor P2 and the third PMOS transistor P3 are turned off, and the load required to be driven by the ring oscillator is reduced, for example, the load required to be driven by the two differential output terminals b and bb of the inverter 122 in the ring oscillator 12 of fig. 1 is reduced, so that the operating speed of the voltage-controlled oscillator 1 may not be further reduced.
In particular implementations, referring to FIG. 1, the ring oscillator circuit 12 may exist in a variety of circuit configurations. In an embodiment of the present invention, in order to reduce the influence of noise on the periodic signal of the corresponding frequency, the ring oscillator circuit 12 may be a differential ring oscillator circuit. The differential ring oscillator circuit 12 may include a plurality of inverters connected end-to-end in series.
For example, the differential ring oscillator 12 includes three inverters 121 to 123 connected end to end in sequence. The output of the latch circuit 13 may be coupled to two differential outputs b and bb of the inverter 122, and the two differential outputs b and bb of the inverter 122 are also two differential inputs of the inverter 123. Of course, the output of the latch circuit 13 may also be coupled to two differential outputs a and ab of the inverter 121, and the two differential outputs a and ab of the inverter 121 are also two differential inputs of the inverter 122. The output of the latch circuit 13 may also be coupled to two differential inputs in and in _ of the inverter 121, and the two differential inputs in and in _ of the inverter 121 are also two differential outputs of the inverter 123.
In a specific implementation, referring to fig. 1, the current supply circuit 11 may include: a first NMOS transistor N1, a fourth PMOS transistor P4 and a fifth PMOS transistor P5. Wherein:
the gate of the first NMOS transistor N1 is coupled to the control voltage input terminal T1, the source thereof is coupled to the second power voltage input terminal VSS, and the drain thereof is coupled to the drain of the fourth PMOS transistor P4;
the grid electrode and the drain electrode of the fourth PMOS pipe P4 are coupled, and the source electrode is coupled with a first power supply voltage input end VDD;
the gate of the fifth PMOS transistor P5 is coupled to the gate of the fourth PMOS transistor P4, the source of the fifth PMOS transistor P5 is coupled to the first power voltage input VDD, and the drain is coupled to the ring oscillator circuit 12.
The control voltage VC generates a reference current I1 through the first NMOS transistor N1 and the fourth PMOS transistor P4, and further obtains a constant current I2 equal to the reference current I1 at the drain of the fifth PMOS transistor P5, and supplies the constant current I2 to the ring oscillator 12.
By adopting the current supply circuit 11, the structure is simple, and a certain temperature compensation effect is achieved.
In an embodiment of the present invention, referring to fig. 3, the voltage-controlled oscillator 1 may further include: an enable signal generating circuit 14 coupled to an enable signal input T2 of the voltage controlled oscillator 1 is adapted to generate the control signal ST at the enable signal input T2.
In a specific implementation, the start signal generating circuit 14 may be a chip for generating the control signal ST, and may also be a specific circuit for generating the control signal ST, which is not limited in particular, as long as the control signal ST can be generated.
In a specific implementation, the control signal ST may be an analog signal, such as a current signal or a voltage signal, and the latch circuit 13 is controlled to be turned on or off by the signal reaching a certain current value or voltage value. The control signal ST may also be a digital signal, and the latch circuit 13 is controlled to be turned on or off by high and low levels.
Fig. 4 is a schematic diagram of a simulation curve of the periodic signals output by the differential output terminals b and bb of the voltage-controlled oscillator 1 shown in fig. 1 under the control of the control signal ST. Wherein, the control voltage VC is 0.55V. Fig. 4(a) is a graph of the control signal ST, fig. 4(b) is a graph of the differential output terminal b of the vco 1, and fig. 4(c) is a graph of the differential output terminal bb of the vco 1.
The following detailed description is made with reference to fig. 1 and 4:
as can be seen from fig. 4, in the phase when the control signal ST is 0, the latch circuit 13 is turned on, the oscillation speed of the voltage-controlled oscillator 1 after stabilization is about 597Mhz, and in the phase when the control signal ST is 1, the latch circuit 13 is turned off, and the oscillation speed of the voltage-controlled oscillator 1 is about 747 Mhz.
Therefore, in the stage that the control signal ST is 0, the latch circuit 13 helps the ring oscillator 12 start oscillation and causes a frequency loss of Δ f 150Mhz, so that the latch circuit 13 is controlled by the control signal ST to turn off the latch circuit 13 after the frequency of the ring oscillator 12 start oscillation until the frequency of the periodic signal reaches the preset frequency, thereby avoiding the frequency loss of the voltage-controlled oscillator 1 about 150 Mhz.
The embodiment of the invention also provides a phase-locked loop, which comprises the voltage-controlled oscillator 1. The voltage-controlled oscillator 1 provides a periodic signal with a certain frequency for the subsequent circuit of the phase-locked loop.
It will be appreciated that the voltage-controlled oscillator 1 described above may also be applied to other integrated circuits, and is not particularly limited. The embodiments of the present invention are not limited to any specific circuit structure, and all such circuit structures are within the scope of the present invention.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (7)

