Variations in chip processing and packaging operations result in deviations of analog circuits and sensors from their target specifications. To optimize the performance of the systems in which these components are placed, it is necessary to “trim” interface circuitry to match a specific analog circuit or sensor. A trimming operation compensates for variations in the analog circuits and sensors due to manufacturing variances of these components. The trimming requirement becomes more important as process nodes shrink due to the increased variability of analog circuit performance parameters at smaller processes, due to both random and systematic variations in key manufacturing steps. This manifests itself as increasing yield loss when chips with analog circuitry migrate to smaller process nodes since a larger percentage of analog blocks on a chip will not meet design specifications due to variability in process parameters and layout. Examples where trimming is used include automotive and industrial sensors, display controllers, and power management circuits. Trimming is also done to increase the yield of LCD displays by ensuring more uniform performance of the display’s individual pixels.
OTP Trimming can also be used to match the performance of a system to individual preferences or, for medical applications, health requirements. Examples of preference matching include frequency response of an audio amplifier and screen characteristics of an HDTV. Medical applications include shaping the audio response spectrum of a hearing aid to compensate for the wearer’s hearing losses and adjusting the triggering threshold levels of an implanted pacemaker.
Automobiles provide many opportunities for OTP-based trimming and calibration systems that interface with a car’s analog circuits and sensors. Examples where automotive trimming and calibration operations occur include secure vehicle ID (VID) storage, in-car communications, infotainment systems, gas tank vapor and tire pressures, temperatures of various subsystems both outside and under the hood, and positioning of electromechanical devices for brake, steering and other systems.
The examples in the following figure are for trimming and calibration of circuits such as analog amplifiers, ADCs/DACs and sensor conditioning. There are also many other uses for OTP, both in automotive and in other market segments, including microcontrollers, PMICs, and many others.
Sidense OTP is used to store trim and calibration settings in an analog device so that the device powers up already calibrated for the system in which it is embedded. This functionality is represented in the following block diagram. The field-programmability of Sidense’s OTP allows these trim and calibration settings to be done in-situ in the system, thus optimizing the system’s operation.