The Investigation Of Measurement Technique And The Transient Thermal Characteristics On FPGA

Field Programmable Gate Array(FPGA) with high flexibility and low cost, plays a vital role in the many areas. With the increasing complexity of FPGA applications, the number of FPGA logic gates increases, the integration improves constantly, power consumption is also growing, which cause the FPGA chip’s temperature increase, these factors have essential effects on the reliability of the chip. Uneven power consumption growth of chip will result in the generation of hot spots and increasing temperature gradient. Single junction temperature can’t reflect the spatial temperature distribution, the total power consumption and the average chip temperature estimation can cause the error to the location of the hot spots. Therefore, research of FPGA working temperature distribution has important significance.This paper presents a smart temperature sensor network which is able to measure the Altera Cyclone Ш FPGA temperature distribution, unlike previous voltage or current architecture, ring oscillator has been the way of sensing the temperature, the temperature signal is converted into the delay time. The temperature sensor can be dynamically inserted, operated, and eliminated from the FPGA circuit. On the basis of above makes a deep research, concretely, it includes several aspects.1. A digital smart temperature sensor based on ring oscillator is proposed, for dynamically monitoring the FPGA temperature distribution. The smart thermal sensors used rely on correspondence between the delay and temperature in a ring oscillator. The tested temperature was converted into a time signal with a thermally-sensitive width. The output frequency is read out by a counter with a scan path, and then, transited to PC by a Universal Serial Bus(USB) interface. The temperature sensor is used in the FPGA to measure the temperature distribution under different operating procedures. Then we discuss the effect of different numbers of inverters and the supply voltage, and calculate the thermal response time.2. We evaluate the smart temperature sensor on vacuum and atmosphere, infrared imager is used as reference temperature. A FLIR SC5000 was used to capture the infrared imager of the FPGA chips distribution. For more accurate temperature measurement, the package of FPGA chip was thinned using a laser. By comparison, the smart temperature sensors can be applied to various types of FPGA. The maximum error is 1.6 ℃.3. The FPGA simulation model is established by HotSpot software, we draw FPGA chip floorplan in the HotSpot software, modify the configuration files and acquire the thermal map of FPGA chip, which compare with the temperature distribution by the temperature sensor.