CN207573331U - A kind of on piece oscillator with self-calibration function - Google Patents

Abstract

The utility model discloses a kind of on piece oscillators with self-calibration function, including oscillating unit, frequency divider, counter, register and correcting current unit, the oscillator signal output termination frequency divider of oscillating unit, the clock signal output terminal of frequency divider connect counter；The numerical signal output termination register of counter, control signal input connect the calibration signal output terminal of external microcontroller；The control signal input of register connects the initialization pulse output terminal of external microcontroller, the calibration code input terminal of the calibration code output termination correcting current unit of register；The current output terminal of correcting current unit connects the current input terminal of oscillating unit.The utility model reduces self calibration iterations, and the high efficiency calibration of on piece oscillator is realized in a manner that a step calibration is without iteration, and output frequency precision is high.

Description

A kind of on piece oscillator with self-calibration function

[technical field]

The utility model is related on piece oscillator more particularly to a kind of on piece oscillators with self-calibration function.

[background technology]

On piece oscillator due to its small power consumption, size is small, price is low, be easily integrated the advantages that, substitute crystal oscillator it is wide It is general to be applied in integrated circuit.However, the major defect of on piece oscillator is its output frequency by technique, supply voltage and temperature The influence of variation is big, such as the frequency variation up to 20% of 3 σ of on piece RC oscillators.Therefore it needs to reduce by the method calibrated The on piece oscillator output frequencies of the on piece prior art to technique, supply voltage, temperature change sensibility, output frequency can be with Temperature, technique, voltage change and change, and also can not with the oscillator output frequencies that different location is distributed on wafer Together, it is therefore desirable to calibrate.

The disclosure of the invention of Publication No. CN103066996A a kind of oscillator and its method for self-calibrating, wherein, it is described to shake Device is swung to include：Oscillating unit, for generating oscillator signal；Converting unit, for being electricity by the frequency conversion of the oscillator signal Press signal；Comparing unit, for by the voltage signal compared with highest frequency voltage and low-limit frequency voltage, and export compare Consequential signal；Add and subtract unit, for preserving calibration value, according to the comparison result signal add and subtract calibration value, and export with it is described The corresponding calibration signal of calibration value；Alignment unit, for calibrating the frequency of the oscillator signal according to the calibration signal.The hair Calibration steps is repeated several times in prover time window in bright oscillator method for self-calibrating needs, until prover time window knot Beam.

The invention of Publication No. CN101212212A is related to a kind of high precision oscillator with self-calibration function and calibration Method, for setting the N byte control word group of digital control oscillation device to generate clock signal, method for self-calibrating first carries out this The circuit initialization of oscillator, (N-1) byte for resetting N byte control word group are 1.Later, compare clock signal and frequency The frequency of rate reference signal, when clock signal frequency is less than the frequency of the frequency reference signal, setting N byte control word group (N-1) byte is 0, when the clock signal frequency is not less than the frequency of frequency reference signal, sets N byte control word The N-1 bytes of group are 1.It repeats the above steps, sequentially to set (N-2) byte of N byte control word group to the 0th word Section.The invention is used to set the N byte control word group of digital control oscillation device, and the digital control oscillation device is according to the N words Control word group is saved to generate clock signal, that is, needs to repeat calibration steps n times.

These method for self-calibrating usually require the process of successive ignition and trim or calibrate to complete the frequency of enough accuracy, core Piece normal work is interrupted longer time, calibration method it is inefficient.

[invention content]

The technical problem to be solved by the present invention is to provide a kind of pieces high with self-calibration function, output frequency precision Upper oscillator.

In order to solve the above-mentioned technical problem, the technical solution adopted in the utility model is, a kind of with self-calibration function On piece oscillator, including oscillating unit, frequency divider, counter, register and correcting current unit, the oscillator signal of oscillating unit Output termination frequency divider, the clock signal output terminal of frequency divider connect counter；The numerical signal output termination register of counter, Control signal input connects the calibration signal output terminal of external microcontroller；The control signal input of register connects external micro-control The initialization pulse output terminal of device processed, the calibration code input terminal of the calibration code output termination correcting current unit of register； The current output terminal of alignment unit connects the current input terminal of oscillating unit.

Above-described on piece oscillator, correcting current unit include amplifier and current mirroring circuit, and current mirroring circuit includes First PMOS, the 2nd PMOS and multidigit electric resistance array；The anti-phase input termination reference voltage of amplifier, the first PMOS's of output termination The grid of grid and the 2nd PMOS；The source electrode of first PMOS and the source electrode of the 2nd PMOS connect chip power, the drain electrode of the first PMOS Connect the in-phase input end of amplifier and the input terminal of multidigit electric resistance array；The output terminal ground connection of multidigit electric resistance array, control termination are posted The output terminal of storage；Signal output end of the drain electrode of 2nd PMOS as correcting current unit.

