Use of a Frequency Divider to Evaluate an SOI NAND Gate Device, Type CHT-7400, for Wide Temperature Applications
Richard L. Patterson, Ahmad Hammoud · 2010
Scope Frequency dividers constitute essential elements in designing phase-locked loop circuits and microwave systems. In addition, they are used in providing required clocking signals to microprocessors and can be utilized as digital c ounters. In some applications, particularly space missions, electronics are often exposed to extreme temperature conditions. Therefore, it is required that circuit s designed for such applications incorporate electronic parts and devices that can t olerate and operate efficiently in harsh temperature environments. While present electronic circuits employ COTS (commercialoff-the-shelf) parts that necessitate and are suppo rted with some form of thermal control systems to maintain adequate temperature for proper operation, it is highly desirable and beneficial if the thermal conditioning elements are eliminated. Amongst these benefits are: simpler system design, reduced weight and size , improved reliability, simpler maintenance, and reduced cost. Devices based on si licon-on-insulator (SOI) technology, which utilizes the addition of an insulation layer in the device structure to reduce leakage currents and to minimize parasitic junctions, are w ell suited for high temperatures due to reduced internal heating as compared to the convent ional silicon devices, and less power consumption. In addition, SOI electronic integrate d circuits display good tolerance to radiation by virtue of introducing barriers or leng thening the path for penetrating particles and/or providing a region for trapping incident ion ization. The benefits of these parts make them suitable for use in deep space and planet ary exploration missions where extreme temperatures and radiation are encountered. Although designed for high temperatures, very little data exist on the operati on of SOI devices and circuits at cryogenic temperatures. In this work, the performa nce of a divide-by-two frequency divider circuit built using COTS SOI logic gates wa s evaluated over a wide temperature range and thermal cycling to determine suitability for use in space exploration missions and terrestrial fields under extreme temperature co nditions. Test Procedure The divide-by-two frequency divider circuit was bui lt using COTS SOI NAND logic gates that were introduced recently by CISSOID Corporation. Three of these quad 2input CHT-7400 NAND gates were used and were connected in a D-type flip-flop, master-slave configuration. Frequency division is achieved by feeding the input pulse train into the clock input, and connecting the nega ted output (Q-bar) to the D input, as shown in Figure 1. The circuit utilized high tempe rature polyimide board, NP0 ceramic capacitors, Teflon-insulated wires, and high temper ature (300 °C) solder. A photograph of the circuit board is shown in Figure 2, and the manufacturer’s specifications for the CHT-7400 NAND gate are shown in Table I [1].