RU206349U1 - PRECISION HIGH VOLTAGE METER SOURCE - Google Patents

Abstract

The utility model relates to measuring technology, in particular to the calibration of measuring modules of a configurable modular system for complex automated testing of semiconductor devices. The technical result consists in ensuring high accuracy of voltage generation and measurement. The claimed device contains a serially connected analog-to-digital converter, control unit, half-bridge driver, power stage, LLC transformer and rectifier. Amplifiers of the current and voltage feedback signal and a subtractor are connected to the input of the analog-to-digital converter. The current feedback amplifier input is connected to the LLC transformer. The input of the voltage feedback signal amplifier is connected to the output of the rectifier. Amplifiers are connected to the input of the subtractor, between the inputs of which a shunt is connected. The control unit is configured to modulate the pulse density. 1 wp f-ly, 4 dwg.

Description

FIELD OF TECHNOLOGY

The utility model relates to measuring technology, in particular to measuring the characteristics of semiconductor devices as part of a configurable modular system for complex automated testing of semiconductor devices.

LEVEL OF TECHNOLOGY

Known high-voltage sources designed to generate high voltages, built using arresters, or a complex control system (RU 2144257 C1, CN 102342007 B, US 5483434 A).

The disadvantages of the known sources are:

limiting the generated voltage 1-2 kV,

low accuracy,

large dimensions and

high level of conducted and radiated noise, which makes it difficult to integrate them into a measuring system with a large number of closely spaced measuring instruments.

ESSENCE OF THE USEFUL MODEL

The task of the utility model is to provide a set of the following operational parameters:

ensuring high accuracy of forming and measuring voltage and current,

the ability to set and measure voltage over 2000 V,

the ability to measure current from 1 μA,

low level of conducted and radiated disturbances,

reduction in size.

The technical result consists in ensuring high accuracy of the formation and measurement of voltage is carried out through the use of a digital system for processing the feedback signal with a software pulse density modulator. The latter, by decimating the signal by skipping pulses, adjusts the output parameters: voltage, current, or power.

The above problem is solved due to the fact that the proposed precision source-measuring modular measuring system contains:

half-bridge driver (1),

power stage (2) connected to the half-bridge driver (1),

LLC transformer (3) connected to power stage (2), rectifier (4) connected to LLC transformer (3), analog-to-digital converter (8),

control unit (5), the output of which is connected to the half-bridge driver (1), and the input to the analog-to-digital converter (8), made with the possibility of modulating the pulse density,

a current feedback signal amplifier (6), the input of which is connected to the LLC transformer (3), and the output to an analog-to-digital converter (8),

voltage feedback signal amplifier (9), the input of which is connected to the output of the rectifier (4), and the output to the analog-to-digital converter (8),

shunt (11),

amplifiers (7, 10), between the inputs of which a shunt (11) is connected, and the outputs of which are connected through a subtractor to an analog-to-digital converter (8).

In one of the preferred embodiments of the meter, the power stage (2) is connected in a bridge circuit.

The pulse density modulator implemented in the control unit (5) regulates the output value (in this case, voltage or current) by skipping a certain number of pulses (see, for example, https://en.wikipedia.org/wiki/Pulse-density modulation) ... In this case, the power stage always operates at the resonant frequency. Due to this, switching (switching on and off) of the keys always occurs at zero current, that is, soft switching is ensured.

Compared to arrester sources, the behavior of which is difficult to control, this tracking system allows stable control of the output signal with high accuracy.

Stability is ensured by the high frequency of control cycles and the absence of unstable elements. At the same time, the system does not have a large number of functional units that complicate it.

Over 2000V voltage measuring range and high efficiency are ensured by digital control of the LLC resonant step-up transformer in low voltage circuits.

The low level of conducted and radiated emissions is ensured by the use of a resonant boost converter with power stage switching at zero current.

The power stage (2) is usually a half-bridge on field-effect transistors, providing the formation of an alternating voltage on the primary winding of the transformer.

The control unit (5) is preferably a digital controller implemented on an FPGA.

The half-bridge driver (1) is a power amplification circuit based on an integrated microcircuit. The driver amplifies the power of the logic signal from the control unit (5), which is necessary to control the transistors of the power stage (2).

LLC transformer (3) (LLC-circuit) is a transformer, the primary winding of which, with a capacitor connected in series to it, forms a resonant circuit.

The rectifier (4) is an AC-to-DC converter.

Feedback amplifiers (6, 7, 9, 10) are circuits that provide voltage signal amplification and are made on integrated circuits.

Subtractor (12) is a circuit that subtracts signals by voltage (the output voltage is equal to the difference between the input voltages).

The subtractor (12) can be implemented on an operational amplifier microcircuit.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a block diagram of a source-meter of a modular measuring system, where:

1 - half-bridge driver;

2 - power stage;

3 - LLC circuit (transformer).

