Download PC-420 - DigChip

®
®
PC-420
FREQUENCY DOMAIN PERFORMANCE (Typical)
Note: Readings are based on visual interpretation of a graphic FFT display. Results will vary depending on FFT algorithm, screen
resolution, and spectrum analyzer performance.
Table 2. Frequency Response - External Bandpass Filter
Frequency = PC-420 Output Frequency
Table 1. Frequency Response - No External Filter
PC420
Output
Frequency
PC420
Filter
Frequency
Noise
Floor
2nd
Harmonic
3rd
Harmonic
10kHz
50kHz
100kHz
500kHz
1MHz
5MHz*
10MHz*
10kHz
50kHz
100kHz
500kHz
1MHz
5MHz
10MHz
–90dB
–80dB
–90dB
–85dB
–83dB
–80dB
–80dB
–75dB
–72dB
–66dB
–60dB
–55dB
–50dB
–45dB
–83dB
–78dB
–73dB
–70dB
–69dB
–58dB
–54dB
PC-420
Output
Frequency
PC-420
Filter
Frequency
Noise
Floor
2nd
Harmonic
3rd
Harmonic
98kHz
480kHz
975kHz
2.45MHz
100kHz
500kHz
1MHz
5MHz
–90dB
–88dB
–88dB
–83dB
–85dB
–88dB
–82dB
–82dB
–83dB
–85dB
–80dB
–80dB
Note: Load impedance = 50Ω, internal filter enabled.
Note: Load impedance = 1MΩ, internal filter enabled
*Load impedance = 50Ω, internal filter enabled
dB
dB
0
0
0 1–
0 2 4- C Py c n e u q r F = z H k 8 9
0 2 4 - C P r e tl i F = 0 1 z H k
l a n r e t x E s a p d n B r e tl i F
r e t n C )( y c n e u q r F = z H k 0 1
0 1–
0 2 4- C P y c n e u q r F = z H k 0 1
0 2 4 - C P r e tl i F = 0 1 z H k
o N l a nr et x E r e t l i F
0 2–
0 2–
0 3–
0 3–
0 4–
0 4–
0 5–
0 5–
0 6–
0 6–
0 7–
0 7–
0 8–
0 8–
0 9–
0 9–
0 1–
0 1–
0
04
08
021
061
02
04 2
08 2
02 3
06 3
0
04
04
08
021
061
02
04 2
08 2
02 3
06 3
04
kHz
kHz
No external filter
External bandpass filter (center frequency = 100kHz)
Figure 2. PC-420 FFT Plots (sinewave inputs)
OUTPUT AMPLITUDE CONSIDERATIONS
Table 3. Output Amplitude vs. Filter Selection
All readings taken into a 1MΩ load with the 20MHz fixed
internal filter. If a 50Ω load is connected the output amplitudes
will attenuate by half.
For signal frequencies up to 1MHz the output amplitude
depends on the filter cutoff frequency. Table 3 reflects the
output levels when the filter frequency equals the signal
frequency, i.e. the full scale amplitude (±10V) is decreased by
3dB. Selecting a filter frequency higher than the output
frequency will result in less attenuation but signal
reconstruction quality will suffer. Above 1MHz the output
amplifier’s finite bandwidth also attenuates the output signal.
Conclusion: Waveform amplitude and signal quality depends
on output frequency and filter selection.
5
Output Frequency
Filter Frequency
Amplitude
(without filter)
Amplitude
(with filter)
10kHz
50kHz
100kHz
500kHz
1MHz
5MHz
10MHz
±10V
±10V
±10V
±10V
±10V
N/A
N/A
±7V
±7V
±7V
±7V
±7V
±5V
±5V