#### DC Inputs

The DC Inputs submenu selects DC voltages or the Power Added Efficiency (PAE) of an active two-port DUT to be measured and displayed.

- DC MEAS 1V
  and DC MEAS 10V select the DC voltages fed to the input connectors DC MEAS
  as measured quantities.

- PAE...
  opens a dialog to select and configure the PAE measurement.

All DC and PAE measurements use the input connectors DC MEAS at the rear of the instrument. The measurement results are real-valued and displayed as a function of sweep variable (frequency, internal source power, time). The measurements can be performed in parallel to all RF measurements.

##### DC MEAS 1 V, DC MEAS 10 V

Select the DC voltages fed to the DC MEAS
input connectors as measured quantities. The input connectors are located at the rear panel of the instrument.

The two DC inputs cover different input voltage ranges; see data sheet or rear panel labelling.

- The left input connector DC MEAS 1V provides the most accurate measurement for smaller voltages but has a restricted input level range.

- The right input connector DC MEAS 10V can be used for larger voltages.

Remote control: | CALCulate<Ch>:PARameter:MEASure "<Trace_Name>", "DC+1V" | "DC+10V" [SENSe<Chn>:]FUNCtion[:ON] "...:VOLTage[:DC] DCIN1 | DCIN2" Create new trace and select name and measurement parameter: CALCulate<Ch>:PARameter:SDEFine "<Trace_Name>", "DC+1V" | "DC+10V"

###### PAE...

Opens a dialog to select the Power Added Efficiency (PAE) of an active 2-port device as measured quantity and to define the parameters for the PAE measurement.

The PAE dialog provides the following settings:

- Used Test Ports selects the analyzer port providing the input signal a1 (DUT Input) and the receiver port for the output signal b2 (DUT Output).

- The radio buttons and input fields in the DC Power panel select the test model and the parameters for measuring the DC power
  PDC supplied to the DUT. The constants can be incremented with the step size defined by clicking the buttons.

- Select Topology opens the Port Configuration
  dialog to define the properties of the test ports. Either physical test ports or logical ports can be used as Input and Output instrument ports. The graphics and messages displayed in the Topology panel are identical to the ones shown in the More S-Parameters
  dialog. When the unbalance-balance conversion is switched on, the PAE is calculated from the single-ended and differential mode wave quantities (see also Mixed Mode Stability Factors
  ).

To obtain reasonable results, the test model and the respective Constant must be selected in accordance to the test setup.

Definition and measurement of PAE

The PAE measurement is based on the standard test setup for forward S-parameter measurements on a 2-port DUT. An additional measurement to determine the supplied power PDC is required.

Definition:

The Power Added Efficiency (PAE) is the ratio of the added RF power generated by an active two-port device (e.g. an amplifier) to the supplied DC power PDC. The added RF power can be expressed as the difference between the power of the outgoing wave b2 at the output of the DUT and the power of the incident wave a1 at the input of the DUT; hence:

Positive PAE values indicate a gain in the RF power, negative values an attenuation. The PAE is always smaller than 1.

Remote control: | CALCulate<Ch>:PARameter:MEASure "<Trace_Name>", "PAE21" | "PAE12" |... Create new trace and select name and measurement parameter: CALCulate<Ch>:PARameter:SDEFine "<Trace_Name>", "PAE21" | "PAE12" |...

###### DC Power Measurement

The power PDC supplied to the DUT can be measured using either one of the DC inputs DC MEAS 10V (for large voltages), DC MEAS 1V (for small voltages) or both inputs. The DC Power panel in the PAE
dialog suggests different models involving different test setups and approximations. The models are selected by means of the radio buttons in the DC Power panel; they depend on the properties of the DC power supply (constant current IDC or constant power UDC) and an optional precision resistor R used to measure the DC current. The values IDC, UDC, and R determine the Constants c and k. These constants must be entered in the DC Power panel, using the appropriate physical units, before a particular model can be activated.

