A 24.5–29.5GHz Broadband Parallel-to-Series Combined Compact Doherty Power Amplifier in 28-nm Bulk CMOS for 5G Applications

This paper proposes a parallel-to-series combined Doherty power amplifier (PA) in 28-nm bulk CMOS technology that improves the operation bandwidth and minimizes the die area for the Doherty output network. The two-stage differential Doherty PA shows a saturated output power (P
OUT
) of >18.8dBm and a peak power-added efficiency (PAE) of >30% at 27GHz CW. Under the 5G NR 64QAM OFDM signal (
$\text{PAPR} > 10\text{dB}$
), the PA achieves a linear P
OUT
of 12.4dBm and an average PAE of 20.2% at an EVM of −25dB. Over the frequency range of 24.5-29.5GHz, the PA exhibits a linear P
OUT
of >11.2dBm and a PAE of >14.5%
$(\text{DE} > 20.8\%)$
. This compact PA IC occupies
$640\times 250\mu\mathrm{m}^{2}$
(core).