1. The document describes characterizing the output power, power added efficiency (PAE), and noise figure of a NE721 GaAs MESFET as a function of input and output matching conditions using load pull and noise figure measurements.
2. The optimum output match for gain is found to be Γout = 0.66/52° at Pin = -27dBm, but shifts to Γout = 0.66/36° at Pin = -4dBm (3dB compression point).
3. The optimum conditions are found to be Γout = 0.66/36° and Γin = 0.76/42° at Pin = -4dBm, producing
5. Step1: Measure your board. Lab board has severe discontinuities at SMA connector.
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7. Step2: Calibration Source Tuner Load Tuner Barrel Barrel DUT Board FET BIAS-T BIAS-T VNA Power Supply Vdrain=3V Vgate=-0.9V Tuner1 file Tuner2 file Contents of typical tuner file Position 1 mag(s11) phase (s11).. Position 2 mag(s11) phase (s11).. Position 3 mag(s11) phase (s11).. .. s2p S2p #1 S2p #2 s2p
8. Step2: Calibration DUT Board Barrel Barrel VNA 1. Apply port extension on a calibrated VNA up-to the open end of the TL. The DUT board is not populated with any MESFET. 340ps 340ps DUT Board Barrel Barrel VNA 340ps S2p file 1 2. Connect another DUT board with thru connection. Disengage port extension on P2 ONLY and measure S-parameters between P1 and P2. Repeat the same process for generating s2p for the other half of the board. P1 P2 P1 P2
9. Step2: Calibration Before De-embedding After De-embedding Increasing the path loss to/from the DUT shrinks the coverage of impedances that can be presented to the MESFET at the source and drain.
13. Step3: Determine Γ out,gain , P in =-27dBm F = 2.5GHz VDD = 3.0V Idd = 10mA Vgs = -0.97V Γ in =0.76 ∕ 42˚ P in =-27dBm Γ out,gain =0.66 ∕ 52˚
14. Step4: Measure Linearity & AM-PM @ Γ out,gain P 3dB,in = -4 dBm, P 1dB,in = -7 dBm, Gain = 17dB. Higher the gain, worse the linearity.
15. Step5: Determine Γ out,gain , P in =-4dBm F = 2.5GHz VDD = 3.0V Idd = 10mA Vgs = -0.97V Γ in=0.76 ∕ 42˚ P in =-4dBm Γ out,gain =0.66 ∕ 36˚ Gain = 14.5dB @ 1.5dB better than Γ out,gain @ Pin = -27dBm The optimum Γ out,gain is changing as device is driven into compression.
16. Step6: Determine Γ out,pout & Γ out,PAE , P in =-4dBm Γ out,pout =0.66 ∕ 36˚ P out = 10dBm Γ out,PAE =0.66 ∕ 36˚ PAE = 28%
17. Γ out,pout & Γ out,PAE , P in =+5dBm Γ out,pout =0.58 ∕ 13˚ P out = 13.2dBm Γ out,PAE =0.58 ∕ 13˚ PAE = 38%
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19. Step7: Determine Γ in,NF F = 2.5GHz VDD = 3.0V Idd = 10mA Vgs = -0.97V Γ out =0.66 ∕ 36˚ Γ in,NF =0.85∕ 43˚ NF = 5.1dB Γ in,NF =0.76∕ 42˚ NF = 5.9dB There is a slight offset between optimum Γ in,gain and Γ in,NF . Preference is given to gain and therefore the noise figure degrades by 0.8dB.