amplifier saturation. Eventually, theampli-Noneofthese errors increase withtime, and times theerror present intheservomecha- fier reaches its maximumoutput voltage and inthissense theyarenotsystematic. If nismitself. Tocheck themultiplying poteni- cani gonohigher. Whilealarger timecon- "state-of-the-art"
Squarer Aa · 1957
devices areused,the tiometers, switches S3toS7maybeclosed as stanit will allow a longer integration time additional error contributed bythisextrarequired. whensaturation isa limiting factor, in- circuitry canbeheldbelowonepercent. Themostcrucial component ofthis creasing theamplifier gainwillhaveno Thatis,iftheintegrator byitself hasan measuring system isthesquarinig device. A effect. Attenuating theinput alsoincreases accuracy oftwopercent, itwouldhavean diode function generator' wasusedforthis theintegrating time. However, iftheinte-accuracy ofaboutthree percentwiththe purpose. Togenerate therequired parabolic grating timeistobeincreased byalargeadditional features. Suchasmall error can function, amultitonic setup maybeusedor number(afactor ofseveral hundred toa onlybemaintained uptovalues ofN of monotonic diodefunction generators may tbousanid) attenuating theinput will usuallyabout1000. Abovethis, errors inthedigital- beplaced inthefeedback loopofoperational decrease thesignal-to-noise ratio byanun- to-analog converter maybecomeexcessive. amplifiers. Itisnotasimportant thatthe bearable amountwhenthenoise isproduced The schemedescribed hererequiresparabolic function begenerated exactly asit intheintegrator, andthephysical size ofthe considerably morecomplexity thanasimpleisthatthefunction bewellbalanced inrecomponenits necessary fora suitable time integrator. However, theadditional cir-spect topositive andnegative inputs. The constant becomes impractical. Forexample,cuitry willoften besmaller, lighter, and diodefunction generator waschosenfor ifanintegrator hasacapacitor whosevalue moreaccurate thanresistors andcapacitors this application because ofitshighspeed of is10microfarads andaslarge aresistor as large enoughtoproduce a corresponding response inrespect tothecomponent under canbeused, acapacitor of5000microfarads effect. testandforitsability togenerate steep isnecessary iftheintegrating timeistobe GEORGEH.MYERS slopes undertheproper setup conditions. inicreased bya factor of500.Whenthis