Fast Analog Outputs

This page contains detailed specifications and performance measurements for Gen 2 fast analog outputs.

Specifications

Parameter	Value	Units	Notes
RF outputs
RF output channels	2	-
Sampling rate	125	MS/s
DAC resolution	14	bit
Load impedance	50 Ω (Hi-Z)	-
Voltage range	±1 @ 50 Ω ±2 @ Hi-Z	V
Output coupling	DC	-
Short circuit protection	Yes	-
Output slew rate	200	V/μs
RF output jitter @40 MHz	20	ps	RMS, typical
Bandwidth	DC - 50	MHz	Typical
Connector type	SMA	-

Note

The output load impedance should be set in the software before connecting the load.

Hardware Details

Output stage schematics

The output stage consists of a buffer amplifier, low-pass filter filter, and DAC driver.

For more information, please refer to each board’s hardware documentation.

Performance Measurements

Output bandwidth

Load impedance	Bandwidth
50 Ω	54.3 MHz (-3 dB)
High-Z	55.0 MHz (-3 dB)

Bandwidth measurement of the output channel 1 at 50 Ω load.

Bandwidth measurement of the output channel 1 at high impedance load.

Output bandwidth flatness

The output bandwidth flattness is within -1 dB from DC to full (-3 dB) bandwidth.

Output impedance

The impedance of the output channels (output amplifier and filter) is shown in the figure below. The original STEMlab 125-14 output impedance is shown for comparison.

Original board and Gen 2 output impedance measurement.

Smith diagram of the output impedance of original board and Gen 2.

Output phase noise

Phase noise measurements between 1 Hz and 1 MHz.

Output SFDR

	OUT 1	OUT 2
f [MHz]	SFDR [dB]	SFDR [dB]
0.1	56	54
1	52	58
10	58	55
20	44	44
30	45	45
40	44	45

SFDR measurement for both output channels.

Measurements at specific frequencies

SFDR at 100 kHz.

SFDR at 1 MHz.

SFDR at 10 MHz.

SFDR at 20 MHz.

SFDR at 30 MHz.

SFDR at 40 MHz.

Output SNR

SNR measurement of the output channel 1 (whole specturm).

SNR measurement of the output channel 1 (VBW 100 kHz).

SNR measurement of the output channel 1 (no signal).

Calibration

Analog output calibration

To calibrate the analog outputs, please refer to the Calibration guide.