SA5219 Datasheet, PDF (7/18 Pages) NXP Semiconductors – Wideband variable gain amplifier

Philips Semiconductors
Wideband variable gain amplifier
Product specification
SA5219
50Ω
SOURCE
4:1 TURNS RATIO
LC TUNED
TRANSFORMER
+5V
5219
50Ω
V_AGC
+1V
Figure 8. Narrowband Gain Optimization
50Ω
OUTPUT
This circuit will exhibit approximate-
ly an 8dB noise figure and 25dB gain.
SR00280
50Ω
SOURCE
+5V
50Ω
5219
50Ω
V_AGC
+1V
Figure 9. Simple Amplifier Configuration
50Ω
OUTPUT
The noise figure of this configuration
will be approximately 15dB.
SR00281
50Ω
SOURCE
+5V
5219
50Ω
V_AGC
+1V
Figure 10. Unterminated Configuration
50Ω
OUTPUT
With the 50Ω source left untermi-
nated, the noise figure is 9dB.
SR00282
+5V
50Ω
SOURCE
50Ω
OUTPUT
5219
V_BG
V_AGC
R₁
R₂
Gain = 19dB + 20log₁₀ V_AGC
50Ω
ƪ ƫ _{where VAGC =}
R₂
R₁ ) R₂
V_BG
and is in units of Volts, for V_AGC ≤ 1V
SR00283
Figure 11. User-Programmable Fixed Gain Block
1997 Nov 07
7