The utility model content
For the deficiencies in the prior art, the utility model provides a kind of filter drive circuit of swept light source, makes the frequency of its output can be at 20KHz to adjustable continuously between 200KHz, and peak-to-peak value voltage can reach 3V, and phase place is also adjustable, and its output loading is in 1 left and right, Europe.
For realizing above function, the utility model is achieved by the following technical programs:
A kind of filter drive circuit of swept light source includes signal generating circuit, filter circuit, gain adjustment circuit and filter load;
Described signal generating circuit, for generation of sine wave signal, described sine wave signal amplitude is consistent, frequency is adjustable;
The input of described filter circuit is connected in the output of described signal generating circuit, and this filter circuit is used for the noise beyond the described sine wave signal frequency band of filtering, and the hybrid waveform of sine wave output signal and narrow-band noise;
The input of described gain adjustment circuit is connected with the output of described filter circuit, and the output of described gain adjustment circuit connects filter load; This gain adjustment circuit is used for the hybrid waveform of described sine wave signal and narrow-band noise is amplified, the sine wave output amplifying signal.
Further comprise the phase bias Circuit tuning after described signal generating circuit, the output of described phase bias Circuit tuning is connected in the input of described filter circuit, and described phase bias Circuit tuning is used for described sine wave signal is carried out the phase place adjustment.
Described phase bias Circuit tuning adopts external adder circuit to realize.
Described signal generating circuit is sinusoidal oscillator or Direct Digital Synthesizer;
The method that described sinusoidal oscillator utilizes master controller to adjust in real time frequency of oscillation is adjusted the frequency of described sinusoidal oscillator.
Described filter circuit is active filter or passive filter; Described filter circuit is low pass circuit or band-pass circuit.
Described gain adjustment circuit is amplifying circuit or auto-gain circuit.
The output of described gain adjustment circuit further is connected with the driving intensifier circuit that comprises amplifier, and this output that drives intensifier circuit connects filter load.
Described driving intensifier circuit further comprises the amplifier Circuit tuning, and described amplifier Circuit tuning is used for controlling the amplifier of described driving intensifier circuit, can stablize under unit gain.
The output of described driving intensifier circuit further is connected with thermostat module, and described filter load is placed in the insulating box of this thermostat module; Described thermostat module is regulated the temperature of described filter load by gathering the actual temperature of filter load.
Described thermostat module comprises controlled source, design temperature circuit, temperature sensor, temperature controller, thermoregulator and insulating box;
Described design temperature circuit, temperature sensor, temperature controller, thermoregulator and insulating box all are connected to described controlled source;
Described design temperature circuit be connected temperature sensor and be connected with described temperature controller respectively, described temperature controller, thermoregulator and insulating box connect successively; Described filter load is located in described insulating box.
The utility model is by providing a kind of filter drive circuit of swept light source, makes the frequency of its output can be at 20KHz to adjustable continuously between 200KHz, and peak-to-peak value voltage can reach 3V, and phase place is also adjustable, and its output loading is in 1 left and right, Europe; Guarantee the stability of filter load, satisfied various lasers to the requirement of modulation amplitude, reached the tunable of sweeping laser wavelength.
Embodiment
Under regard to the filter drive circuit of a kind of swept light source that the utility model proposes, describe in detail in conjunction with the accompanying drawings and embodiments.
Embodiment 1:
As shown in Figure 1, the present embodiment provides a kind of filter drive circuit of swept light source, includes signal generating circuit, filter circuit, gain adjustment circuit and filter load;
Described signal generating circuit, for generation of sine wave signal, described sine wave signal amplitude is consistent, frequency is adjustable;
The input of described filter circuit is connected in the output of described signal generating circuit, and this filter circuit is used for the noise beyond the described sine wave signal frequency band of filtering, and the hybrid waveform of sine wave output signal and narrow-band noise;
The input of described gain adjustment circuit is connected with the output of described filter circuit, and the output of described gain adjustment circuit connects filter load; This gain adjustment circuit is used for the hybrid waveform of described sine wave signal and narrow-band noise is amplified, the sine wave output amplifying signal.
Described signal generating circuit is sinusoidal oscillator or Direct Digital Synthesizer; The method that described sinusoidal oscillator utilizes master controller to adjust in real time frequency of oscillation is adjusted the frequency of described sinusoidal oscillator.
