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Model 6120, 2-Channel Strain/Bridge/IEPE Amplifier-Filter-Analog Output

  • Dual inputs, strain/bridge or IEPE transducers
  • Programmable bridge configuration
  • Voltage & current excitation with remote sensing per channel
  • Automatic zero & balance
  • Voltage substitution and two or four step shunt calibration
  • Gains 1 to 5,000 up to 100 kHz bandwidth with 0.05% accuracy
  • Programmable low-pass filters
  • Dual buffered 10 Volt analog outputs


Model 6120 is a two-channel, fully automated, high bandwidth, signal conditioning amplifier and filter with dual inputs. The bridge input has voltage and current excitation, automatic balance, shunt calibration and programmable configuration for 1/4, 1/2 and full bridge transducers. The AC-coupled auxiliary input is for ICP/IEPE, dynamic strain and other voltage output transducers.

The 6120 employs an amplifier-per-channel architecture which provides the highest accuracy and completely eliminates crosstalk between channels. Using Pacific's PI660 software zero and gain calibration and correction are automatic.

The bridge inputs have programmable constant voltage or constant current excitation, automatic balance and a shielded 8-wire input that supports remote sensing, shunt calibration and programmable bridge completion for 120 and 350 Ohm gages. Strain gages other than 120 or 350 Ohms are accommodated by changing a completion resistor. A two-wire auxiliary input for ICP type transducers has 1-20 mA constant current excitation with AC signal coupling.

Two-step local and remote shunt calibration is standard. Four-step remote shunt with plug-in resistor card is optional. Voltage substitution is provided for gain calibration with programmable attenuation, which makes the distribution of calibration signals less susceptible to contamination by noise and offsets. The programmable attenuator has steps of 1, 0.1 and 0.01 with 0.02% accuracy and a post-attenuator output is available for verification and calibration.

The differential instrumentation amplifier has programmable gains from 1 to 5,000 and automatic zero. Zero and gain calibration and correction are automatic using Pacific's PI660 software. Bandwidth is up to 100 kHz. The amplifier is followed by a low-pass filer that reduces alias errors in the sampled data. Each channel has a ±10 Volt calibrated analog output and a ±10 Volt monitor output.

The standard filter is a programmable four-frequency, eight-pole Bessel low-pass. A programmable, four-pole Bessel, low-pass filter with 1 Hz or 5 Hz frequency resolution is optional. Either the standard or optional filters may be obtained with Butterworth or other response characteristic.

Overview  · Input  · Bridge Input  · IEPE Input  · Voltage Excitation / Transducer Power  · Current Excitation / Transducer Power  · Amplifier  · Filter  · Digitizer  · Digitizer (6030)  · Calibration  · Mechanical  · Ordering Information   · Excitation/Transducer Power


Measurement Type


Strain Gage

Analog Bandwidth

50 kHz

Excitation/Transducer Power





Analog Output

Buffered Analog Output



Dual input for Bridge or ICP/IEPE transducers with analog outputs

Bridge Input

Bridge Configuration

2 channels, 2 to 8 wire inputs, input (2), excitation (2), excitation sense (2) and shunt calibration (2) with shield. Programmable bridge completion for half bridges and 120 Ohm and 350 Ohm quarter bridges. Other gage resistances by request.

Bridge Balance

Automatic by program control. Balance accuracy ±0.05% of range, ±1 mV RTO.

Bridge Stability

±0.02% for 8 hours, ±0.005%/°C. Range set by resistor up to 25 mV/V, 2.5 mV/V (350 Ohms) installed.

IEPE Input

IEPE Configuration

AC-coupled, 2-wire with shield. High-pass <1 Hz.

IEPE Excitation

Current source 1 to 20 mA, 6 mA supplied.

IEPE Input Impedance

100K Ohms

IEPE Input Protection

±50 Volts without damage.

Voltage Excitation / Transducer Power

Voltage Excitation

Programmable from 0.1 to 10.24 Volts with 2.5mV resolution.
Calibrated 1-Volt steps ±0.1%. 50 mA limited to 70 mA maximum.

Voltage Excitation Regulation

Each channel individually regulated.
±0.01% over input voltage range and no-load to full load.

Voltage Excitation Stability

±0.01% for 30 days. Temperature coefficient less than ±0.005%/ºC.

Voltage Excitation Noise

200 µV peak-to-peak, DC to 10 kHz

Voltage Monitor

Excitation voltage or current is read by a program instruction. Accuracy is ±0.2%.

Current Excitation / Transducer Power

Current Excitation

Programmable 0.1 mA to 51.2 mA with 12.5 µA resolution. Calibrated 5 mA steps ±0.1%.

Minimum Compliance

0.1 to 10 V

Current Regulation

±0.01% or ±0.1 µA for 10% line change.

Current Excitation Noise

2 µA or 5 µV peak-to-peak DC to 10 kHz.

Current Stability

±0.01% or ±2 µA for 30 days. Temperature coefficient is less than ±0.005% or ±1 µA/ºC.

