CN102751964A - Variable-order fully integrated loop filter - Google Patents
Variable-order fully integrated loop filter Download PDFInfo
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- CN102751964A CN102751964A CN2012102672004A CN201210267200A CN102751964A CN 102751964 A CN102751964 A CN 102751964A CN 2012102672004 A CN2012102672004 A CN 2012102672004A CN 201210267200 A CN201210267200 A CN 201210267200A CN 102751964 A CN102751964 A CN 102751964A
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Abstract
The invention discloses a variable-order fully integrated loop filter which is used in phase-locked loop based low-power consumption and high-performance frequency synthesizers and system-on-chips (SoCs) of wireless transmitter receivers. The variable-order fully integrated loop filter comprises a loop filter and a loop parameter correction module, wherein the loop parameter correction module comprises a reference circuit (RC) and a parameter adjustment logical circuit; and the loop filter comprises a basic second-order loop filter, a loop selection switch and a high order RC accessorial circuit. According to the variable-order fully integrated loop filter, the RC and the parameter adjustment logical circuit are used for adjusting resistor capacitance so that the loop parameter changes caused by changes of manufacturing technological parameters, supply voltages and temperatures are eliminated, and the stability of a phase-locked loop circuit is enhanced.
Description
Technical field
The invention belongs to wireless communication technology field, relate to the fully integrated loop filter of a kind of variable-order, be used for frequency synthesizer and the transceiver SoC of low-power consumption high-performance based on phase-locked loop.The resistance capacitance parameter that it adopts RC reference circuit structure (26) to come the adjustment loop filter; So that eliminate because fabrication process parameters, supply power voltage, and variation of temperature cause the variation of loop parameter; Thereby strengthened cycle of phase-locked loop stability, be used for realizing not being subject to the transceiver or the emitter chip of ambient temperature, process deviation, mains voltage variations factor affecting such as (PVT).
Background technology
Wireless communication technology is along with developing rapidly of personal consumption class portable terminal market obtained using very widely.For reliable and effective transmission information; Need modulate initial data; In wireless communication technology, to the transmission of digital signal, in transceiver or emitter structures; Digital baseband is handled the emission data; Modulation signal through base-band digital modulator output carries out amplitude, frequency or phase shift keying modulation to the radio-frequency carrier signal that VCO or frequency divider produce, and the signal after the modulation is launched through antenna outward through the power amplifier output chip, accomplishes the wireless transmission of digital signal.
Phase-locked loop then provides the module of carrier signal; At transmitting terminal, the local oscillation signal and the baseband modulation signal that are provided by phase-locked loop carry out mixing, perhaps by baseband modulation signal local oscillation signal are modulated; Amplify via power amplifier or radio frequency amplifier again, launch by antenna.At receiving terminal, wireless signal needs down-conversion, and carrier wave generally must be provided by phase-locked loop.Phase-locked loop can provide reference frequency accurately, and loop filter wherein is a low pass filter, mainly is used for the high fdrequency component of filtering phase frequency detector (PFD), thereby obtains the frequency of stable average voltage level control generator.Current technology allows whole phase-locked loop to be integrated on the same chip with technology, and the bandwidth that the output of oscillator is made an uproar with filter mutually has very big relation, in order to obtain lower phase noise; The bandwidth of common loop filter need obtain less, and the resistance capacitance value is just bigger in the loop filter, has increased area of chip and cost; The another one aspect; In IC design, one very important problem be that process deviation, voltage fluctuation, ambient temperature factors such as (PVT) can affect greatly circuit performance and consistency, therefore from design point of view; Need phase-locked loop circuit to have the correcting circuit of factor affecting such as stronger robustness and inhibition PVT; Because it is bigger that bigger resistance capacitance receives the influence of factors such as temperature drift, process deviation, gain of the loop function of signal path and amplitude etc. show inconsistency, need address this problem from design; And existing disclosed document has been done some trials to the temperature-compensating mode, but effect receives more restriction.
Summary of the invention
The present invention seeks to propose the fully integrated loop filter of a kind of variable-order in order to overcome prior art performance and structural limitation.The resistance capacitance parameter that it adopts RC reference circuit structure to come the adjustment loop filter; So that eliminate because fabrication process parameters, supply power voltage, and variation of temperature cause the variation of loop parameter; Thereby strengthened cycle of phase-locked loop stability, be used for realizing not being subject to the transceiver or the emitter chip of ambient temperature, process deviation, mains voltage variations factor affecting such as (PVT).
