The A275 is a high performance hybrid differential op-amp developed as a pulse amplifier for instrumentation.

Its low power dissipation (15 mW), high slew rate (100 V/µs), and low input noise (4 nV/√ Hz), make it ideal for use in a wide range of op-amp applications. The A275 is packaged in a standard 14 Pin hybrid DIP and is also available in a SIP as the A275F.

Features

  • Power 15 mW
  • Slew Rate 100 V/µs
  • Input Noise 4 nV/√Hz
  • Stable DC Operation
  • 200 MHz Gain-Bandwidth Product
  • High Reliability Screening
  • Unity Gain Stable

a275

Absolute Maximum Ratings

Supply Voltage ±8 V
Input Voltage ±VS
Operating Temperature -55 °C to +125 °C
Storage Temperature -65 °C to +150 °C
Lead Temperature Range (Soldering, 10 sec.) +300 °C

Physical

Package 14 Pin hybrid DIP, also available in a SIP as the A275F.
Weight 3.8 g

Electrical Characteristics

VS = ±6 V, TA = +25 °C

Parameter Symbol Conditions Min Typ Max Units
Input Offset Voltage
Uncompensated/Compensated
VOS 2 5/7 mV
Input Offset Current IOS 0.1 0.6 µA
Input Bias Current IB 1.5 4 µA
Input Capacitance CIN 4 pF
Differential Input Resistance RIN 44 kohm
Common-Mode Input Resistance RIN >5 8 Mohm
Common-Mode Rejection Ratio CMRR 90 95 dB
Common-Mode Input Range IVR ±4.5 V
Power Supply Rejection Ratio PSRR 60 dB
Large-Signal Voltage Gain
@5kHz
@5kHz
@10MHz
@10MHz
ALFC
ALF
AHFC
AHF
compensated
uncompensated
compensated
uncompensated
64
72
16
24
66
74
20
28
dB
Pulse Risetime (AV = 10) trc
tr
compensated
uncompensated
15
9
22
15
ns
Output Voltage Swing VOP
VON
positive
negative
+4.2 +4.4
-5.0
-5.5 V
Open Loop Output Resistance RO 750 ohm
Output Short-Circuit Current IOSC source
sink
11
-4
mA
Slew Rate SRP
SRN
positive
negative
65
35
100
40
V/µs
Input Noise Voltage Density eN 4 nV/√Hz
Supply Current IS ±1.1 ±1.25 ±1.4 mA
Power Consumption PD 15 mW

Connection Diagram and Pin Out

a275 connection diagram

Pin Function
1 Inverting input
2 Non-inverting input
3 Bias adjust to Pin 4, (R > 3 kohm) Frequency De-Compensation
This resistor will increase the current to the input stage and increase the bandwidth
4 -Vs direct
5 -Vs through 50 ohms
6 Compensation to Pin 7, (C = 0 to 5 pF)
Frequency Compensation to decrease the bandwidth
7 Case and Ground
8 Output through 50 ohms
9 Output direct
10 +Vs through 50 ohms
11 +Vs direct
12,13,14 Compensation (leave open for gain < 10, short for gain > 10)

The A275 is also available in a SIP package as the A275F.

A275 gain & phase

a275 gain and phase

A275 pulse characteristics

a275 pulse

Upper: Input pulse
First output: 3 pole
Second output: 5 pole

Circuit Layout Considerations

Due to the high bandwidth of the A275, care should be taken in circuit layout. In general, ground plane construction is recommended. Input and output lines should be well separated and in most cases shielding will be necessary. Grounding the physical case of the A275 (in addition to Pin 7) to the ground plane can be used to avoid oscillations or electronic pick-up.

Connection to a solid state detector with 5 pole shaping and active baseline restoration

pc275 schematic

General case for 3 and 5-pole response for different peaking times (TP)

a275 general case

PC-275

The A275 can be tested as a shaping amplifier by using the circuit shown below.
The PC-275 Test Board accommodates three (3) A275s and a BLR1 and produces a 5-pole pulse with 1 µs risetime (2.3 µs peaking time).

pc275 layout
Figure 4. PC-275 layout. Dimensions: 3.5 in X 1.75 in (88.9 mm X 44.45 mm)

pc275 schematic
Figure 5. The A250 connected to a solid state detector with 5-pole shaping and active baseline restoration (BLR1). The PC-275 Schematic begins at the output of A250.

14 pin dip