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Model 6068, 2-Channel Transducer Amplifier-Filter-Digitizer, 300CMV
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Features
- 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
- Up to 200 kS/s per channel with 16-bit resolution
- Continuously programmable 6-pole low pass filter
- Dual buffered 10 Volt analog outputs
Description
The 6068 is a two-channel signal conditioning amplifier-digitizer module featuring 100 kHz bandwidth and both digitized 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 and the digitized output may be selected independently for wideband or filtered response. The digital output is provided by a successive approximation ADC at up to 200K samples per second providing excellent time alignment between channels. Voltage Substitution using an external source that is distributed to all channel inputs provides traceable gain calibration.
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Configuration
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Input configuration based on installed Features Cards. Features cards available for Bridge, IEPE, Charge and RTD. Other features cards available upon request.
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Charge Configuration
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Two ranges: 1 mV/pC (high) and 0.1 mV/pC (low).
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Charge Gain Range
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0.05 mV/pC to 2,500 mV/pC with 0.05% resolution.
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Charge Gain Steps
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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.
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Charge Stability
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±0.005%/ºC.
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Charge Linearity
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0.1% of full scale at 1 kHz.
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Noise (10 kHz)
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0.02 pC RMS plus 0.006 pC RMS per 1000 pF of source capacitance referred to input.
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Maximum Input
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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.
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Overload Flag
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Overload flag set when output of charge converter exceeds full scale.
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O.L. Reset
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Program command provides recovery when using long time constants.
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Charge Calibration
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Signal from external calibration source applied through a 2,000 pF capacitor to the charge input and calibrated to ±0.1%.
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Charge Test
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Signal from external calibration source applied in series with the input transducer for testing transducer, cable, connections and amplifier.
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Input Range
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±2 mV to ±10 Volts full scale, DC or AC coupled.
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Gain
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Programmable from 1 to 5,000 with 0.05% accuracy.
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Gain Stability
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±0.01% for 30 days, ±0.005%/ºC.
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Gain Linearity
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±0.01% for gains < 1000, ±0.02% gain 1000, and above
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Input Impedance
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50 Megohms, shunted by 500 pF DC coupled, 100K Ohms AC coupled.
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Input Protection
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±50 Volts, differential without damage.
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Common Mode
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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.
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CM Voltage
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±300 Volts operating, ±350 Volts without damage.
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Zero (Amplifier)
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Automatic zero to ±2 µV RTI or ±1.0 mV RTO whichever is greater.
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Zero Stability
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±5 µV RTI, ±1 mV RTO at constant temperature, ±1 µV RTI, ±0.2 mV RTO/ºC.
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Source Current
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±40 nA, ±0.05 nA/ºC.
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Noise (10 kHz)
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2.0 µV RTI plus 0.3 mV RTO, RMS.
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Bandwidth
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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.
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Overload Recovery
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120 µS to within ±0.1% for a 10 times overload to ±10 Volts.
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Analog Output (Amplifier)
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Two ±10 Volt full scale outputs. Accuracy is ±0.05%. Each may be programmed for filtered or wideband response.
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Ordering Information
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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. 6068-PF4/30K-BE6 - 2-Channel Transducer Amplifier, PF 4Hz-30kHz 6-Pole Bessel. 6068-PF4/30K-BU6 - 2-Channel Transducer Amplifier, PF 4Hz-30kHz 6-Pole Butterworth.
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The 6068 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.
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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.
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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.
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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.
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