Above-described on piece oscillator, oscillating unit include logic control circuit, the 3rd PMOS, the 4th PMOS, first NMOS, the 2nd NMOS, the 3rd NMOS, comparator, capacitance and 4 electronic switches, the source electrode ground connection of the first NMOS, drain and gate Connect the signal output end of correcting current unit；The source electrode ground connection of 2nd NMOS, grid connect the grid of the first NMOS, and drain electrode connects third The drain and gate of PMOS, the source electrode of the 3rd PMOS connect chip power；The source electrode of 4th PMOS connects chip power, and drain electrode passes through the One electronic switch connects the anode of capacitance, and grid connects the grid of the 3rd PMOS；The drain electrode of 3rd NMOS is connect by the second electronic switch The anode of capacitance, source electrode ground connection, grid connect the grid of the first NMOS；The anode of capacitance connects the in-phase input end of comparator, cathode Ground connection, the inverting input of comparator connect limit comparison voltage V by third electronic switch_H, connect down by the 4th electronic switch Limit comparison voltage V_L；The output terminal of the input termination comparator of logic control circuit, the output terminal of logic control circuit, which is used as, to shake Swing the output terminal of unit, the control terminal for connecing 4 electronic switches.

Above-described on piece oscillator, the logic control circuit are rest-set flip-flops.

The utility model reduces self calibration iterations, and by a step calibration, the mode without iteration realizes on piece The high efficiency calibration of oscillator, output frequency precision are high.

[description of the drawings]

The utility model is described in further detail with reference to the accompanying drawings and detailed description.

Fig. 1 be the utility model proposes the functional block diagram with a step self-calibration function on piece oscillator.

Fig. 2 be the utility model proposes one step self-calibration process of on piece oscillator output frequencies oscillogram.

Fig. 3 is the utility model embodiment on piece oscillator principle block diagram.

Fig. 4 is the functional block diagram of the utility model embodiment RC- oscillators.

Fig. 5 is the flow diagram of the utility model embodiment on piece oscillator calibration method.

[specific embodiment]

The utility model is in order to solve the on piece oscillator output frequencies in integrated circuit with technique, temperature, voltage change And the problem of changing, propose a kind of on piece oscillator architecture and its calibration method with a step self-calibration function.

What Fig. 1 was provided be the utility model proposes the on piece oscillator block diagram with a step self-calibration function.The oscillation Device includes oscillating unit, divider unit, counter unit, register cell and correcting current unit.

Oscillating unit is used to generate oscillator signal CLK, frequency F_OSC；

Divider unit, for generating a clock signal clk after oscillator signal CLK frequency dividings_COUNT, frequency is F_COUNT；Counter is sent into as clock signal；

Counter unit is used for clock CLK_COUNTIn the reference pulse (T that microcontroller is sent out_{REF_PULSE}) period in Pulse number is counted, exports count value n, which is sent by microcontroller (MCU)；The rising edge of reference pulse is believed for calibration It is carved at the beginning of number, the failing edge of reference pulse is the finish time of calibration signal；

The initialization pulse that register cell is sent out according to MCU recalls the calibration code of initialization, i.e. K_INITIAL= K_TARGET(K_TARGETIt is output target frequency F_TARGETWhen, the Theoretical Design value of calibration code K), and after calibration signal, more New calibration code is counter output valve, i.e. K_TRIM=n；

Correcting current unit is when MCU sends out initialization pulse, according to calibration code K_INITIAL=K_TARGETGenerate I_OSCAnd it send Enter oscillating unit, oscillating unit is allowed to generate the clock signal clk of initialization, after calibration signal, according to calibration code K_TRIM=n generates new I_OSCCalibrate oscillation signal frequency.

Fig. 2 gives the on piece oscillator output frequencies calibration process with a step self-calibration function of the utility model Oscillogram.With the variation of technique, temperature, voltage, the output frequency of on piece oscillator deviates desired value and needs into line frequency Calibration.Microcontroller (MCU) sends out initialization pulse first, and register cell recalls the calibration code of initialization, i.e. K_INITIAL =K_TARGET, K_TARGETThe theoretical value of calibration code K when being on piece oscillator output target frequency；Subsequent microcontroller (MCU) hair Go out calibration signal, when counter unit detects the rising edge of calibration signal, proceed by frequency calibration, once detect school The failing edge of calibration signal, frequency calibration terminate.

