Operate HF2LI dual-channel lock-in amplifier with one reference frequency

This blog quickly described how to synchronize the lock-in reference for both lock-in channels of HF2LI lock-in amplifier. HF2LI lock-in amplifier comes with two independent lock-in channels which offers HF2LI users substantially more flexibility compared to the single lock-in setup. With the software release 12.08.1, HF2LI lock-in amplifier users can now enjoy even more benefits for their dual lock-in setup. In this blog, a quick overview will be given on the advantages of the new dual-channel synchronization feature.

The ziControl screenshot below shows the new 12.08.1 release feature that allows users to use the same internal reference for both lock-in channels. HF2LI users can now generate a reference signal using one channel and then select the same internal reference to demodulate both lock-in inputs. In this case, HF2LI users can accurately obtain the amplitude and especially the phase information of both input signals since they are both derived from the same lock-in reference.

internal reference setting

Another advantage, which may not be obvious, is the simultaneous measurement of up to 6 harmonics up to 50 MHz. In comparison, the amplitude and the phase information of 3 harmonics can be measured up to 50 Mhz in a single channel using previous software releases. In order to achieve 6 harmonics measurement, the simplest way would be to connect the two inputs through a T-junction as shown in the diagram below. In this example, we set the second channel reference to CH1 as well as the demodulators to 6 different harmonics. Consequently, one can obtain the amplitude and the phase of 6 different harmonics on the same signal. This is very useful when measuring a highly non-linear signal similar to the one displayed in the oscilloscope. We can see that information exists at the multiple frequencies of 10 MHz. Of course any harmonics beyond 50 Mhz will experience attenuation as expected. Another thing to watch out for is perhaps the attenuation and asymmetry caused by the T-connection at high frequencies. Nevertheless, the amplitude and the phase information of 6 harmonics can be conveniently recovered simultaneously.

lock-in-double-input

I hope that you will find this new 12.08.1 feature useful in your measurement setup.