- IDC = const., R = 0 —> PDC = c * U (DC Meas 10 V) Assume that the DC power supply provides a constant current IDC and that the voltage applied to the DUT is measured via DC MEAS 10 V (R = 0). PDC = IDC * U(DC MEAS 10 V), hence the Constant c must be set equal to IDC. The unit field shows the SI unit of a current (W/V). The input field for k is disabled (k is not used).

- UDC = const., R << RDUT, PR = 0 —> PDC = c * U (DC MEAS 1 V) Assume that the DC power supply provides a constant voltage UDC and that the current through the DUT is measured by means of a precision resistor R connected in series and DC INP 2. If R << RDUT the power consumption of the resistor can be neglected so that PDC = UDC / R * U(DC MEAS 1 V), hence the Constant c must be set equal to UDC / R. The unit field shows the SI unit of a current (W/V). The input field for k is disabled (k is not used).

- R << RDUT, PR = 0 —> PDC = k * U (DC MEAS 10 V) * U (DC MEAS 1 V) Assume that the DC power supply provides a constant voltage UDC and that the current through the DUT is measured by means of a precision resistor R connected in series and DC INP 2. PDC = UDUT / R * U(DC MEAS 1 V) = (UDC – UR)/ R * U(DC MEAS 1 V) = UDC / R * U(DC MEAS 1 V) – 1 / R * U(DC MEAS 1 V)2, hence the Constant c must be set equal to UDC / R and k must be set equal to 1/R. The unit fields for c and k show the SI units of a current (W/V) and an inverse resistance (W/V2), respectively.
  Assume that the DC power supply provides an arbitrary (not necessarily constant) voltage UDC and current IDC. The current through the DUT is measured by means of a precision resistor R connected in series and DC INP 2. The voltage applied to the DUT and R is measured via DC MEAS 10 V. If R << RDUT the power consumption of the resistor can be neglected so that PDC = 1/ R * U(DC MEAS 10 V) * U(DC MEAS 1 V), hence the Constant k must be set equal to 1/ R. The unit field shows the SI unit of an inverse resistance (W/V2). The input field for c is disabled (c is not used).

- UDC = const., PR = U (DC INP2)2/R —> PDC = c * U (DC MEAS 1 V) + k * U (DC MEAS 1 V)^2 Assume that the DC power supply provides a constant voltage UDC and that the current through the DUT is measured by means of a precision resistor R connected in series and DC INP 2. PDC = UDUT / R * U(DC MEAS 1 V) = (UDC – UR)/ R * U(DC MEAS 1 V) = UDC / R * U(DC MEAS 1 V) – 1 / R * U(DC MEAS 1 V)2, hence the Constant c must be set equal to UDC / R and k must be set equal to 1/R. The unit fields for c and k show the SI units of a current (W/V) and an inverse resistance (W/V2), respectively.

Models 1 and 4 provide the exact DC power supplied to the DUT, the two other models are based on the approximation PR = 0.

Remote control: | [SENSe<Chn>:]PAE:EXPRession [SENSe<Chn>:]PAE:C [SENSe<Chn>:]PAE:K

#### Power Sensor...

Opens a configuration dialog for the measurement of wave quantities using an external power meter.

Power Sensor measurement example

The simplest test setup for a Power Sensor measurement involves one analyzer source port and a power sensor. The power sensor is connected e.g. to the analyzer's USB port and provides the (scalar) wave quantity results.

- The controls in the Power Meter panel show the configured power meters, open the System Configuration – External Power Meters
  dialog for adding and configuring external power meters, and start Auto Zeroing for the selected power meter.

- Show as selects the physical unit of the displayed trace. It is possible to display the measured Voltage U or convert the wave quantity into an effective power according to P = V2/Re(Z0). Z0 denotes the reference impedance of the source port (for wave quantities an) or of the receive port (for wave quantities bn). The reference impedances are defined in the Port Configuration
  dialog.

- Source Port selects one of the available test ports of the analyzer as a source of the stimulus signal.

Remote control: | CALCulate<Ch>:PARameter:MEASure "<Trace_Name>", "Pmtr1D1" | ... Create new trace and select name and measurement parameter: CALCulate<Ch>:PARameter:SDEFine "<Trace_Name>", "Pmtr1D1" |...