Agilent E8267C/E8257C/E8247C PSG Application Note Obtain flat-port power with Agilent’s PSG user flatness correction or external leveling functions
E8247C PSG CW signal generator Agilent E8244A E8257C PSG analog signal generator Agilent E8254A E8267C PSG vector signal generator 2
Table of Contents Introduction Using External Leveling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 The PSG synthesized signal generators provide extremely flat power at your test port for testing power sensitive devices such as amplifiers, mixers, diodes, or detectors. The user flatness correction feature of the PSGs compensates for attenuation and power variations created by components between the source and the test device.
Using External Leveling The PSG signal generator can be leveled externally by connecting an external sensor at the point where leveled RF output power is desired. The sensor detects changes in RF output power and returns a compensating voltage to the signal generator’s ALC input. The ALC circuitry raises or lowers (levels) the RF output power based on the voltage received from the external sensor, ensuring constant power at the point of detection. Two types of external leveling are available on the PSG.
Configure the signal generator 1. Press [Preset]. 2. Press [Frequency] > [10] > {GHz}. 3. Press [Amplitude] > [0] > {dBm}. 4. Press [RF On/Off]. 5. Press {Leveling Mode} > {External Detector}. This configuration deactivates the internal ALC detector and switches the ALC input path to the front panel ALC INPUT connector. The EXT indicator is activated in the AMPLITUDE area of the display. NOTE For signal generators with Option 1E1, notice that the ATTN HOLD (attenuator hold) enunciator is displayed.
Figure 3-2 shows the input power versus output voltage characteristics for typical diode detectors from Agilent Technologies. Using this information, you can determine the leveled power at the diode detector input by measuring the external detector output voltage. The range of power adjustment is approximately –20 to +25 dB External leveling with Option 1E1 signal generators Signal generators with Option 1E1 contain a step attenuator prior to the RF output connector.
Leveling with a Millimeter-Wave Source Module Millimeter-wave source module leveling is similar to external detector leveling. The power level feedback signal to the ALC circuitry is taken from the millimeter-wave source module, rather than the internal signal generator detector. This feedback signal levels the RF output power at the mm-wave source module output through the signal generator’s rear panel source module interface connector. Figure 3-3.
Figure 3-4. External Millimeterwave source module leveling with an Option 1EA signal generator. Signal generator MENUS E8254A 250 kHz – 40 GHz PSG -A Series Signal Generator AM Frequency FREQUENCY GHZ 10.00 RF ON Amplitude dBm Print LINE Local FM/ ΦM Utility Pulse LF Out EXT 2 INPUT MOD ON Hold O EXT 1 INPUT Sweep/ List AMPLITUDE 40.000 000 000 000 Incr Set Save Recall 7 8 9 4 5 6 1 2 3 Trigger 0 .
Creating and Applying User Flatness Correction Using an Agilent E4416A/17A or E4418B/19B power meter, you can create user flatness correction arrays to correct RF output amplitude variances at user-defined frequencies. After completing a user flatness correction, the correction array data can be saved to the signal generator’s memory catalog and recalled on demand.
Figure 3-5. User Flatness Correction Equipment Setup. GPIB Signal generator MENUS E8254A 250 kHz – 40 GHz PSG -A Series Signal Generator AM Frequency FREQUENCY GHZ 10.00 RF ON Amplitude dBm Print LINE Local FM/ ΦM Utility Pulse LF Out EXT 2 INPUT MOD ON Hold O EXT 1 INPUT Sweep/ List AMPLITUDE 40.000 000 000 000 Incr Set Save Recall 7 8 9 4 5 6 1 2 0 .
Configure the signal generator 1. Press [Preset]. 2. Press [Amplitude] > {More (1 of 2)} > {User Flatness} > {Configure Cal Array} > {More (1 of 2)} > {Preset List} > {Confirm Preset}. This opens the User Flatness table editor and presets the correction array frequency/correction list. 3. Press {Configure Step Array}. This opens a menu for entering the user flatness step array data. 4. Press {Freq Start} > [1] > {GHz}. 5. Press {Freq Stop} > [10] > {GHz}. 6. Press {# of Points} > [10] > [Enter].
Performing the user flatness correction manually If you are not using an Agilent E4416A/17A/18A/19A power meter or if you do not have GPIB interface capability, you can perform the user flatness correction manually. Complete the steps in this section and then continue with the User Flatness Correction tutorial. 1. Press {More (1 of 2)} > {User Flatness} > {Configure Cal Array}. This opens the user flatness table editor and places the cursor over the frequency value (1 GHz) for row 1.
Recalling and applying a user flatness correction array Before performing the steps in this section, complete Creating a User Flatness Correction Array. 1. Press [Preset]. 2. Press [Amplitude] > {More (1 of 2)} > {User Flatness} > {Configure Cal Array} > {More (1 of 2)} > {Preset List} > {Confirm Preset}. 3. Press {More (2 of 2)} > {Load/Store}. 4. Ensure that the file FLATCAL1 is highlighted. 5. Press {Load From Selected File} > {Confirm Load From File}.
Array Using a MM-Wave Source Module In this example, a user flatness correction array is created to provide flatness-corrected power at the output of an Agilent 83554A millimeterwave source module driven by an Agilent E8247C signal generator. The flatness correction array contains 28 frequency correction pairs (amplitude correction values for specified frequencies), from 26.5 to 40 GHz in 500 MHz intervals. This will result in 28 evenly spaced flatness corrected frequencies between 26.
Figure 3-6. User flatness with mm-wave source module for a signal generator without Option 1EA. GPIB Signal generator MENUS E8254A 250 kHz – 40 GHz PSG -A Series Signal Generator FREQUENCY GHZ 10.00 RF ON dBm AM Sweep/ List Amplitude FM/ ΦM Utility Pulse LF Out EXT 2 INPUT MOD ON Hold Print O LINE Power meter EXT 1 INPUT Frequency AMPLITUDE 40.000 000 000 000 Local Incr Set Save Recall 7 8 9 4 5 6 Trigger 1 2 3 0 .
Configure the signal generator 1. Turn on the signal generator’s line power. Upon power-up, the signal generator automatically: senses the mm-wave source module, switches the signal generator’s leveling mode to external/source module, sets the mm-wave source module frequency and amplitude to the source module’s preset values, and displays the RF output frequency and amplitude values available at the mm-wave source module output.
Perform the user flatness correction NOTE If you are not using an Agilent E4416A/17A/18A/19A power meter, or if you do not have GPIB interface capability, you can perform the User Flatness Correction manually. For instructions, see “Performing the User Flatness Correction Manually.” 1. Press {More (1 of 2)} > {User Flatness} > {Do Cal}. This performs the user flatness correction. The signal generator enters the user flatness correction routine and a progress bar is shown on the display. 2.
User Flatness Correction Manually If you are not using an Agilent E4416A/17A/18A/19A power meter or if you do not have GPIB interface capability, you can perform the User Flatness Correction manually. Complete the steps in this section and then continue with the User Flatness Correction tutorial. 1. Press [More (1 of 2)] > {User Flatness} > {Configure Cal Array}. This opens the User Flatness table editor and places the cursor over the frequency value (26.5 GHz) for row 1.
Save the User Flatness Correction Data to the Memory Catalog This process allows you to save the user flatness correction data as a file in the signal generator’s memory catalog. With several user flatness correction files saved to the memory catalog, specific files can be recalled, loaded into the correction array, and applied to the RF output to satisfy various RF output flatness requirements. 1. Press {Load/Store}. 4. Press {Enter}.
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