181 results about "Dc bias voltage" patented technology

A control method and system for a resonant converter. The control method for a resonant converter comprises: in each switching cycle, determining a target power value on the basis of an input power control amount and a compensation amount corresponding to a bridge leg (S101); on the basis of the target power value, an input voltage, circuit parameters of the resonant converter, and the current operating mode of a full-bridge inverter module, determining a target slope control amount corresponding to a counter which corresponds to a switching transistor (S102); determining a comparison threshold on the basis of the target slope control amount, the current count value of the counter which corresponds to the switching transistor, and a DC bias voltage of a resonant capacitor corresponding to the current operating mode, wherein the counter starts counting using the DC bias voltage as an initial value in each switching cycle until the actual voltage of the resonant capacitor is equal to the comparison threshold (S103); and determining a control signal on the basis of the actual voltage of the resonant capacitor and the comparison threshold, and controlling the switching transistor on the basis of the control signal (S104).

The invention discloses a DP-MZM-based reconfigurable mixer with phase shift and image rejection functions, and belongs to the field of microwave photon signal processing. By adjusting an input radio frequency signal and a direct current bias voltage of the DP-MZM1, four different LO frequency doubling and mixing functions can be realized. By controlling the angle alpha between the polarization direction of the polarization analyzer and one axis of the modulator, the phase of the generated signal can be flexibly tuned in the range of 0-360 degrees. When combined with the optical frequency comb, the multi-channel multi-band frequency conversion system can be expanded into a multi-channel multi-band frequency conversion system with independent phase tuning capability by utilizing the channel switching and frequency slot selection functions of the wavelength selection switch, and parallel output of various frequency mixing results can be realized. By adjusting the phase difference between the two-channel output signals, I / Q mixing, double-balanced mixing and image rejection mixing can be configured. The scheme is not influenced by direct current bias drift, the system complexity is reduced, and the frequency conversion efficiency is improved.

A method for harmonic trapping in a matching network of a power amplifier includes determining primary inductance and secondary inductance of a differential transformer of the matching network, based on a signal operating frequency of the power amplifier. An inductance value for an L-C filter is determined based on the secondary inductance and a harmonic frequency of a local oscillator (LO) signal. A capacitance value for the L-C filter is determined based on the inductance value and the harmonic frequency of the LO signal. The L-C filter is provided on an electric connection between a direct current (DC) bias voltage source and a secondary inductor of the differential transformer. The L-C filter is configured with the determined inductance value and the determined capacitance value.

The invention belongs to the technical field of integrated circuits, and particularly discloses a numerical control programmable gain amplifier chip, which adopts an SIP (Session Initiation Protocol) packaged operational amplifier, a digital potentiometer, an input end Vin and an output end Vout, and is characterized in that an alternating current signal is input from the Vin end and is connected to an inverted input end of the operational amplifier through a capacitor C1 and an input resistor R1; a positive power supply pin of the operational amplifier is connected with a power supply positive electrode VDD, a negative power supply pin is grounded, and a VDD / 2 direct current bias voltage is obtained by an in-phase input end through a precision resistance voltage dividing network and is accessed after low-pass filtering; the high end of the digital potentiometer is connected with the Vout end, the low end is connected with the inverting input end of the operational amplifier, and a feedback path is formed through a sliding end. The digital potentiometer and the operational amplifier are integrated, high integration and modularization of the programmable gain amplification circuit are achieved, and the problems that in a traditional discrete scheme, due to analog switch conduction resistance, gain precision is insufficient, reliability of a multi-element system is lowered, and the circuit size is large are solved.

The invention discloses a preparation method of a high-quality self-supporting polycrystalline diamond substrate. The preparation method comprises the following steps: obtaining a larger first substrate and a smaller second substrate; the molybdenum substrate is a polished molybdenum metal substrate; sowing diamond seed crystals on the first substrate by using an ultrasonic sowing method, and growing a nanocrystalline diamond epitaxial layer by using a CVD (Chemical Vapor Deposition) process; cutting the first substrate by using precise laser to obtain an annular polycrystalline diamond solid seed crystal of which the inner diameter is greater than that of the second substrate; placing a second substrate in the inner diameter of the second substrate, guiding generated tiny diamond grains to the second substrate through a boundary induction mechanism and applying direct current bias voltage, and uniformly wrapping the tiny diamond grains to form a self-supporting polycrystalline diamond substrate; according to the preparation method of the self-supporting polycrystalline diamond substrate, the orientation consistency and the crystallization quality of a diamond film are remarkably improved, and the prepared self-supporting polycrystalline diamond substrate has the advantages of being low in surface roughness, compact in structure, simplified in follow-up process and the like.

