【正文】 the analog section of a given design for a variety of reasons: the availability of mixing ponents for the two technologies, the plexity of the digital design or again because of the existence of pure digital processing parts as standard products. Placing the analog elements in an integrated circuit definitively allows the system designer to optimize the costs of its entire module. This integration approach is usually difficult for advanced markets such as telemunications or puters, but makes sense for more mature or conservative markets such as automotive, medical and industrial. For most of these mature market’s applications, digital functions are finding their way onto what once were pure analog designs. Adding digital functions to an analog design is helped in part by the development of new process technologies that can handle both shortchannel, fastswitching digital transistors as well as highvoltage analog transistors. For example, AMI Semiconductor’s latest mixedsignal technology offers digital and analog integration capabilities on the same design platform. The I3T technology family is based on standard CMOS 181。m, limiting the maximum gate voltage to V. Some consider this technology outdated, from a pure digital designer’s point of view, but it is at the forefront for the automotive, industrial and medical markets. 蘭州理工大學(xué)畢業(yè)設(shè)計 27 This list of optional features that enables the design of real SoCs includes high voltage interfacing up to 80 V, microprocessing capabilities up to 32 bits, wireless capabilities up to GHz, and dense logic design up to 15 K gates/mm2. Beside these capabilities, NVM integration is possible: E2PROM up to 4 Kbytes, Flash memory up to half a megabit or OnTimeProgrammable (OTP) cells for application calibrations. The ability to integrate all these features on a chip gives the customer the possibility to be independent from the obsolescence of the standalone NVM market, which is more or less driven by the puter market. This advantage is quite relevant when we consider the cost of requalifying a module for the OEMs in automotive, for instance. It also makes sense when considering the long lifespan of the applications embedded into cars, the industrial environment or medical selftreatment devices where patient cost is an important consideration. Nevertheless bridging the gap from digital to analog on a single chip does not occur without issues. Clocking noise from highspeed digital circuits, for instance, often interferes with noisesensitive analog functions. In addition, switching currents from highpower analog functions can interfere with lowvoltage digital processors. The goal is to protect lowvoltage transistors from the electric field effects of voltages that are 10 to 30 times higher. These important issues are not without solutions. For example, one of the latest releases in the I3T family, the I3T50 DTI, uses a deep trench isolation technique. This technique uses a series of isolating trenches that bury deep into the IC substrate。 effectively creating onchip “pockets” where noise and power supply parameters are carefully controlled. On top of its protection skills, the deep trench technology also helps to minimize die area by allowing dense packing of highvoltage analog pockets with lowvoltage regions. You can obtain improvements in die area of 10 to 60 percent over designs that use standard junction isolation techniques. As mentioned earlier, the reason that system designers are using deep submicron technologies in those markets is often linked to the availability of devices in those technologies, not the plexity of the application itself. The plexity can be handled in many cases by an 8bit microcontroller, or 32bit for highend applications. Products such as 蘭州理工大學(xué)畢業(yè)設(shè)計 28 the 181。m I3T are able to manage the integration at a reasonable cost. A typical application diagram of a real mixedsignal SoC is shown in Figure . Basically, the chip integrates the system functionality from the sensor to the actuator, going through some digital processing. Conventional mixedsignal technology allows analog control and signal processing functions such as amplifiers, analogtodigital converters (ADCs) and filters to be bined with digital functionality such as microcontrollers, memory, timers and logic control functions on a single, customized chip. All signals that process an algorithm or arithmetic calculation are digital, so conversion of analog to digital signals is mandatory when submitting data for parison or processing by via a microcontroller, while conversion from digital output signals to analog highvoltage signals is required to drive an actuator or a load. The most recent mixedsignal technology AMIS developed, significantly simplifies the implementation of such driver functionality by allowing much higher voltage functionality to be integrated into an IC alongside the relatively low voltages required for conventional mixedsignal functions. This highvoltage mixedsignal technology is particularly relevant to automotive electronics applications where higher voltage outputs — to drive a motor or actuate a relay — need to be bined with analog signal conditioning functions and plex digital processing. A growing trend in mixedsignal circuit design is to add some type of central processing circuit to the analog circuits. For many applications the suitable choice of processing intelligence is an 8bit microcontroller core such as an 8051 or 6502. 8 bits remains the most popular choice as this type of SoC is not intended to replace plex highend central microcontrollers but more decentralized or slave applications such as sensor conditioning circuitry with local (as close to the sensor as possible) simple intelligence to control relays or motors. An automotive