PFA-2 Two-Channel Compact Filter/Amplifier

Precision quality and performance in an economical benchtop package

Precision PFA-2 Filter/Amplifier offers 2 channels of high-performance signal conditioning for low-level voltage inputs in an economical benchtop package.

PFA-2 Description

The PFA-2, Precision Filters’ dual-channel filter/amplifier, is compact, rugged, and versatile. Its low-noise, high common-mode rejection balanced differential input with programmable AC/DC input coupling makes the PFA-2 ideal for conditioning static or dynamic signal inputs. Its 6-pole low-pass filters can address applications in the time domain, such as shock measurements, or in the frequency domain, such as spectral analysis or anti-aliasing applications.

Gain is distributed before and after the filter, eliminating out-of-band energy such as transducer resonant peaking, which can clip the amplifier and ruin the data. Front-panel overload detectors warn about pre- and postfilter overload conditions that might otherwise be masked by the filter. The optional 2-pole high-pass filter provides programmable low-frequency roll-off to attenuate sources of low-frequency noise.

PFA2 gui

PFA-2 Spreadsheet-Style GUI

The PFA-2 is highly programmable via its spreadsheet-style graphical user interface. The GUI controls up to eight PFA-2 units as a single system. Alternatively, you can control the PFA-2 using a high-level command interface via a USB 2.0 connection. Save configurations to the host computer and recall them later. Or save settings to nonvolatile memory for field deployment—no host computer needed.

 

PFA-2 Front Panel

Innovative Technologies and Features:

Pre-Filter and Post-Filter Gain

The PFA-2 distributes amplifier gain both before and after the filter to provide protection from large out-of-band energy or transients that could cause clipping before the filter, distorting the data... Read More

The PFA-2 distributes amplifier gain both before and after the filter to provide protection from large out-of-band energy or transients that could cause clipping before the filter, distorting the data. Postfilter gain has resolution of better than 0.025% to enable system scaling of the outputs to match the full-scale input of the external recording device. Overload detectors alert the user to overvoltage conditions.

Flat/Pulse Low-Pass Filter Technology

PFA-2 low-pass filters may operate either in a flat mode, for maximally flat pass-band amplitude response with sharp roll-off, or in a pulse mode, for low phase distortion and optimized transient response... Read More

PFA-2 low-pass filters may operate either in a flat mode, for maximally flat pass-band amplitude response with sharp roll-off, or in a pulse mode, for low phase distortion and optimized transient response. Flat mode provides passband characteristics nearly identical to a Butterworth filter while providing a much sharper roll-off. This mode is a good choice for applications such as spectral analysis. Pulse mode has time-domain response similar to the Bessel filter yet provides superior amplitude response characteristics. Pulse mode is ideal for time-domain applications, including transient (shock) measurements and waveform analysis.

Learn more about PFI's flat/pulse mode filters

Balanced Differential Input Topology

The PFA-2 Filter/Amplifier input stage is a balanced differential input topology that may be used to receive differential signals from a bridge type transducer or to condition grounded (single-ended) ... Read More

The PFA-2 Filter/Amplifier input stage is a balanced differential input topology that may be used to receive differential signals from a bridge type transducer or to condition grounded (single-ended) voltage sources without introducing ground loops. The input is versatile in that it has low DC drift for DC measurement applications, low noise for wideband AC measurements and is equipped with programmable AC/DC coupling. AC coupling is useful for eliminating large DC bias on the signal so that more channel gain can be applied in order to emphasize small AC fluctuations in the signal.

PFA-2 Salient Features:

Number of Channels:

  • 2 per system

Input Connectors:

  • Standard: Coaxial BNC’s at front panel
  • Option 1: Twinaxial BNC input ... Read More

Number of Channels:

  • 2 per system

Input Connectors:

  • Standard: Coaxial BNC’s at front panel
  • Option 1: Twinaxial BNC input

Output Connectors:

  • Individual isolated BNC’s at rear panel

Inputs:

  • Balanced differential input with programmable AC/DC coupling

Outputs:

  • DC coupled, single-ended output, short circuit protected

Test Support:

  • Amplifier Short: A switch at the amplifier input is utilized to ground the input stage for measurement of noise and DC offset.
  • Test Input: Switch disconnects signal from input connector and inject signal on Test Input BNC at the amplifier input.

