DiProWa - The Lock-In Amplifier for AFM measurement

Our scanning probe microscopes are using our fully digital controller and our scan software ScanTool™.

There exist many add-ons to our instruments, depending on the type of desired measurement. One example is our FPGA based Lock-In combination device DiProWa, which supports various electrical measurements like Kelvin-Probe-Force-Microscopy (KFPM).

The DME lock-in amplifier DiProWa is a combination of the following components: Loginverstärker

Both inputs are sampled with 14 bit high speed digital analog converters. All other functions are realized fully digitally (FPGA based). This results in a linearity unreached by conventional analog systems and allows arbitrary combining of the different functional groups without disadvantages in signal bandwidth and cross talk.

The user front end is realized in Java and runs on all suited operating systems as for example Windows / MAC / Linux etc. No drivers are needed, all communication runs via standard ethernet.

The following table gives an overview of the technical parameters:

Input / Output Configuration:2 input and 2 output channels
In-/Output voltage range:±10 V
Oscilloscop sampling speed range:0,61 kHz … 40 MHz
Number of data points per oscilloscope curve:512
Spectrum analyzer frequency resolution:sampling-frequency / 1024
A/D converter dynamics:14 bit at 40 MHz
Frequency generator base frequency:80 MHz
Frequency generator frequency dynamic:32 bit
Frequency generator waveform look-up table depth:4096
Frequency generator phase resolution:0,088 °
Lock-In amplifier dynamics:28 bits
Lock-In amplifier filter dynamics:54 bits
PI controller integrator dynamics:30 bits
Overall noise:typ. <6 nV / √ Hz
Processing units:1 FPGA and 1 32 bit DSP
Analog bandwidth:Limited to approx. 5 MHz, optionally up to 40 MHz