An RF probe is a coupling device used to measure the RF signal directly from an electronic circuit. Reed Gleason and Eric Strid invented RF Probes in 1980 and later in 1983, they found Cascade Microtech.
To learn more about RF and Microwave communication components and systems, we recommend you to check the following article consisting of RF and Microwave bestsellers.
To understand the RF probes in detail, we recommend you to understand the following RF and Microwave components.
In this RF and microwave Probes article, we will cover,
RF probes help to solve the challenges of measuring the RF energy directly from a circuit using the measuring equipment at hand. Following are the prime challenges RF designers and test engineers face during the testing of RF and Microwave signals in a circuit.
One of the prime challenges is the unavailability of high frequency measuring equipment for measuring high-frequency RF signals such as the need to measure RF signals using a low-bandwidth oscilloscope. In this case, the only option is to convert the RF signal directly to a DC or near-DC signal for the measurement.
The simple form of RF probe is an RF detector, which is used to convert the RF signal to DC and it also works as an RF rectifier and generates corresponding pulsed DC voltage. These converted signals can be easily measured in an oscilloscope.
The second challenge of measuring RF energy from a circuit that is highly sensitive to small changes in the electrical environment. For example, ordinary wiring within a few centimetres away of the active components like high sensitivity oscillator circuits may lead to a change in the amplitude or frequency response of oscillations, or even lead to the malfunctioning of the oscillator itself.
To solve this challenge RF probe can extracts even very little RF energy from the circuit without creating any impedance to the circuit. This is achieved by using very thin conductors, or coils, placing at minimum separation distance from an active element needed to measure in the circuit.
In RF circuits, it is important to match the probe impedance with DUT to avoid reflection, which in turn may lead to affect the efficient power transfer. RF probes help to keep the insertion loss in the coupling mechanism as low as possible. Impedance mismatch and insertion loss are more critical challenges for high-frequency measurement applications.
Spring contact RF probes are ideal probes for RF measurement applications and they will have a coaxial connector at another terminal for interfacing to RF measurement instruments. The dimension and design of inner and outer conductors of the RF probes help to align to the RF measurement challenges like impedance match, sensitivity etc.
RF probes are used to send or receive the RF signal through a transmission line to the DUT and back. To send and receive RF signals, probes need two conductors, one for the signal and the other for the ground. RF Proves are classified on the basis of how these conductors are configured in the probe structure.
GS RF probes: GS RF probe configurations consist of Ground and Signal transmission lines.
GSG RF probes: GSG RF probes configuration consist of two Ground transmission lines and one Signal line, configured as Ground-Signal-Ground.
GSSG RF probes: GSSG RF probes configuration consist of four transmission lines configured as Ground -Signal-Signal- Ground.
The most common RF Probe configuration type is the GSG, this configuration is similar to the co-planar waveguide. RF Wafer Probe is designed to be a vibration-free probing mechanics, and rigid.
An RF probe is a component that is used to couple the RF signal from the electronic circuit for measurement applications.
Coaxial spring-loaded RF probes are used in modern electronics communication components mass-production, and in-line testing of circuits in the mobile phone industry. RF Wafer Probe are basically configured for the test and measurement in the microwave range (0.3 GHz to 300 GHz) components.
RF probes are designed in such a way that, they can establish a suitable transmission line interface to instruments like VNA, Load pull systems etc for the wafer level testing of the IC circuit.
RF probes frequency range, sensitivity and power handling levels are the prime factors that need to consider in the selection process. In addition, it is ideal to check the below-listed specifications of the RF probes for confirming the suitability for the RF and microwave test and measurement application.
Frequency Response is the range of frequency over with the RF probe is designed to operate by meeting all other characteristics. Need to select RF probes that support the operating frequency of the DUT in the circuit. Currently, Probes are available in the market which can support microwave frequencies up to 110 GHz.
Configuration of the RF probes indicates the positioning of the conductors in the probe for the signal and ground. Designers need to select a suitable configuration among the available configuration like GS, GSG, and GSSG.
Probe Pitch indicates the distance between the centre of the RF and microwave probe tips. It is expressed in microns. Small probe pitch is suitable for very high frequencies.
The sensitivity of the RF probe indicates the lowest power level which can be measured from the circuit using the RF Probe. It is the level below which an RF probe is unable to detect the signal. It is critical to use an RF probe for the circuits which have very low signals level. The sensitivity of high sensitivity RF probes is in the range of a few hundred mV/m.
The field strength range of the RF probes is the maximum amplitude level a probe can read. The higher the range, the better an RF probe for the test and measurement applications. It is measured in V/m.
The dynamic range of the RF probe indicates the measurement capability range between the lowest and highest field strengths of the RF and Microwave Probe.
The linearity of an RF probe indicates the measurement accuracy of the probes over the dynamic operating range of it. The RF probe's response may vary over the dynamic range of the applied field level.
Power Overload indicates the maximum RF power level an RF probe can handle before breaking down. It is important to select an RF probe with higher Power handling than the maximum expected RF power into it. The overload power level of the RF probe indicates in watt for the pulsed and CW signals.
Temperature Stability is an environmental parameter. The temperature stability of the RF probe indicates the deviation of the reading over the variation in temperatures in its frequency operating range. This is important to consider as the RF probes with high-temperature stability as the probes are getting heated up when the continuously high power RF signal is applied to it.
RF probes play an important role in testing the RF circuits during the technology development, design verification, model parameter extraction, debug to final production test. RF probes are useful for the measurement and characteristics of the RF and microwave components at the wafer level of its design.
If you would like to share the details of the latest advancements in RF probe technologies on this page or details of any advanced RF probe manufacturers, feel free to reach out to us over the contact us page or the manufacture registration button.
Thanks & Regards