CN102158658B - A System Realizing EMCCD's Unique Driving Signal - Google Patents

Abstract

The invention discloses a system for realizing a peculiar driving signal of an electron-multiplying charge coupled device (EMCCD), which belongs to the technical field of CCD driving. The system comprises a controller, a first voltage transformer, a second voltage transformer, an integrated driver, a blocking circuit, a DC level clamping circuit, an adjustable inductor, an adjustable resistor and a matching capacitor. The system mainly solves the problems of high power consumption and implementation difficulties of a conventional driving method, generates high-speed high-voltage driving signals by an RLC series resonance circuit, changes the amplitude and DC level values of output signals by digital control signals respectively, can realize digital control over the output signals, and greatly reduces the circuit power consumption and dependence on high-speed high-power devices.

Description

A kind of system that realizes the peculiar drive signal of EMCCD

Technical field

The invention belongs to CCD Driving technique field, be specifically related to the system of the peculiar high speed and high pressure drive signal of a kind of EMCCD of realization (Electron Multiply CCD).

Background technology

At present, the implementation method of the peculiar high speed and high pressure drive signal of domestic EMCCD report seldom; Usually adopt integrated chip for driving to realize the driving of CCD,, can adopt discrete triode and MOSFET to realize for some special high-voltage driven signals.

When dark target is carried out to picture, if the sense amplifier noise ratio of CCD is bigger, usually can cover useful signal, especially under the reading speed condition with higher, reading noise can increase along with the raising of reading speed.Along with the continuous development of CCD manufacture craft, the appearance of EMCCD makes small signal also can overcome the noise of sense amplifier, and this type of CCD can access the much the same picture quality with ICCD under the situation of additional structure; The basic structure of EMCCD and traditional frame transfer CCD are roughly the same, but between readout register and sense amplifier, have added hundreds of gain register, and its electrode structure is different from branch register, and signal has obtained gain here.In gain register; Realize that the required high voltage electric field of avalanche multiplication is formed by big potential difference between adjacent electrode in gain register; The amplitude signal of about 20～50V on the common electrode and another electrode keeps low Dc bias, thus the potential difference regulation and control multiplication factor between two electrodes changed through the high level of regulating the amplitude pulse.

Summary of the invention

The system that the purpose of this invention is to provide the peculiar drive signal of a kind of EMCCD of realization, it can realize digital control to the output signal, greatly reduces circuit power consumption and to the dependence of high-speed high-power device.

To achieve these goals, technical scheme of the present invention is following:

A kind of system that realizes the peculiar drive signal of EMCCD; Comprise controller, the first adjustable electric depressor, the second adjustable electric depressor, integrated drive, block isolating circuit, DC level clamp circuit, controllable impedance, adjustable resistance and matching capacitance; Said controller is connected with integrated drive, the first adjustable electric depressor, the second adjustable electric depressor respectively; Controller is to integrated drive input timing drive signal; And according to current gain requirement, respectively to the first adjustable electric depressor and the corresponding digital parameters value of second adjustable electric depressor output; The said first adjustable electric depressor is connected with integrated drive, and it for integrated drive provides power supply, realizes the digital control of integrated drive amplitude output signal according to the corresponding voltage of digital parameters value output of the said controller output that receives; Said block isolating circuit is connected with integrated drive, and it is used to remove the DC level of integrated drive output signal; The said second adjustable electric depressor is connected with the DC level clamp circuit, and its digital parameters value according to the said controller output that receives is exported corresponding voltage, and to the LC resonant circuit direct current biasing is provided through the DC level clamp circuit; Said controllable impedance, adjustable resistance and matching capacitance link to each other with the EMCCD pin, form the RLC series resonant circuit; Controllable impedance and matching capacitance are used to guarantee that rlc circuit circuit under specific operating frequency is in resonance condition; Adjustable resistance is used for the quality factor of trimming circuit, in the debug process of circuit resonance, is used for current limliting simultaneously and prevents that the signal on the EMCCD pin from exceeding the normal range of operation of EMCCD.

