CN202652146U - Self-excited multivibrator with adjustable frequency - Google Patents

Abstract

A self-excited multivibrator with an adjustable frequency comprises a memristor control circuit, a memristor, a feedback time delay circuit and a Schmidt switch circuit. The memristor control circuit, the memristor and the feedback time delay circuit are successively connected in series. The Schmidt switch circuit is arranged between an output terminal of the feedback time delay circuit and the output terminal of the memristor control circuit. By using the multivibrator of the utility model, frequency stability is high; an adjustable scope is wide; elements required by the circuit are simple; debugging is simple and oscillation is easy to generate; a size is small and cost is low; an integration chip is easy to be made.

Description

The astatic multivibrator that a kind of frequency is adjustable

Technical field

The utility model relates to a kind of astatic multivibrator, is specifically related to the adjustable astatic multivibrator device of a kind of frequency.

Background technology

The astatic multivibrator that traditional frequency is adjustable has various ways, and they all have following design feature: electric routing switch device, delay of feedback link, external modulation circuit or PLL the electric circuit constitute.Switching device can be gate, voltage comparator, timer etc., and its effect is the high and low level that produces pulse signal.The general RC circuit of delay of feedback link, after the RC circuit is delayed time output voltage, feed back to rightly the switching device input, changing its output state, and by external modulation circuit or PLL circuit so that astatic multivibrator can be adjustable continuously in the certain frequency scope, such astatic multivibrator is because required element is more, therefore but the integrated level of system is relatively poor, cost is high, when mains fluctuations, can make frequency of oscillation unstable.

Therefore for above-mentioned phenomenon, how to design a kind of cheaply, the product that stability is high is those skilled in the art's research direction place.

Summary of the invention

The astatic multivibrator circuit that provides a kind of frequency adjustable is provided main purpose of the present utility model, and its circuit is simple, but integrated level is high, and is low in energy consumption, and has the frequency adjustable function, can be widely used in the higher system of bandwidth requirement.

The astatic multivibrator that a kind of frequency is adjustable, comprise memristor control circuit, memristor, delay of feedback circuit and Schmidt switch circuit, memristor control circuit, memristor are sequentially connected with the delay of feedback circuit, are connected to Schmidt switch circuit 4 between the output of the output of delay of feedback circuit and memristor control circuit.

Further, memristor control circuit 1 comprises NPN type triode 5 and positive-negative-positive triode 6, the collector electrode of NPN type triode 5 connects positive voltage, the emitter of NPN type triode 5 connects the emitter of positive-negative-positive triode 6, the collector electrode of positive-negative-positive triode 6 connects negative voltage, the emitter of NPN type triode 5 is connected the first end of memristor 2 with the phase contact of the emitter of positive-negative-positive triode 6, the second end ground connection of memristor 2.

Further, delay of feedback circuit 3 comprises operational amplifier 9, the first resistance 7 and electric capacity 8, the negative terminal of operational amplifier 9 is through the output of the first resistance 7 concatenation operation amplifiers 9, and the negative terminal of operational amplifier 9 also connects an end of electric capacity 8, the other end ground connection of electric capacity 8; The anode of operational amplifier 9 connects the first end of memristor 2.

Further, be connected to the second resistance 10 between the first end of the output of operational amplifier 9 and memristor 2.

Further, pricking by microscope on the top electrode of memristor 2 has the top electrode probe, and the bottom electrode of memristor 2 is pricked by microscope the bottom electrode probe, and the upper/lower electrode probe is respectively as first end and second end of memristor 2.

The beneficial effects of the utility model are:

Because memristor can be by applying different directions, the voltage of size changes its resistance automatically, thereby causes the change of Schmidt switch circuit threshold voltage, and then reaches the purpose of automatic change multivibrator frequency.Compare with common linear resistance, memristor is a kind of Special Nonlinear resistance that can remember the electric charge on it of flowing through.By applying different directions, the voltage of size can make the memristor resistance continuously change between maximum and minimum value.According to needed multivibrator frequency range, can pass through the memristor control circuit, apply control signal and adjust the memristor resistance, thereby obtain corresponding delay of feedback link time constant, thereby realize the adjustable astatic multivibrator of frequency.Advantage of the present invention is mainly reflected in:

1. frequency stability is high;

2. frequency is adjustable continuously, and adjusting range is wide, and frequency can be adjustable continuously in the 10KHz-40MHz scope;

3. the required element of circuit is simple, and volume is little, and cost is low, easily makes integrated chip;

4. debugging is simple, easily starting of oscillation;

5. can be widely used in the higher modulation circuit of bandwidth requirement.