The invention discloses a wide-temperature-range solid insulation space charge measurement method, and belongs to the technical field of electrical insulation test and dielectric physical measurement. A solid insulation sample is mounted between double-layer composite electrode modules in a closed high-low temperature test cavity, and a flexible compensation gasket is adopted to absorb thermal expansion difference; a PID closed-loop control system is utilized to realize accurate and stable control of the temperature of the sample in a wide temperature range; applying a direct-current bias voltage and pulse voltage superposition signal, and collecting an acoustic signal generated by space charge displacement through a wide-temperature-range PVDF piezoelectric sensor module; and based on a sound velocity and sensitivity temperature calibration curve established by a pre-experiment, carrying out deconvolution processing on a sound wave signal to correct a temperature dependence error, and finally obtaining accurate space charge density distribution at different temperatures. According to the invention, the precision and reliability of space charge measurement of the solid insulating material in a wide temperature range are effectively improved.

A non-interferometric thin film lithium niobate electro-optical modulator for data transmission including a laser, configured to generate an input continuous wave light beam; a non-interferometric thin film lithium niobate modulator including an optical waveguide situated along with the coplanar transmission lines and the DC bias conductors. The propagation constant of the optical waveguide is tuned and modulated by the RF data signal and the DC bias voltage traveling on the coplanar transmission lines and the DC bias conductors. The modulator can be tuned at quadrature point by the DC bias voltage. The optical power can be modulated by the RF data signal travelling on the coplanar transmission line; a low noise RF amplifier for data signal amplification; and a bias tee for combining the data signal and DC bias voltage and send them to the coplanar transmission lines.

The application discloses an implementation device and method of a controllable nonreciprocal circuit, and the device comprises a vector network analyzer, a left coupling capacitor, a right coupling capacitor and a nonlinear LC resonant cavity, wherein the resonant frequency of the nonlinear LC resonant cavity is jointly regulated by a direct current bias voltage loaded on a varactor diode and a microwave signal. The application utilizes the difference in coupling efficiency of microwave energy coupled into the nonlinear LC resonant cavity when the microwave signal is transmitted forward and reversely, and utilizes the regulation of the direct current bias voltage on the nonlinear interaction between the microwave signal and the LC resonant cavity mode in the nonlinear LC resonant cavity, so that the nonlinear LC resonant cavity can be in different bistable states when the microwave signal is transmitted forward and reversely, and thus the controllable nonreciprocal transmission with high contrast can be realized for the microwave signal in a larger working bandwidth.

The application discloses an online permanent magnet flux identification method of a permanent magnet synchronous motor considering cross coupling effect and belongs to the permanent magnet flux identification technology of the permanent magnet synchronous motor. The application aims at solving the problem that the existing permanent magnet synchronous motor flux identification method does not consider the cross coupling influence of the motor, thereby causing the error of the flux observation result to be large. The application comprises the following steps: under the online stable working condition of the motor, injecting a sinusoidal current signal into the dq axis of the motor to realize three-phase direct current signal injection; calculating the motor stator resistance; injecting two groups of direct current bias voltage into the d-axis of the motor through the current loop, establishing three motor voltage equations, and then obtaining two motor voltage difference equations which eliminate the flux terms; solving to obtain the motor d-axis self-inductance L d and the motor dq-axis mutual inductance L dq ; establishing the dq-axis voltage equation considering the cross coupling, calculating the motor permanent magnet flux based on the motor stator resistance, the motor d-axis self-inductance L d and the motor dq-axis mutual inductance L dq . The application is used for the online identification of the permanent magnet flux of the permanent magnet synchronous motor.

The present application relates to the technical field of quantum precision measurement, in particular to a Roland C signal receiving method and system based on Rydberg atoms, which utilizes atomic antennas to prepare Rydberg atoms in an alkali metal atom gas chamber to obtain an electromagnetically induced transparency (EIT) spectrum; a Roland C signal reaches the alkali metal atom gas chamber through free space, and the EIT spectrum produces an oscillation peak by utilizing the Stark effect of the Rydberg atoms; the coupling laser frequency is locked to the maximum position of the oscillation peak amplitude; by applying a direct current bias voltage to the parallel electrodes built in the alkali metal atom gas chamber, on the one hand, the received Roland C signal is corrected, and on the other hand, the alternating current Stark effect is amplified, so that the receiving sensitivity of the Roland C signal is significantly improved.