When counter unit detects the rising edge of calibration signal, the output of reset count device, i.e. counter is 0, is counted Device starts to clock CLK_COUNTPulse number is counted, until the failing edge for detecting calibration signal just stops counting.This hour counter Output for n, register cell update calibration code, i.e. K=n, alignment unit calibrates electric current I according to calibration code_OSC, and give Enter oscillating unit and obtain accurate frequency, one step self-calibration process of oscillator output frequencies is completed.

Fig. 3 gives the on piece oscillator block diagram of the embodiment of the utility model, with reference to Fig. 3 and embodiment to this reality It is described in detail with novel specific implementation process.

The utility model proposes a step self calibration mode and traditional calibrating mode it is different, be not by continuous iteration The size of process change calibration code K values carrys out calibration frequency.The pass of one step self calibration scheme of the utility model on piece oscillator One of key thinking is as output target frequency F_TARGETWhen, the Theoretical Design value K of calibration code K_TARGETWith the reason of counter output By value N_TARGETIt is equal, i.e. K_TARGET=N_TARGET, another operating conditions is the product energy of counter output valve N and calibration code K Enough reflect the variation of RC products.When carrying out frequency calibration, by K_TARGETCalibration code K as initialization_INITIAL=K_TARGET, If output frequency F_OSC=F_TARGET, then the output N=N of counter_TARGETIf F_OSC≠F_TARGET, then N ≠ N_TARGET.No matter Which kind of situation is all the last look K using the output valve N of counter as calibration code after calibrating_TRIM, complete output frequency A step calibration.

The present embodiment alignment unit is formed by amplifier A1 and with current mirroring circuit, and current mirroring circuit includes metal-oxide-semiconductor M_P1、 Metal-oxide-semiconductor M_P2With M electric resistance array R_trimming, generate to the capacitance charge and discharge electric current I of RC oscillating units_OSC, electric resistance array Signal Cal [0 is trimmed by the number of M-bits (M):M-1] control, if representing Cal [0 with calibration code K:M-1] ten into Numerical value processed, then by reference voltage V_REFThe reference current I generated with electric resistance array_REFIt can be expressed asWherein R It is the unitary resistance value of electric resistance array, metal-oxide-semiconductor M_P2Mirror image metal-oxide-semiconductor M_P1Electric current and output

Oscillating unit is RC oscillators as shown in Figure 4, flows through M_P4And M_N3Electric current be respectively I_CHAnd I_DISCH, difference table Show the electric current to capacitor charging and electric discharge, I_CHAnd I_DISCHIt is by metal-oxide-semiconductor M_P3、M_N1And M_N2The I that mirror image alignment unit is sent into_OSC, V_HIt is the upper limit comparison voltage of comparator, V_LIt is the lower limit comparison voltage of comparator, the two values set the voltage value on capacitance V_CAmplitude range, V_CMeet in-phase input end, the V of comparator_AConnect the inverting input of comparator, control logic circuit according to than Output result compared with device selects V_A=V_HOr V_A=V_L.Work as V_C<V_LWhen, then comparator output is 0, and after rest-set flip-flop, RS is touched Send out the output V of device₁=0, select electronic switch S₁And S₃Conducting is closed, makes V_A=V_H, and pass through metal-oxide-semiconductor M_P4It is filled to capacitance C Electricity, charging current I_CH；When capacitor charging to V_L<V_C<V_HWhen, comparator output is 0, still passes through metal-oxide-semiconductor M_P4It is filled to capacitance C Electricity, charging current I_CH；When capacitor charging to V_C>V_HWhen, comparator output is 1, after rest-set flip-flop, rest-set flip-flop it is defeated Go out V₁=1, select electronic switch S₁And S₃It cut-offs, electronic switch S₂And S₄Conducting is closed, makes V_A=V_L, and pass through metal-oxide-semiconductor M_N3 It discharges to capacitance C, discharge current I_DISCH；When capacitance is discharged to V_C<V_LWhen, and start to repeat above-mentioned charge and discharge process.From this The course of work of RC oscillators is it is found that its frequency of oscillation F_oscIt can be expressed asWherein I_OSCIt represents Give capacitance charge and discharge current value, I_OSC=I_CH=I_DISCH, C is capacitance, and Δ V is signal V_CAmplitude, be represented by Δ V herein =V_H-V_L, A is time delay coefficient, and for RC oscillators, A is equal to 2.RC oscillator output frequencies can be with operating voltage, environment Temperature, changes in process parameters and change, due to F_OSCIt is proportional to I_OSC, and I_OSCIt is proportional to I_REF, therefore F_OSCIt can be expressed as by electricity The function of RC sum of products calibration codes K that pressure, temperature, technique influence, i.e.,Therefore as long as revised calibration code K can reflect RC The variation of product can then eliminate the influence of RC products variation, so as to alignment oscillator output frequency.It can also from the expression formula Go out, if reference voltage V_REF, V_H,V_LValue changed with technique, temperature, voltage and lead to output frequency F_OSCChange, It is also that can frequency calibration be returned by target frequency by such calibration method.

