Pulse Amplifier

A275

The A275 is a high performance hybrid differential
op-amp developed as a pulse amplifier for spaceborne
nuclear instrumentation.
Its low power dissipation (15 mW), high slew rate
(100 V/µs), and low input noise (4 nV/√Hz), make itideal for use in a wide range of op-amp applications.
The A275 is packaged in a standard 14-pin hybridDIP.

Features

Applications• 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• Space instrumentation• Portable instrumentation• Nuclear instrumentation• Precision active filter design• Pulse shaping

CONNECTION and PACKAGE DIAGRAMS
Compensation
Compensation

1413+6 V

121147 nF

106<5 pF

750

2Input

1A275

947 nF

3>3 k5050

4Bias Adjust

5-6 V

8Output

PIN
12
34
56
7
8910
1112,13,14

AMPTEK INC.

FUNCTION
Inverting input
Non-inverting Input
Bias adjust to Pin 4, (R>3 kohm)-Vs direct-Vs through 50 ohms
Compensation to Pin 7, (C = 0-5 pF)
Case and Ground
Output through 50 ohms
Output direct+Vs through 50 ohms
+ Vs direct
Compensation: Leave open for gain <10;
Short for gain >10

14 De Angelo Drive, Bedford, MA 01730-2204 U.S.A.
Tel: +1 (781) 275-2242 Fax: +1 (781) 275-3470 e-mail: sales@amptek.com www.amptek.com

APPLICATION NOTESThe A250 Connected to a Solid State Detector
with 5 pole shaping and active baseline restoration+6 V

13.................

3 M (pole-zero)
44 mV/MeVA250

1410 M

9100 pF (NPO)

8JFET
7 12 6 4

10 nF (HV)

5-6 V

Solid state detector

1.07 K....................................................

..........................................................

...................................
3-pole shaping

2-pole shaping+6 V
14 13 12 11 102+1+6 V

A275

14 13 12 11 10866

47 MH

2440 mV/MeV

168 pF(NPO)

91+

34A275914 13 12 11 10300 ns time to peak

499

27 MH

2A

152 pF(NPO)

1+22 V/MeV

A275

9857 634859K

7 63459K-6V+6 V+6 V

1.5 V/MeV

87 6

PC275 Schematic

8K-6 V

1K-6 V

2K1K712+ 4
BLR1

Active baseline restoration

68 1 9B..........................................................

10 nF (HV)

10........................

1 2 3 11

1M........................

+HVOutput......................................................................................................
-6 V

General Case for 3 and 5 Pole Response for Different Peaking Times (Tp)

Detector

TF

A250

Pole Zero
R0A275

C1R1L2R2C2A275

A

L33 pole output

R3A275C3R1 = 1.07 K
C1 = 360 pFxTp
L2 = 150 µHxTp
R2 = 834
C2 = 592 pFxTp
L3 = 82 µHxTp
R3 = 457
C3 = 564 pFxTp
Tp = Desired Peaking Time in µs for 5 Pole Response
R0 = TF/C1				
Peaking Time at the 3 Pole Output = (2/3) Tp
Note: Trim C2 for optimum baseline recovery at “A,” then trim C3 for optimum baseline recovery at “B.”For more information visit www.amptek.com

5 pole output
B

OPERATING NOTESPC275 Input/Output Waveforms

Gain (dB)80

Upper: Input Pulse
First Output (A): 3 Pole
Second Output (B): 5 Pole

A275 Gain/Phase

-20

70-40

60-60

50-80

40-10030-12020-14010-160

01 KHz 10 KHz 100 KHz 1 MHz 10 MHz
Frequency (Hz)100 MHz-180

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

Actual SizeDimensions: 3.5in x 1.75in (88.9mm x 44.45mm)

A275F
The A275FC and A275FN are high density versions of the Amptek A275 and feature aSingle In-line Package (SIP).
Please visit our web site at www.amptek.com for complete details.
For more information visit www.amptek.com

A275 SPECIFICATIONS
Absolute Maximum Ratings
Supply Voltage±8 V

Input Voltage± VS

Operating Temperature-55 C to +125OC

Storage Temperature-65OC to +150OC

O

Lead Temperature Range (Soldering, 10 sec.)

300OC

Electrical Characteristics  VS = ±6V,  TA = +25OC
PARAMETERSYMBOL

CONDITIONS

MIN

TYP

MAXUNITSmVInput Offset Voltage

VOS

25Input Offset Current

IOS

0.1

0.6

Input Bias Current

IB

1.5

4Input Capacitance

CIN

4pF

Differential Input ResistanceRIN

44k Ohm

Common-Mode Input ResistanceRIN

58M Ohm

Common-Mode Rejection Ratio

CMRR

9095

dB

Common-Mode Input Range

IVR

±4.5V

Power Supply Rejection Ratio

PSRR

60dB

Large-Signal Voltage Gain
@5 kHz@5 kHz@10 MHz@10 MHz

ALFC
ALF
AHFC
AHF

CompensatedUncompensatedCompensatedUncompensated6876
2128dBdBdB
dB

Pulse Risetime (AV = 10)trctrCompensatedUncompensatedOutput Voltage Swing

VOP
VON

Positive
NegativeOpen Loop Output ResistanceRO

Output Short-Circuit Current

IOSC

SourceSink

Slew Rate

SRP
SRN

Positive
Negative

66
73
1826

+4.2

65
35m

AA

m

15
92215

ns
ns

+4.4
-5.0

-5.5

VV

750

Ohm

11-4mAmA

100
40

V/s
V/s

4nV/Hzmm

Input Noise Voltage DensityenSupply Voltage

VS±4.5±6±8V

Supply Current

IS±1.1±1.25±1.4mA

Power ConsumptionPdÖ

15mWGeneralPackage

14 Pin Hybrid DIP

Test Board

PC275Screening(see web site: www.amptek.com/hybrids.html)

Amptek High Reliability Screening (Standard)
Option 1Option 2

Other Package(see web site: www.amptek.com/A275f.html)

A275FC or A275FN High-density versions of theAmptek A275 in a Single In-line Package (SIP).

AMPTEK INC. 14 DeAngelo Drive, Bedford, MA 01730-2204 U.S.A.
Tel: +1 (781) 275-2242 Fax: +1 (781) 275-3470 e-mail: sales@amptek.com www.amptek.com