4 - rectifier;

5 - digital control unit on FPGA;

6 - loop current feedback amplifier;

7, 10 - shunt signal amplifiers;

8 - analog-to-digital converter (ADC);

9 - voltage feedback amplifier (operational amplifier);

11 - current-measuring shunt;

12 - subtractor.

FIG. 2 illustrates the phase lock algorithm, where:

13 - driver signal;

14 - loop feedback signal;

15 - the system works in resonance;

16 - downed mode, phase lost.

FIG. 3 illustrates a block diagram of a digital control unit, where:

17 - PID controller;

18 - phase-locked loop;

19 - pulse density modulator.

FIG. 4 shows the bridge connection of the power stage (2).

IMPLEMENTATION OF THE USEFUL MODEL

The data of the pulse parameters (pulse time, voltage, current, rise time) are fed to a digital control unit (5), which includes PID controllers, a phase-locked loop (PLL) system, and a pulse density modulator.

The clocking of the LLC circuit (3) is enabled via the driver (1) with a switching delay and a power stage (2).

The signal from the capacitor of the resonant LLC circuit (3) through the amplifier (6) is fed to the ADC (8) synchronized with the signal of the half-bridge driver (1), and then to the PLL of the control unit (5).

Since the ADC is phase locked to the clock signal, the phase deviation between the loop feedback signals and the signal at the driver is measured. This phase difference is used by the PLL to adjust the frequency of the LLC loop (3).

The voltage at the output of the rectifier (4) and the current at the shunt (11) are measured using an ADC (8) through amplifiers (7, 9, 10). This signal goes to the PID controller, and then to the pulse density modulator inside the control unit (5).

By changing the modulator coefficient, the number of allowed pulses is adjusted for every 100 pulses of the driver clock. Thus, the regulation of the output parameters - current / voltage - is carried out.

The structure of the proposed source-meter allows you to set and measure voltages in the range over 2000 V with current control. Thus, it is possible to measure the parameters of semiconductor devices with high accuracy in a wide range of voltages.

FIG. 2 shows the ADC phase lock and the difference between resonant mode and resonance loss. From the difference in levels at points on a sinusoidal voltage, you can determine the magnitude and direction of the phase shift. As you can see, for the correct operation of the control system, the phase difference between the loop feedback signals and the signal on the driver must be minimized. This is provided by the PLL.

FIG. 3 shows a block diagram of a digital control unit of a precision source-meter, which reflects the relationship of PID controllers, a PLL system and a pulse density modulator.

The proposed solution provides high accuracy of forming and measuring voltage and current, while providing:

the ability to set and measure voltage over 2000 V,

the ability to measure current from 1 μA,

low level of conducted and radiated disturbances,

reduction in size.

High measurement accuracy is ensured by the high frequency of the modulator (Pulse-density modulation, PDM modulator). The high frequency of the modulator, together with the high speed of parameter measurements, forms a small value of the discrete deviation, which the system can compensate for. Thus, with an increase in the frequency, the control resolution increases significantly.

The ability to set and measure voltages above 2000 V is ensured by the fact that regulation is carried out on the low-voltage side using half-bridge driver 1, power stage 2 and LLC transformer 3, thus, the requirements for high-voltage elements are reduced. Only rectifier diodes (rectifier 4) remain on the high voltage side. This approach allows you to simplify the structure and requirements for the system components.

The ability to measure current from 1 μA is provided by the structure of the meter. The measurement is carried out by the shunt signal meters 7, 10, then the total signal is formed by the subtractor 12. This structure provides a high input impedance (low leakage currents of the amplifier inputs), which in turn makes it possible to measure very low load currents.

The use of a PDM modulator in conjunction with a resonant converter can significantly reduce the level of conducted and radiated noise. This is achieved due to the "soft" switching of the transistors of the power stage 2. The switching is carried out at zero current through the transistor.

The low dynamic losses provided by such switching make it possible to increase the operating frequency, as well as to reduce the size of the electromagnetic elements, which ultimately leads to an overall reduction in the size of the system.

Claims (2)

1. Precision source-meter of a modular measuring system, containing a half-bridge driver (1), a power stage (2) connected to a half-bridge driver (1), an LLC transformer (3), connected to a power stage (2), a rectifier (4), connected to the LLC transformer (3), an analog-to-digital converter (8), a control unit (5), the output of which is connected to the half-bridge driver (1), and the input to an analog-to-digital converter (8), made with the possibility of modulating the pulse density , a current feedback signal amplifier (6), the input of which is connected to the LLC transformer (3), and the output to an analog-to-digital converter (8), a voltage feedback signal amplifier (9), the input of which is connected to the output of the rectifier ( 4), and the output - to an analog-to-digital converter (8), a shunt (11), amplifiers (7, 10), between the inputs of which a shunt (11) is connected, and the outputs of which are connected through a subtractor to an analog-to-digital converter (8) ... 2. A source-meter according to claim 1, characterized in that the power stage (2) is connected in a bridge circuit.

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