RHK Technology R9 - Channel 1 Input and Channel 2 Input; Hardware Space; Figure B.4. Hardware Space - Channel 1 Input

Hardware Space Components
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The Attenuation (12) and Oscillation Range Dividers (13) are specialized controls that help to optimize
the Channel 1 drive when very low signal levels are needed. When bias voltages and oscillation
amplitudes of more than 10 mV are being used, these controls can be left with settings of 1.
The Frequency (14) data entry box sets the oscillation frequency of the AC signal that is summed into
the Bias Voltage.
The Limit Maximum (15) and Limit Minimum (16) are parameters that will limit the voltage range of
most of the DACs in R9. Entering in values less than the normal full scale can prevent damage to
components that should not be exposed to the full output range of a DAC. This control is most frequently
used on the High Voltage Amplifier outputs. The outputs of the High Voltage Amplifiers can range from -
215 V to + 215 V. If a piezo element can only be safely operated between 0 V and 150 V, entering these
limits into the High Voltage Amplifier's limits will prevent the amplifier from exceeding the safe operating
area of the piezo element.
Note
When the R9 Controller is first turned on, the values of the DACs are set to zero. After an
IHL file has been loaded and initialized, the Values on R9 controls are first Hard Set. Once
the system has started up and initialized, the full capability of the R9 controls can be
utilized. The purpose of these panels in hardware space is to allow testing as well as to
allow the system to come up in a defined state. The power of these controls will be more
fully utilized in Procedure Space and in the Dashboard. The Offset Enable radio button
allows the Offset DAC to be summed into the Channel 1 Drive. This is one of the few
analog summing junctions in the R9 controller. This summing junction adds approximately
1 nV of noise to the output signal. This can be safely ignored by almost every experiment
as it is so far below the noise floor of most experiments. The parameter is provided for the
customer working in the mK range where the absolutely lowest noise level is desired. For
other users, the radio button should be checked to allow the offset to be used to null out
any output offset errors.
The Modulation Enable radio button allows an external signal to be summed with the bias voltage
output. This capability is typically not used in STM measurements, but can be used with other types of
modulation experiments. Unless this capability is required, the Modulation Enable radio button should be
left unchecked as noise picked up by the connector will be summed with the drive signal.
B.2. Channel 1 Input and Channel 2 Input
The Channel 1 Input is used for the below examples, assuming it is connected to the preamplifier in an
STM. The Channel 2 Input is identical to the Channel 1 Input.
B.2.1. Hardware Space
Figure B.4. Hardware Space - Channel 1 Input