CN101951258B - Multidigit variable system asynchronous counting circuit based on memory resistor - Google Patents

Abstract

The invention relates to a multidigit variable system asynchronous counting circuit based on a memory resistor. The multidigit refers to N counting digits, and N can be any positive integer; in an asynchronous working way, all counting units have no uniform counting signal, and a low-digit counting unit provides a counting signal for a high-digit counting unit; a variable system changes the impedance variation of each counting pulse on the memory resistor so as to change the range of the counting unit by setting parameters of the counting pulse, including cycle T, duty ratio eta and current strength I. The counting unit based on the memory resistor comprises the memory resistor, a counting pulse input port, a test pulse input port, a test pulse output port, a carry signal output port and a resetting port. The counting circuit is used for counting by utilizing the memory characteristics of the memory resistor on charge and can accurately control counting.

Description

Based on the asynchronous counting circuit of the variable system of the multidigit of memristor

Technical field

The present invention is the design of the asynchronous counting circuit of the variable system of a kind of multidigit based on memristor.

Background technology

Memristor is the 4th kind of basic circuit elements that is realized through nanometer technology by the breadboard research team of Hewlett Packard in 2008; Its discovery has caused the dramatic change of circuitry, and its principle and application relate to circuitry, materialogy; Physical chemistry; A plurality of crossing domains such as microelectronics are the focuses and one of advanced problems that international circuit is learned research, study also in continuous expansion around the application circuit of memristor.

At present; On the experimental data of research institutions such as HP Lab and result's basis, set up the memristor model; In computer, utilize model to describe out the circuit characteristic of memristor accurately; Design the application circuit based on memristor on this basis, for method is laid a solid foundation, sets for this platform, provided in further Physical Experiment research, this is a current research direction to the memristor main flow.

Counting circuit is that a kind of quilt is reported to the police automatically, time-program(me) is controlled automatically, timing opens and closes the widely used circuit of various electronic equipments such as circuit; Traditional counting circuit mainly comprises Digital Logical Circuits such as quartz oscillator, frequency divider, counter, works through the count pulse actuation counter.Memristor still can be remembered the electric charge of flowing through on it under the situation of outage, and Memorability is embodied in the variation of memristor impedance, itself has the ability of storage data, and this characteristic is suitable for designing counting circuit.

The present invention is based on the electric charge memory characteristic of memristor.In contrast to common linear resistance, memristor is a kind of special nonlinear resistance that can remember the electric charge on it of flowing through, and Memorability is embodied in the impedance of memristor self.At first the electric charge memory characteristic of memristor is explained that as follows accompanying drawing 1 is the memristor conversion that the HP Lab provides.

Shown in accompanying drawing 1, the conversion of memristor is made up of metal platinum electrode, doped region and non-doped region three parts.The composition of doped region is the titanium dioxide of anoxic, i.e. TiO _2-X, the composition of non-doped region is a titanium dioxide, i.e. TiO ₂Two-part total length is D, and wherein doped region length is w, and the length of non-doped region is D-w.If two parts are all by the TiO of non-doping ₂Form, then overall impedance is R _OFF, its value is approximately 10K Ω; Otherwise, if two parts are all by the TiO that mixes _2-XForm, then overall impedance is R _ON, its value is approximately 100 Ω.It is linear with its length respectively with the impedance of non-doped region to mix, and memristor can be considered two variable-resistance series connection, so the total impedance of memristor is the algebraical sum of two regional impedances, promptly

$M\left(w\right)=\frac{w}{D}{R}_{\mathrm{ON}}+(1-\frac{w}{D})R_{\mathrm{OFF}}---\left(1\right)$

Wherein, M (w) is the impedance of memristor, promptly recalls resistance.The HP Lab is through experimental verification, and doped region length w rate over time is linear with the current instantaneous value of flowing through, and concrete expression formula is following

$\frac{\mathrm{dw}\left(t\right)}{\mathrm{dt}}={\mathrm{\μ}}_V\frac{R_{\mathrm{ON}}}{D}i\left(t\right)---\left(2\right)$

Wherein i (t) is the current strength of the memristor of flowing through, μ _vBeing the average ion mobility, is the build-in attribute of this material of titanium dioxide, is a constant.

