Base station power supply output voltage range

This is when the PSU is no longer powering the PA, which is the main power draw, but still needs to power other electronics. The current target for low-load efficiency is about 30 W. Some OEMs would like to see that drop to nearly 10 W.

The performances of RF power amplifiers for base station transceivers results in a tradeoff between linearity, efficiency and gain. This tradeoff leads to an optimum quiescent current.

Site-selection considerations also are driving changes to the PA and PSU designs. The higher the frequency, the shorter the signals travel, which means mmWave-based 5G will require a much higher density of small cells compared to 4G. Many 5G sites will also need to be close to street level, where people are.

During quiescent periods—typically 5 ms to 100 ms—the PSU must minimize all load power with the basic functions of the antenna unit remaining active. It also must be able to ramp up to full power whenever the antenna wants to check for any active users within its range.

For class AB biasing, this coefficient is around --2mV/C. For full thermal tracking, more than one diode may be required because of the ratio R1 in R1 + R2 equation 2. However, this standard biasing circuit presents two major limitations: Limitation 1: the manufacturing spread of threshold voltage leads to a different R1 ratio for each die.