The summing amp is prepared to allow up to use bipolar full range of the FSS box output

This means that the FSS fast PZT output is now nominally 0V and can range +/-10V.

- FSS Box has the output range of +/-10V

- Thorlabs HV amp MDT694 accepts 0V ~ +10V

- This circuit add an offset of +5V while the main signal is attenuated by a factor of 2. The offset voltage is produced from the voltage reference IC AD586.

- In addition, a summing node and voltage monitors before and after the summing node are provided. They are useful to test the crossover frequency of the fast/PC loops.

- The output noise level at 10kHz was ~60 nV/rtHz. The transfer function of the circuit was measured and flat up to 100kHz. The phase delay is negligible at 10kHz and less than 3deg at 100kHz

- Although the schematic was drawn in Altium, the board is a universal 1U eurocard and all wires were hand soldered.