## CONSTPOUT - Constant Output Power

#### How does the CONSTPOUT block work?

#### That CONSTPOUT stuff sounds simple, so why am I having problems?

#### How do I read the CONSTPOUT simulation output file?

## XDB - User Specified Compression Point

#### How does the XDB block work?

The XDB block performs several different analyses. The first analysis subtracts the specified XDB block GAIN_BACKOFF parameter from the input power level to compute the linear gain at every sweep point. If compression is defined from maximum gain rather than linear gain then the next analysis uses optimization to find the maximum gain. During the optimization, the input power starts at the input power level specified on the schematic and ramps up to find the maximum gain. The last analysis uses optimization to find the specified compression. During the optimization, the input power ramps up from the input power level specified on the schematic when compression is relative to linear gain and ramps up from the maximum gain point when compression is defined relative to the maximum gain.

#### That XDB stuff sounds simple, so why am I having problems?

There are two common issues that users find with the XDB block

- During each optimization, the input power is limited by the XDB block MAX parameter which specifies that the maximum input source scale factor (in W or V depending on the specified source)
- For example, if the input power level specified on the schematic is 0 dBm and MAX=100 then the input power level is limited to 20 dBm when searching for the maximum gain or specified compression point (0 dBm → 1 mW, 1 mW * 100 = 100 mW, 100 mW → 20 dBm)

- For example, if the input power level specified on the schematic is 0 dBm and MAX=100 then the input power level is limited to 20 dBm when searching for the maximum gain or specified compression point (0 dBm → 1 mW, 1 mW * 100 = 100 mW, 100 mW → 20 dBm)
- The second is that the optimization does not find the desired compression point before hitting the XDB block MAX_ITER number of iterations
- This can be caused by the optimization getting limited by MAX as discussed above, or, like any optimization, simply not having enough iterations to converge on the specified answer

The good news is that both of these are easy to diagnose by inspecting the simulation output file link in the Status Window

#### How do I read the XDB simulation output file

First, find the link to the output file in the Status Window (the Output - file link below) and click on it which will open the output file in AWRDE.

Simulation - NLN:One_Tone_1_dB_Compression.AP_HB.$FDOC 10:41:19 AM Begin Simulate 10:41:19 AM Freq - 11 points 10:41:19 AM Netlist - file://C:\My Dropbox\awr\appdata\jomoore\13.0\temp\High_Power_BJT_Amp(1)\NLN_One_Tone_1_dB_Compression.AP_HB.$FDOC\mwo_aplac_netlist.i 10:41:19 AM Output - file://C:\My Dropbox\awr\appdata\jomoore\13.0\temp\High_Power_BJT_Amp(1)\NLN_One_Tone_1_dB_Compression.AP_HB.$FDOC\mwo_aplac_output.txt 10:41:20 AM End Simulate (0.87s)

The first section of the file shows the input power used to find the linear gain and the linear gain values computed for each sweep point. Any simulation warnings will appear only under the first sweep point.

APLAC 9.10 Wed Apr 05 2017 at 10:27:52 Copyright (c) AWR-APLAC Corporation, Finland, 2005- ________________________________________________________________________________ FIND SMALL SIGNAL GAIN POWER IN=-110.000 dBm SWPVAL 1 LINEAR GAIN = 24.942 dB APLAC 9.10 WARNING: Extrapolating up in frequency from 1 GHz to 1.1 GHz (_S1_S7_S1) APLAC 9.10 WARNING: Extrapolating up in frequency from 1 GHz to 1.1 GHz (_S1_S1_S1) SWPVAL 2 LINEAR GAIN = 24.505 dB . . . SWPVAL 25 LINEAR GAIN = 22.818 dB

The next section of the file shows the max gain calculations.