Avago Technologies MGA-81563 - Manual (Page 4)

Page 4 of 6
A second approach to extending the low frequency performance of the
MGA-81563 / 82563 amplifiers is to add a shunt resistor at the input as
shown in Figure 4. Since the input of the MGA-81563 / 82563 amplifiers is
at a DC potential of zero volts, it is possible to add a shunt resistor directly
to the input of the amplifier without disturbing the amplifier's internal DC
bias. The value of the shunt resistor may be selected to provide as good a
match at the input as desired. The trade-off is, of course, lower gain and
higher noise figure. The shunt resistor approach is the simplest and has the
advantage of improving performance down to DC frequency.
Figure 4. MGA-82563 Circuit with Input Shunt Resistor.
Figure 5 shows a test circuit with a shunt resistor placed at the input of the
MGA-82563.
Figure 5. Test Circuit with Input Shunt Resistor.
The test results of the shunt R circuit are shown in Figure 6. Data is shown
for both gain and input return loss for several values of shunt resistor.
A second approach to extending the low frequency performance of the