The PGA-103+ is a monolithic amplifier for the 50-4000 MHz range with excellent noise figure and a high dynamic range (1 dB compression point: 22.5 dBm and ultra-high OIP3, 44 dBm typ. @ 2GHz). Due to the intrinsic nature of the GaAs PHEMT, it is not unconditionally stable (stability factor k>1 and stability measure B>0) as k.

Figure 1: PGA-103+: stability factor.

In order to improve stability additional components need to be added at input, see Figure 2 and associated component values in Table 1.

Figure 2: Stabilization circuit (Ref: TB-761-103+).
Table 2.

The stability parameters of the amplifier with the stabilizing network are shown in Figure 3. Note: k>1 and B>0 over entire range.

The performance of the stabilized amplifier:

Performace with and without stabilization is shown in Figures 3 – 11:

Figure 3: Stability factor (k-factor).
Figure 4: Stability measure.
Figure 5: Gain.
Figure 6: Isolation.
Figure 7: Input return loss.
Figure 8: Output return loss.
Figure 9: Output IP3.
Figure 10: Output power at 1 dB compression.
Figure 11: Noise figure.


  • Use of the stabilization circuitry has minor impact on all parameters.
  • The use of the stabilization circuitry guarantees amplifier’s unconditional stability.

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