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I/Q Out Block

This topic describes the parameters accessed from the I/Q Out block. These settings allow you to configure the I/Q outputs of the instrument.

I/Q Output controls as based on the optional configuration of the instrument.

For M9484C, Option AN1 is required. For multi-channel instruments, Option AN1 is available on Channel 1 only. For instruments with Option AN1 and without Option DIQ, the controls available are shown below:

For M9484C, instruments with Options AN1 and DIQ, the controls available are shown below:

Common Mode I Offset

Common Mode Q Offset

Diff Mode I Offset

Diff Mode Q Offset

Amplitude Control

Enable Amplitude Control

I Amplitude

Q Amplitude

Common Mode I Offset

This option is used to specify the common mode offset voltage routed to the external I+/- output ports. The Common Mode Offset Voltage raises or lowers the voltage of the signal applied to the I+/- output ports by the same value. A positive Common Mode Offset Voltage raises the voltage of the signal applied to external I+/I- output port above the baseline values, while a negative Common Mode Offset Voltage lowers the voltage of the signal applied to external I+/I- output port above the baseline values. For example, if the Common Mode Offset Voltage is 0.03 volts, both the external I+/I- outputs will be at 0.03 volts (when the output voltages are at their baseline voltage).

Common Mode Q Offset

This option is used to specify the common mode offset voltage signal routed to the external Q+/- output ports. The Common Mode Offset Voltage raises or lowers the voltage of a signal applied to the Q+/- output ports by the same value. A positive Common Mode Offset Voltage raises the voltage of the signal applied to external Q+/Q- output port above the baseline values, while a negative Common Mode Offset Voltage lowers the voltage of the signal applied to external Q+/Q- output port above the baseline values. For example, if the Common Mode Offset Voltage is 0.03 volts, both the external Q+/Q- outputs will be at 0.03 volts ( when the output voltages are at their baseline voltage).

Diff Mode I Offset

Differential I output requires Option DIQ.

Specifies a differential offset voltage for an in-phase (I) signal routed to the I+/- output ports.

This option is used to specify the total differential offset voltage routed to the external I output port. The Offset Voltage offsets the signal routed to the external I output port by the value of this voltage. This is accomplished by adding half of the Offset Voltage to the signal applied to the external I+ output port and subtracting half of the Offset Voltage from the signal applied to the external I- output port. For example, if the desired I Offset Voltage is 0.05 volts, then 0.025 volts is added to the signal applied to the external I+ output port while 0.025 volts is subtracted from the signal applied to the external I- output port.

Diff Mode Q Offset

Differential Q output requires Option DIQ.

Specifies a differential offset voltage for a quadrature-phase (Q) signal routed to the Q+/- output ports.

This option is used to specify the total differential offset voltage routed to the external Q output port. The Offset Voltage offsets the signal routed to the external Q output port by the value of this voltage. This is accomplished by adding half of the Offset Voltage to the signal applied to the external Q+ output port and subtracting half of the Offset Voltage from the signal applied to the external Q- output port. For example, if the desired Q Offset Voltage is 0.05 volts, then 0.025 volts is added to the signal applied to the external Q+ output port and 0.025 volts is subtracted from the signal applied to the external Q- output port.

Amplitude Control

The I/I+ and Q/Q+ output voltage can be adjusted when RF output is not being I/Q modulated, thus CW on the RF output.

For M9484C the I/I+ and Q/Q+ output voltage can be adjusted while continuing to provide modulated RF output.

Enable Amplitude Control

Option DIQ only.

For use cases where you need to drive higher voltages on the I and Q outputs, and you are not modulating the RF output from the internal baseband, you can enable the Amplitude Control. When Amplitude Control is enabled, use the I and Q Output Amplitude settings to adjust the output voltages. When Amplitude Control is enabled, the RF output will be CW.

I Amplitude

Option DIQ only.

Sets the maximum voltage on I+ and I-. Maximum voltage occurs when waveform I data is 16-bit integer maximum (+32767), with minimum voltage occurring when I data is -32768. The voltage is for I into a 50 Ohm load.

Q Amplitude

Option DIQ only.

Sets the maximum voltage on Q+ and Q-. Maximum voltage occurs when waveform Q data is 16-bit integer maximum (+32767), with minimum voltage occurring when Q data is -32768. The voltage is for Q into a 50 Ohm load.