Apply certain bias voltage v (t) at the memristor two ends, then can know according to Kirchhoff's laws of electric circuit

$M\left(w\right)=\frac{v\left(t\right)}{i\left(t\right)}---\left(3\right)$

Equality (1) (2) (3) united find the solution the impedance expression that can obtain memristor and do

$M\left(w\right)=R_{\mathrm{OFF}}(1-\frac{{\mathrm{\μ}}_v{R}_{\mathrm{ON}}}{D^2}q\left(t\right))---\left(4\right)$

Wherein q (t) is the electric charge of the memristor of flowing through.Can know that by equality (4) impedance of memristor is the monodrome linear function of the electric charge of flowing through, Here it is memristor can remember the flow through circuitry basis of electric charge on it.Need to prove especially, when the sense of current of the memristor of flowing through not simultaneously, the electric charge of flowing through is also different to the change trend of memristor impedance.For example when forward current through the time, the memristor impedance increases progressively, negative current is successively decreased through memristor impedance then.

Major function of the present invention is based on the 4th kind of basic circuit elements memristor of succeeding in developing in 2008 and has designed a kind of counting circuit, and this counting circuit utilizes the memory characteristic counting of memristor to electric charge, is essentially different with traditional counting circuit.Wherein, accurately control is the key technology of this counter with the impedance of identification memristor, also is the basis that memristor constitutes resistive random access storage device memory cell.

Summary of the invention

The present invention has the electric charge memory characteristic just because of memristor, has designed a kind of counter based on memristor, through memristor being applied specific recurrent pulses, accurately controls and reads the memristor impedance and realize tally function.

At first introduce the operation principle of counting unit below.

The first, the design of count pulse.In order to guarantee that the impedance of memristor can both change a fixed value Δ M after each count pulse is through memristor, need a kind of special pulse.Because physically electric charge is an electric current about the integration of time, so in theory as long as in a certain period of time, have the electric current of a fixed current intensity to flow through, the electric charge of then flowing through is fixed.Based on this thinking, count pulse q (t) is designed to have some cycles T and duty ratio η, the constant-current pulse that current strength I is constant The impedance variations scope of memristor is at M _LowTo M _HighBetween, count pulse changes Δ M through making the memristor impedance each time, and then the count range N of counting unit does $N=\frac{M_{\mathrm{High}}-M_{\mathrm{Low}}}{\mathrm{\Δ\; M}}.$

For example, it is I=10mA that memristor is applied current strength, and the cycle is T=1s, and duty ratio is the constant-current pulse of η=10%, and the electric charge of the memristor of then at every turn flowing through does

$q\left(t\right)={\∫}_t^{t+\mathrm{\ηT}}I\left(\mathrm{\τ}\right)\mathrm{d\τ}$

$={\∫}_0^{0.1}0.01\mathrm{d\τ}---\left(5\right)$

$=0.001C$

The impedance variations scope of supposing memristor is at M _Low=100 Ω to M _HighBetween=10.1K the Ω, i.e. [100,10.1K], count pulse changes Δ M=100 Ω through making the memristor impedance each time, and then the count range N of counting unit does

$N=\frac{M_{\mathrm{high}}-M_{\mathrm{low}}}{\mathrm{\ΔM}}$

$=\frac{10.1\×{10}^3-100}{100}---\left(6\right)$

$=100$

The second, the reading of counter.Whenever through a constant-current pulse, the impedance of memristor changes a fixed value Δ M, and counter also will add up once, for example become 2 by 1.The number that the impedance of memristor and count pulse pass through has relation one to one, so the value of counter is just represented in the impedance of memristor.Reading of memristor impedance that is to say that the value with counter reads and shows.Adopt the positive and negative detection pulse that replaces to reading the memristor impedance.Because the direction of two pulses is opposite, under identical pulse amplitude and duration, positive pulse and the negative pulse electric charge that produces behind the memristor of flowing through equates, thus finally memristor flow through positive negative pulse stuffing to after impedance do not change.Read the voltage at memristor two ends in the moment that applies positive pulse, can obtain the impedance of memristor according to Ohm's law.The counting unit peripheral circuit compares impedance of reading and predefined resistance value, and the result is shown.