The present invention realizes through following technical scheme: the fully integrated loop filter of described variable-order comprises loop filter and loop parameter correction module; Said loop parameter correction module comprises RC reference circuit and parameter adjustment logical circuit; Loop filter comprises: first resistance, one termination filtering input; Another termination filtering output, parallelly connected loop selector switch on first resistance, first resistance, one end connects an end of first electric capacity; The other end ground connection of first electric capacity; The first resistance other end connects second resistance, one end and the 3rd electric capacity one end respectively, and the second resistance other end connects second electric capacity, one end, the second electric capacity other end and the 3rd electric capacity other end ground connection; Said first resistance, second resistance, first electric capacity, second electric capacity, the size of the 3rd electric capacity is by the control signal control of parameter adjustment logical circuit output; The parameter adjustment logical circuit comes the resistance capacitance value in the adjustment loop filter according to the resistance R value and the capacitor C value of RC reference circuit; Make the resistance R value of RC reference circuit become fixed proportion with said first resistance, second resistance value, the capacitor C value of RC reference circuit becomes fixed proportion with said first electric capacity, second electric capacity, the 3rd capacitance.
Resistance R value and capacitor C value are calibrated by the fixed reference clock signal in the said RC reference circuit, and the value of R and C makes that the fixed reference clock signal frequency is the integral multiple of the inverse of R and C product in the adjustment RC reference circuit; Parameter adjustment logical circuit assignment is used for exporting the control word of resistance in the loop filter, capacitance, the resistance capacitance value that the representative of Different control word is different; According to the proportionate relationship of resistance capacitance value in resistance R value in the RC reference circuit and capacitor C value and the loop filter come in the adjustment loop filter first resistance, second resistance and, first electric capacity, second electric capacity, the 3rd capacitance.
The figure place of the control word through increasing the output of said parameter adjustment logical circuit, the adjustable range and the adjustment of loop parameter that improves loop filter is interval.
In the said loop filter, second resistance, second electric capacity, these 2 rank loop filters of the 3rd electric capacity primordial, first resistance and first electric capacity constitute the High Order RC adjunct circuit; When the loop selector switch cut out, second resistance R 2 and first electric capacity, second electric capacity, the 3rd electric capacity had been formed a traditional second-order loop filter jointly; When the loop selector switch was opened, first resistance R 1, second resistance R 2, first electric capacity, second electric capacity, the 3rd electric capacity had then been formed one 3 rank loop filter.
Said RC reference circuit is to have comprised some parts in the integrated circuit unit of whole phase-locked loop: such as being to receive a part of sending the filter in the link; Or an independent RC pierce circuit, or be specifically designed to a RC circuit of adjustment loop parameter.
Beneficial effect of the present invention is:
1, the loop filter that is proposed than traditional structure, can realize that 2 rank, 3 stage structures are multiplexing; Only can realize through a selector switch; And as 2 stage structures the time, C1 and the addition of C3 appearance value have reduced the area of filter effectively as filter capacitor.
2, adopt the structure that is similar to the RC oscillator to be used as the foundation that loop filter parameters is adjusted, the resistance capacitance parameter of coming the adjustment loop filter.The parameter adjustment logical circuit through a series of computing, has drawn the control word that is used for exporting the value of resistance capacitance in the loop filter, the resistance capacitance value that the representative of Different control word is different according to the result of fixed reference clock signal calibration RC reference circuit.This calibration structure is than traditional simple in structure and practical, and be and phase-locked loop compatible, can be integrated in in a chip, improved integrated level and reduced system cost.
3, the calibration circuit that is proposed (RC reference circuit and parameter adjustment logical circuit) can be eliminated because of fabrication process parameters, supply power voltage, reach the variation that variation of temperature causes loop parameter; Thereby strengthen cycle of phase-locked loop stability, thereby let the characteristic of loop filter not receive the influence of factors such as process deviation, temperature drift or power-supply fluctuation.
4, the loop filter with self-calibration function of the present invention's proposition is applicable to wireless radiofrequency communication transceiver or reflector, is applicable to CMOS technology.
Description of drawings
Fig. 1 is applied in the circuit block diagram in the phase-locked loop for loop filter proposed by the invention.
Fig. 2 is a circuit structure block diagram of the present invention.
Fig. 3 (a) is the structural representation of the RC reference circuit of the embodiment of the invention one.
Fig. 3 (b) is the structural representation of the RC reference circuit of the embodiment of the invention two.