The invention provides a spaceborne fiber-optic gyroscope and an on-orbit regulation and control method thereof, and relates to the technical field of fiber-optic gyroscopes, a circuit part of the spaceborne fiber-optic gyroscope comprises a signal processing unit, an optical power detection unit and an optical power regulation and control unit; the signal processing unit receives superposed signals which are output by the optical path part and contain direct-current bias voltage and high-frequency alternating-current voltage for signal conditioning, the conditioned high-frequency alternating-current voltage is converted into digital angular velocity signals, and the direct-current bias voltage is extracted from the superposed signals through the optical power detection unit. The direct-current bias voltage is amplified and converted into a digital optical power signal, the digital optical power signal and / or the digital angular velocity signal are / is sent to a satellite service computer through an optical power regulation and control unit, and the optical power regulation and control unit is further used for responding to an optical power regulation and control instruction which is forwarded by the satellite service computer and generated by a ground station. And generating a driving current to adjust the output light power of the light path part until the precision of the spaceborne fiber-optic gyroscope meets the satellite service requirement.

The invention discloses a control method, a control device, an integrated circuit control chip and a switching power supply, and the method comprises the steps: level shift: receiving a sampling voltage signal representing the size and change trend of a whole-period resonance current in a resonant cavity of a resonant converter, the sampling voltage signal is boosted into a first voltage signal which is all positive voltage, and a direct-current bias voltage signal is generated at the same time; a charge signal generation step of generating a charge signal representing the power transmission quantity of the resonant converter according to the first voltage signal and the DC bias voltage signal, the charge signal including a slope compensation component with a set proportion; and a feedback control step of controlling the switching circuit according to the charge signal and the feedback voltage signal to realize energy conversion. According to the invention, the design difficulty and design cost of the integrated circuit control chip can be reduced, and the applicability of the integrated circuit control chip can be improved.

The application belongs to the technical field of integrated circuits, and specifically discloses a digital control programmable gain amplifier chip, which adopts an SIP packaged operational amplifier, a digital potentiometer, an input end Vin and an output end Vout, an alternating current signal is input from the Vin end, is connected to the inverting input end of the operational amplifier through a capacitor C1 and an input resistor R1, a positive power supply pin of the operational amplifier is connected to a positive electrode VDD of a power supply, a negative power supply pin is connected to the ground, a same-phase input end obtains a VDD / 2 direct current bias voltage through a precision resistor voltage dividing network and is connected after low-pass filtering, a high end of the digital potentiometer is connected to the Vout end, a low end is connected to the inverting input end of the operational amplifier, and a feedback path is formed through a sliding end. The operational amplifier and the digital potentiometer are integrated, high integration and modularization of the programmable gain amplification circuit are realized, and the problems of insufficient gain precision, decreased reliability of a multi-element system and large circuit volume caused by the on-resistance of an analog switch in a traditional discrete scheme are solved.

The present application provides a compensation circuit, method, device, and storage medium for an audio DAC. The audio DAC compensation method is applied to a compensation circuit for an audio DAC. The compensation circuit includes a DAC module and an ADC module. The compensation method includes: obtaining a first voltage output by the ADC module when the input terminal of the ADC module is short-circuited; obtaining a second voltage output by the ADC module when the output terminal of the DAC module and the input terminal of the ADC module are electrically conductive; and compensating the DAC module based on the first and second voltages. This compensation method is used to automatically and accurately compensate for the DC bias voltage of the DAC.

The application discloses a nano-channel transistor structure with an auxiliary anode and a driving method. The structure comprises an insulating substrate, a cathode, a gate and an anode which are made on the substrate, and at least one auxiliary anode is additionally arranged on the side of the anode away from the cathode. The auxiliary anode and the anode can have a height difference. By applying different direct-current voltages, a regulating electric field is formed between the anode and the auxiliary anode, the moving direction and speed of the electrons passing through the anode are changed, and the electrons are collected by the anode or directly collected by the auxiliary anode. The application also provides a corresponding driving method. The gate applies a direct-current bias voltage superimposed with a high-frequency modulation signal, and the anode and the auxiliary anode respectively apply direct-current voltages. The amplified high-frequency signals collected by the anode and / or the auxiliary anode are output through a capacitor, and the multi-output signals can be superimposed after the phase compensation system makes the phases of the multi-output signals consistent. The application effectively improves the utilization efficiency of the cathode emitted electrons and the total output current of the device.

