MGA-81563 데이터 시트보기 (PDF) - Avago Technologies
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MGA-81563 Datasheet PDF : 11 Pages
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50
PAE
40
30
IP3
20
Power
10
0
-10
-20 -15 -10 -5 0
POWER IN (dBm)
5 10
Figure 18. Output Power, IP , and Power-Added-Efficiency vs. Input Power.
3
(Vd = 3.0 V)
As the input power is increased beyond the linear range
of the amplifier, the gain becomes more compressed. Gain
as a function of either input or output power may be de-
rived from Figure 18. Gain compression renders the ampli-
fier less sensitive to variations in the power level from the
preceding stage. This can be a benefit in systems requiring
fairly constant output power levels from the MGA-81563.
Increased efficiency (45% at full output power) is another
benefit of saturated operation. At high output power lev-
els, the bias supply current drops by about 15%. This is
normal and is taken into account for the PAE data in Fig-
ure 18.
Noise figure and input impedance are also affected by
saturated power operation. As a guideline, the input im-
pedance is lowered, resulting in an improvement in input
VSWR of approximately 20%.
Like other active devices, the intermodulation products
of the MGA-81563 increase as the device is driven further
into nonlinear operation. The 3rd, 5th, and 7th order in-
termodulation products of the MGA-81563 are shown in
Figure 19 along with the fundamental response. This data
was measured in the test circuit in Figure 10.
30
20
10
Pout
0
-10
3rd
-20
-30
-40
5th
7th
-50
-60
-30 -15 -10 -5 0 5 10 15
FREQUENCY (GHz)
Figure 19. Intermodulation Products vs. Input Power.
(Vd = 3.0V)
Operation at Bias Voltages Other than 3 Volts
While the MGA-81563 is designed primarily for use in +3
volt applications, the internal bias regulation circuitry al-
lows it to be operated with any power supply voltage from
+1.5 to +5 volts. Performance of Gain, Noise Figure, and
Output Power over a wide range of bias voltage is shown
in Figure 20. As can be seen, the gain and NF are fairly
flat, but an increase in output power is possible by using
higher voltages. The use of +5 volts increases the P by
1dB
2 dBm.
18
16
Power
14
12
Gain
10
8
6
4
NF
2
0
0
1
2
3
4
5
SUPPLY VOLTAGE (V)
Figure 20. Gain, Noise Figure, and Output Power vs. Supply Voltage.
Some thermal precautions must be observed for operation
at higher bias voltages. For reliable operation, the channel
temperature should be kept within the 165°C indicated in
the “Absolute Maximum Ratings” table. As a guideline, op-
erating life tests have established a MTTF in excess of 106
hours for channel temperatures up to 150°C.
There are several means of biasing the MGA-81563 at
3 volts in systems that use higher power supply voltages.
The simplest method, shown in Figure 21a, is to use a se-
ries resistor to drop the device voltage to 3 volts. For ex-
ample, a 47Ω resistor will drop a 5-volt supply to 3 volts
at the nominal current of 42 mA. Some variation in per-
formance could be expected for this method due to varia-
tions in current within the specified 31 to 51 mA min/max
range.
+5 V
+5 V
+5 V
47 Ω Silicon
Diodes
Zener
Diode
(a)
(b)
(c)
Figure 21. Biasing From Higher Supply Voltages.
8
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