LPD, VPD and IVR: Power Delivery Architectures for the AI Computing Era
2026.9.14
Articles
GOTREND
Introduction
As artificial intelligence (AI) servers, graphics processing units (GPUs), application-specific integrated circuits (ASICs), and high-performance computing (HPC) platforms continue to scale, processor core voltages are decreasing while load currents are rising rapidly.
In high-current systems, power-delivery challenges are no longer limited to DC-DC conversion efficiency. Parasitic resistance, parasitic inductance, and physical distance within the power delivery network (PDN) directly affect voltage drop, power loss, and transient performance.As a result, shortening the power-delivery path and reducing PDN impedance have become critical design objectives, bringing Lateral Power Delivery (LPD), Vertical Power Delivery (VPD), and Integrated Voltage Regulators (IVRs) into focus for next-generation AI platforms.
In high-current systems, power-delivery challenges are no longer limited to DC-DC conversion efficiency. Parasitic resistance, parasitic inductance, and physical distance within the power delivery network (PDN) directly affect voltage drop, power loss, and transient performance.As a result, shortening the power-delivery path and reducing PDN impedance have become critical design objectives, bringing Lateral Power Delivery (LPD), Vertical Power Delivery (VPD), and Integrated Voltage Regulators (IVRs) into focus for next-generation AI platforms.
1. Why Does AI Computing Create a High-Current Power-Delivery Challenge?
Processor power can be broadly understood as the product of voltage and current. As core voltage decreases while computing power continues to increase, the required supply current rises accordingly.
At current levels of several hundred amperes and beyond, even very small resistance in PCB power planes can generate significant I²R conduction loss and temperature rise. Parasitic inductance in the power path can also create substantial voltage deviation during rapid load transients. For this reason, AI power design is expanding beyond the traditional objective of maximizing VRM conversion efficiency. Key goals now include:
• Shorter power-delivery paths
• Lower PDN parasitic impedance
• Reduced conduction loss and temperature rise
• Faster transient current delivery
• Higher current density per unit area
At current levels of several hundred amperes and beyond, even very small resistance in PCB power planes can generate significant I²R conduction loss and temperature rise. Parasitic inductance in the power path can also create substantial voltage deviation during rapid load transients. For this reason, AI power design is expanding beyond the traditional objective of maximizing VRM conversion efficiency. Key goals now include:
• Shorter power-delivery paths
• Lower PDN parasitic impedance
• Reduced conduction loss and temperature rise
• Faster transient current delivery
• Higher current density per unit area
2. What Is LPD (Lateral Power Delivery)?
Lateral Power Delivery (LPD) is a mature power-delivery architecture widely used in servers and high-performance computing platforms. In a typical LPD design, voltage regulator modules (VRMs), DrMOS power stages, and power inductors are placed around the CPU, GPU, or ASIC. High current is then delivered laterally through PCB surface layers or internal power planes. LPD benefits from a mature ecosystem, extensive validation experience, established PCB manufacturing processes, and relatively straightforward thermal design. As load current increases, however, the longer lateral current path introduces greater parasitic resistance and inductance. High current flowing through PCB copper also increases conduction loss. These effects reduce efficiency and make voltage regulation more difficult during high-di/dt load transients.3. What Is VPD (Vertical Power Delivery)?
The central concept of Vertical Power Delivery (VPD) is to move the final-stage power module directly underneath the processor or very close to the load. Instead of routing high current over a relatively long lateral path, current is delivered through PCB vias and vertical interconnects along the Z-axis. By shortening the high-current path, VPD can reduce IR drop, I²R loss, parasitic inductance, and voltage deviation during rapid load changes. Another important advantage is board-space utilization. Moving part of the power stage to the back side of the motherboard can free valuable top-side area around the processor for high-speed I/O breakout, PCIe and CXL routing, decoupling components, and other dense signal interconnects. VPD does, however, introduce additional engineering challenges. High-current vias, advanced PCB stack-ups, bottom-side thermal management, mechanical clearance, and manufacturing requirements can all become more demanding.
4. Key Differences Between LPD and VPD
• Placement: LPD places the power stage around the processor, while VPD places it underneath or very close to the processor.
• Current path: LPD relies mainly on lateral PCB conduction; VPD uses vias and vertical interconnects to shorten the power path.
• Power path and PDN: LPD has a longer path and relatively higher parasitic impedance; VPD can reduce PDN parasitics by minimizing path length.
• Board space: LPD occupies more of the processor perimeter, whereas VPD can free top-side area for high-speed signal routing and decoupling.
• Implementation: LPD is mature and cost-effective, while VPD requires tighter PCB, thermal, package, and mechanical integration.
VPD therefore should not be viewed as an architecture that will automatically replace LPD in every application. The appropriate solution depends on processor power, current density, PCB area, thermal constraints, manufacturing capability, and system cost.
• Current path: LPD relies mainly on lateral PCB conduction; VPD uses vias and vertical interconnects to shorten the power path.
• Power path and PDN: LPD has a longer path and relatively higher parasitic impedance; VPD can reduce PDN parasitics by minimizing path length.
• Board space: LPD occupies more of the processor perimeter, whereas VPD can free top-side area for high-speed signal routing and decoupling.
• Implementation: LPD is mature and cost-effective, while VPD requires tighter PCB, thermal, package, and mechanical integration.
VPD therefore should not be viewed as an architecture that will automatically replace LPD in every application. The appropriate solution depends on processor power, current density, PCB area, thermal constraints, manufacturing capability, and system cost.