The invention discloses a capacitive load voltage correction method. The method comprises the following steps: carrying out direct current blocking and voltage reduction on an actual alternating current signal for driving a capacitive load to work; dC bias voltage is applied to the actual AC signal after voltage reduction; calculating a voltage value corresponding to the signal according to the actual alternating current signal added with the direct current bias voltage; comparing the voltage value with a preset voltage, judging whether an error value between the voltage value and the preset voltage is within a preset error range or not, and if not, adjusting the size of the actual alternating current voltage to enable the actual alternating current voltage to be calibrated as a driving voltage required for driving the capacitive load to work. According to the invention, the driving voltage of the capacitive load is calibrated and adjusted, so that the driving voltage output to each channel of the capacitive load is consistent or nearly consistent, thereby improving the hearing effect of the capacitive load for playing audio signals, and realizing the automatic calibration of the driving voltage of multiple channels of the capacitive load.

Embodiments of the present application relate to an amplifying device and a transmitter. An amplifying device and a transmitter capable of compensating for a parasitic component of a circuit element without complicating a circuit structure are provided. The amplifying device includes a first amplifier that performs an amplifying operation on a signal; N-1 second amplifiers that perform an amplifying operation on the signal in sequence according to an amplitude of the signal in a case where the first amplifier performs the amplifying operation; N input networks connected to an input terminal that inputs the signal; N output networks connected between an output node of the first amplifier and a load connection node and connected between output nodes of the N-1 second amplifiers and the load connection node; and a first bias network that supplies a direct current bias voltage to at least one of the N output networks, an electrical length of the first bias network being less than 90 degrees.

The invention discloses a single-pole double-throw switch filtering assembly based on an LTCC (Low Temperature Co-Fired Ceramic) technology. A switching circuit and an LTCC resonator are integrated, and the on-off state of a switching diode in the working process is controlled by an externally applied direct current bias voltage. When the diode is in a conducting state, the parasitic inductor and the capacitor form series resonance, and the equivalent coupling admittance converter passing through the resonator can be inverted and equivalent to an open circuit, so that a branch signal is cut off, and channel isolation is realized; and when the diode is in a closed state, the electromagnetic field distribution of the substrate integrated waveguide resonator is not obviously influenced, the filter keeps normal work, and signal passband transmission is realized. According to the structure, on one hand, the SIW waveguide integration form is used for achieving the low insertion loss characteristic; and on the other hand, the stop-band suppression degree is effectively improved by introducing the cross coupling topology. The whole circuit has the advantages of being compact in structure, low in loss, high in isolation degree, excellent in out-of-band rejection performance and the like, and the requirements of 5G and future high-speed wireless communication systems can be met.

The invention discloses a direct-current-bias-free high-power LED visible light signal transmission method and system, and relates to the technical field of optical communication, and the method comprises the steps: carrying out 64QAM-OFDM modulation and IQ modulation on original audio and video data, carrying out AC coupling peak-to-peak value extraction and DC component filtering, and then carrying out single-power-supply amplification and pre-equalization; and a driving positive voltage signal is generated to drive a high-power LED to emit light, and an optical communication signal is generated. Through a low-loss alternating-current coupling transmission mode, the modulated real signal peak-to-peak value is subjected to coupling transmission and single positive power supply amplification, so that the signal is changed into positive voltage to control the LED light intensity and form an LED optical communication signal, direct-current voltage does not need to be introduced into a digital domain, the problem of bandwidth reduction is avoided, and the signal transmission efficiency is improved. The direct-current bias voltage of the LED can be kept stable, the LED works in a linear modulation area, bandwidth expansion is carried out through the pre-equalization circuit, and the functions of LED illumination and high-speed communication can be considered.

