5
LT1251/LT1256
CONTROL VOLTAGE (V)
0
GAIN
(V/
V)
1.0
0.8
0.6
0.4
0.2
0
2.0
1251/56 G01
0.5
1.0
1.5
2.5
VFS = 2.5V
IN2
IN1
TYPICAL PERFORMANCE CHARACTERISTICS
UW
LT1251/LT1256
Control Path Bandwidth
FREQUENCY (Hz)
VOLTAGE
GAIN
(dB)
10
8
6
4
2
0
–2
–4
–6
–8
–10
10k
1M
10M
100M
1251/56 G04
100k
VOLTAGE DRIVE VC
VS = ±5V
PIN 4 NOT IN SOCKET
THD Plus Noise vs Frequency
FREQUENCY (Hz)
0.01
THD
+
NOISE
(%)
0.1
1
10
1k
10k
1251/56 G08
0.001
100
100k
VC
CC
= 10%
VC
CC
= 50%
VC
CC
= 100%
VS
CC
= ±5V, VIN = 1VRMS
AV = 1, RF = 1.5k, VFS = 2.5V
CONTROL VOLTAGE (V)
0
GAIN
(V/
V)
1.0
0.8
0.6
0.4
0.2
0
2.0
1251/56 G02
0.5
1.0
1.5
2.5
VFS = 2.5V
IN2
IN1
FREQUENCY (Hz)
100k
OUTPUT
VOLTAGE
(V
P-P
)
8
7
6
5
4
3
2
1
1M
10M
100M
1251/56 G07
AV = 10
AV = 1
VS = ±5V
RL = 1k
RF = 1.5k
VC = VFS = 2.5V
Undistorted Output Voltage
vs Frequency
FREQUENCY (Hz)
VOLTAGE
GAIN
(dB)
10
8
6
4
2
0
–2
–4
–6
–8
–10
10k
1M
10M
100M
1251/56 G05
100k
VOLTAGE DRIVE RC
VC = GND
VS = ±5V
LT1251/LT1256
Control Path Bandwidth
FREQUENCY (MHz)
05
3RD
ORDER
INTERCEPT
(dBm)
10
20
15
25
30
1251/56 G10
50
45
40
35
30
25
20
15
10
VS
CC
= ±15V
AV = 1
RF = 1.5k
RL = 100
VC = VFS = 2.5V
3rd Order Intercept vs Frequency
2nd and 3rd Harmonic Distortion
vs Frequency
FREQUENCY (MHz)
1
DISTORTION
(dBc)
–20
–30
–40
–50
–60
–70
10
100
1251/56 G09
VS
CC
= ±5V
AV = 1
RF = 1.5k
RL = 1k
VO = 2VP-P
VC = VFS = 2.5V
3RD
2ND
FREQUENCY (Hz)
10
1
10
100
1k
10k
1251/56 G06
SPOT
NOISE
(nV/
√
Hz
OR
pA/
√
Hz)
+in
en
–in
Spot Input Noise Voltage and
Current vs Frequency
LT1251
Gain vs Control Voltage
LT1256
Gain vs Control Voltage