How Bias Is Generated - Anritsu MS2024B Manual

10-3 How Bias is Generated

The bias can be turned on only when the instrument is in vector network analyzer mode and
when the lowest frequency is set greater than or equal to 2 MHz. Below 2 MHz, both internal
and external bias tee are not supported. When bias is turned on, the LED indicator on the
MS20xxC connector panel turns green, and the actual bias voltage and current are displayed
in the upper left corner of the measurement display screen. The display shows the voltage
and current for the selected port when using internal bias tee, and for both ports when using
external bias tee.
Depending on the load that is presented by the device under test, the bias voltage
value that is displayed on the screen may be different than the value that was set
Caution
using the soft key menu. The value that is displayed on the screen is the actual
measured value of the voltage that is being delivered to the device under test.
The internal bias tee is designed to continuously deliver a maximum of 450 mA between
12 VDC and 32 VDC in steps of 0.1 V.
When using external bias tee on MS20xxC models, a maximum of ± 50 VDC at
Warning
500 mA is supported.
Figure 10-2 shows the bias tee architecture within the VNA Master.
variable bias tee on a Tower Mounted Amplifier (TMA-DD).
10-3 How Bias is Generated
The ability to provide DC bias voltage at the RF port is an important feature of a VNA. The
architecture of the VNA Master, when equipped with Option 10, allows for internal and
external bias at both RF ports.
Figure 10-1 shows how the MS20xxB and the S412E can provide an internal voltage between
12 volts and 32 volts that is applied to the center conductor of VNA Port 2 or of the RF In port
(SPA Input). That voltage would be available at the port along with the RF signals.
Port 1
Bridge / Coupler
Source
Figure 10-1. Internal Bias (MS20xxB and S412E shown)
10-2
S
21
S
11
DUT
Receiver
LO
Port 1
Reference
Receiver
PN: 10580-00289 Rev. K
Port 2
Internal Bias
+12 to +32 V
450 mA Max
Internal
Bias Tee
Bias Tee, Option 10
Figure 10-3 shows a
SPA Input
Internal
Bias Tee
SPA
Vector Network Analyzer MG