The invention discloses a capacitive inductive voltage sensor ultra-wideband response performance expansion circuit and a test method. According to the circuit, the ultra-wideband response capability is improved by cascading a hybrid integrating circuit, a high-pass filtering module and a voltage follower; the hybrid integrating circuit is formed by connecting a passive integrator (self-integrating to process low frequency and suppress high-frequency noise) and an active integrator (reducing high frequency in a differential mode) in series to cooperatively broaden the frequency band; the high-pass filter filters DC bias, and the voltage follower realizes impedance matching and signal isolation. Experiments prove that the hybrid voltage sensor can realize good waveform reduction on sinusoidal signals as low as 5Hz and steep waves as high as 10MHz, and the voltage division ratio is stable; for a 1kHz signal, after the circuit is inserted, the output phase is consistent with the input, the amplitude is accurately restored according to the designed voltage division ratio, the phase lead and the amplitude attenuation are effectively inhibited, the traditional frequency band limitation is broken through, and the circuit is suitable for an ultra-wideband voltage measurement scene.

The application discloses a kind of MZM array bias point control method and circuit based on high harmonic suppression, it is related to circuit control technical field, comprising the following steps: S1, generate low-frequency sinusoidal signal, after processing, load to MZM array;S2, the optical signal output to MZM array is preprocessed;S3, the optical signal after preprocessing is sampled, and the amplitude spectrum in frequency domain is obtained;S4, according to the amplitude spectrum in frequency domain, calculate harmonic ratio;S5, based on harmonic ratio, the corresponding direct-current bias voltage is output, the locking of bias point is realized.The application uses digital FFT algorithm to replace expensive analog demodulation circuit, while ensuring high performance, substantially reduce hardware cost and PCB area, conducive to engineering batch application.

A method for measuring DC bias aging characteristics of a multilayer capacitor includes applying a first poling voltage to a multilayer capacitor including a body having a dielectric layer including a plurality of dielectric grains and an internal electrode disposed alternately with the dielectric layer in a first direction, and an external electrode disposed on the body, maintaining the first poling voltage for a first period of time (t1), applying a DC bias voltage lower than the first poling voltage, maintaining the DC bias voltage for a second period of time (t2), and measuring saturated capacitance after the DC bias voltage is applied.

The application provides an E-FSR unit with an absorption and transmission mode controlled by an HPM and a direct current bias, comprising a plurality of periodically arranged E-FSR units, each unit being a five-layer cascade structure, and from top to bottom, the five-layer cascade structure is sequentially a first loss layer, a first air layer, a second loss layer, a second air layer and a frequency selection layer; the first loss layer, the second loss layer and the frequency selection layer each comprise a dielectric substrate, a metal pattern printed on the upper and lower sides of the dielectric substrate and a metal connecting column penetrating through the dielectric substrate; the frequency selection layer and the first loss layer and the second loss layer each are provided with a diode, the absorption and transmission mode is switched by applying a direct current bias voltage to the diode or driving the diode by using high-power microwave incidence, so as to meet the antenna mute stealth requirement, and the absorption and transmission mode is adaptively switched to an absorption band when high-power microwave is incident, so as to realize a protection function. The application solves the in-band strong scattering problem when the antenna is muted, has the advantages of dual-polarization characteristics, wide-band absorption and low insertion loss and the like.

The application discloses a MEMS loudspeaker device, system and preparation method driven by electrostatic and piezoelectric mixed driving, relates to the technical field of loudspeakers, and aims at solving the problems of high driving voltage, easy occurrence of suction effect and insufficient low-frequency response caused by single electrostatic driving mode of the prior art, and the problem of poor high-frequency response caused by single piezoelectric driving. The MEMS loudspeaker device comprises, from bottom to top, a substrate, an electrostatic driving unit formed on the substrate, at least a fixed electrode and a movable diaphragm of the electrostatic driving unit, and a piezoelectric driving unit integrated on the movable diaphragm. The piezoelectric driving unit receives a preset direct-current bias voltage of a preset size to control the movable diaphragm to generate a preset static displacement in the direction of the fixed electrode, and the piezoelectric driving unit processes middle-low frequency signals in input wide-band audio signals; the electrostatic driving unit processes high frequency signals in the wide-band audio signals. The application is used for improving loudspeaker quality of the loudspeaker and reducing power consumption.

