AD8314 Analog Devices, AD8314 Datasheet - Page 17

• Manufacturer Part Number: AD8314
• Description: 100 MHz to 2.7 GHz, 45 dB RF Detector/Controller
• Manufacturer: Analog Devices

Figure 40 shows the relationship between the setpoint voltage,
V
function is linear in dB for a dynamic range of over 40 dB.
Figure 41 shows a similar circuit for a single band handset
power amplifier. The BGY241 (Phillips) is driven by a nominal
power level of 0 dBm. A 20 dB directional coupler, DC09-73
(Alpha), is used to couple the signal in this case. Figure 42
shows the relationship between the control voltage and the
output power at 0.9 GHz.
In both of these examples, noise on the V_DN pin can be reduced
by placing a simple RC low-pass filter between V
control pin of the power amplifier. However, the value of the
resistor should be kept low to minimize the voltage drop across
it due to the dc current flowing into the gain control input.
Figure 40. POUT vs. VSET at 0.9 GHz for Dual Mode Handset Power Amplifier
SET
and output power at 0.9 GHz. The overall gain control
–10
–20
–30
40
30
20
10
0
0
0.2
0.4
Application
VSET (V)
0.6
0.8
1.0
DN
and the gain
1.2
Rev. B | Page 17 of 20
0V TO 1.1V
ANTENNA
ATTN
15dB
TO
VSET
Figure 42. POUT vs. VSET at 0.9 GHz for Single Mode Handset
–10
–20
–30
–40
–50
40
30
20
10
Figure 41. A Single Mode Power Amplifier Control Circuit
0
0
15dBm
0dBm
MAX
52.3Ω
V
S
6
3
DC09-73
0.2
1
1
2
3
4
RFIN
ENBL
VSET
FLTR
2
4
5
AD8314
0.4
35dBm
220pF
MAX
C
F
VSET (V)
COMM
VPOS
V_DN
V_UP
0.6
BGY241
8
7
6
5
0.1µF
680pF
2.2µF
3.5V
47µF
0.8
RF INPUT
V
2.7V
S
AD8314
1.0
P
0dBm
IN