Datasheet

LT1630/LT1631
14
16301fa
Typical perForMance characTerisTics
Harmonic Distortion vs Frequency 5V Small-Signal Response 5V Large-Signal Response
FREQUENCY (kHz)
100
HARMONIC DISTORTION (dBc)
0
–20
–40
–60
–80
–100
1000
1630/31 G30
200 500
3RD
2ND
2ND
3RD
V
S
= 5V, 0V
A
V
= 1
V
IN
= 2V
P-P
R
L
= 150Ω
R
L
= 1k
V
S
= 5V, 0V
A
V
= 1
R
L
= 1k
163031 G26
V
S
= 5V, 0V
A
V
= 1
R
L
= 1k
163031 G27
Harmonic Distortion vs Frequency ±15V Small-Signal Response ±15V Large-Signal Response
FREQUENCY (kHz)
100
HARMONIC DISTORTION (dBc)
0
–20
–40
–60
–80
–100
1000
1630/31 G31
200 500
3RD
2ND
3RD
V
S
= 5V, 0V
A
V
= –1
V
IN
= 2V
P-P
R
L
= 150Ω
R
L
= 1k
2ND
V
S
= ±15V
A
V
= 1
R
L
= 1k
163031 G28
V
S
= ±15V
A
V
= 1
R
L
= 1k
163031 G29
applicaTions inForMaTion
Rail-to-Rail Input and Output
The LT1630/LT1631 are fully functional for an input and
output signal range from the negative supply to the posi-
tive supply. Figure 1 shows a simplified schematic of the
amplifier. The input stage consists of two differential am-
plifiers, a PNP stage Q1/Q2 and an NPN stage Q3/Q4 that
are active over different ranges of input common mode
voltage. The PNP differential input pair is active for input
common mode voltages V
CM
between the negative supply
to approximately 1.4V below the positive supply. As V
CM
moves closer toward the positive supply, the transis-
tor Q5 will steer the tail current I
1
to the current mirror
Q6/Q7, activating the NPN differential pair and the PNP
pair becomes inactive for the rest of the input common
mode range up to the positive supply.
The output is configured with a pair of complementary
common emitter stages Q14/Q15 that enables the output
to swing from rail to rail. These devices are fabricated on
Linear Technology’s proprietary complementary bipolar
process to ensure similar DC and AC characteristics. Ca-
pacitors C1 and C2 form local feedback loops that lower
the output impedance at high frequencies.