EDITOR’S CHOICE
How to achieve Ultrafast Power Supply Transient Response for RF applications
Xinyu Liang, applications engineering manager at Analog Devices, presents practical methods for achieving an ultrafast power supply transient response in wireless and, especially, RF applications
S
ignal processing units and system- on-a-chip (SoC) units usually possess abruptly changing load transient profi les. This load transient will result in a disturbance on the supply voltage that is critical in radio frequency (RF) applications, as the clock frequency will be highly affected by the varying supply voltage.
As a result, RFSoCs usually apply blanking time during the load transient. In 5G applications, information quality is highly related to this blanking period during the transition. Thus, there is an increasing need to minimise the load transient effect on the power supply side to improve the system- level performance for any RFSoC system. This article will introduce several methods used in RF applications to achieve fast transient response in a power supply design.
Fast Transient Silent Switcher 3 Family for RF applications
One of the most straightforward methods to achieve fast transient power rails is to select regulators that feature fast transient performance. The Silent Switcher 3 family of ICs features exceptionally low frequency output noise, fast transient response, low EMI emissions, and high effi ciency. It features an ultrahigh performance error amplifi er design that can provide extra stabilisation even with an aggressive compensation. The 4MHz maximum switching frequency enables the IC to push the control loop bandwidth to the mid-hundred kHz range in a fi xed frequency peak current control mode.
The Silent Switcher 3 ICs that designers can select to achieve fast transient performance are listed in Table 1. Figure 1 shows a typical 1V output power supply based on the LT8625SP for the 5G RFSoC, which needs fast transient response and low ripple/noise level at the same time. The 1V load consists of both transmitted/ received related circuits as well as local oscillators (LOs) and voltage controlled oscillators (VCOs). The transmitted/received loads see abrupt load current change in the frequency division duplex (FDD) operation.
Table 1: Silent Switcher 3 Family Parameters
Figure 1: Typical application circuits for LT8625SP in dynamic/static separated RF loads
Figure 2: Load transient response is fast with minimum VOUT
deviation and won’t affect the static load NOVEMBER 2023 | ELECTRONICS FOR ENGINEERS 21
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50
