Reverse Power Solution

Troubleshooting

RF Output Power Problems

Figure 12-2	Reverse Power Solution
	SIGNAL GENERATOR
	OUTPUT CONTROL
	ALC LEVEL/
	RF OUTPUT
	= +2 dBm
RF LEVEL
CONTROL
	DETECTOR
DETECTOR	MEASURES
DETECTOR	- 15 dBm
MEASURES	REVERSE
+2 dBm	POWER
ALC LEVEL

		RF INPUT MIXER
	10 dB	= - 8 dBm
	10 dB	LO
	ATTEN	LO
	ATTEN

LO FEEDTHRU	LO LEVEL
= - 5 dBm	= +10 dBm
	IF

Compared to the original configuration, the ALC level is 10 dB higher while the attenuator reduces the LO feedthrough (and the RF output of the signal generator) by 10 dB. Using the attenuated configuration, the detector is exposed to a +2 dBm desired signal versus the - 15 dBm undesired LO feedthrough. This 17 dB difference between desired and undesired energy results in a maximum 0.1 dB shift in the signal generator’s RF output level.

Signal Loss While Working with a Spectrum Analyzer

The effects of reverse power can cause problems with the signal generator’s RF output when the signal generator is used with a spectrum analyzer that does not have preselection capability.

Some spectrum analyzers have as much as +5 dBm LO feedthrough at their RF input port at some frequencies. If the frequency difference between the LO feedthrough and the RF carrier is less than the ALC bandwidth, the LO’s reverse power can cause amplitude modulation of the signal generator’s RF output. The rate of the undesired AM equals the difference in frequency between the spectrum analyzer’s LO feedthrough and the RF carrier of the signal generator.

Reverse power problems can be solved by using one of two unleveled operating modes: ALC off or power search.

Setting ALC Off Mode

ALC off mode deactivates the automatic leveling circuitry prior to the signal generator’s RF output. In this mode, a power meter is required to measure the output of the signal generator and assist in achieving the required output power at the point of detection.

Use the following steps to set the signal generator to the ALC off mode:

1.Preset the signal generator: press Preset.

2.Set the desired frequency: press Frequency and enter the desired frequency.

3.Set the desired amplitude: press Amplitude and enter the desired amplitude.

246	Chapter 12

E8267D PSG, E8257D PSG specifications

Agilent Technologies, a recognized leader in electronic measurement and communications solutions, offers a comprehensive range of signal generators, including the E8257D PSG (Pulsed Signal Generator) and E8267D PSG. These instruments are engineered to meet the demanding requirements of wireless communication, aerospace, defense, and various research applications.

The E8257D PSG is known for its versatility and reliability. It operates within a frequency range of 250 kHz to 40 GHz, making it suitable for a wide array of applications, from signal generation to vector modulation. With an output power capability of up to +30 dBm, it delivers high-quality signals with exceptional precision. Its low phase noise performance is especially critical for applications such as radar and communication system testing, where signal integrity is paramount.

One of the standout features of the E8257D is its advanced modulation capabilities, including analog and digital modulation schemes. This flexibility allows engineers to simulate real-world communications environments accurately. The PSG also features a built-in arbitrary waveform generator that enables users to create complex waveforms tailored to specific testing needs, providing a significant advantage in research and development.

On the other hand, the Agilent E8267D PSG is designed to cater to the needs of users requiring a combined signal generation and analysis solution. With the capability to generate signals from 250 kHz to 67 GHz, the E8267D is ideal for millimeter-wave applications, as well as testing next-generation wireless technologies.

This model includes features such as enhanced phase noise performance and faster switching speed, which are crucial for signal integrity in sophisticated networks. The instrument's intuitive user interface and powerful software integration facilitate effortless operation and automation, thereby improving workflow efficiency.

Both the E8257D and E8267D PSG instruments incorporate cutting-edge technologies such as low-noise microwave and RF components, as well as digital signal processing capabilities. They provide users with enhanced accuracy and reliability in their measurements.

In summary, Agilent Technologies' E8257D and E8267D PSG signal generators represent the pinnacle of precision in signal generation technology. With their extensive feature sets, advanced modulation capabilities, and robust performance specifications, these instruments are invaluable tools for engineers and researchers working across various high-tech industries.

Agilent Technologies E8267D PSG, E8257D PSG Signal Loss While Working with a Spectrum Analyzer

Models: E8267D PSG E8257D PSG

ATTEN

Signal Loss While Working with a Spectrum Analyzer

Setting ALC Off Mode

E8267D PSG, E8257D PSG specifications