LT1630/LT1631
20
16301fa
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507
●
www.linear.com
LINEAR TECHNOLOGY CORPORATION 2009
LT 0210 REV A • PRINTED IN USA
relaTeD parTs
Typical applicaTion
RF Amplifier Control Biasing and DC Restoration
Taking advantage of the rail-to-rail input and output, and
the large output current capability of the LT1630, the
circuit, shown in Figure 6, provides precise bias currents
for the RF amplifiers and restores DC output level. To
ensure optimum performance of an RF amplifier, its bias
point must be accurate and stable over the operating
temperature range. The op amp A1 combined with Q1,
Q2, R1, R2 and R3 establishes two current sources of
21.5mA to bias RF1 and RF2 amplifiers. The current of
Q1 is determined by the voltage across R2 over R1, which
is replicated in Q2. These current sources are stable and
precise over temperature and have a low dissipated power
due to a low voltage drop between their terminals. The
amplifier A2 is used to restore the DC level at the output.
With a large output current of the LT1630, the output can
be set at 1.5VDC on 5V supply and 50Ω load. This circuit
has a 3dB bandwidth from 2MHz to 2GHz and a power
gain of 25dB.
–
+
A1
1/2 LT1630
V
OUT
1630/31 F06
5V
5V
HP-MSA0785
HP-MSA0785
R3
10k
L1
220µH
C5
0.01µF
L2
220µH
Q1
2N3906
Q2
2N3906
C6
0.01µF
R5
50Ω
R1
10Ω
R2
453W
R4
10Ω
C3
1500pF
–
+
A2
1/2 LT1630
C4
1500pF
C2
1500pF
C1
0.01µF
V
IN
L4
3.9µH
L3
3.9µH
+
+
+
RF1
RF2
Figure 6. RF Amplifier Control Biasing and DC Restoration
PART NUMBER DESCRIPTON COMMENTS
LT1211/LT1212 Dual/Quad 14MHz, 7V/µs, Single Supply Precision Op Amps Input Common Mode Includes Ground, 275µV V
OS(MAX)
,
6µV/°C Max Drift, Max Supply Current 1.8mA per Op Amp
LT1213/LT1214 Dual/Quad 28MHz, 12V/µs, Single Supply Precision Op Amps Input Common Mode Includes Ground, 275µV V
OS(MAX)
,
6µV/°C Max Drift, Max Supply Current 3.5mA per Op Amp
LT1215/LT1216 Dual/Quad 23MHz, 50V/µs, Single Supply Precision Op Amps Input Common Mode Includes Ground, 450µV V
OS(MAX)
,
6µV/°C Max Drift, Max Supply Current 6.6mA per Op Amp
LT1498/LT1499 Dual/Quad 10MHz, 6V/µs Rail-to-Rail Input and Output
C-Load™ Op Amps
High DC Accuracy, 475µV V
OS(MAX)
, 4µV/°C Max Drift,
Max Supply Current 2.2mA per Amp
LT1632/LT1633 Dual/Quad 45MHz, 45V/µs Rail-to-Rail Input and Output Op Amps High DC Accuracy, 1.35mV V
OS(MAX)
, 70mA Output Current,
Max Supply Current 5.2mA per Amp