Input Power:

  • 10 to 30 VDC external AC to DC power supply provided with unit

Pre-Filter Gain:

  • x1 to x128 in binary steps

Post-Filter Gain:

  • x1/16 to x16 with 0.025% minimum resolution

Filters:

  • 4-pole low-pass filters with programmable flat/pulse characteristics
  • Wideband mode: Filter may be removed from the signal path, resulting in 3-pole Butterworth wideband amplifier frequency response with nominal –3 dB frequency at 500 kHz.
  • Optional 2-pole high-pass filter (Option H) for band-pass operation

Control:

  • USB remote control with field upgradable firmware
  • Spreadsheet-style GUI interface for control of up to 8 PFA-2 units
  • Nonvolatile memory saves programmed state for field deployment without an attached control computer
  • Input and output overload detection with programmable threshold

Comparison Chart of Precision Filter/Amplifiers Products

System/CardPFA-2 Filter/Amplifier SystemPF-1U-FA High-Performance Filter/Amplifier SystemPF-1U-FA Standard-Performance Filter/Amplifier System28608B 8-Channel 200 kHz Filter/Amplifier Module28618 8-Channel 200 kHz Filter/Amplifier Module28612 2-Channel 3 MHz Filter/Amplifier Module
Channels/ Card2 per system8 (PF-1U-8FA)
or
16 (PF-1U-16FA)
8 (PF-1U-8FA)
or
16 (PF-1U-16FA)
8 per card; up to 128 per 28000 system8 per card; up to 128 per 28000 system2 per card; up to 32 per 28000 system
InputsBalanced differential inputs with programmable AC/DC couplingBalanced differential inputs with programmable AC/DC coupling; Option I: IEPE Current SourceBalanced differential inputs with programmable AC/DC coupling; Option I: IEPE Current SourceBalanced differential inputs with programmable AC/DC couplingBalanced differential inputs with programmable AC/DC couplingProgrammable single-ended/differential input with programmable AC/DC input coupling (10 HZ or 100 Hz)
Filter6-pole Flat/Pulse Low-Pass;
Option H: 2-pole High-Pass
4- or 8-pole Flat/Pulse Low-Pass or 8-Pole Band-Pass4-Pole Flat/Pulse Low-Pass4- or 8-pole Flat/Pulse Low-Pass or 8-Pole Band-Pass4-pole Flat/Pulse Low-Pass6-pole Flat/Pulse Low-Pass
GainPre-filter Gain:
×1 to ×128 in ×2 steps

 

Post-filter Gain:
×1/16 to ×16 with 0.025% min resolution

Pre-filter Gain:
×1 to ×512 in ×2 steps

 

Post-filter Gain:
×0.25 to ×16 with 0.05% resolution

Pre-filter Gain:
×1 to ×512 in ×2 steps

 

Post-filter Gain:
×0.5 to ×16 with 0.05% resolution

Pre-filter Gain:
×1 to ×512 in ×2 steps

 

Post-filter Gain:
×1/16 to x16 with 0.05% resolution

Pre-filter Gain:
×1 to ×64 in ×2 steps

 

Post-filter Gain:
×1/16 to ×16 in binary steps with 0.05% resolution

x1, x2, x5, x10, x20, x50, x100, x200, x500, x1000
Cutoff Frequencies5 Hz to
2.555 kHz in
5 Hz steps

 

2.75 kHz to
127.5 kHz in
250 Hz steps

Flat Mode:
2 Hz to 2.046 kHz in 2 Hz steps 2.2 kHz to 204.6 kHz in 200 Hz steps;  bypass option

 

Pulse Mode:
1 Hz to 1.023 kHz in 1Hz steps      1 kHz to 102.3 kHz in 100 Hz steps; bypass option

FX02: 300 Hz, 1 kHz, 3 kHz, 10 kHz, 30 kHzFlat Mode:
2 Hz to 2.046 kHz in 2 Hz steps 2.2 kHz to 204.6 kHz in 200 Hz steps;  bypass option

 

Pulse Mode:
1 Hz to 1.023 kHz in 1Hz steps                1 kHz to 102.3 kHz in 100 Hz steps; bypass option

FX02: 300 Hz, 1 kHz, 3 kHz, 10 kHz, 30 kHz

5 kHz to 315 kHz in 5 kHz steps

350 kHz to 3.15 MHz in 50 kHZ steps

OutputsDC-coupled, Single-endedDC-coupled, Single-endedDC-coupled, Single-endedSingle-ended with Ground SenseSingle-ended with Ground SenseSingle-ended