Fig. 3 (c) is the structural representation of the RC reference circuit of the embodiment of the invention three.
Fig. 4 is the automatic correcting process figure of the embodiment of the invention.
Embodiment
The present invention proposes the fully integrated loop filter of a kind of variable-order, be used for frequency synthesizer and the transceiver SoC of low-power consumption high-performance based on phase-locked loop, its position in whole phase-locked loop is as shown in Figure 1 with effect.
Fig. 1 is the frequency synthesizer block diagram that has comprised the whole phase-locked loop of loop filter proposed by the invention; It also is a preferred embodiment; Comprising phase frequency detector 11; Charge pump 12, loop filter 13, voltage controlled oscillator (VCO) 14, variable ratio frequency changer frequency divider 15, loop parameter correction module 16.According to the order in the loop; Both phase differences (difference on the frequency) are compared in reference clock signal and VCO 14 outputs through phase frequency detector 11 through the frequency division output signal of variable ratio frequency changer frequency divider 15; What determine charge pump 12 is charging or discharge to loop filter 13; Certainly this is also determined (to select positive voltage frequency curve characteristic usually by the voltage frequency characteristics curve of VCO 14; The negative voltage frequency characteristics is then opposite): if the frequency of reference clock is higher than the frequency division output signal frequency; Perhaps the reference clock signal phase place is ahead of the phase place of frequency division output signal, and phase frequency detector 11 makes 12 pairs of loop filters 13 of charge pump charge with charge pump 12 actings in conjunction so, to improve VCO 14 frequencies of oscillation; If the frequency of reference clock is lower than the frequency division output signal frequency; Perhaps the reference clock signal phase place lags behind the phase place of frequency division output signal; Phase frequency detector 11 makes 12 pairs of loop filters 13 of charge pump discharge with charge pump 12 actings in conjunction so, to reduce VCO 14 frequencies of oscillation; Dwindle with reference to fractional frequency signal and frequency division output signal frequency difference or phase difference, until both frequencies and phase place identical (phase difference also possibly be a fixed value, is not 0) so always.
As shown in Figure 2, present invention includes described loop filter 13 and loop parameter correction module 16.Loop filter 13 comprises basic 2 rank loop filters (second resistance R, 2, the second capacitor C, 2, the three capacitor C 3), loop selector switch S1, High Order RC adjunct circuit (first resistance R, 1, the first capacitor C 1).Wherein, first resistance R, 1 one termination filtering input Vi, another termination filtering output Vo; Parallelly connected loop selector switch S1 on first resistance R 1; First resistance R, 1 one ends connect an end of first capacitor C 1, the other end ground connection of first capacitor C 1, and first resistance R, 1 other end connects second resistance R, 2 one ends and the 3rd capacitor C 3 one ends respectively; Second resistance R, 2 other ends connect second capacitor C, 2 one ends, second capacitor C, 2 other ends and the 3rd capacitor C 3 other end ground connection.The size of said first resistance R, 1, the second resistance R, 2, the first capacitor C, 1, the second capacitor C, 2, the three capacitor C 3 is by the control signal control of parameter adjustment logical circuit 162 outputs.
When loop selector switch S1 closed, second resistance R 2, first-Di, three capacitor C 1-C3 had formed a traditional second-order loop filter jointly, and first capacitor C 1 and the 3rd capacitor C 3 are equivalent to a filter capacitor in the traditional structure altogether.When loop selector switch S1 opens; First resistance R 1, second resistance R 2, first-Di, three capacitor C 1-C3 have then formed one 3 rank loop filter; Because each element (R1, R2, C1-C3) all is the control that receives 162 outputs of parameter adjustment logical circuit; The loop parameter adjustable range of loop filter 13 and adjustment interval can be very accurate so, as long as the figure place of the control word of parameter adjustment logical circuit 162 outputs is abundant.The i.e. figure place of the control word through increasing by 162 outputs of parameter adjustment logical circuit, loop parameter adjustable range and adjustment that can corresponding raising loop filter be interval, make that the error of loop parameter and set point of loop filter is littler.