The invention provides an on-line measurement method for ground capacitance current of a power distribution network, and relates to the technical field of power system measurement, and the method comprises the steps: injecting a sine AC signal at an opening triangle of an electromagnetic voltage transformer of the power distribution network; the initial phase angle of the sine alternating current signal is zero; acquiring an acquired voltage response signal generated by the bus of the power distribution network during the period of injecting the sine alternating current signal; extracting a direct current bias voltage component from the voltage response signal; determining equivalent ground capacitance of the power distribution network based on the direct current bias voltage component; and determining the total capacitance current of the power distribution network under the rated voltage based on the equivalent ground capacitance. The method can achieve the purpose of online, safe, low-cost, high-precision and high-interference-resistance ground capacitance current measurement of the power distribution network.

This invention belongs to the field of microwave communication and electromagnetic protection technology, specifically providing a fast-response limiting and filtering integrated HPM protection device based on carbon nanotube field emission, to overcome many shortcomings of the existing technology. Based on existing limiting and filtering integrated high-power microwave protection devices, this invention introduces a carbon nanotube field emission limiting structure. Through carbon nanotube field emission, high-density deterministic seed electrons are provided, significantly shortening the gas breakdown avalanche setup time, thereby significantly reducing the total response time. Simultaneously, a metal-dielectric-metal three-layer coaxial DC bias structure is designed to apply a DC bias voltage to the carbon nanotube film to modulate the field emission current density, achieving real-time control of the response speed. Ultimately, the limiting and filtering integrated high-power microwave (HPM) protection device of this invention has a faster response speed, more stable limiting performance, and the response speed can be actively controlled.

The utility model relates to the technical field of power electronics, and discloses a rotary transformer excitation circuit. The circuit comprises at least one power integrated operational amplifier unit and a direct current bias voltage unit, the power integrated operational amplifier unit comprises a signal input end, a bias voltage input end and a signal output end; the DC bias voltage unit is connected with the bias voltage input end. According to the application, the power integrated operational amplifier unit is arranged to carry out power amplification on the received excitation sinusoidal signal based on the direct current bias voltage and then output the excitation sinusoidal signal to the external main control chip, and due to the adoption of the power integrated operational amplifier design circuit, the circuit structure is simplified, the total number of devices in the circuit is reduced, and control blind spots are reduced.

The invention discloses a superfluid helium second sound wave attenuation measurement system. The system comprises a signal generation module, a transducer module, a signal conditioning module, a bias power supply module, a protection isolation module, a data processing module, a temperature control module and a pressure control module. The signal generation module outputs AC excitation signals, the transducer module converts electric signals and second sound waves mutually, the signal conditioning module extracts effective signals and outputs direct-current signals, the bias power supply module provides direct-current bias voltage, the protection isolation module guarantees equipment safety and signal isolation, and the temperature and pressure control module maintains the superfluid helium state to be stable. The data processing module supports a steady state measurement mode and a transient state measurement mode, and vortex line density is analyzed and calculated through harmonic peaks. Compared with an existing measurement system, the system is high in signal stability, standard in calibration process, suitable for various measurement scenes, convenient to operate and wide in applicability, and high-precision quantitative measurement of superfluid helium second sound wave attenuation is achieved.

The invention relates to a terahertz transmission wave modulator based on multilayer microstructure heterogeneous integration. The terahertz transmission wave modulator comprises a metal radiation layer, a substrate material, a metal ground layer, an insulating material, a direct current wiring layer, a resin material and a metal receiving layer which are sequentially arranged from top to bottom, the metal radiation layer comprises two diodes; when a terahertz incident wave of which the electric field direction is parallel to the transverse central axis of the metal receiving layer enters the metal receiving layer, a direct current bias voltage signal generated by the direct current wiring layer is transmitted to the two diodes of the metal radiation layer so as to control the conduction state switching of the two diodes; and the amplitude and phase of the terahertz transmission wave emitted by the metal radiation layer are subjected to 1-bit modulation. The terahertz modulator is diversified in regulation and control mode and excellent in performance, can play an important role in terahertz application fields such as tracking and pointing communication, radar perception and object imaging, and has a wide application prospect.

Embodiments of the disclosure describe an apparatus that includes a processing chamber having a grounded chamber shield that at least partially defines a processing region. An electrode is disposed within the processing region of the processing chamber. The electrode includes apertures extending through the electrode and the electrode is disposed between a sputtering target and a substrate. A voltage source is configured to apply a positive DC bias to the electrode. A grounded electrode shield is disposed within the processing region and extends a distance from the electrode. The distance is adjustable to vary a ratio of a surface area of the electrode to a surface area of the grounded electrode shield.