Local Oscillator Distributor (LOD)

Double 1:16 ultra low-noise RF signal splitter

Overview

The “Local Oscillator Distributor” (LOD) is a double 1:16 ultra low-noise RF signal splitter whose main functionality is the distribution of sine clocks with minimal degradation at short distances ( tens of meters). For large distance please consider to use the specifically designed timing products.

LOD basic block diagram is shown on the next picture.

The system FPGA is dedicated to configure and monitoring the RF signals. An embedded softprocessor is used to provide a simple remote interface to the users. It is complemented with an EPICS driver based on Asyn and StreamDevice module, fully compliant with the EPICS official specifications.

LOD can be handled through the Ethernet port and the SCPI protocol. This SCPI protocol was released as an additional layer for the IEEE-488.2 standard, used for controlling and monitoring the instruments through GPIB. The FPGA modules scheme and EPICS interface are presented on the next figure.

Main characteristics

Performance examples

Phase noise outputs using a SMB100A signal generator at 380 MHz and 12 ± 1 dBm has been characterized by means of a signal analyser (E5052B) with a 98.2 fs RMS (integration range 10Hz-10 MHz) phase noise as shown on the left image. Then, SMB100A signal is distributed using LOD. The total phase noise measured at the output of LOD is 98,2 fs RMS. This is really small RMS additive phase noise representing a outstanding result.

Similar results has been found with 100 and 175 MHz signals. Below the results for a 175 MHz signal case operating at 12 dBm.