Setting The Amplitude Offset - HP E1340A User Manual

Turning Attenuation Off
Amplitude Correction
Caution
Setting the
Amplitude Offset
246 HP E1340A Register-Based Programming
Setting bit 7 (Atten) of the MSB to "1" sets no attenuation (Table C-2). Bit
7 should be set to "1" for amplitudes > 0.51175V into 50 , or for
amplitudes > 1.0235V into an open circuit. Setting bit 7 to "0" attenuates
the output by 20 dB. Bit 7 should be set to "0" for amplitudes < 0.51175V
into 50 , or for amplitudes < 1.0235V into an open circuit.
Setting bit 6 (Corr) to "1" (adding 64) turns off amplitude correction (Table
C-2). Setting bit 6 to "0" enables amplitude correction. When enabled, the
output is corrected such that the amplitude remains level for all frequencies
up to 15 MHz. The correction computation is only valid and should only be
enabled with a reference oscillator frequency (internal or external) of
42.94967296 MHz.
If amplitude correction is in effect for a programmed number of cycles
(burst), correction will remain in effect after the burst completes. This can
result in an output signal 2.5 times the programmed value. Sine wave
correction is recommended for a continuous signal only.
The offset of the output signal is controlled by the 12-bit DAC. The offset
value written to the AFG is based on the desired offset and the output load:
Offset with no signal attenuation into 50 :
Offset = (Voff / .0025) + 2048
Offset with no signal attenuation into open circuit:
Offset = (V / .005) + 2048
off
Offset with 20 dB attenuation into 50 :
Offset = ((V / .0025) * 10) + 2048
off
Offset with 20 dB attenuation into open circuit:
Offset = ((V / .005) * 10) + 2048
off
Offset is the offset value set from the Parameter Register and
desired offset.
V is the
off
Appendix C