Figure 1-4 N8480 Series Power Sensor Simplified Block Diagram - Keysight Technologies N8480 Series Operating And Service Manual

RF Power
Thermocouple
Sensor

Figure 1-4 N8480 Series power sensor simplified block diagram

Figure 1- 4
thermocouple power sensing elements. From the RF or microwave signal
input, the thermocouple detector mounts generate a very low voltage — in
the order of nV. As the DC voltage is very low, it requires amplification
before it can be transferred to the power meter on the standard cables.
The amplification is provided by an input amplifier assembly that consists
of a balanced chopper and an AC coupled low- noise amplifier. The DC
voltage is routed through gold wires to the chopper circuit, which converts
the low- level DC voltage to an AC voltage. To do this, the chopper is
controlled by a 440 Hz square- wave generated by the power meter (the
chop signal). The result is an AC output signal proportional to the DC
input. The AC signal is then amplified to a relatively high- level AC signal
that can be routed to the power meter by standard cables (Keysight 11730
Series cables are available up to 61 metres from –5 °C to 45 °C).
N8480 Series Power Sensors Operating and Service Guide
Thermistor
Power Supply
illustrates a basic power sensor block diagram for
Reference Source
Chopper
Pre-amplifier
440 Hz
I2C Remote I/O
Introduction
Gain-select
Circuit
Amplifier
I2C Buffer Circuit
EEPROM
1
11