2-tones measurement panel: Sweep settings

Acquisition Mode:

Power per Frequency: for each frequency acquisition a ramp of RF power will be sent to the DUT
Fast CW is a sweeping method that can be used to improve the measurement speed. Contrary to the classical power sweep where IQSTAR is sweeping the VNA power, the VNA is here asked to sweep the power for a fixed frequency, asking the instruments to bufferize the measured values, and resulting in a great speed improvement.

DANGER: When using this type of sweep, the measurement stop conditions will not be verified because of the VNA sweeping entire power sweeps. The DUT will not be under IQSTAR protection and measurement can lead to damages. It is important to know the limits to not exceed in this case.

For more informations about how to setup a Fast CW bench, see Getting Started : "Fast CW measurements".

Fequency Sweep Settings:

Frequency sweep:
- Select the reference frequency for the sweep: Central frequency (f0, which is (f2+f1)/2) or one of the frequencies of the 2-tones signal (f1 or f2)
- By default the frequency list is filled with frequencies from the calibration. Click on icon to open the 'Frequency editor' and modify the frequency list
  Note: 'Frequency editor' is a tool used to define frequency sweeps or frequency segments. Click on 'Clear' or 'Inject into list' to add or remove frequencies. It is possible to select the frequencies available in the selected calibration file by clicking on 'Select frequencies from calibration'. It's also possible to save or load a frequency list (*.freq files) using icons.
Delta sweep:
- Delta value: is the spacing between f1 and f2. Use icon to modify the list of delta sweep
- IMD order: select the IMD order to record (from 3 to 9)
Allow frequency interpolation: if the list of RF stimulus frequencies is different from the calibrated one, IQSTAR will interpolate the errors terms

Power Sweep Settings

Sweep settings configurations depend on the acquisition mode selected:

Type: the power sweep can be of different types:
- Raw power: Total raw power. IQSTAR will divide the value by two (in Watts) in order to send the command to both RF source (P_totalraw=P_rawSRC1+P_rawSRC2)
  Note: If Driver Amplifier is defined in the schematic, the power defined will take into account the driver amplifier offset set in the schematic.
- Raw power (calibrated): Total raw power calibrated. Available if the Raw Power Calibration has been performed. There is no optimization but the power is offsetted from the Raw Power Calibration coefficients
- Total available input power: the total available power is optimized at the input of the DUT (P_{in_avs_total}=P_{in_avs_@f1}+P_{in_avs_@f2})
- Total delivered input power: the total delivered power is optimized at the input of the DUT (P_{in_del_total}=P_{in_del_@f1}+P_{in_del_@f2})
- Total output power: the total output power is optimized at the output of the DUT (P_{out_total}=P_{out_@f1}+P_{out_@f2})
Ignore level setting errors until first success: if there is a power optimization IQSTAR moves to next power level if the optimisation does not reach the previous target

Note: It is important to note that input powers at f1 and f2 are balanced in order to compensate for the dispersive effects of external passive components or driver amplifiers. IQSTAR embeds its own 2-tones optimizer and the tolerance and number of iterations can be configured in the schematic main option.

From this panel, select whether the 2 tones have to be balanced and what is the 'Maximum iterations' of this optimization and the acceptable tolerance (with f1 as the reference):

VSWR

In order to affect on purpose the DUT, it is possible to control a load tuner and change the load impedance of the DUT. The pattern consists of impedance points that are 50-Ohms centered. If this VSWR module is enabled, the tuner will be initialized before the measurement begins.

Enable preview (blue points):set active the preview in the smith chart. Red points are already added, blue are the current ones being set up.

Max VSWR: pattern max VSWR
VSWR res.: pattern VSWR resolution
Angular res.: pattern VSWR angular resolution
Filled: if check, the pattern is filled with points distance of VSWR resolution value. If unchecked only the circumference points will be active.
Central point: activates the 50 Ohms point if checked.

Important: Once the pattern is created, the ADD button needs to be pressed to turn them into red and use them during the measurements. The CLEAR button can be used to empty the pattern.

Fast CW settings (Available with Fast CW only):

When fast power sweeps are needed and the device is know well enough (Stop conditions ignored in this mode), the Fast CW mode can be used.

If the used IV multimeters are compatible with burst measurements, instrument measurement ranges will need to be selected in this table. If some instruments do not have this burst capability, please refer to DC Measurement. Triggers also needs to be defined and are positive edge by default.

If an instrument has no burst capability, the following message should appear:

Minimum setting time: sets a delay between the VNA power sweep points. Can be used to achieve a DUT steady state before measuring a value.

Quiescent current stabilization (Available with Power per Frequency, Smart and Fast measurements):

When the DUT’s hysteresis, thermal or trapping effects are present, it is recommended to sweep 'Frequency per Power' rather than 'Power per Frequency' or add dwell time to minimize the effects from previous measurements. IQSTAR includes the 'Quiescent current stabilization' feature in order to monitor the quiescent current in function of time between each power sweep. Therefore, an appropriate dwell time will be automatically defined between each power sweep. The aim is to define a tolerance on the quiescent current to achieve before starting a new power sweep.

Start measurement for: set the level (in % of initial value) of quiescent current to be reached before a new sweep can start
Current access: choose the current access to apply the condition
Note: It is also possible to create an expression in order to define a custom current (e.g. sum of two currents).
Stabilized value count: set the number of consecutive measurements that must be within the tolerance
When 'Quiescent current stabilisation' is enabled. An additional window will pop up during measurements to display the quiescent current value, the reference current level and the current tolerance. This curve can then be saved in a file if needed.