N7614C Signal Studio for Power Amplifier, CFR, DPD and ET Test

Simplify Signal Creation for PA Test

Keysight Technologies, Inc. Signal Studio software is a flexible test suite of signal-creation and measurement tools that will reduce the time you spend on signal simulation. With the N7614C power amplifier test software, Signal Studio’s performance-optimized test flow—validated by Keysight—enhances the characterization and verification of your devices. Through its application-specific user-interface you’ll create a test flow with CFR, and/or ET, and/or DPD technologies for power amplifier test.

Modern mobile communications, such as LTE and 802.11ac place new demands on linearity, bandwidth and power consumption in wireless components and place unprecedented battery requirements on mobile terminals or base stations. One of the most power-hungry and non-linear components is the PA. The design of the power amplifier must allow it to:

·  Increase spectral efficiency

· Increase power added efficiency (PAE)

· Reduce distortion and non-linearity

Techniques such as crest factor reduction, envelope tracking and digital pre-distortion, can be implemented to increase PA efficiency. All of these methods are supported by the N7614C Signal Studio for power amplifier test software.

Envelope Tracking Technology

Modern modulated signals have high PAPR. Power amplifiers that must amplify these high PAPR signals, if using a fixed bias, must be operated at a relatively high output power back-off, to avoid greatly distorting the signal when the envelope excursion is near its peak. However, as the amount of back-off increases, the power amplifier becomes less efficient. Envelope tracking (ET) is the leading solution for this issue in mobile RF front end design. ET dynamically adjusts the DC supply voltage based on the “envelope” of the PA input signal and delivers higher voltages only when needed, improving battery consumption and heat dissipation in the PA. N7614C supports ET technology, which can be applied on its own, or combined with DPD. When combined with DPD, ET can be applied and optimized before or after DPD is applied. Precise timing adjustment, down to a nanosecond or a fraction of a nanosecond, is required to optimize ET system performance. N7614C software supports:

· Automatic time delay adjustments (based on ACP measurement results)

· Manual time delay adjustments (based on ACP or EVM measurement results or an external oscilloscope)

Apply your signals in real-world testing

To use N7614C Signal Studio for Power Amplifier Test software, you must have a properly configured PC and several properly configured instruments, as described here. Signal Studio software complements these platforms by providing a cost-effective way to tailor them to your test needs in design, development and production test.

Digital Pre-Distortion Test

As discussed earlier, the PA is required to have higher linearity to amplify high PAPR signals. However, due to the limitations of cost, power consumption, and physical space, it is not easy to find higher linearity components that meet all of a particular system’s requirements. DPD, one of the most cost-effective linearization techniques, adds an expanding nonlinearity in the baseband that complements the compressing characteristic of the RF power amplifier (Figure 5). Ideally, the cascade of the pre-distorter and the power amplifier becomes linear and the original input is amplified by a constant gain. With the pre-distorter, the power amplifier can be utilized up to its saturation point while still maintaining good linearity, thereby significantly increasing its efficiency (Figure 6).