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3. I/Q

M9383B VXG-m, M9384B VXG, and M9484C VXG

E8267D PSG

RF Flatness Correction

(M9383B/M9384B/M9484C only)

Choice: On | Off

Default: On

Double-click or use the drop-down menu to turn the internal channel correction Off or On.

I/Q Adjustments

Choice: Off | On

Default: Off

Double-click or use the drop-down menu to turn the I/Q adjustments On or Off.

On – The values entered for I Offset, Q Offset, and so on are applied to the I and Q signals.

Off – I/Q adjustment values are not applied to the I and Q signals.

I Offset

Range:

N5172B/N5182B/N5166B: -20% to 20%

All other models: -50% to 50%

Step: 0.025%

Default: 0.00%

Enter a DC offset value to apply to the I signal before the I/Q modulator. Use this offset to remove imperfections in the in-phase signal or to introduce calibrated impairments.

When using this setting to minimize the LO feed-through signal, optimum performance is achieved when the adjustment is made after any other I/Q path adjustments. If other adjustments are made after minimization is performed, the LO feed-through signal may increase.

Set I/Q Adjustments to On to enable this parameter.

Q Offset

Range:

All other models: -50% to 50%

Default: 0.00%

Enter a DC offset value to apply to the Q signal before the I/Q modulator. Use this offset to remove imperfections in the quadrature-phase signal or to introduce calibrated impairments.

When using this setting to minimize the LO feed-through signal, optimum performance is achieved when the adjustment is made after any other I/Q path adjustments. If other adjustments are made after minimization is performed, the LO feed-through signal may increase.

Set I/Q Adjustments to On to enable this parameter.

I/Q Gain Balance

Range:

N5172B/N5182B/N5166B: -1 dB to 1 dB in 0.001 dB steps

All other models: -4 dB to 4 dB in 0.01 dB steps

Default: 0.00 dB

Enter a gain ratio, by which I gain exceeds Q gain.

For example, if you enter a value of 1 dB, the I signal will have 1 dB more amplitude than the Q signal. Use the gain balance to remove imperfections in I and Q or introduce calibrated impairments.

Set I/Q Adjustments to On to enable this parameter.

Quadrature Angle Adjustment

Range: -10 to 10 degrees

Default: 0.00 degrees

Enter a value to adjust the Q phase angle. When the quadrature skew is zero, the phase angle between the I and Q vectors is 90 degrees. Positive skew increases the angle from 90 degrees; negative skew decreases the angle from 90 degrees.

Set I/Q Adjustments to On to enable this parameter.

I/Q Timing Skew Path

Choice: RF | BB (Baseband)

Default: RF

Double-click or use the drop-down menu to select the I/Q timing skew path.

Set I/Q Adjustments to On to enable this parameter.

This parameter is not available for all instrument model numbers and may be grayed out.

I/Q Correction Optimization Path

Choice: RF Output | External I/Q Output | Dig Bus Output (only for N5182B MXG)

Default: RF Output

Double-click or use the drop-down menu to select the I/Q correction optimized path.

This parameter is not available for all instrument model numbers and may be grayed out.

I/Q Skew

Range:

N5172B/N5182B/N5166B: −500 to 500 ns, in 1 ps steps

N5182A: −800 to 800 ns, in 1 ps steps

M9381A: depends upon sample rate.

All other models: −2.0 to 2.0 seconds, in 1 ps steps

Default: 0.0 seconds

Sets the time delay between I and Q. A positive value delays the I signal relative to the Q signal, and a negative value delays the Q signal relative to the I signal.

M9381A: Sets the timing delay skew (in nanoseconds) between the channels. Range is dependent on sample rate, corresponding to time duration of +/- 50 samples. For example, at 200 MS/s (160 MHz bandwidth) the limit is 250 ns, and at 80 Ms/s (64 MHz bandwidth) the limit is 625 ns.

Enter a value to change the absolute phase of both I and Q with respect to triggers and markers. A positive value delays I and Q. This value affects both the external I/Q out signals and the baseband signal modulated on the RF output. This adjustment cannot be used with constant envelope modulation and does not affect external I/Q inputs.

Set I/Q Adjustments to On to enable this parameter.

I/Q Delay

Range:

N5172B/N5182B/N5166B/M9381A: −250 to 250 ns, in 1 ps steps

N5182A: −400 to 400 ns, in 1 ps steps

M9381A: −250 to 250 ns, in 1 ns steps

All other models: −1.0 to 1.0 seconds, in 1 ps steps

Default: 0.0 seconds

Enter a value to change the absolute phase of both I and Q with respect to triggers and markers.

A positive value delays I and Q.

This value affects both the external I/Q out signals and the baseband signal modulated on the RF output. This adjustment cannot be used with constant envelope modulation and does not affect external I/Q inputs.

The limits are determined by the rate of the current format.

Set I/Q Adjustments to On to enable this feature.

Swap I/Q

(M9383B/M9384B/M9484C only)

Choice: On | Off

Default: Off

Double-click or use the drop-down menu to enable or disable the inverse phase rotation of the IQ signal by swapping the I and Q inputs.

Optimize Dynamic Range with OBW

(M9383B/M9384B/M9484C only)

Choice: On | Off

Default: On

Filters the system RF flatness correction coefficients over the instantaneous bandwidth indicated in the waveform header (or in the “Occupied Bandwidth” settings area under the Signal block when Waveform File is the Vector Modulation Signal Mode). This has the potential to improve EVM performance by not having to correct for flatness errors outside the requested bandwidth.

I/Q Phase

Range: −360.00 to 360.00 degrees

Default: 0.00 degrees

Enter a value to adjust the I/Q phase. This value adjust the absolute phase of the internal I/Q channel by rotating both I and Q.

Set I/Q Adjustments to On to enable this parameter.

I/Q Path

(E8267D PSG only)

Choices: Wide

Default: Wide

Gets or sets the External analog I/Q inputs mode.

Wide: Using the Wideband external I/Q inputs, up to 2 GHz RF modulation bandwidth is now easily realized.

I/Q Enabled

(E8267D PSG only)

Choices: On | Off

Default: On

Double-click or use the drop-down menu to control the signal generator's I/Q state.

Instrument