For example, the positive pulse amplitude of detection pulse is I ₁=10mA, the duration is T ₁=0.01s, the negative pulse amplitude is I ₂=10mA, the duration is T ₂=0.01s, the direction and the positive pulse of negative pulse are opposite.Then positive pulse and the negative pulse electric charge that produces behind the memristor of flowing through is

$q\left(I_1\right)=q\left(I_2\right)$

$={\∫}_0^{T_1}{I}_1\mathrm{dt}$

(7)

$={\∫}_0^{0.01}0.01\mathrm{dt}$

$={10}^{-4}C$

The 3rd, the carry of counting unit.When counting unit reaches the counting range, need be to more high-order counting unit carry, while self zero clearing restarts counting.This process comprises two steps, carry and zero clearings.It at first is the design of carry pulse; The carry signal of this counting unit will be as the count signal of next counting unit; So carry signal is identical with count signal, be that to have a some cycles T, duty ratio η identical with count pulse with the concrete parameter of the constant-current pulse

of current strength I.Next is the design of reset signal, when counting unit being applied the detection pulse and learning this counting unit full scale, this counting unit is applied reset signal, makes the impedance of memristor return to initial value, and the amplitude of quenching pulse is I _Reset, the duration is T _Reset, then the quenching pulse electric charge that memristor produces of flowing through does $q\left(I_{\mathrm{Reset}}\right)={\∫}_0^{T_{\mathrm{Reset}}}{I}_{\mathrm{Reset}}\mathrm{Dt}.$

For example, the amplitude of quenching pulse is I _Reset=1000mA, the duration is T _Reset=0.1s, then the quenching pulse electric charge that memristor produces of flowing through does

$q\left(I_{\mathrm{reset}}\right)={\∫}_0^{T_{\mathrm{reset}}}{I}_{\mathrm{reset}}\mathrm{dt}$

$={\∫}_0^{0.1}1\mathrm{dt}---\left(8\right)$

$=0.1C$

$=N\×q\left(t\right)$

More than introduce the operation principle of counting unit, introduce the workflow of the asynchronous variable system counting circuit of multidigit below.

On the basis of counting unit mentality of designing, design the asynchronous variable system counting circuit of a kind of multidigit.More than one of the figure place that multidigit is promptly counted can be the N position, and N is any positive integer.The asynchronous working mode is meant that the individual count unit does not have unified count signal, and low level counting unit is that high-order counting unit provides count signal.Variable system is meant that promptly cycle T, duty ratio η and current strength I change the change amount of each count pulse to the memristor impedance through setting the parameter of count pulse, thereby changes the range of counting unit.Set forth the workflow of the asynchronous variable system counting circuit of multidigit below in conjunction with concrete design.

The first, the chief component of circuit.Shown in accompanying drawing 6, this circuit mainly comprises counting unit, counts, detects and reset (zero clearing) pulse generating circuit, logic gates (mainly containing and door and or door) and attached peripheral circuit.The main interface of counting unit has count pulse input (counter), detects pulse input end (test/in), testing result output (test/out), quenching pulse input (reset) and carry pulse output (add).

The second, the operation principle of circuit and flow process.The workflow of counting unit is described in detail in front, below the operation principle of the counter that constitutes of a plurality of counting units of main explanation.Adopt the mode of asynchronous counting, the carry signal of low level counting unit is that high-order counting unit provides count signal, by that analogy.The count pulse input is that high level is effective, and the flip-flop number unit begins counting when the count pulse rising edge arrives; The testing result output is that high level is effective, and promptly when the counting unit full scale, this port is exported high level; The quenching pulse input is that high level is effective, when input signal drives the counting unit zero clearing during for high level, on the contrary not zero clearing.The carry pulse output is that high level is effective.

