This paper presents a highly efficient 5G NR RF transmitter (TX) system consisting of a SAW-less RF transmitter IC, an RF power amplifier module (PAM) and a supply modulator IC (SM-IC). The RF TX with a 12-bit current-steering digital-to-analog converter (DAC) generates +7 dBm of output power to drive the PAM for high power user equipment (HPUE) in the 5G NR n77 band. The SM-IC generates a maximum output power of 10W at a 5-V peak envelope output voltage and provides an envelope tracking supply voltage of a 100-MHz NR signal to the n77 PAM. The PAM employing a differential topology generates a saturation output power of 32.5 dBm including the loss of the SOI switch and output filter. The designed PAM in ET mode achieves an ACLR of -37 dBc at a 27-dBm output power and saves 950 mW in comparison to APT mode.