Beneficial effect of the present invention is following:

1, the high speed and high pressure drive signal does not obtain through the traditional driving circuit; But mainly utilize equivalent capacity, equivalent resistance and outside inductor, the RLC series resonant circuit that resistor is formed of CCD pin to obtain; Greatly reduce requirement, also greatly reduce the power consumption of this circuit simultaneously driving element;

2, thereby the amplitude adjusted of output signal changes the output voltage of the first adjustable electric depressor through the resistance value that changes digital regulation resistance in the first adjustable electric depressor and then has changed the supply voltage of integrated drive, has realized the digital control of amplitude output signal;

3, the digital parameters value that receives through the second adjustable electric depressor changes the resistance value of internal digital potentiometer; Thereby change the output voltage values in the DC-DC booster circuit; And to the RLC resonant circuit direct current biasing being provided through the DC level clamp circuit, the high-low level that makes output signal after each change amplitude output signal value is still in normal working range;

4, can change the quality factor q of resonant circuit through the resistance that changes adjustable resistance, thereby under the constant situation of input signal amplitude, change the amplitude of output signal; For reducing the difficulty of rlc circuit resonance debugging; Can be during near resonance at circuit; The DC level value that the amplitude that tests out the output signal required input signal amplitude and phase place and clamp circuit under different value is required also is stored in controller inside; The mode that employing is tabled look-up, controller are exported corresponding range parameter, clamp level parameter simultaneously according to required amplitude output signal value and are adjusted the phase place of output timing drive signal, guarantee that the CCD drive signal of final output satisfies the work schedule requirement.

Description of drawings

Fig. 1 is a high speed and high pressure drive signal circuit principle schematic of the present invention.

Fig. 2 is the structured flowchart that the present invention realizes the system of the peculiar drive signal of EMCCD.

Embodiment

Below in conjunction with accompanying drawing and embodiment the present invention is explained further details.

As shown in Figure 1, the model that EMCCD drives pin is the less resistance of resistance and the series connection of an electric capacity; The model of inductor is the series connection of resistance and inductance, requires the resistance value in the inductor model very little in the present invention; R among the figure is the equivalent resistance sum that inductor and EMCCD drive pin; L is the equivalent inductance of inductor, and C is the equivalent capacity that EMCCD drives pin; The drive signal amplitude of input is VIN, and angular frequency is ω, and frequency is f; The capacitive reactance of electric capacity

When the sinusoidal signal amplitude U that requires its two ends is 50V, frequency f is 20MHz, and when appearance value C was 100pF, then current amplitude did $I=\frac{U}{X_C}=2\mathrm{\π\; FUC}=2\mathrm{\π}\×20\×{10}^6\×50\×100\×{10}^{-12}=0.2\mathrm{\π}\left(A\right).$ When adopting the traditional driving working method, the peak power P=UI=10 π (W) of driver output, and the maximum working voltage of integrated high-speed driver can not satisfy the requirement about 50V about 20V; Adopt two discrete high-speed high-power MOSFET to satisfy and drive requirement, but optional MOSFET kind is limited and buy difficulty, the power consumption of entire circuit is big, has increased the weight of the EMCCD low temperature environment burden of work down.

When the change inductance L makes circuit be in resonance condition, promptly

The time, the impedance of entire circuit is pure resistance R, the circuit output voltage amplitude

Be directly proportional with the amplitude of input signal; The quality factor of circuit

EMCCD CCD60 with E2V company is an example, and the equivalent resistance of R Φ 2HV pin is 8 Ω, and equivalent capacity is 94pF; When the pixel transfering clock is 18MHz, the quality factor of circuit $Q=\frac{\mathrm{VOUT}}{\mathrm{VIN}}=\frac{1}{R2\mathrm{\π\; FC}}=\frac{1}{8\×2\mathrm{\π}\×18\×{10}^6\×94\×{10}^{-12}}=\frac{36.94}{\mathrm{\π}};$

Import very little signal amplitude and then can obtain very big amplitude output signal; When amplitude output signal is 50V, require only 1.35 π V of input signal amplitude.

As shown in Figure 2, the present invention realizes that the system of the peculiar drive signal of EMCCD comprises controller, the first adjustable electric depressor, the second adjustable electric depressor, integrated drive, block isolating circuit, DC level clamp circuit, controllable impedance, adjustable resistance and matching capacitance.

