DC to 500kHz spectrum, 10kHz carrier, no filtering

The WFD22 is a 22 bit Waveform Digitizer for medium-speed / high resolution waveform capturing and analyzing. It combines superior dynamic performance with a very high DC accuracy.
The module features fully differential inputs to reduce common-mode level disturbances. It can also be used in Single Ended mode where an internal DC-offset source sets the midscale level. In this mode the negative input can be used as a GND Sense input, so the DC performance won’t be compromised due to ground currents. The user can select between a 100 MΩ low bias current input for highest absolute accuracy, or a 1 MΩ ultra-low noise input for highest dynamic performance. There are 10 input ranges from 0.425 Vpp to 10.2 Vpp, which allows easy adaptation to a wide range of Device Under Test output voltages. A filter-bank with 3 Low Pass filters (40 kHz, 250 kHz and 500 kHz) provides excellent signal conditioning resulting in lower noise and proper anti-aliasing.

Our proprietary technology combines four 20 bit ADCs to create an advanced 22 bit converter. This results in excellent SNR and linearity with a resolution down to 0.1 µV. The large capture memory of 32M-word (96 MB) allows capturing long waveforms. This can be very useful when a high number of averages is required. All these features together result in the highest accuracy available when performing analog measurements. DAC linearity and dynamic performance measurements are a breeze with the WFD22 in the ATX7006 system. Also applications like: Power meter testing, MRI amplifier test, Quantum effect research, etc. will benefit from the outstanding analog performance of the WFD22.

Block Diagram

Key Features

  • 1 MHz sample rate with 22 bit resolution
  • Fully differential input with 10 ranges
  • 100 MΩ low I-bias, 1 MΩ Ultra-low noise input
  • 1.5 ppm typical linearity
  • ±(25 µV + 10 ppm of range) absolute accuracy
  • Selectable filters to reduce out-of-band noise
  • -122 dB THD typical (f-in = 1 kHz)
  • 105 dB SNR typical (DC- 500 kHz)
  • Programmable DC-offset voltage
  • For ATX series hardware platform

Technical Specifications

General

Resolution 22 bit
Sample rate 0 - 1 MHz
Pattern depth 32M words

Input characteristics

Input impedance / mode 100 MOhm low bias current mode / 1 MOhm low noise mode
Input configuration Differential / Single Ended (-Input to Gnd, Gnd-sense or DC offset)
Input ranges (Vpp) 0.425, 0.637, 0.850, 1.275, 1.70, 2.55, 3.40, 5.10, 6.80, 10.20
Input filters Bypass, 40 kHz (4-pole Butterw.), 250 kHz (5-pole Butterworth), 500 kHz (7-pole elliptic)
Bandwidth -3 dB (typical) 1.1 MHz (5.10 Vpp range)
0.1 dB flatness (typical) 200 kHz (5.10 Vpp range)
Input Common mode range +/- 10.2 V

Accuracy (DC-offset off, 100 ksps)

Absolute accuracy, ranges 1.70 - 10.2 Vp ±(25 µV + 10 ppm of range)
Absolute accuracy, ranges 0.425 - 1.275 Vp ±(25 µV + 15 ppm of range)
Non Linearity error ±3 ppm of range (1.5 ppm typical)
Input bias current (typical) 1 pA in 100 MOhm mode / 50 nA in 1 MOhm mode

Accuracy (DC-offset off, 100 ksps)

Resolution 20 bit (10 µV)
Voltage range -5.1 V to +5.1 V
DC-offset accuracy ±(10 µV + 6 ppm of value)
Non Linearity ±3 ppm of range

Dynamic characteristics

(conditions: 1 MOhm input mode, 1 MS/s, 500 kHz filter on)

SNR (5 Vpp, 1 kHz input) 99 dB (105 dB typical)
SNR (5 Vpp, 10 kHz input) 97 dB
SNR (5 Vpp, 100 kHz input) 93 dB
SNR (1 kHz input, A-weighted) 110 dB (BW 20 Hz - 20 kHz)
THD (5 Vpp, 1 kHz input) -115 dB (-122 dB typical)
THD (5 Vpp, 10 kHz input) -110 dB
THD (5 Vpp, 100 kHz input) -94 dB
SFDR (5 Vpp, 1 kHz input) 112 dB
CMRR (typical) 110 dB

Clock & Trigger inputs

Input impedance > 1 MOhm
Threshold level 3.3 V CMOS/TTL (5 V tolerant)