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Model 6168, 2-Channel Transducer Amplifier-Filter-Analog Output, 300CMV


  • Plug-in module configures channel for multiple transducer types & calibration modes
  • Voltage & current excitation with remote sensing
  • Isolated excitation & input with 300 Volts common mode
  • Voltage & shunt calibration
  • Gains 1 to 5,000 with 100 kHz bandwidth
  • Continuously programmable 6-pole low pass filter
  • Dual buffered 10 Volt analog outputs


The 6168 is a two-channel signal conditioning amplifier module featuring 100 kHz bandwidth and analog outputs. The base board contains both constant voltage with remote sensing and constant current programmable excitation supplies, high-bandwidth instrumentation amplifier with programmable step and variable gain, 4 Hz to 30 kHz, continuously programmable six-pole, low-pass filter and dual buffered outputs. A plug-on module configures the base board for multiple types of transducers including voltage, full and partial bridge, voltage output charge (IEPE) and charge output piezoelectric.

The input and excitation are isolated from the outputs, power and control interface. This gives the user complete freedom to ground the input without creating ground loops that introduce noise and offset errors. It also provides up to 300 Volt common mode operating voltage.

The differential instrumentation amplifier has DC or AC input coupling, programmable gains from 1 to 5,000 and automatic zero. The two analog outputs may be selected independently for wideband or filtered response. Voltage Substitution using an external source that is distributed to all channel inputs provides traceable gain calibration.

Overview  · Input  · Bridge Input with FC1 Features Card  · IEPE Input with FC4 Features Card  · Charge Mode Input with FC9 Features Card  · Voltage Excitation / Transducer Power  · Current Excitation / Transducer Power  · Amplifier  · Filter  · Digitizer  · Calibration  · Mechanical  · Ordering Information   · Features Cards  · Bridge Modules  · IEPE Modules  · Charge Modules


Measurement Type




Strain Gage

Analog Bandwidth

50 kHz

Excitation/Transducer Power





Analog Output

Buffered Analog Output



Input configuration based on installed Features Cards. Features cards available for Bridge, IEPE, Charge and RTD. Other features cards available upon request.

Bridge Input with FC1 Features Card

Bridge Configuration

2 to 10 wire plus shield; input (2), excitation (2), sense (2) and shunt calibration (4). 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. Stability ±0.02% for 8 hours, ±0.005%/ºC.

IEPE Input with FC4 Features Card

IEPE Configuration

Voltage input, AC-coupled, 2-wire with shield.

IEPE Excitation

Current source 1 to 20 mA, set for 6 mA.

IEPE Input Impedance

100K Ohms

IEPE Input Protection

±30 Volts without damage.

Charge Mode Input with FC9 Features Card

Charge Configuration

Two ranges: 1 mV/pC (high) and 0.1 mV/pC (low).

Charge Gain Range

0.05 mV/pC to 2,500 mV/pC with 0.05% resolution.

Charge Gain Steps

Calibrated gains of 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, 500, 1,000, 2,000, and 5,000 mV/pC with ±0.1% accuracy.

Charge Stability


Charge Linearity

0.1% of full scale at 1 kHz.

Noise (10 kHz)

0.02 pC RMS plus 0.006 pC RMS per 1000 pF of source capacitance referred to input.

Maximum Input

200,000 pC on low range (0.05 to 250 mV/pC), 20,000 pC on high range (0.5 to 2,500 mV/pC) without charge converter overload.

Overload Flag

Overload flag set when output of charge converter exceeds full scale.

O.L. Reset

Program command provides recovery when using long time constants.

Charge Calibration

Signal from external calibration source applied through a 2,000 pF capacitor to the charge input and calibrated to ±0.1%.

Charge Test

Signal from external calibration source applied in series with the input transducer for testing transducer, cable, connections and amplifier.

Voltage Excitation / Transducer Power

Voltage Excitation

Programmable from 0.1 to 20 Volts with 0.5 mV resolution. Calibrated 2-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 1 µA resolution. Calibrated 5 mA steps ±0.1%.

Minimum Compliance

0.1 to 20 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 Excitation 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%.


Input Range

±2 mV to ±10 Volts full scale, DC or AC coupled.


Programmable from 1 to 5,000 with 0.05% accuracy.

Gain Stability

±0.01% for 30 days, ±0.005%/ºC.

Gain Linearity

±0.01% for gains < 1000, ±0.02% gain 1000, and above

Input Impedance

50 Megohms, shunted by 500 pF DC coupled, 100K Ohms AC coupled.

Input Protection

±50 Volts, differential without damage.

