ECRI Microelectronics

HCA2 High-Precision Charge Amplifier

Features:
Connected with capacitive sensor

Gain: 2mV/pC adjustable
High charge/voltage accuracy: ≤0.5%
-3dB bandwidth: 3.6Hz~300kHz (typical value)
Volume is 25×20×5.5mm3, hybrid integrated metal airtight package case
Quality class: commercial, industrial, military and aerospace class
Range of operating temperature: 0~70℃, -40~85℃, -55~85℃, -55~125℃


1.Keywords of HCA2 High-Precision Charge Amplifier:

Charge, amplifier, high-precision, shock, acceleration, military

2.Description of HCA2 High-Precision Charge Amplifier:

HCA2 high-precision charge amplifier is a type of charge amplifier designed for accurate shock and acceleration measurement, and combined with it is a capacitive piezoelectric sensor. According to the principle of charge amplifier, it is very easy to achieve connection with long cable without affecting its accuracy, this is an advantage of charge amplifier over high-resistance voltage amplifier. By adopting metal case airtight package, it is also very easy to achieve signal shielding and noise reduction. Moreover, the internally interconnecting medium adopts ceramic wafer, the input impedance can be higher than that of PCB medium board, making the low-frequency response of electric circuit reach as low as 3.6Hz. The product has small volume and light weight, its main indexes reach or exceed the level of charge amplifier for general instrument such as LC0601, YE5850, HXC2102 etc., and complies with military standard on reliability.

3.Application of HCA2 High-Precision Charge Amplifier:

Measurement of shock, vibration and pressure
Measurement of slow varying acceleration

4.Schematic block diagram of HCA2 High-Precision Charge Amplifier

hca2-high-precision-charge-amplifier

HCA2 high-precision charge amplifier is a single-stage charge/voltage converter with A1 as its core and gain fixed at 2mV/pC.
Ca in the circuit is the self capacitor of sensor Q, Cc is the cable capacitor for connection and Ci is the input capacitor of circuit module. From the principle of charge amplifier, it can be derived that the gain of the first stage is V1=Q/Cf, where Q is the quantity of electric charge of the sensor. So it can be seen that V1 is independent of Ca, Cc, Ci etc., this is the reason that the charge amplifier adapts to signal measurement of high-sensitivity sensor.

5.Pin designation of HCA2 High-Precision Charge Amplifier


The module is of DIL construction. Pins of the circuit are as follows:
hca2-high-precision-charge-amplifier
Bottom view

Pin

Symbol

Meaning

Pin

Symbol

Meaning

1

NOP

Blank

7

GND

Ground

2

NOP

Blank

8

NOP

Blank

3

IN3

Input 3

9

IN4

Input 4

4

IN1

Input 1

10

-15V

Negative power source

5

FBP

Filtration

11

OUT

Output

6

IN2

Input 2

12

+15V

Positive power source


6.Electric performance of circuit of HCA2 High-Precision Charge Amplifier


Table 1  Electric characteristics

Characteristics

Symbol

Condition

(Unless otherwise specified,

VCC=15±0.1V

VEE=-15±0.1V

-55℃≤TA≤125℃)

Limit value

Unit

Min.

Max.

Input charge range

Q


0.05

10,000

pC

Gain1)

A1


1.99

2.01

mV/pC

Bandwidth (-3dB)

f


5

20,000

Hz

Max. output voltage

Vmax


11.5

-

V

Gain accuracy

Ac


-

0.5

%

Harmonic distortion

α


-

0.5

%

Noise voltage

VN


-

2

mV

Notes:
1) The output is phase reversed

7.Characteristic curve of HCA2 High-Precision Charge Amplifier


hca2-high-precision-charge-amplifier

Amplitude-frequency characteristic

8.Application block diagram of HCA2 High-Precision Charge Amplifier

hca2-high-precision-charge-amplifier

9.External dimensions of HCA2 High-Precision Charge Amplifier


hca2-high-precision-charge-amplifier
The type of package and performance indexes of the circuit can be adjusted and customized according to customer’s demand.

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