It is F to frequency that divider unit, which is exactly,_OSCClock signal clk divided, such as m frequency dividing, generate frequency beClock signal clk_COUNTGive counter unit.When counter unit is detected from microcontroller (MCU) during the rising edge of the calibration signal sent out, reset count device is exported, and starts to clock signal clk_COUNTCount pulse Number when the failing edge for detecting calibration signal, stops counting, the reference pulse time can be expressed as T_{REF_PULSE}=N/F_COUNT, Wherein N is count value.Therefore F_OSCIt can be expressed as F_OSC=N × m/T_{REF_PULSE}.If oscillator output frequencies are accurately etc. In design object value F_TARGET, i.e. F_OSC=F_TARGET, then meet The output N=N of counter unit_TARGET。

From F_OSCExpression formulaIt can obtain counting The relationship of device output valve N and calibration code K isIt can be seen that N and K Product can reflect the variation of RC products (this is also the factor of output frequency variation).The process of calibration frequency is first will calibration Code K is initialized, that is, sets K_INITIAL=K_TARGET, then be sent to alignment unit and generate I_OSC, oscillating unit mirror image I_OSCIt generates To the electric current I of capacitance charge and discharge_CHAnd I_DISCH.The frequency of oscillation F of oscillating unit output initialization_OSC, divided device unit and meter After number device cell processing, count value n is obtained, by N=n and K_INITIAL=K_TARGET=N_TARGETSubstituting into can be in the relational expression of N and K It obtainsI.e.That is N=n reflects voltage, temperature, technique change The variation of caused RC products (i.e. output frequency), as long as calibration code K is set as K_TRIM=n substitutes into F_OSCExpression formula can Calibrate Output frequency F afterwards_{OSC_TRIM}Equal to design object value F_TARGET, realize a step self-calibration function.

Below with an example, to be explained to the utility model：The on piece of one 12.8MHz is vibrated Device, required precision are ± 0.5%, the register of a 9bit are selected electric resistance array to store calibration code, trimming precision is The theoretical value of calibration code to ensure that positive and negative maximum trims range, therefore is set as median i.e. K by ± (100/256) %_TARGET= 256.When one of operating conditions due to the utility model are output target frequencies, the theoretical value N of counter output_TARGETAnd school The theoretical value K of quasi- code_TARGETIt is equal, therefore N_TARGET=256.Frequency divider m=F can be calculated according to formula_OSE×T_{REF_PULSE}/ N, Wherein F_OSC=12.8MHz, can be according to the reference pulse time T that MCU gives_{REF_PULSE}To set the value of frequency divider m, for example set T_{REF_PULSE}=1ms, then m=50.After microcontroller (MCU) sends initialization pulse, K_INITIALIt is set as K_TARGET, i.e. K_INITIAL= 256, after waiting for several cycles of oscillation, MCU sends out calibration signal, and when the rising edge of calibration signal is detected, counter is multiple Then position is F to frequency in 1ms_COUNTClock CLK_COUNTPulse number is counted, until the failing edge of calibration signal is detected It arrives, counter stops counting.This hour counter output valve is n, such as n=250, represents the F before calibration_OSC=12.5MHz, i.e.,And Represent that RC products become theoretical value (R × C)_theoretical'sTimes, and K is updated to 250 i.e. K from 256 at this time_TRIM=250, Then K values become theoretical valueTimes, the variation of RC products is counteracted, subsequent output frequency is F_{OSC_TRIM}The oscillation of=12.8MHz Signal CLK_TRIM, precision is ± (100/256) %, completes a step self-calibration process of on piece oscillator, meets simultaneously Design accuracy.If reference voltage V_REF, V_H,V_LValue changed with technique, temperature, voltage and lead to output frequency F_OSC Change and reflected by the output valve N of counter, therefore calibration code K is updated to this of counter output valve N One step calibration method is can to solve the problems, such as on piece oscillator output frequencies with technique, temperature, voltage change, defeated so as to calibrate Go out frequency.