The operation principle of system of the present invention is: controller is to integrated drive input timing drive signal, and according to current gain requirement, respectively to the first adjustable electric depressor and the corresponding digital parameters value of second adjustable electric depressor output; The first adjustable electric depressor is according to the corresponding voltage of digital parameters value output that receives, and this voltage can be realized the digital control of integrated drive amplitude output signal like this as the power supply of integrated drive; Block isolating circuit is used to remove the DC level of integrated drive output signal; The second adjustable electric depressor is exported corresponding voltage according to the digital parameters value that receives, and to the LC resonant circuit direct current biasing is provided through the DC level clamp circuit; Controllable impedance, adjustable resistance and matching capacitance link to each other with the EMCCD pin, form the series resonant circuit of RLC; The effect of controllable impedance and matching capacitance is to guarantee that rlc circuit circuit under specific operating frequency is in resonance condition; Adjustable resistance is used for the quality factor q of trimming circuit, can in the debug process of circuit resonance, be used for current limliting simultaneously and prevent that the signal on the EMCCD pin from exceeding the normal range of operation of this device.When circuit is in the disresonance state; Output signal and phase of input signals difference are with the changes in amplitude of input signal; For reducing the difficulty of rlc circuit resonance debugging; Can be during near resonance at circuit, the DC level value that the amplitude that tests out the output signal required input signal amplitude and phase place and clamp circuit under different value is required also is stored in controller inside, the mode of employing look-up table; Controller is exported corresponding range parameter, clamp level parameter simultaneously according to required amplitude output signal value and is adjusted the phase place of output timing drive signal, guarantees that the EMCCD drive signal of final output satisfies the work schedule requirement.

Embodiment:

As shown in Figure 2, controller can adopt the FPGA of Xilinx company; Integrated drive can adopt the high-speed driver of intersil company; The first adjustable electric depressor is mainly linear LDO power supply chip and digital regulation resistance, and the denumerable tone of Chinese characters of output voltage is whole; Block isolating circuit is mainly withstand voltage high magnetic sheet electric capacity; The DC level clamp circuit is mainly the speed-sensitive switch diode; The second adjustable electric depressor is mainly DC-DC booster power chip and digital regulation resistance, and the denumerable tone of Chinese characters of output voltage is whole; Controllable impedance is the inductance of manual coiling, can carry out meticulous inductance value adjustment, and dc resistance is very little; Adjustable resistance and matching capacitance are respectively bigger resistance of rated disspation and withstand voltage higher magnetic sheet electric capacity; EMCCD is the CCD60 of E2V company.

Claims (1)

1. system that realizes the peculiar drive signal of EMCCD; It is characterized in that; This system comprises controller, the first adjustable electric depressor, the second adjustable electric depressor, integrated drive, block isolating circuit, DC level clamp circuit, controllable impedance, adjustable resistance and matching capacitance; Said controller is connected with integrated drive, the first adjustable electric depressor, the second adjustable electric depressor respectively; Controller is to integrated drive input timing drive signal, and according to current gain requirement, respectively to the first adjustable electric depressor and the corresponding digital parameters value of second adjustable electric depressor output; The said first adjustable electric depressor is connected with integrated drive, and it for integrated drive provides power supply, realizes the digital control of integrated drive amplitude output signal according to the corresponding voltage of digital parameters value output of the said controller output that receives; Said block isolating circuit is connected with integrated drive, and it is used to remove the DC level of integrated drive output signal; The said second adjustable electric depressor is connected with the DC level clamp circuit, and its digital parameters value according to the said controller output that receives is exported corresponding voltage, and to the LC resonant circuit direct current biasing is provided through the DC level clamp circuit; Said controllable impedance, adjustable resistance and matching capacitance link to each other with the EMCCD pin, form the RLC series resonant circuit; Controllable impedance and matching capacitance are used to guarantee that rlc circuit circuit under specific operating frequency is in resonance condition; Adjustable resistance is used for the quality factor of trimming circuit, in the debug process of circuit resonance, is used for current limliting simultaneously and prevents that the signal on the EMCCD pin from exceeding the normal range of operation of EMCCD.