As shown in Figure 2, described sinusoidal oscillator comprises a bipolarity operational amplifier 1, and the in-phase end of this bipolarity operational amplifier 1 is connected with resistance R 1, capacitor C 1, the other end ground connection of described resistance R 1, capacitor C 1; The feedback loop of the in-phase end of this bipolarity operational amplifier 1 is in series by capacitor C 2, resistance R 2; Ground connection after the end of oppisite phase of this bipolarity operational amplifier 1 is connected with resistance R 3, and the end of oppisite phase of this bipolarity operational amplifier 1 be connected to output V after resistance R 4 is connected
oThe frequency of oscillation W=1/RC of described sinusoidal oscillator is determined by the RC series network with selecting frequency characteristic; Namely by resistance R 1, capacitor C 1 and capacitor C 2, the product of resistance R 2 determines.The starting condition for oscillation of described sinusoidal oscillator is A〉3, namely require the voltage gain of amplifier more than or equal to 3, being slightly larger than 3 reason is due to the various losses in circuit, causes amplitude descend and recompense.But A much bigger can cause sine wave output deformation poor than 3; Similar principle, typical sinusoidal oscillator also can be by fet oscillator or capacitance connecting three point type oscillator, and inductance connecting three point type forms.
Because described filter drive circuit need to have the adjustable frequency function, therefore need the frequency of oscillation of offset of sinusoidal oscillator dynamically to adjust, namely need resistance R shown in Figure 21, capacitor C 1, capacitor C 2, resistance R 2 is adjusted; The method of utilizing in the present embodiment described master controller to adjust in real time frequency of oscillation is adjusted in real time to frequency of oscillation; The method is that the resistance R 1 in Fig. 2 and resistance R 2 are replaced with digital regulation resistance, and digital regulation resistance is a kind of digital adjustable resistance, can change in real time easily parameter; For guaranteeing accurate frequency of oscillation, need to select precision resister, need to have 1% with interior precision, the low gain error can be provided in whole resistance range.
Can adjust easily frequency, phase place by Direct Digital Synthesizer DDS, and control precision is high, the frequency switch speed fast, phase place can freely be adjusted.
The waveform that produces due to sinusoidal oscillator or Direct Digital Synthesizer is that amplitude is consistent, the sine wave signal that frequency is adjustable, also need pass through the phase bias Circuit tuning, further comprise the phase bias Circuit tuning after described signal generating circuit, the output of described phase bias Circuit tuning is connected in the input of described filter circuit, and described phase bias Circuit tuning is used for described sine wave signal is carried out the phase place adjustment; Described phase bias Circuit tuning adopts external adder circuit to realize, due to comparatively general, is not therefore given unnecessary details in the present embodiment.
Described filter circuit is active filter or passive filter; Described filter circuit is low pass circuit or band-pass circuit, common circuit is active second-order filter circuit and typical passive single order RC low-pass filter circuit, described active second-order filter circuit is typical Sallen-Key low-pass filter circuit connection, and its annexation as shown in Figure 3; This operational amplifier 2 is for homophase excites, and the input impedance of filter is higher, and output impedance is lower, and circuit performance is stable, and gain is easily adjusted.Also can form the filter of band pass filter or other exponent number through similar design.
The annexation of described passive single order RC low-pass filter circuit as shown in Figure 4; This low pass filter can provide the speed of roll-offing of 20db after corner frequency, similarly design also can form LC low pass circuit, LC bandwidth-limited circuit; Wherein, the time constant that is comprised of resistance R 9 and capacitor C 5 forms the corner frequency of this low pass filter.
Described filter circuit can suppress the out-of-band noise of described sine wave signal, reduces the problems such as wave distortion, hydraulic performance decline.
Described gain adjustment circuit is amplifying circuit or auto-gain circuit.Be illustrated in figure 5 as amplifying circuit; Can carry out signal by in-phase amplification circuit or see-saw circuit amplifies; In adjusting figure, feedback resistance R12 can change the peak-to-peak value amplitude of multiplication factor and then control filter driver output waveform; The difference of in-phase amplification circuit and see-saw circuit is that the output signal of in-phase amplification circuit is identical with the phase place of input signal, and see-saw circuit differs 180 degree.
Be illustrated in figure 6 as auto-gain circuit (AGC) theory diagram; By controlling G+, the voltage of G-, output waveform that can the real time altering amplifier circuit.