Said loop parameter correction module 16 comprises RC reference circuit 161 and parameter adjustment logical circuit 162.With a fixing reference clock signal as the calibration foundation; Parameter adjustment logical circuit 162 is according to the inverse of the product of R and C in the RC reference circuit 161; This inverse can be regarded a frequency meter as, if counted by the fixed reference clock signal, through the value of R and C is set; Can make the fixed reference clock signal be R and C product inverse integral multiple K doubly; K can be provided with arbitrarily, and mainly according to the R1-R2 of needs in fixed reference clock signal frequency and the loop filter, the value of C1-C3 determines.The value of R and C in the adjustment RC reference circuit makes that the fixed reference clock signal frequency is integral multiple K times of inverse of R and C product, can confirm that so the value of R, C can not change with the variation of technology, temperature, supply voltage.And then come the R1-R2 in the adjustment loop filter 13, the value of C1-C3 according to the proportionate relationship of resistance R 1-R2, capacitor C 1-C3 in resistance R, capacitor C and the loop filter 13 in the RC reference circuit 16; Make R1-R2 in the loop filter, C1-C3 still with RC reference circuit 16 in resistance R, capacitor C satisfy certain proportionate relationship.Parameter adjustment logical circuit 162 assignment are used for exporting the control word of resistance, capacitance in the loop filter 13, the resistance capacitance value that the representative of Different control word is different.Said RC reference circuit 161 possibly be a module in the whole transceiver, also possibly be an independent module, can be integrated among the IC of whole transceiver.
The resistance capacitance value that the present invention adopts RC reference circuit 161 structure and parameters adjustment logical circuit 162 to come adjustment loop filter 13; So that eliminate because fabrication process parameters, supply power voltage, and variation of temperature cause the variation of loop parameter, thereby strengthened cycle of phase-locked loop stability.
The present invention is as three stage structures, if from being input to output, with traditional third order PLL path filter structure be inverted fully.But the loop function that these two kinds of inverted structures of input and output draw but is identical, because components and parts wherein also are inverted.
Described RC reference circuit can be to have comprised some parts in the integrated circuit unit of whole phase-locked loop; For example receive a part of sending the filter in the link; Also can be independent one and be similar to the RC pierce circuit, or be specifically designed to a RC circuit of adjustment loop parameter.
Embodiment below in conjunction with concrete RC reference circuit 161 does further explanation to embodiment of the present invention.
Embodiment one
According to the order in the loop; Both phase differences (difference on the frequency) are compared in reference clock signal and VCO 14 outputs through phase frequency detector 11 through the frequency division output signal of variable ratio frequency changer frequency divider 15; What determine charge pump 12 is charging or discharge to loop filter 13; Certainly this is also determined (to select positive voltage frequency curve characteristic usually by the voltage frequency characteristics curve of VCO 14; The negative voltage frequency characteristics is then opposite): if the frequency of reference clock is higher than the frequency division output signal frequency; Perhaps the reference clock signal phase place is ahead of the phase place of frequency division output signal, and phase frequency detector 11 makes 12 pairs of loop filters 13 of charge pump charge with charge pump 12 actings in conjunction so, to improve VCO 14 frequencies of oscillation; If the frequency of reference clock is lower than the frequency division output signal frequency; Perhaps the reference clock signal phase place lags behind the phase place of frequency division output signal; Phase frequency detector 11 makes 12 pairs of loop filters 13 of charge pump discharge with charge pump 12 actings in conjunction so, to reduce VCO 14 frequencies of oscillation; Dwindle with reference to fractional frequency signal and frequency division output signal frequency difference or phase difference, until both frequencies and phase place identical (phase difference also possibly be a fixed value, is not 0) so always.
Because very big variation has taken place for technology, supply power voltage and variation of temperature, the loop parameter of whole phase-locked loop, the stability of loop is difficult to be guaranteed.Therefore, before this locking process, must there be loop parameter to proofread and correct.In the important module of loop parameter correction module is the RC reference circuit; Shown in Fig. 3 (a); Said RC reference circuit 161 comprises a RC nucleus module 301, the module 302 of current source or voltage bias is provided for the RC nucleus module; And 303 (possibly be LDO, perhaps a DC-DC module) of giving these two module for power supply.Most crucial module RC nucleus module 301 in this RC reference circuit 161; It is a filter (low pass; Or high pass, or band is logical) in a part, and this filter possibly be a module in the whole transceiver; Also possibly be an independent module, can be integrated among the IC of whole transceiver.
The loop parameter correcting process is as shown in Figure 4.At first system provides an enabling signal; Loop parameter is proofreaied and correct beginning; RC reference circuit 161 and 162 work of parameter adjustment logical circuit; System will extract the value of R and C from RC nucleus module 301, again through the respectively value and the value of capacitor C of changes in resistance R, make that the fixed reference clock signal frequency is integral multiple K times of inverse of R and C product.If satisfy K multiple proportions value relation, parameter adjustment logical circuit 162 control word that will change the resistance R capacitor C in the RC nucleus module 301 changes the value of R and C so, till satisfying predetermined condition.
