Eightfold Linear Tester for Gandalf Devices

To test the functionality of the GANDALF transient analyzer we need at least eight similar analog signals with high precision in time and signal amplitude. To be able to test the whole dynamic input range we developed an active eight channel signal splitter. The transient analyzer measures very short time spans in the range of some ps, so it is important that all channels of ELROND have the same delay. This was achieved by aligning the path length of all channels on the PCB.

We aimed at a bandwidth of DC to 240 MHz since that is approximately the bandwidth of the photomultipliertube pulse\'s spectrum. One can see the FFT of a 240 MHz signal being split up by ELROND. The upper trace is the input signal from the AFG, the lower is the signal coming from one ELROND channel. There are little harmonics, but this was observed on the reference design for our amplifier as well.

 ELROND can be operated in symmetric or asymmetric power supply mode. Symmetric means the power supply of the opamps is adjusted to -7..7 Volts, in asymmetric Mode it is -11..3 Volts. The signal should be in the range from -2..2 Volts or -4..0 Volts respectively.  One can switch these modes either by a hardware switch or a TTL Level input to make automatic switching and tests possible.

 Technical Data:

• Channels:                                           8
• Dynamic Range:                                4Vpp
• Connector Type:                                 SMA
• Amplifier used:                                   www.ti.com/product/ths3201