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Method for a board-level dynamic device current (ICC) real-time measurement

IP.com Disclosure Number: IPCOM000074574D
Publication Date: 2005-Feb-23

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a board-level dynamic device current (ICC) real-time measurement. Benefits include improved capability to detect the dynamic device current change, improved measurement accuracy, and improved ability to be proliferated to additional applications.

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Method for a board-level dynamic device current (ICC) real-time measurement

Disclosed is a method for a board-level dynamic device current (ICC) real-time measurement. Benefits include improved capability to detect the dynamic device current change, improved measurement accuracy, and improved ability to be proliferated to additional applications.

Background

              The disclosed and conventional methods are tested in the high-volume manufacturing (HVM) test environment, illustrated in Figure 1. A test interface unit (TIU) is a multi-layer printed circuit board used to provide electrical connectivity between the automated test environment (ATE) tester and the device under test (DUT). A top view of this arrangement is shown in Figure 2. A cross-sectional view is illustrated in Figure 3. In terms of electrical functionality, the TIU is similar to the motherboard in a system application.

      A typical application that requires the dynamic device current information is active thermal control, as shown in Figure 4. Active thermal control maintains the junction temperature of the DUT within a specified tolerance by controlling the thermal dissipation of the DUT. Because the dynamic device current is an indicator of the device activity and heat generation, it must be monitored on the fly so that accurate thermal management can be achieved.

              Two conventional methods of board-level device current measurement exist. One method consists of the insertion of a multitude of precision resistors along the power delivery path of the PCB, as shown in Figure 5. The current is then obtained by dividing the measured voltage drop across the resistors over the known resistance with the help of instrumentation op-amps. However, this method is only applicable for low-current consumption device of which the voltage droop performance is loosely governed. It is not suitable for high-current low-voltage devices (for example, a high-performance microprocessor) with a tight voltage noise specification. The second method consists of a current measurement at the customized power supply module, which is equipped with current sensing capability, as shown in Figure 6.

              The conventional methods require the PCB power planes carrying the current supply to the device to be split so that a multitude of precision resistors can be physically placed across the split planes. This requirement has been proven to have adverse impact to both signal integrity and power delivery performance of the high-speed high-current device, for instance, high performance microprocessors.

•            

Split

plane, if not well designed, may cause impedance mismatch that affects the signal transmission.

•             From the power delivery perspective, the effective resistance of the precision resistors has to be extremely small so that the device supply voltage noise specification is not violated (because V=IR, R must be small).

•             In contradiction with the requiremen...