Common Mode

74 dB plus gain in dB to 120 dB for balance input and 110 dB for a 350 Ohm source unbalanced, ±300 Volts, DC to 60Hz.

CM Voltage

Common Mode ±300 Volts operating, ±350 Volts without damage.

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, ±0.2 mV RTO/ºC.

Source Current

±40 nA, ±0.05 nA/ºC.

Noise (10 kHz)

2.0 µV RTI plus 0.3 mV RTO, RMS.


100 kHz (-3 dB) for gains 1 to 1,000, 50 kHz (-3 dB) for gains above 1,000. Slew rate is 5 V/µS.

Overload Recovery

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



Six-pole, low-pass Bessel or Butterworth (36dB/octave).


Continuous programmable filter frequency from 4 Hz to 30 kHz with 1 Hz resolution below 1 kHz and 10 Hz resolution above 1 kHz and wideband.


Other filter characteristics and cut offs are available.


Digitizer Note

See Series 6000 to add the following onboard digitizing capability.


±50 ns channel-to-channel time correlation.


16 bits, two's complement output.


Programmable up to 200 kS/s 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.


Voltage Substitution

Voltage substitution, signal from external calibration source is applied to the amplifier input. Programmable attenuator with steps of 1, 0.1 and 0.01, ±0.02% accuracy. Output of the attenuator is provided for calibration.

Shunt Calibration

Shunt Calibration based on capability of Installed Features Card. FC1: Four steps of unipolar resistive shunt (8-wire). Four-step bipolar resistive shunt (10-wire) is optionally available. Jumpers provided for 4 and 6-wire connections and for shunting the internal completion resistor.

Zero Calibration

Amplifier input disconnected and shorted.



Occupies one slot in Series 6000 enclosures.


Bridge Inputs are 15-pin and Charge/IEPE are BNC. Outputs are 9-pin Type D. Mating connectors supplied for bridge input.

Operating Temperature

0 to +50 ºC

Ordering Information 

Ordering Information

6068-FC1 - Features Card: Bridge, 4-step shunt.
6068-FC2 - Features Card: Bridge, single-step shunt.

6068-FC4 - Features Card: IEPE, AC coupled voltage.

6068-FC5 - Features Card: 4-20mA.

6068-FC8 - Features Card: RTD.

6068-FC9 - Features Card: Charge, piezoelectric.

6168-PF4/30K-BE6 - 2-Channel Transducer Amplifier, PF 4Hz-30kHz 6-Pole Bessel.

6168-PF4/30K-BU6 - 2-Channel Transducer Amplifier, PF 4Hz-30kHz 6-Pole Butterworth.

Features Cards
The 6168 uses a plug-in module to configure the input of each channel for a particular type of transducer or specific type of calibration. Modules can be easily modified or created to handle special customer requirements. The more popular modules are described here and include those for AC and DC coupled voltage, full and partial bridges, and IEPE or piezoelectric charge.

Bridge Modules
The bridge input is eight or ten-wire shielded accommodating even the most complex transducer wiring schemes. The base board provides both programmable constant voltage with remote sensing and constant current excitation. Programmable completion is provided on the bridge module for quarter, half and full bridge transducers. Automatic bridge balance accommodates large unbalances without limiting dynamic range or loading the transducer output. It can be used to provide voltage offsets in the hundreds of millivolts for non-bridge transducers such as MEMS and variable capacitance.

Depending on the function card selected the capability is provided for up to four-steps of bipolar resistive shunt calibration or DAC shunt calibration that provides 4096 calibration steps using a single calibration resistor. The FC1 Bridge Module shown has four steps of unipolar resistance shunt that can be applied to either an external bridge arm or strain gage or to the internal completion resistor. This module may also be used to apply low-level voltage inputs to the instrumentation amplifier on the base board.

IEPE Modules
The IEPE module is for piezoelectric and other transducers with built-in electronics and a voltage output. It provides constant current excitation to the transducer that is programmable from 1 to 20 mA with 26 Volt compliance. The output of the transducer is AC coupled to the input of the instrumentation amplifier on the base board.

Charge Modules
The Charge Amplifier module accepts charge signals from piezoelectric transducers. It has two charge ranges that accommodate most charge transducers and applications. Other customer specified ranges can be provided. It has programmable time constant that can be made long or short as required and a two frequency four-pole high-pass filter between the charge amplifier output and the input to the instrumentation amplifier on the base board. The filter is used to eliminate noise such as cable whip. The filter may be bypassed for quasi-DC measurements.


Model 6168
(PDF, 158KB)

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