Fig. 5 gives the flow diagram of a step method for self-calibrating of the on piece oscillator of the utility model embodiment.Its Self calibration step is as follows：First, microcontroller sends initialization pulse, the calibration code K initialized in register_INITIAL= K_TARGETIt is admitted to correcting current unit and generates I_OSC, initialization oscillator signal CLK is obtained after being sent into oscillating unit, frequency is F_OSC, and export clock signal clk after divided device frequency dividing_COUNT, frequency F_COUNT.After several cycles of oscillation, micro-control Device processed sends calibration signal, when counter unit detects the rising edge of calibration signal, reset count device, and start counting up, Until counter unit detects the failing edge of calibration signal, just stop counting, register cell makees the output valve n of counter For updated calibration code K_TRIM, handled through correcting current unit and oscillating unit, the oscillator signal after output calibration CLK_TRIM, frequency F_TRIM.So far, one step self calibration flow of on piece oscillator is completed.

In conclusion the utility model above example propose on piece oscillator with a step self-calibration function and its Calibration method, solve the problems, such as on piece oscillator output frequencies with technique, temperature, voltage change and change, reduce self-correcting Quasi- iterations realize the calibration of on piece oscillator output frequencies high-efficiency high-accuracy.And the calibration method can at any time into Row, once find frequency shift (FS), it is possible to it is calibrated, exports target frequency.

Above-described embodiment is only for illustrating the citing of the utility model implementation process, but it is not for limiting Determine the utility model, it is therefore, every above-described embodiment to be made any without departing from the technical spirit of the utility model Simple modification, equivalent variations and modification belong to the protection domain of technical solutions of the utility model, and the utility model institute The interest field of opinion should be subject to described in claim, not just the above examples.

Claims (4)

1. a kind of on piece oscillator with self-calibration function, which is characterized in that including oscillating unit, frequency divider, counter, post Storage and correcting current unit, the oscillator signal output termination frequency divider of oscillating unit, the clock signal output terminal of frequency divider connect Counter；The numerical signal output termination register of counter, control signal input connect the calibration signal of external microcontroller Output terminal；The control signal input of register connects the initialization pulse output terminal of external microcontroller, the calibration generation of register The calibration code input terminal of code output termination correcting current unit；The electric current that the current output terminal of alignment unit connects oscillating unit is defeated Enter end.

2. on piece oscillator according to claim 1, which is characterized in that correcting current unit includes amplifier and current mirror electricity Road, current mirroring circuit include the first PMOS, the 2nd PMOS and multidigit electric resistance array；The anti-phase input termination reference voltage of amplifier, The grid of the first PMOS of output termination and the grid of the 2nd PMOS；The source electrode of first PMOS and the source electrode of the 2nd PMOS connect chip electricity Source, the drain electrode of the first PMOS connect the in-phase input end of amplifier and the input terminal of multidigit electric resistance array；The output of multidigit electric resistance array End ground connection, the output terminal of control termination register；Signal output end of the drain electrode of 2nd PMOS as correcting current unit.

3. on piece oscillator according to claim 2, which is characterized in that oscillating unit includes logic control circuit, third PMOS, the 4th PMOS, the first NMOS, the 2nd NMOS, the 3rd NMOS, comparator, capacitance and 4 electronic switches, the first NMOS's Source electrode is grounded, and drain and gate connects the signal output end of correcting current unit；The source electrode ground connection of 2nd NMOS, grid connect first The grid of NMOS, drain electrode connect the drain and gate of the 3rd PMOS, and the source electrode of the 3rd PMOS connects chip power；The source electrode of 4th PMOS Chip power is connect, drain electrode connects the anode of capacitance by the first electronic switch, and grid connects the grid of the 3rd PMOS；The leakage of 3rd NMOS Pole connects the anode of capacitance, source electrode ground connection by the second electronic switch, and grid connects the grid of the first NMOS；The anode of capacitance, which connects, to be compared The in-phase input end of device, cathode ground connection, the inverting input of comparator connect limit comparison voltage V by third electronic switch_H, lead to It crosses the 4th electronic switch and meets lower limit comparison voltage V_L；The output terminal of the input termination comparator of logic control circuit, logic control The output terminal of circuit as oscillating unit output terminal, connect the control terminals of 4 electronic switches.

4. on piece oscillator according to claim 3, which is characterized in that the logic control circuit is rest-set flip-flop.