5. What Is an IVR (Integrated Voltage Regulator)?
An Integrated Voltage Regulator (IVR) represents a different architectural dimension from LPD and VPD. LPD and VPD describe where the power stage is located and how current is physically delivered to the processor. IVR describes how closely the voltage-regulation function is integrated with the load. The objective of an IVR is to move part or all of the final voltage-conversion function from the motherboard toward the processor package, die, or another location very close to the load. In some integrated voltage-regulation architectures, power can be distributed at a relatively higher voltage and lower current before final conversion takes place close to the processor. Individual voltage rails can then be generated near the circuits that consume them. This approach reduces the need to transport very high current at very low voltage over long PCB distances and can also shorten the electrical path between the regulator and the compute load. Therefore, VPD and IVR are neither synonymous nor mutually exclusive. An advanced AI processor can employ vertical power delivery while also using highly integrated voltage regulation.
6. How Are TLVR, LPD, VPD, and IVR Related?
Regardless of whether LPD or VPD is used, AI GPUs and ASICs must respond to extremely fast changes in load current.
In a conventional multiphase buck regulator, each phase primarily relies on the current slew rate of its own output inductor. During a rapid load step, insufficient inductor-current slew rate can result in output-voltage droop.
A Trans-Inductor Voltage Regulator (TLVR) uses coupled transformer-inductor structures together with interconnected secondary windings and a compensation path. This allows multiple phases to contribute more effectively during a load transient. The objective is to increase the total current slew rate during transient events while maintaining acceptable steady-state ripple, thereby reducing output-voltage undershoot and overshoot. TLVR and VPD therefore address different design problems. VPD reduces power-path length and PDN impedance, whereas TLVR improves the transient behavior of a multiphase voltage regulator through magnetic coupling. GOTREND GTLVR and GTLVRM products are targeted at high-current multiphase VRM applications, where low DCR, high-current capability, low leakage flux, low-profile construction, and high power density are important design considerations.
In a conventional multiphase buck regulator, each phase primarily relies on the current slew rate of its own output inductor. During a rapid load step, insufficient inductor-current slew rate can result in output-voltage droop.
A Trans-Inductor Voltage Regulator (TLVR) uses coupled transformer-inductor structures together with interconnected secondary windings and a compensation path. This allows multiple phases to contribute more effectively during a load transient. The objective is to increase the total current slew rate during transient events while maintaining acceptable steady-state ripple, thereby reducing output-voltage undershoot and overshoot. TLVR and VPD therefore address different design problems. VPD reduces power-path length and PDN impedance, whereas TLVR improves the transient behavior of a multiphase voltage regulator through magnetic coupling. GOTREND GTLVR and GTLVRM products are targeted at high-current multiphase VRM applications, where low DCR, high-current capability, low leakage flux, low-profile construction, and high power density are important design considerations.
7. What Does Next-Generation AI Power Require from Magnetic Components?
• Low DCR to reduce conduction loss and temperature rise at high current.
• High Isat and Irms to maintain saturation and thermal-current capability as component size decreases.
• Low core and AC winding losses at high switching frequencies.
• Low leakage flux and low EMI to reduce magnetic coupling into nearby high-speed circuits.
• Low-profile, high-power-density construction for VPD, SiP, 3D packaging, and stringent Z-height requirements.
• Strong thermal and mechanical reliability under high temperature, high current, and repeated power cycling.
• High Isat and Irms to maintain saturation and thermal-current capability as component size decreases.
• Low core and AC winding losses at high switching frequencies.
• Low leakage flux and low EMI to reduce magnetic coupling into nearby high-speed circuits.
• Low-profile, high-power-density construction for VPD, SiP, 3D packaging, and stringent Z-height requirements.
• Strong thermal and mechanical reliability under high temperature, high current, and repeated power cycling.
Conclusion
As AI computing performance continues to increase, power delivery is evolving from a motherboard-level VRM design problem into a system-level engineering challenge involving the PCB, power modules, advanced packaging, silicon, thermal design, and magnetic components. LPD will remain important because of its maturity and cost advantages. VPD can reduce PDN loss and improve transient performance and board-space utilization by shortening the high-current delivery path. IVRs move voltage regulation closer to the load, while TLVR technology can improve the transient response of high-current multiphase regulators through magnetic coupling. Future AI power systems are therefore unlikely to converge on a single architecture. Instead, LPD, VPD, IVR, and TLVR are likely to coexist and complement one another according to current level, power density, thermal constraints, packaging requirements, manufacturing capability, and cost. For magnetic components, low DCR, high-current capability, low core and AC winding losses at high switching frequencies, low EMI, low-profile construction, and effective thermal management will remain fundamental requirements for next-generation high-density AI power systems.
Conclusion
As AI computing performance continues to increase, power delivery is evolving from a motherboard-level VRM design problem into a system-level engineering challenge involving the PCB, power modules, advanced packaging, silicon, thermal design, and magnetic components. LPD will remain important because of its maturity and cost advantages. VPD can reduce PDN loss and improve transient performance and board-space utilization by shortening the high-current delivery path. IVRs move voltage regulation closer to the load, while TLVR technology can improve the transient response of high-current multiphase regulators through magnetic coupling. Future AI power systems are therefore unlikely to converge on a single architecture. Instead, LPD, VPD, IVR, and TLVR are likely to coexist and complement one another according to current level, power density, thermal constraints, packaging requirements, manufacturing capability, and cost. For magnetic components, low DCR, high-current capability, low core and AC winding losses at high switching frequencies, low EMI, low-profile construction, and effective thermal management will remain fundamental requirements for next-generation high-density AI power systems. If you are interested in our products, please Contact Us: service@gotrend.com.tw