The 3rd, the realization principle of counting unit zero clearing.When the detection pulse output end of counting unit is high level, through with the logic and operation of high level output high level, carry out the logic OR computing with reset signal again, the output high level also drives counting unit and resets.When detecting output and be low level, through with the logic and operation output low level of high level, and be low level still after the computing of reset signal logic OR, counting unit does not reset.

The advantage of this counter is accurately to realize tally function.

Description of drawings

Fig. 1 is linear impurity drift memristor model sketch map

Fig. 2 is the count pulse sketch map of counting unit

Fig. 3 detects the pulse sketch map

Fig. 4 is the quenching pulse sketch map

Fig. 5 is the counting unit workflow diagram

Fig. 6 is the asynchronous variable system counting circuit sketch map in N position

Embodiment:

With linear impurity drift memristor Mathematical Modeling is foundation, and this counting circuit is made up of counting unit and the peripheral auxiliary circuits based on memristor.Counting unit based on memristor is made up of memristor, count pulse input port, test pulse input port, test pulse output port, carry signal output port and reseting port.Peripheral circuit comprises that mainly circuit takes place in the constant-current pulse source, detects pulse generating circuit, reset pulse generation circuit, logic gates formation.

It is constant at first by the constant-current pulse source the pre-set current strength of circuit generation to take place, the constant-current pulse with certain duty ratio, and this pulse will be corresponding one by one with the system of counter.Low level counting unit begins counting under the driving of this count pulse, its state will read and be mapped as the numeral of being counted through detecting pulse.When low level counting unit meter was full, this unit sent with the carry signal of constant-current pulse identical parameters to the high-order counting unit of closing on and also accepts the reset signal from reset pulse generation circuit, and counting unit realizes resetting.Set when the counting unit meter is full, the test pulse output is a high level, otherwise then is low level, and reseting port is that high level is effective.When the counting unit meter was full, the test pulse output was a high level, carries out logical operation with the peripheral logic gate circuit, drives this counting unit and resets.

Set forth the realization of the asynchronous variable system counting circuit of multidigit below in conjunction with instantiation.When adopting n counting unit, be exactly the asynchronous variable system counting circuit in n position.Like n=6, then the range of counter be [1, α ⁶], wherein α representes the range of each counting unit.The impedance variations scope of supposing the memristor of each counting unit is [100 Ω, 10.1k Ω], when count pulse is current strength I=10mA; When cycle T=1s, the constant-current pulse of duty ratio η=10%, the range of single counting unit is [1; 100], the system of counter is 100; When adjustment duty ratio during to η=20%, the change amount of memristor impedance after each count pulse increases doubly, and then the range of single counting unit is [1,50], and the system of counter is 50.The current strength or the cycle of adjustment count pulse can both reach the effect that changes system, and principle is similar with the adjustment duty ratio.For example when count pulse be current strength I=5mA, when cycle T=1s, the constant-current pulse of duty ratio η=10%, the range of single counting unit is [1,200], the system of counter is 200; When count pulse is current strength I=10mA, when cycle T=2s, the constant-current pulse of duty ratio η=10%, the range of single counting unit is [1,50], and the system of counter is 50.

Claims (1)

1. based on the asynchronous counting circuit of the variable system of the multidigit of memristor; It is characterized in that: this counting circuit is made up of counting unit and the peripheral auxiliary circuits based on memristor, and said counting unit based on memristor is made up of memristor, count pulse input port, detection pulse input end mouth, testing result output port, carry signal output port and reseting port; Circuit takes place by the constant-current pulse source in peripheral auxiliary circuits; Detect pulse generating circuit, reset pulse generation circuit, logic gates formation, the impedance of said memristor adopts the positive and negative detection pulse that replaces to read, and the counting unit of low level provides count pulse for high-order counting unit; Through setting the parameter of count pulse; Be cycle T, duty ratio η and current strength I, change the change amount of each count pulse, thereby change the range of said counting unit the impedance of said memristor.

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