1. A voltage controlled oscillator, comprising:
the current providing circuit is coupled with the control voltage input end of the voltage-controlled oscillator and is suitable for outputting a current signal with a preset current value under the control of the control voltage input by the control voltage input end;
the ring oscillation circuit is coupled with the output end of the current providing circuit and the control voltage input end and is suitable for outputting periodic signals of corresponding frequencies based on the current signals output by the current providing circuit under the control of the control voltage output by the control voltage input end;
the latch circuit is coupled with a starting signal input end of the voltage-controlled oscillator and the ring-shaped oscillation circuit, is suitable for starting based on a control signal input by the starting signal input end before the ring-shaped oscillation circuit starts oscillation, increases the gain of the ring-shaped oscillation circuit, and is closed based on the control signal input by the starting signal input end after the ring-shaped oscillation circuit starts oscillation and the frequency of the periodic signal reaches a preset frequency;
wherein the latch circuit comprises: the first switch is coupled with the starting signal input end and is suitable for being switched on or switched off under the control of a control signal input by the starting signal input end; a gain adjustment circuit coupled to the first switch and the ring oscillator circuit and adapted to increase a gain of the ring oscillator circuit when the first switch is turned on;
the first switch includes: a first PMOS tube; the gain adjustment circuit includes: the second PMOS tube and the third PMOS tube are in cross coupling; the grid electrode of the first PMOS tube is coupled with the starting signal input end, the drain electrode of the first PMOS tube is coupled with the source electrodes of the second PMOS tube and the third PMOS tube, and the source electrode of the first PMOS tube is coupled with the first power supply voltage input end; and the drain electrodes of the second PMOS tube and the third PMOS tube are coupled with the ring oscillation circuit, and the substrate is coupled with the first power supply voltage input end.
2. The voltage controlled oscillator of claim 1, wherein the ring oscillator circuit is a differential ring oscillator circuit.
3. The voltage controlled oscillator of claim 2 wherein the differential ring oscillator circuit includes three inverters connected end to end in sequence.
4. The voltage controlled oscillator of claim 1, wherein the current providing circuit comprises:
the bias current generating circuit is suitable for generating a current signal of the preset current value under the control of the control voltage input by the control voltage input end;
and the mirror image circuit is coupled with the bias current generating circuit and the ring oscillation circuit, is suitable for mirroring the current signal generated by the bias current generating circuit and outputting the current signal to the ring oscillation circuit.
5. The voltage controlled oscillator of any one of claims 1 to 4, further comprising:
and the starting signal generating circuit is coupled with the starting signal input end of the voltage-controlled oscillator and is suitable for generating a control signal of the starting signal input end.
6. The voltage controlled oscillator of claim 5 wherein the control signal at the enable signal input is a digital signal.
7. A phase locked loop comprising a voltage controlled oscillator as claimed in any one of claims 1 to 6.
CN201710365839.9A 2017-05-22 2017-05-22 Voltage controlled oscillator and phase locked loop Active CN108933594B (en)

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Publication number Priority date Publication date Assignee Title
CN113452367A (en) * 2020-03-27 2021-09-28 奇景光电股份有限公司 Oscillation circuit and self-starting control circuit
CN116667822A (en) * 2022-02-21 2023-08-29 华为技术有限公司 Ring voltage controlled oscillator, driving method thereof, phase locked loop and electronic equipment

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US5936478A (en) * 1997-10-01 1999-08-10 Davicom Semiconductor, Inc. Voltage-controlled oscillator including a stabilized ring oscillator
CN1248823A (en) * 1998-08-24 2000-03-29 日本电气株式会社 Phase-locked loop circuit and control method
CN1596507A (en) * 2001-11-30 2005-03-16 夏普株式会社 Oscillator circuit, booster circuit, nonvolatile memory device, and semiconductor device
CN101630942A (en) * 2008-12-30 2010-01-20 天津南大强芯半导体芯片设计有限公司 Voltage controlled oscillator circuit
CN103036558A (en) * 2011-09-30 2013-04-10 中芯国际集成电路制造(上海)有限公司 Voltage-controlled oscillator
CN103475366A (en) * 2013-09-26 2013-12-25 昆山锐芯微电子有限公司 Voltage-controlled oscillator
CN103716047A (en) * 2012-09-28 2014-04-09 英特尔移动通信有限责任公司 Ring oscillator, mobile communication device, and method
CN104270147A (en) * 2014-10-22 2015-01-07 桂林电子科技大学 Ring oscillator
CN104734699A (en) * 2015-03-27 2015-06-24 灿芯半导体(上海)有限公司 Delay unit with starting circuit and self-adaptive starting type ring oscillator

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5936478A (en) * 1997-10-01 1999-08-10 Davicom Semiconductor, Inc. Voltage-controlled oscillator including a stabilized ring oscillator
CN1248823A (en) * 1998-08-24 2000-03-29 日本电气株式会社 Phase-locked loop circuit and control method
CN1596507A (en) * 2001-11-30 2005-03-16 夏普株式会社 Oscillator circuit, booster circuit, nonvolatile memory device, and semiconductor device
CN101630942A (en) * 2008-12-30 2010-01-20 天津南大强芯半导体芯片设计有限公司 Voltage controlled oscillator circuit
CN103036558A (en) * 2011-09-30 2013-04-10 中芯国际集成电路制造(上海)有限公司 Voltage-controlled oscillator
CN103716047A (en) * 2012-09-28 2014-04-09 英特尔移动通信有限责任公司 Ring oscillator, mobile communication device, and method
CN103475366A (en) * 2013-09-26 2013-12-25 昆山锐芯微电子有限公司 Voltage-controlled oscillator
CN104270147A (en) * 2014-10-22 2015-01-07 桂林电子科技大学 Ring oscillator
CN104734699A (en) * 2015-03-27 2015-06-24 灿芯半导体(上海)有限公司 Delay unit with starting circuit and self-adaptive starting type ring oscillator

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