Alpha-A Modular Dielectric/Impedance Measurement System
The Alpha-A mainframe is the master unit of the Alpha-A modular measurement system for electric frequency domain measurements.
For dielectric, conductivity and impedance spectroscopy the mainframe has to be operated in combination with one or more test interfaces.
The mainframe contains a frequency response analyzer with a sine wave and dc-bias generator and two ac voltage input channels.
In addition, the mainframe contains the power supplies, analog and digital control lines and the firmware for operation of the test interfaces.
After power on, the mainframe automatically detects the connected test interface and adjust the system functionality to it.
All system functions of the mainframe and a connected test interfaces are controlled by the mainframe IEEE488 GPIB interface port by high level GPIB commands via an external host computer as shown below.
Without a test interface, the mainframe can perform two channel frequency response or gain phase measurements.
Alpha-A Mainframe Types
The following mainframe types with different frequency ranges are available.
|Alpha mainframe types||Type Code|
|Upper frequency limit 40 MHz||Alpha-AT|
Upper frequency limit 20 MHz
Upper frequency limit 3 MHz
Upper frequency limit 0.3 MHz
If operated in combination with a test interface, the available frequency range may be reduced by the test interface frequency range. Impedance measurements up to 40 MHz (using the Alpha-AT) are currently supported by the Alpha active sample cell ZGS and the general purpose test interfaces ZG2 and ZG4.
|Alpha mainframe options||Additional Type Code Letters|
|Dc bias ±40V, 70mA||B if installed, missing else|
|High measurement speed. Support of measurement rates up to 600 impedance data points per second via GPIB port for online monitoring of fast time variant processes.||F if installed, missing else|
- The recommended mainframe type with best performance/price ratio is the Alpha-ANB (20 MHz with dc bias).
- Without the dc bias option B, the maximum selectable dc bias Vdc is given by |Vdc| < 4.3 V - Vp for the test interfaces ZG2, ZG4, and ZGS. Here Vp = 1.41*Vrms stands for the peak ac voltage selected for the measurement.
Short specification Alpha-A Rev. C mainframe (2017)
|Frequency range:||3 µHz ... 40 MHz (13 decades) max., depending on type|
|Frequency accuracy:||10 ppm, 32 bit resolution|
|Display:||bright numerical display with online status and value messages|
|Interfaces:||GPIB / IEEE488 system control port,
DP25 Sub-D test interface connector
|Output, input connections:||BNC, 3 terminals|
|Standalone gain phase operation|
|AC signal out||45 µV .. 1.36 Vrms|
|DC bias out||only available in combination with a test interface|
|Signal generator output impedance||50 Ω|
|V1, V2 voltage channels ranges||0.045 .. 45 Vp in 13 ranges ac or dc coupled, single ended|
|Voltage channels input impedance||< 1MΩ | 20 pF|
|V2 / V1 voltage ratio||3.10-4 *|
|Phase angle (φ):||
|V2 / V1 voltage ratio||3.10-5|
|Phase angle (φ):||
* For details refer to specification charts