Rohde & Schwarz launches its novel wideband modulated load pull solution. Based on the R&S RTP oscilloscope, this solution offers an extension to traditional vector network analyzer (VNA)-based solutions for non-linear device characterization. By enabling load pull with wideband modulated signals, it allows precise validation of key performance indicators across varying impedances, such as error vector magnitude (EVM) and adjacent channel leakage ratio (ACLR), to support the development of RF components for next-generation wireless technologies.
The new wideband modulated load pull solution from Rohde & Schwarz takes a novel approach to RF frontend testing. By using the R&S RTP oscilloscope instead of a traditional vector network analyzer (VNA), this solution enables wideband modulation characterization of RF frontends across varying impedances.
A traditional modulated load pull solution validates modulation characteristics under different impedances with a test setup consisting of a vector signal generator and vector signal analyzer. A passive tuner is used to simulate different load conditions. This method, although widely used, has several key limitations: there is a significant frequency response and group delay of the tuner in amplitude and phase leading to measurement uncertainties. While these may be ignored for narrowband applications, they become significant for higher signal bandwidths, typically around 100 MHz and above.
Innovative oscilloscope-based approach
The Rohde & Schwarz wideband modulated load pull solution addresses these limitations with a new test setup that is ideal for verifying power amplifier performance when connected to an antenna, which typically shows a dispersive impedance. This solution is based on the R&S RTP084 oscilloscope, equipped with the wideband modulated load-pull option R&S RTP-K98, and paired with the R&S SMW200A vector signal generator. The oscilloscope’s internal architecture guarantees absolute phase and time synchronization for forward and reverse wave measurements. The dual path vector signal generator R&S SMW200A offers accurate timing and phase stability between the input and tuning signal for load pull operation. The R&S RTP-K98 software processes the oscilloscope’s measured data, performs the necessary calculations to achieve the target impedance value and controls the signal generator. Hence, it is well-suited to verify the performance of RF frontends, which are typically used over wider frequency ranges and multiple transmission bands, such as 5G or Wi-Fi.
The R&S RTP oscilloscope combines high-class signal integrity with fast acquisition and analysis. Dedicated acquisition and processing ASICs enable high acquisition and processing rate for 750,000 waveforms/s. The unique 3 Gpoints per channel allow for long acquisition periods, and the high-precision digital trigger operates with a hardware-based clock data recovery (CDR) on embedded clock signals at an industry-leading rate of 16 Gbps.
Markus Lörner, Market Segment Manager RF & Microwave Components at Rohde & Schwarz, says: “Our innovative approach for wideband modulated load pull utilizes standard test instruments readily available in many labs, directly addressing the growing need for verifying wideband RF frontends across varying impedances, as experienced in wideband antenna usage. The incorporation of the oscilloscope as the key instrument is a game-changer, offering rapid wideband signal capture, which is absolutely vital in this application.”
The new wideband modulated load pull solution is available now from Rohde & Schwarz. More information on load pull testing from Rohde & Schwarz.