Embodiment 2:
The filter drive circuit of a kind of swept light source that the present embodiment provides is identical with technical scheme described in embodiment 1, as shown in Figure 7, the output that is described gain adjustment circuit further is connected with the driving intensifier circuit that comprises amplifier, and this output that drives intensifier circuit connects filter load; This driving intensifier circuit is used for reducing the impedance of described sinusoidal wave amplifying signal, strengthens driving force.
Through embodiment 1 described drive circuit, obtained satisfactory signal waveform, but the amplifier of described gain adjustment circuit exports that often output resistance is larger, driving force is not enough.Drive the high frequency capacitive load, special driving intensifier circuit need to be arranged, this circuit has that output impedance is little, and gain bandwidth product is large, supports the characteristics such as bipolarity high voltage drive.
Fig. 8 and Fig. 9 are two kinds of driving intensifier circuits.As shown in Figure 8, be to adopt the method for amplifier host-slave parallel to drive enhancing; By the given end of oppisite phase that is linked into amplifier 5, R13 one end ground connection, the in-phase end of other end concatenation operation amplifier 5; The output of described operational amplifier 5 is connected with the in-phase end of operational amplifier 6, and described operational amplifier 6 is homophase follower connection, access load resistance R15 after being connected with the resistance R 14 of operational amplifier 5 in-phase ends with resistance R 17 by balance resistance R16.Fig. 9 adopts the outside circuit that promotes to drive enhancing; What adopt is the push-pull connection method of the rear access triode of operational amplifier 7; Resistance R 18, resistance R 19 and resistance R 23 are used for the matched static balance point, and resistance R 20, resistance R 21 and resistance R 22 are current-limiting resistances; Capacitor C 6 is electric capacity by way of compensation, regulates frequency and the phase characteristic of amplifier.
What pay special attention to is, some amplifiers can't be stable and the voltage-tracing pattern, and therefore, described driving intensifier circuit further comprises the amplifier Circuit tuning, described amplifier Circuit tuning is used for controlling the amplifier of described driving intensifier circuit, can stablize under unit gain.
Described amplifier Circuit tuning as shown in figure 10, the anti-phase connection of the amplifier of employing, the end of oppisite phase of resistance R 24 and capacitor C 8 access operational amplifiers 14 is regulated cut-off frequency in the feedback control loop of resistance R 25 and capacitor C 7 access operational amplifiers 14; When low gain, the noise of amplifier also will come by control capacittance C7, capacitor C 8, resistance R 24 and resistance R 25 noise of balance different frequency simultaneously; Make operational amplifier stable under unit gain by adjustment capacitor C 7, capacitor C 8; Also can adopt in addition the small-signal response method that circuit parameter is optimized in real system.
Embodiment 3:
In actual motion, the stability of filter there is strict requirement, in numerous influencing factors, temperature is to play an important role.Therefore need to add thermostat module to guarantee the consistency of temperature.The filter drive circuit of a kind of swept light source that the present embodiment provides, on the basis of above embodiment, as shown in figure 11, the output of described driving intensifier circuit further is connected with thermostat module, and described filter load is placed in the insulating box of this thermostat module; Described thermostat module is regulated the temperature of described filter load, to guarantee the temperature stabilization of described filter by gathering the actual temperature of filter load.
Described thermostat module comprises controlled source, design temperature circuit, temperature sensor, temperature controller, thermoregulator and insulating box;
Described temperature controller comprises subtracter, proportional amplifier, integral amplifier, differentiating amplifier, adder;
Described design temperature circuit, temperature sensor, temperature controller, thermoregulator and insulating box all are connected to described controlled source;
Described design temperature circuit be connected temperature sensor and be connected with described temperature controller respectively, described temperature controller, thermoregulator and insulating box connect successively; Described filter load is located in described insulating box.
Drawn by above embodiment, the utility model is by providing a kind of filter drive circuit of swept light source, makes the frequency of its output can be at 20KHz to adjustable continuously between 200KHz, and peak-to-peak value voltage can reach 3V, phase place is also adjustable, and its output loading is in 1 left and right, Europe; Guarantee the stability of filter load, satisfied various lasers to the requirement of modulation amplitude, reached the tunable of sweeping laser wavelength.
Above execution mode only is used for explanation the utility model; and be not limitation of the utility model; the those of ordinary skill in relevant technologies field; in the situation that do not break away from spirit and scope of the present utility model; can also make a variety of changes and modification; therefore all technical schemes that are equal to also belong to category of the present utility model, and scope of patent protection of the present utility model should be defined by the claims.