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PGA-105+: Stabilizing Network

The PGA-105+ is a 15dB gain monolithic amplifier for the 40-2600MHz range with excellent gain flatness and a high dynamic range (1dB compression point: 19.3dBm @ 2GHz).

S parameters for the PGA-105+ can be found here. Unconditional stability requires stability factor k>1 and stability measure B>0. However, an analysis of the S-parameters shows the amplifier has k<1 for frequencies under 60MHz.

Figure 1 - PGA-105+: stability parameters

In order to improve stability, addition components need to be added at input and output, see Figure 2:

Figure 2: stabilization circuit
Figure 2: stabilization circuit

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

Figure 3 - PGA-105+: k-factor
Figure 4 - PGA-105+: k-factor

The stabilized amplifier has an amplification of about 14.5 dB

The performance of the stabilized amplifier:

Figure 5 - Return Loss
Figure 6 - Amplification
Figure 7 - Compression
Figure 8 - IP3
Figure 9 - Noise Figure


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