Description of drawings

Fig. 1 is the adjustable astatic multivibrator composition frame chart of a kind of frequency of the utility model;

Fig. 2 is a kind of novel adjustable astatic multivibrator circuit theory diagrams of frequency of the utility model;

Fig. 3 is the square wave schematic diagram;

Fig. 4 is the utility model test schematic diagram.

1. memristor control circuits among the figure, 2. memristor, 3. delay of feedback circuit, 4. Schmidt switch circuit, 5.P type triode, 6.N type triode, 7. the first resistance R ₁, 8. electric capacity, 9. operational amplifier, 10. the second resistance R ₂, 11. top electrode probes, 12. bottom electrode probes.

Embodiment

Below in conjunction with accompanying drawing, the feature and advantage of the multivibrator of the utility model band frequency adjustable function are described in more detail.

See also Fig. 1, be the adjustable astatic multivibrator composition frame chart of a kind of frequency of the utility model, the utility model comprises memristor control circuit 1, memristor 2, delay of feedback circuit 3, Schmidt switch circuit 4.Wherein, described memristor control circuit 1 links to each other with described memristor 2 and described Schmidt switch circuit 4, cooperation is consulted shown in Figure 2, memristor control circuit 1 of the present utility model comprises a pair of NPN type triode 5 and positive-negative-positive triode 6, better adopted C9014 and C9015 triode, this triode is a high frequency, high-gain, low noise triode, has larger dynamic range and good current characteristics.The collector electrode of wherein said NPN type triode 5 links to each other with positive 5 volts of power supplys, emitter links to each other with the emitter of positive-negative-positive triode 6, and link to each other with the first end of memristor 2, the collector electrode of positive-negative-positive triode 6 links to each other with negative 5 volts of power supplys, the base stage of NPN type triode 5 and positive-negative-positive triode 6 all respectively with control signal V _PAnd V _NLink to each other.The anode of operational amplifier 9 connects the first end of memristor 2.

Described delay of feedback circuit 3 links to each other with Schmidt switch circuit 4, has the first resistance 7 to link to each other with electric capacity 8, and is connected to the negative terminal of operational amplifier 9, and an end of electric capacity 8 is connected to ground.The other end of the first resistance 7 links to each other with the output of operational amplifier 9.

Described Schmidt switch circuit 4 and memristor control circuit 1, memristor 2, delay of feedback circuit 3 links to each other.Wherein, the second resistance 10 links to each other with memristor 2, and simultaneously they link to each other with anode that amplifier 9 is calculated by unit.The first end ground connection of memristor 2, the other end of the second resistance 10 links to each other with operational amplifier 9 outputs.

Because Schmidt trigger has V _T+And V _T-Two different threshold voltages, and frequency of the present utility model is adjustable exactly by controlling memristor 2 so that threshold voltage changes.Suppose that operational amplifier is ideal amplifier, then Schmidt trigger output high level is positive voltage+V _DD, output low level is for negative

Supply voltage-V _DD, then have

$V_{T+}={+V}_{\mathrm{DD}}\frac{M}{M+{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="HDA0000143915420000012.png"\; state="\{\{state\}\}">R</figure-callout>}}_2}$

$V_{T-}={-V}_{\mathrm{DD}}\frac{M}{M+{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="HDA0000143915420000012.png"\; state="\{\{state\}\}">R</figure-callout>}}_2}$

Wherein, M is the resistance of memristor 2, and unit is ohm, as pulse control signal V _PWhen opening triode 5, memristor 2 is under forward power supply+5V effect, and resistance can reduce, and the amplitude that reduces is with pulse control signal V _PThe length of time is proportionate.In like manner, as pulse control signal V _NWhen opening triode 6, memristor 2 is under negative sense power supply-5V effect, and resistance can increase, and the amplitude of increase is proportionate with the length of external pulse control signal VP time.

If plugged moment, the initial voltage on the capacitor C is zero, output voltage V _OutBe high level.V _OutBy 7 pairs of capacitor chargings of the first resistance, work as V _CReach V _T+The time, Schmidt trigger overturns, V _OutSaltus step is low level.After this, capacitor C begins again discharge, V _CDescend, when it drops to V _T-The time, circuit begins turning again, V _OutBe high level by low transition again, C is charged again again.So go round and begin again, at the output of circuit, just obtained square wave.V _CAnd V _OutWaveform as shown in Figure 3.

