ca3160t Intersil Corporation, ca3160t Datasheet - Page 4

• Manufacturer Part Number: ca3160t
• Description: 4mhz, Bimos Operational Amplifier With Mosfet Input/cmos Output
• Manufacturer: Intersil Corporation

Schematic Diagram
Application Information
Circuit Description
Refer to the Block Diagram of the CA3160 series CMOS
Operational Amplifiers. The input terminals may be operated
down to 0.5V below the negative supply rail, and the output
can be swung very close to either supply rail in many
applications. Consequently, the CA3160 series circuits are
ideal for single supply operation. Three class A amplifier
stages, having the individual gain capability and current
consumption shown in the Block Diagram provide the total
gain of the CA3160. A biasing circuit provides two potentials
for common use in the first and second stages. Terminals 8
and 1 can be used to supplement the internal phase
compensation network if additional phase compensation or
frequency roll-off is desired. Terminals 8 and 4 can also be
used to strobe the output stage into a low quiescent current
state. When Terminal 8 is tied to the negative supply rail
(Terminal 4) by mechanical or electrical means, the output
potential at Terminal 6 essentially rises to the positive supply-
rail potential at Terminal 7. This condition of essentially zero
current drain in the output stage under the strobed “OFF”
condition can only be achieved when the ohmic load
BIAS CURRENT
Z
8.3V
40k
1
R
INV. INPUT
1
NON-INV.
5k
R
INPUT
Q
2
1
3
2
+
-
D
D
D
D
1
2
3
4
NOTE: Diodes D
4
INPUT STAGE
D
5
5
1k
1k
R
R
Q
3
5
CURRENT SOURCE
9
OFFSET NULL
5
FOR Q
Through D
Q
6
Q
Q
2
4
6
Q
AND Q
CA3160, CA3160A
7
D
6
Q
7
R
1k
R
1k
10
Provide Gate Oxide Protection For MOSFET Input Stage.
4
6
7
1
D
7
COMP IF DESIRED
SUPPLEMENTARY
resistance presented to the amplifier is very high (e.g., when
the amplifier output is used to drive MOS digital circuits in
comparator applications).
Input Stage - The circuit of the CA3160 is shown in the
Schematic Diagram. It consists of a differential-input stage
using PMOS field-effect transistors (Q
mirror-pair of bipolar transistors (Q
resistors together with resistors R
pair transistors also function as a differential-to-single-ended
converter to provide base drive to the second-stage bipolar
transistor (Q
by connecting a 100,000 potentiometer across Terminals 1
and 5 and the potentiometer slider arm to Terminal 4.
Cascode-connected PMOS transistors Q
constant-current source for the input stage. The biasing circuit
for the constant-current source is subsequently described.
The small diodes D
against high-voltage transients, including static electricity
during handling for Q
Second-Stage - Most of the voltage gain in the CA3160 is
provided by the second amplifier stage, consisting of bipolar
SECOND
STAGE
“CURRENT SOURCE
LOAD” FOR Q
Q
2k
30
pF
11
Q
Q
3
5
11
). Offset nulling, when desired, can be effected
11
5
through D
6
OUTPUT
STAGE
and Q
8
STROBING
7
.
7
provide gate-oxide protection
Q
3
Q
9
12
8
through R
, Q
6
10
7
, Q
4
) functioning as load
2
V+
7
, Q
OUTPUT
) working into a
4
6
6
. The mirror-
, are the