Current Monitor

Excitation voltage or current is read by a program instruction. Accuracy is ±0.2%.



±2 mV to ±10 Volts.


Programmable 1 to 5000, in 1, 2, 3, 5 steps, with ±0.05% accuracy.

Gain Stability

±0.02% for 30 days, ±0.005%/ºC.

Gain Linearity

±0.01% for gains < 1,000, ±0.02% for gains 1,000 and above.

Input Impedance

50 Megohms, shunted by 500.

Input Protection

±50 Volts differential, ±30 Volts common mode without damage.

Common Mode

60 dB plus gain in dB to 120 dB for balanced input and 110 dB for a 350 Ohm source unbalanced, DC to 60 Hz.

CM Voltage

±10 V

Zero (Amplifier)

Automatic zero to ±2 µV RTI or ±1.0 mV RTO whichever is greater.

Zero Stability

±5 µV RTI, ±1 mV RTO at constant temperature, ±1 µV RTI/ºC, ±0.2 mV RTO/ºC.
Short term: ±2 µV RTI, ±0.4 mV RTO for 8 hours.

Source Current

±5 nA, ±0.05 nA/ºC

Noise (10 kHz)

2.0 µV RTI plus 0.3 mV RTO, RMS.


6120 - 50 kHz (-3 dB) for gains to 1,000, 20 kHz for gains above 1,000.
6120HF - 100 kHz (-3 dB) for gains to 1,000, 50 kHz for gains above 1,000.

Slew Rate

5 V/µS

Overload Recovery

Recovery time is 120 µS to within ±0.1% for a 10 times overload to ±10 Volts.

Analog Output (Amplifier)

Two outputs, one calibrated and one monitor. ±10 Volts full scale either filtered or wideband.


Standard Filter

6120: 4-Frequency 8, Pole Bessel. 150 Hz, 625 Hz, 2.5 kHz, 10 kHz and wideband.
6120HF: 4-Frequency 8, Pole Bessel. 300 Hz, 1.25 kHz, 5 kHz, 20 kHz and wideband.

Programmable Filter

6120: 4-Pole Bessel, continuously programmable from 4 Hz to 1 kHz, 1 Hz resolution, ±2% accuracy. 1 kHz to 10 kHz, 5 Hz resolution, ±5% accuracy.
6120HF: 4-Pole Bessel, continuously programmable from 10Hz to 20kHz, 5 Hz resolution, ±5% accuracy.


Other filter characteristics and cut offs available.

Type (Standard Filter)

Eight-pole, low-pass Bessel (48 dB/octave).

Type (Optional Programmable Filter)

Four-pole, low-pass Bessel (24 dB/octave).


Digitizer Note

See Series 6000 to add the following onboard digitizing capability.

Digitizer (6030)


±50 ns channel-to-channel time correlation.


16-bits, two's complement output.


6030: Programmable up to 100 kS/s digitizer per channel.
6030HF: Programmable up to 200 kS/s digitizer per channel.


±1-1/2 LSB (±0.004%).


Monotonic to 15 bits.


Two alarms each with upper and lower limits that are programmable from negative to positive full scale. Limits checked on each ADC sample.


See Model 6030 for the Digitizing Capabilities.


Voltage Substitution

Alternate input for external calibration source. Programmable 1, 0.1 and 0.01, attenuation with ±0.01% accuracy. Attenuator output may be connected to bus for external monitoring.

Zero Calibration

Amplifier input disconnected and shorted for zero calibration.

Shunt Calibration

Standard: Two steps, single shunt. Calibration resistors mount in bifurcated terminals.
Program selection of internal or external shunt connection.

Optional: Four-step, single, external shunt. Calibration resistors mounted on a plug-in card.
May be wired for local shunt at the input connector.

Resistors: Installed shunt resistors provide 0.502 and 0.250, ±0.1% mV/V for 350 Ohm bridge.
Customer specified and 0.01% shunt resistors are available.



Occupies one slot in Series 6000 enclosures.


Input connectors are 15-pin Type D. Outputs are a 9-pin Type D. Type D mates supplied.

Operating Temperature

0 to +50 ºC

Ordering Information 

Ordering Information

6120HF-PF10/20K-BE4 - 2-Channel Transducer Amplifier, 10 Hz to 20 kHz Programmable Filter, 200 kS/s
6120HF-PF4-BE8 - 2-Channel Transducer Amplifier Four Step Filter, 200 kS/s.

6120-PF4/10K-BE4 - 2-Channel Transducer Amplifier, 4 Hz to 10 kHz Programmable Filter, 100 kS/s

6120-PF4-BE8 - 2-Channel Transducer Amplifier, Four Step Filter, 100 kS/s

6120-S4 - Four-Step Shunt Calibration with Plug-In Resistor Card (resistors not installed).

Excitation/Transducer Power

Current (Constant Voltage)

50 mA limited to 70 mA maximum.


Model 6120
(PDF, 168KB)

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