The output voltage V of Fig. 3 then _OutCycle T=T ₁+ T ₂, be calculated as follows:

, then have according to RC circuit transient state transient process formula as start time with t1 among Fig. 3

So can obtain ${\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="HDA0000143915420000011.png"\; state="\{\{state\}\}">T</figure-callout>}}_1=\frac{v_I(\&infin;)-v_I\left(0^{+}\right)}{v_I(\&infin;)-v_I\left(T_1\right)}=R_{1}C\ln (1+\frac{2M}{R_2})$

, then have according to RC circuit transient state transient process formula as start time with t2 among Fig. 3

v _I（0 ⁺）＝V _T+，v _I（T ₂）＝V _T-，v _I（∞）=-V _DD,τ=RC

So can obtain the calculating of T cycle of oscillation

${\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="HDA0000143915420000012.png"\; state="\{\{state\}\}">T</figure-callout>}}_2=\frac{v_I(\&infin;)-v_I\left(0^{+}\right)}{v_I(\&infin;)-v_I\left(T_1\right)}=R_{1}C\ln (1+\frac{2M}{R_2})$

Then the frequency f of adjustable astatic multivibrator is

$f=\frac{1}{T}=\frac{1}{2R_{1}C\ln (1+\frac{2M}{R_2})}$

As shown in Figure 4, during test the utility model, by microscope top electrode probe 11 is pricked on memristor 2 top electrodes, bottom electrode probe 12 is pricked on the memristor bottom electrode.Memristor top electrode probe links to each other with the circuit remainder by wire with the bottom electrode probe.Output waveform V with the oscilloscope service oscillator _OutThereby, judge whether oscillator works.

The invention will be further described below in conjunction with drawings and Examples.

Get a memristor sample and link to each other with the circuit remainder according to the method for Fig. 4, wherein the initial condition M value of memristor is 1k Ω, the first resistance R ₁Be 1k Ω, capacitor C is 22pF, the second resistance R ₂Be 1k Ω, then can calculate to such an extent that this oscillator frequency f is 22MHz according to frequency formula, verified this experimental result with oscilloscope measurement.As external pulse control signal V _PDo the time spent, memristor loading+5V voltage, memristor M value can reduce, thereby so that this oscillator frequency f increase, in like manner, V _NDo the time spent, memristor M value can increase, and this oscillator frequency f can reduce.Can be by the external pulse control signal V of control _PAnd V _NAction time length and rate of change adjust the scope of oscillator frequency change and change speed degree.

Observe this utility model by oscilloscope, the power output that can be measured this oscillator by oscilloscope is 8dBm, opens the heated constant temperature platform, and heating and constant temperature to 60 ℃ record and changes oscillator frequency stability in room temperature to the 60 ℃ scope and can reach 8ppm/ ℃.

The above is just illustrative for the utility model; and it is nonrestrictive; those of ordinary skills understand; in the situation that does not break away from the spirit and scope that following claims limit; can make many modifications; change or equivalence, but all will fall in the protection range of the present utility model.

Claims (5)

1. astatic multivibrator that frequency is adjustable, it is characterized in that, comprise memristor control circuit (1), memristor (2), delay of feedback circuit (3) and Schmidt switch circuit (4), memristor control circuit (1), memristor (2) are connected with delay of feedback circuit (3) order, are connected to Schmidt switch circuit (4) between the output of the output of delay of feedback circuit (3) and memristor control circuit (1).

2. the adjustable astatic multivibrator of frequency according to claim 1, it is characterized in that, memristor control circuit (1) comprises NPN type triode (5) and positive-negative-positive triode (6), the collector electrode of NPN type triode (5) connects positive voltage, the emitter of NPN type triode (5) connects the emitter of positive-negative-positive triode (6), the collector electrode of positive-negative-positive triode (6) connects negative voltage, the emitter of NPN type triode (5) is connected the first end of memristor (2), the second end ground connection of memristor (2) with the phase contact of the emitter of positive-negative-positive triode (6).

3. the adjustable astatic multivibrator of frequency according to claim 2, it is characterized in that, delay of feedback circuit (3) comprises operational amplifier (9), the first resistance (7) and electric capacity (8), the negative terminal of operational amplifier (9) is through the output of the first resistance (7) concatenation operation amplifier (9), the negative terminal of operational amplifier (9) also connects an end of electric capacity (8), the other end ground connection of electric capacity (8); The anode of operational amplifier (9) connects the first end of memristor (2).

4. the adjustable astatic multivibrator of frequency according to claim 3 is characterized in that, is connected to the second resistance (10) between the first end of the output of operational amplifier (9) and memristor (2).

5. according to claim 2 or the adjustable astatic multivibrator of 3 or 4 described frequencies, it is characterized in that, prick on the top electrode of memristor (2) the top electrode probe is arranged, the bottom electrode of memristor (2) is pricked the bottom electrode probe, and the upper/lower electrode probe is respectively as first end and second end of memristor (2).

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