Below will be by the control word of parameter adjustment logical circuit 162 according to the R in the RC nucleus module 301, C value; And R1-R2 in R, C and the loop filter 13 in the RC nucleus module, the proportionate relationship of C1-C3 is provided with R1, R2 in the loop filter 13; The control word of C1-C3 numerical value; Make R in the resistance capacitance and 301 in the loop filter 13, C keeps certain ratio, promptly consistent variation.
Embodiment two
Shown in Fig. 3 (b), said RC reference circuit 161 comprises a RC nucleus module 301, the module 302 of current source or voltage bias is provided for the RC nucleus module, and 303 (possibly be LDO, perhaps a DC-DC module) of giving these two module for power supply.Most crucial module RC nucleus module 301 in this RC reference circuit 161; This RC nucleus module 301 is parts in the RC oscillator; The typical embodiment of this RC oscillator makes two transistorized Vgs differences on resistance R, produce a reference current through the nmos pass transistor that different breadth length ratios are set shown in Fig. 3 (b), and this electric current charges to C through the mirror image circuit mirror image; Output signal frequency is just closely related with the value of R and C; And this oscillator possibly be a module in the whole transceiver, also possibly be an independent module, can be integrated among the IC of whole transceiver.
The loop parameter correcting process is as shown in Figure 4.At first system provides an enabling signal, and loop parameter is proofreaied and correct beginning, RC reference circuit 161 and 162 work of parameter adjustment logical circuit, system will extract the value of R and C from RC nucleus module 301, be exactly in fact its frequency of oscillator be 1/RC.By of the clock cycle inside counting of fixed reference clock signal at oscillator, if count value equals K, explain so the fixed reference clock signal frequency be R and C product inverse integral multiple K doubly, also just satisfied predetermined condition.If satisfy K multiple proportions value relation, parameter adjustment logical circuit 162 control word that will change the resistance R capacitor C in the RC nucleus module 301 changes the value of R and C so, till satisfying predetermined condition.
Below will be by the control word of parameter adjustment logical circuit 162 according to the R in the RC nucleus module 301, C value; And R1-R2 in R, C and the loop filter 13 in the RC nucleus module, the proportionate relationship of C1-C3 is provided with R1, R2 in the loop filter 13; The control word of C1-C3 numerical value; Make R in the resistance capacitance and 301 in the loop filter 13, C keeps certain ratio, promptly consistent variation.
Embodiment three
Shown in Fig. 3 (c); Said RC reference circuit 161 comprises a RC nucleus module 301; A module 302 of current source or voltage bias being provided for the RC nucleus module, and 303 (possibly be LDO, perhaps a DC-DC module) of giving these two module for power supply.RC nucleus module 301 is parts in the RC oscillator; The typical embodiment of this RC oscillator is shown in Fig. 3 (c); Make the difference of Vbe of two triodes on resistance R, produce a reference current through the NPN triode that different area is set; This electric current charges to C through the mirror image circuit mirror image, and output signal frequency is just closely related with the value of R and C, and this oscillator possibly be a module in the whole transceiver; Also possibly be an independent module, can be integrated among the IC of whole transceiver.
The loop parameter correcting process is with embodiment two.
Claims (5)
1. the fully integrated loop filter of variable-order is characterized in that: comprise loop filter (13) and loop parameter correction module (16); Said loop parameter correction module (16) comprises RC reference circuit (161) and parameter adjustment logical circuit (162); Loop filter (13) comprising: first resistance (R1) termination filtering input (Vi); Another termination filtering output (Vo); First resistance (R1) is gone up parallelly connected loop selector switch (S1); First resistance (R1) end connects an end of first electric capacity (C1), the other end ground connection of first electric capacity (C1), and first resistance (R1) other end connects second resistance (R2) end and the 3rd electric capacity (C3) end respectively; Second resistance (R2) other end connects second electric capacity (C2) end, second electric capacity (C2) other end and the 3rd electric capacity (C3) other end ground connection; Said first resistance (R1), second resistance (R2), first electric capacity (C1), second electric capacity (C2), the size of the 3rd electric capacity (C3) is by the control signal control of parameter adjustment logical circuit (162) output; Parameter adjustment logical circuit (162) comes the resistance capacitance value in the adjustment loop filter (13) according to the resistance R value and the capacitor C value of RC reference circuit (161); Make the resistance R value of RC reference circuit (161) be worth into fixed proportion with said first resistance (R1), second resistance (R2), the capacitor C value of RC reference circuit (161) is worth into fixed proportion with said first electric capacity (C1), second electric capacity (C2), the 3rd electric capacity (C3).
