Agilent Technologies 4284A Service Manual page 71

The A4 high power amplifier/dc bias board generates the DC output voltage using the DAC,
and also amplifies the AC output signal from the A5 board. The A4 high power amplifier/dc
bias board consists of the reference voltage, the D-A converter, the attenuator, the power
amplifier (x 1 0) , two switching relays. (Refer to Fig ure
AC
o�--- -- -- -- -- -- -- -- --o
Figure 3-6 . H ig h Power Amplifier/DC Bias (A4) Simplified Block Diagrams
The reference voltage (Vref) is ±5 V whose sign depends on the polarity of the dc bias set­
ting. The Vref output is applied to the D-A converter (DAC). The output from the DAC is
atten uated by the attenuator, and the attenuated dc bias signal is added to the ac sig nal
from the A5 board . The added sig nal is amplified
I n the case of t he 4284A with t h e Option 001 , you can select the high power m ode (ON/O FF)
which swiches two relays.
DC B IAS
ON (HI-PW mode)
OFF (HI-PW mode)
3-26
3-6.)
X 10
ON (HI-PW mode)
OFF (HI-PW mode)
(x
1 0) , and is output to the Hcur Terminal.
Terminal