What Is a High-Current Amplifier?

The role of the current amplifier is to provide current to the inductive current load according to the current command, which is essentially a controlled current source. The current amplifier is generally composed of four parts: power supply, power electronic circuit, inductive load, and controller. It adopts output current closed-loop control.

There are some inductive current-type loads in industrial production (such as generator field windings, electromagnetic actuators, etc.). Their common feature is that they have strict dynamic and steady-state requirements for the load current, and they require output current while meeting the stable output current Quickly follow current instructions. The role of the current amplifier is to provide current to the inductive current load according to the current command, which is essentially a controlled current source. ^[1]

An amplifier is a device that increases the amplitude or power of a signal. It is

Keithley's 428-PROG programmable current amplifier is capable of amplifying fast low currents. The 428 current amplifier quickly converts a small current into a voltage signal, which can then be displayed or measured using an oscilloscope, waveform analyzer, or data acquisition system.

Main features and advantages :

1, 2s rise time;

2. 1.2fA rms noise;

3. Gain up to 1011 V / A;

4. Compatible with IEEE-488 interface / 5, 428 uses advanced "feedback current" circuit to achieve fast rise time and noise lower than picoamps. The gain of 428 is adjustable from 103V / A to 1011V / A, the step size is 10 times, and the rise time can be selected from 2s to 300ms. ^[3]

Figure 4.428 Current amplifier

Application :

Biochemical measurement: Ion channel current across cell wall and cell membrane.

Beam direction monitoring: for electronic storage rings and synchrotrons.

Surface Science Research: Amplifiers for Scanning Tunneling Electron Microscope Systems.

Observe secondary electron emission (such as in X-ray and electron beamline current), laser and light measurement combined with PMT (photomultiplier tube) and photodiode fast sensitivity amplifier, fast analysis of photoconductive material, IR detection amplifier.