Benthowave Instrument Inc.

BENTHOWAVE INSTRUMENT INC. Acoustic Transducer & System 

Variable Gain Amplifier

BII-1030 series amplifiers are designed primarily to be used as programmable gain preamplifiers with analog gain control signal (for example, analog output of DAQ modules or potentiometers) to amplify the weak signals from hydrophones, receiving arrays and ultrasound transducers. It can also be used as TVG (Time Variable Gain) amplifiers in active SONAR and ultrasound system to compensate the transmission loss when working with voltage ramp gain control signals (for example, analog output of DAQ module generates voltage ramp signal to control the gain of BII-1030s.)

A bandpass filter is built in BII-1030 series amplifiers. To achieve lower output noise level (white noise), bandwidth of the amplifiers should be limited. Customized -3dB bandwidth should be specified when ordering to meet your project requirements on noise level and bandwidth.

Please consult DAQ module manufacturers for more information about DAQ (Data Acquisition Systems).

TVG (Time Variable Gain) Amplifier

Technical notes
The noise at Gain Control causes gain variation or output variation. Gain control signal shall be of very low noise. The BII-1030 series PCB shall be shielded completely to reduce electromagnetic noise coupling.
The cable has adverse effects on the signal quality in high frequency range. The longer the cable is, the worse the adverse effects is. If you use long cable in your project, you may specify customized output impedance of BII's preamplifiers to match cable impedance and the DAQ input impedance, for example, customized 50 ohms output impedance of BII preamplifier for 50 ohms RG58 coax of DAQ system.

BII-1030 Series   0 to 80 dB Variable Gain Amplifier

Suggested Application  
Programmable Hydrophone/Ultrasound Preamplifier/NDT
TVG (Time Variable Gain) Amplifier, Range Compensation
Echo Sounding System: Image/Fishery/Plankton Sonar
Communication, Array Amplitude Shading
96 dB Gain Range, Programmable
Low Noise, Built-in Bandpass Filter
Wide Frequency Range: 20Hz to 30MHz
Power Down Mode: Low Power
Related Products  
BII-2000 AGC (Automatic Gain Control) Amplifier BII-1090 Preamplifier With Programmable Gain


TVG Amplifier BII-1031 BII-1032 BII-1033 BII-1034 BII-1035
Gain Range: 
(±0.3 dB Gain Error)
0 to 80 dB -11 to 69 dB -22 to 58 dB 0 to 80 dB 0 to 80 dB
Gain Range: 
(±1.25 dB Gain Error)
0 to 96 dB -14 to 82 dB -28 to 68 dB 0 to 96 dB 0 to 96 dB
-3dB Bandwidth: 30Hz to 3MHz 30Hz to 3MHz 30Hz to 3MHz 30Hz to 3MHz 500kHz to 30MHz
Noise (RTI) at 1kHz: 10 nV/√Hz
0.8 (fA/√Hz)
10 nV/√Hz
0.8 (fA/√Hz)
10 nV/√Hz
0.8 (fA/√Hz)
1.3 nV/√Hz
0.8 (pA/√Hz)
1.8 nV/√Hz
2.7 (pA/√Hz)
Input Impedance: 1. Default:44MΩ
2. Customized
1. Default:44MΩ
2. Customized
1. Default:44MΩ
2. Customized
1. Default:200kΩ
2. Customized
1. Default:350Ω
2. Customized
Supply Voltage: +8.5 to +24 VDC +8.5 to +24 VDC +8.5 to +24 VDC +7.5 to +24 VDC +5.5 to +24 VDC
Current (Quiescent): Active, 43 mA
Shut-Down: 11 mA
Active, 43 mA
Shut-Down: 11 mA
Active, 43 mA
Shut-Down: 11 mA
Active, 50mA
Shut-Down: 18 mA
Active, 39 mA
Shut-Down: 8 mA
Miscellaneous: BII-1030 Series Preamplifier
Suggested DC Supply: +9VDC Battery, Marine Battery, Automobile Battery, Fixed DC Linear Power Supply, Not Included.
DO NOT use variable power supply whose maximum supply voltage is higher than the above rated voltage.
DO NOT use switching mode DC power supply.
Shut-Down/Active: Active: Control Voltage Vc > 50mV
Shut-Down: Control Voltage Vc: 0 to 50mV
Gain Control Voltage Vc: DC Coupling
+0.4 to +2.4 VDC (80 dB Gain Range)
+0.1 to +2.9 VDC (96 dB Gain range)
Vc must be in the range: 0VDC ≤ Vc ≤ +5VDC.
Vc < 0VDC or Vc> +5VDC will damage the device permanently.
Gain Scaling Factor:  40 dB/V
Response Time: <= 0.2 μs
Bandpass Filter: Built-in, customized, specify when ordering.
Note: White noise level is proportional to the square root of bandwidth. Narrow bandwidth should be customized to reduce the white noise level at output.
Input Type: Differential (either single ended or differential input signals are accepted).
Input Wiring: Coated PCB: 3cm wires; Potted Unit: 0.15m Cables/Wires.
Output Type: Single-ended
Output Wiring: Coated PCB: 3cm wires; Potted Unit: 0.15m Cables/Wires.
Maximum Input Level:   6 Vpp
Maximum output Level:    3 Vpp
Output Impedance:   1. Default: 50Ω
2. Customized, Specify when ordering
Cable Drive Capability: 1000 meters
Connector: Wire leads (no connector) in default for coated PCB
Size:  Coated PCB: LxWxH = 56x22x13mm; Potted Unit: ΦDxL = 73x23mm
Operating Temperature:  -40°C to 85°C
Storage Temperature:  -50°C to 105°C
DAQ Wiring: Click DAQ Wiring for detailed wiring information to data acquisition devices.
How to order:
BII-103x -xxx -xxx
Refer to specification Highpass -3dB cut-off Frequency in kHz Lowpass -3dB cut-off Frequency in kHz
BII-1031-0.02-100: BII-1031, 20Hz HP filter, 100kHz LP filter.
BII-1031-1-5: BII-1031, 1kHz HP filter, 5kHz LP filter.
BII-1034-80-150: BII-1034, 80kHz HP filter, 150kHz LP filter.

Gain vs. Vc

TVG Amplifier

Coated Preamplifier Wiring

Variable Gain Amplifier 

Potted Unit

Hydrophone Preamplifiers

Technical Notes

Transmission loss results from spreading and attenuation.

Spherical Spreading:
    TL = 20 * log R         R - Range (m)

Absorption Coefficient below 50 kHz:
    α (dB/km)) = 1.0936 [0.1*f*f/(1 + f*f) + 40*f*f/(4100 + f*f)]
    f - Frequency (kHz)

For more information about transmission loss, please refer to textbooks on Underwater Acoustics.

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