# Agnostic Envelope Linearization of Dynamically Supplied Power Amplifiers for Mobile Terminals
## 3 Experimental Setup and Linearization Results
### Experimental Results with the NR-60 MHz Test Signal
Figure 13: Spectra of different supply envelopes without and with different linearization approaches. Table 1 provides a comparison of different linearization approaches. As observed, without any kind of linearization, the ET PA output presents \(-24.39\) dB of NMSE and \(-28.57\) dBc of ACPR, with a power efficiency of \(16.58\%\). By considering the GMP-based I-Q DPD with \(128\) complex-valued coefficients, the ACPR requirement of \(-36\) dBc cannot simply be met. However, with the ELC or the proposed EOPT linearization, the ACPR requirement of \(-36\) dBc cannot simply be met. However, with the ELC or the proposed EOPT linearization, the ACPR requirement of \(-36\) dBc cannot simply be met. However, with the ELC or the proposed EOPT linearization, the ACPR requirement of \(-36\) dBc cannot simply be met. However, with the ELC or the proposed EOPT linearization, the ACPR requirement of \(-36\) dBc cannot simply be met. However, with the ELC or the proposed EOPT linearization, the ACPR requirement of \(-36\) dBc cannot simply be met. However, with the ELC or the proposed EOPT linearization, the ACPR requirement of \(-36\) dBc cannot simply be met. However, with the ELC or the proposed EOPT linearization, the ACPR requirement of \(-36\) dBc cannot simply be met. However, with the ELC or the proposed EOPT linearization, the ACPR requirement of \(-36\) dBc cannot simply be met. However, with the ELC or the proposed EOPT linearization, the ACPR requirement of \(-36\) dBc cannot simply be met. However, with the ELC or the proposed EOPT linearization, the ACPR requirement of \(-36\) dBc cannot simply be met. Therefore, with the ELC or the proposed EOPT linearization, the ACPR requirement of \(-36\) dBc cannot simply be met. Figure 14: Spectra of the ET PA output signal without and with different linearization approaches. Figure 15: Spectra of the ET PA output signal when combining the use of different envelope linearization approaches and I-Q DPD. requirements can be met with 84 real-valued coefficients. Regarding the computational resources, each GMP coefficient results in a complex-to-real and a complex-to-complex multiplication; while each ELC/EOPT coefficient only uses two real-to-real multiplications. The actual number of multiplication depends on the implementation architecture. For example, by considering three real multipliers for the complex-to-complex multiplication, then 128 GMP coefficients end up using \(5\times 128=640\) multipliers; while 84 ELC/EOPT coefficients only require \(2\times 84=168\) multipliers. It is important to note that both ELC and EOPT approaches use the same EGMP basis functions with maximum memory depth of 20 taps and maximum power order of 6. The only difference between both approaches is the procedure to extract the EGMP coefficients (i.e., the ETM output is not available to extract the EGMP coefficients in the EOPT approach). Both approaches show similar performance; however, the ELC has slightly better NMSE and power efficiency while the EOPT has slightly better ACPR performance. Finally, by combining the use of envelope optimization and I-Q DPD, the linearity can be further improved. As shown in Table 1, despite the fact that the ELC+GMP combination presents the best linearity performance with \(-33\) dB of NMSE and \(-40.32\) dBc of ACPR, the EOPT+GMP alternative shows very competitive results not only in terms of linearity but also in terms of power efficiency. In addition, since the proposed EOPT approach is agnostic on the ETM behavior, the cost of an extra ADC to monitor the ETM output is saved.