2. the fully integrated loop filter of a kind of variable-order according to claim 1; It is characterized in that; Resistance R value and capacitor C value are calibrated by the fixed reference clock signal in the said RC reference circuit (161); The value of R and C makes that the fixed reference clock signal frequency is the integral multiple of the inverse of R and C product in the adjustment RC reference circuit (161); Parameter adjustment logical circuit (162) assignment is used for exporting the control word of resistance, capacitance in the loop filter (13), the resistance capacitance value that the representative of Different control word is different; According to the resistance R value in the RC reference circuit (161) and the proportionate relationship of capacitor C value and the middle resistance capacitance value of loop filter (13) come in the adjustment loop filter (13) first resistance (R1), second resistance (R2) and, first electric capacity (C1), second electric capacity (C2), the 3rd electric capacity (C3) value.
3. the fully integrated loop filter of a kind of variable-order according to claim 1; It is characterized in that; In the said loop filter (13); Second resistance (R2), second electric capacity (C2), these 2 rank loop filters of the 3rd electric capacity (C3) primordial, first resistance (R1) and first electric capacity (C1) constitute the High Order RC adjunct circuit; When loop selector switch (S1) when closing, second resistance R 2 and first electric capacity (C1), second electric capacity (C2), the 3rd electric capacity (C3) have been formed a traditional second-order loop filter jointly; When loop selector switch (S1) when opening, first resistance R 1, second resistance R 2, first electric capacity (C1), second electric capacity (C2), the 3rd electric capacity (C3) have then been formed one 3 rank loop filter.
4. the fully integrated loop filter of a kind of variable-order according to claim 1; It is characterized in that; The figure place of the control word through increasing said parameter adjustment logical circuit (162) output, the adjustable range and the adjustment of loop parameter that improves loop filter (13) is interval.
5. the fully integrated loop filter of a kind of variable-order according to claim 1; It is characterized in that; Said RC reference circuit (161) is to have comprised some parts in the integrated circuit unit of whole phase-locked loop: be to receive a part of sending the filter in the link; Or an independent RC pierce circuit, or be specifically designed to a RC circuit of adjustment loop parameter.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103986464A (en) * | 2014-05-22 | 2014-08-13 | 无锡中科微电子工业技术研究院有限责任公司 | Self-calibration device and method for loop parameters of phase-locked loop |
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| JP2003517755A (en) * | 1999-10-01 | 2003-05-27 | エリクソン インコーポレイテッド | PLL loop filter using switched capacitor resistor |
| US20040085206A1 (en) * | 2001-02-07 | 2004-05-06 | David Wadlow | Control system with capacitive detector |
| CN1813407A (en) * | 2003-08-27 | 2006-08-02 | 诺基亚公司 | Calibrating a loop-filter of a phase locked loop |
| CN1879304A (en) * | 2003-10-03 | 2006-12-13 | 模拟设备股份有限公司 | Phase-locked loop bandwidth calibration circuit and implementation method thereof |
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| JP2003517755A (en) * | 1999-10-01 | 2003-05-27 | エリクソン インコーポレイテッド | PLL loop filter using switched capacitor resistor |
| US20040085206A1 (en) * | 2001-02-07 | 2004-05-06 | David Wadlow | Control system with capacitive detector |
| CN1813407A (en) * | 2003-08-27 | 2006-08-02 | 诺基亚公司 | Calibrating a loop-filter of a phase locked loop |
| CN1879304A (en) * | 2003-10-03 | 2006-12-13 | 模拟设备股份有限公司 | Phase-locked loop bandwidth calibration circuit and implementation method thereof |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103986464A (en) * | 2014-05-22 | 2014-08-13 | 无锡中科微电子工业技术研究院有限责任公司 | Self-calibration device and method for loop parameters of phase-locked loop |
| CN103986464B (en) * | 2014-05-22 | 2017-08-29 | 无锡中科微电子工业技术研究院有限责任公司 | A kind of cycle of phase-locked loop parameter self-calibrating device and method |
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