A275 Pulse Amplifier

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/盜), and low input noise (4 nV/Ö 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.

Features

Power 15 mW
Slew Rate 100 V/盜
Input Noise 4 nV/ÖHz
Stable DC Operation
200 MHz Gain-Bandwidth Product
High Reliability Screening
Radiation Hard to 10⁵ rad(Si)
Unity Gain Stable

Applications

Space Instrumentation
Portable Instrumentation
Nuclear Instrumentation
Precision Active Filter Design
Pulse Shaping

Figure 1. - Connection diagram.

Pin Configuration
Pin	Function
1	Inverting input
2	Non-inverting input
3	Bias adjust to Pin 4, (R > 3 kohm)
4	-Vs direct
5	-Vs through 50 ohms
6	Compensation to Pin 7, (C = 0 to 5 pF)
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)

Absolute Maximum Ratings
Supply Voltage
±8 V

Input Voltage
±V_S

Operating Temperature
-55 蚓 to +125 蚓

Storage Temperature
-65 蚓 to +150 蚓

Lead Temperature Range (Soldering, 10 sec.)
+300 蚓

Absolute Maximum Ratings
Supply Voltage	±8 V
Input Voltage	±V_S
Operating Temperature	-55 蚓 to +125 蚓
Storage Temperature	-65 蚓 to +150 蚓
Lead Temperature Range (Soldering, 10 sec.)	+300 蚓

Electrical Characteristics V_S = ? V, T_A = +25 蚓
Parameter Symbol Conditions
Min
Typ
Max
Units

Input Offset Voltage V_OS
2
5
mV

Input Offset Current I_OS
0.1
0.6
渙

Input Bias Current I_B
1.5
4
渙

Input Capacitance C_IN
4

pF

Differential Input Resistance R_IN
44

kohm

Common-Mode Input Resistance R_IN
5
8

Mohm

Common-Mode Rejection Ratio CMRR
90
95

dB

Common-Mode Input Range IVR
?.5

V

Power Supply Rejection Ratio PSRR
60

dB

Large-Signal Voltage Gain
@5kHz
@5kHz
@10MHz
@10MHz
A_LFC
A_LF
A_HFC
A_HF
compensated
uncompensated
compensated
uncompensated
64
72
16
24
66
74
20
28
dB

Pulse Risetime (A_V = 10) trc
tr compensated
uncompensated
15
9
22
15

ns

Output Voltage Swing V_OP
V_ON positive
negative
+4.5

+4.7
-4.5

-4.5
V

Open Loop Output Resistance R_O
750

ohm

Output Short-Circuit Current I_OSC source
sink
11
-4

mA

Slew Rate S_RP
S_RN positive
negative
65
35
100
57

V/盜

Input Noise Voltage Density e_N
4

nV/ÖHz

Supply Current I_S
±1.1

±1.25

±1.4

mA

Power Consumption P_D
15

mW

Electrical Characteristics V_S = ? V, T_A = +25 蚓
Parameter	Symbol	Conditions	Min	Typ	Max	Units
Input Offset Voltage	V_OS			2	5	mV
Input Offset Current	I_OS			0.1	0.6	渙
Input Bias Current	I_B			1.5	4	渙
Input Capacitance	C_IN			4		pF
Differential Input Resistance	R_IN			44		kohm
Common-Mode Input Resistance	R_IN		5	8		Mohm
Common-Mode Rejection Ratio	CMRR		90	95		dB
Common-Mode Input Range	IVR			?.5		V
Power Supply Rejection Ratio	PSRR			60		dB
Large-Signal Voltage Gain @5kHz @5kHz @10MHz @10MHz	A_LFC A_LF A_HFC A_HF	compensated uncompensated compensated uncompensated	64 72 16 24	66 74 20 28		dB
Pulse Risetime (A_V = 10)	trc tr	compensated uncompensated		15 9	22 15	ns
Output Voltage Swing	V_OP V_ON	positive negative	+4.5	+4.7 -4.5	-4.5	V
Open Loop Output Resistance	R_O			750		ohm
Output Short-Circuit Current	I_OSC	source sink		11 -4		mA
Slew Rate	S_RP S_RN	positive negative	65 35	100 57		V/盜
Input Noise Voltage Density	e_N			4		nV/ÖHz
Supply Current	I_S		±1.1	±1.25	±1.4	mA
Power Consumption	P_D			15		mW

Figure 2. - A275 gain & phase

Figure 3. - A275 pulse characteristics
Upper: Input pulse
First output: 3 pole
Second output: 5 pole

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 盜 risetime (2.3 盜 peaking time).

PC275
Dimensions: 3.5in X 1.75in (88.9mm X 44.45mm)

Figure 4. - The A250 connected to a solid state detector with 5-pole shaping and active baseline restoration.

Figure 5. - General case for 3 and 5-pole response for different peaking times (T_P)