1、PDF英文：http:/ A Novel Built- in CMOS Temperature Sen sor for VLSICircuits Wang Nailong, Zhang Sheng and Zhou Runde ( Institu te of M icroelectronics, T sing hua U niversity , B eij ing 100084, Ch ina) Abstract: A novel temperature sensor is developed and presented especially for the purpose of
2、online the rmalmoni to ring of VLSI chips. This sensor requires very small silicon area and low power consumption, and the simulation results show that its accuracy is in the o rder of 018 . The proposed sensor can be easily implemented using regular CMOS process techno logies, and can be easily int
3、egrated to any VLS I circuits to increase their reliability. Key words: temperature sensor； thermal testability； frequency output. EEACC: 1265A； 2560； 2570D CLC number: TN 47 Document code: A Article ID: 025324177 (2004) 0320252205 1 Introduction Due to th
4、e advances in the fabricaion processfield of in tegrated circu its, the component den sityand the overall power dissipat ion of the highperfo rmance VLSI chips increase cont inuously. At thebeginning of this century, the power dissipated in asingle ch ip has exceeded 100W , and tightly packedchip as
5、semblies as the multichip modules can evendissipate thou sandswatts. Therefore, the thermalstate of integrated circu its has been always a greatprob lem concerned and is considered as abottleneck in increasing the in tegrat ion of elect ron ic system s.To overcome this problem , many researchersdeve
6、loped low 2power design techn iques for VLS Isystems. In order to avoid thermal damages,continuous thermal monitoring should be appliedduring both theproduction reliability testing andthe field operation. An eff icient way is to buildtemperatu resensors in to all VLSI chips, with theapp ropriate cir
7、cuitryp roviding easy readout. Insome earlier works , the researchers used theparasitic, lateral or sub strate bipolartran sistors,which can be realized in mo st of the CMOS processes, as thermal sen so rs. These are u suallyPTAT sensors. The weakness of these senors isthat the bipolar structuresare
8、 not well characterized in a MOS process. Thus, although they canp rovide a sat isf iect solution for a given process, thecircu its can not be regarded as a general CMOS approach and can not be widely used. 2 Problem formulation There are various temperature sensors suitable for thermals
9、tate verification of in tegrated circuit microstructures such as thermoresistors, pnjunctions, and the exploitation ofthe weakinversionofMOS transistors. Our objective is to convertthe temperature to an oscillat ing signal to make itcompat ib le to digital circu it design method and facilitate the e
10、valuat ion of the temperaturesensed. Atemperatu re sen so r based on a ringo scillator is introduced in Ref., this cell guarantees a accuracyof 3 that is marginally accep table as a chiptemperature sensor but the silicon area required israther big. AMOS temperature controlled oscillato risused as as
11、ensor to monitor the thermal stateof microelectronic structu res in Ref. How ever,this sensor requires about 10 to 15mW power todrive the thermal delay line and the dissipatertran sistor. To overcome these inconven iences, w e th inkthat the temperature sensors to be used as builtinun its for VLSI c
12、ircuits online thermalmonitoringshould meet some special requirements as follows: ( 1 ) Nearly linearity in a temperatu rerange(usually 0100 ) ； ( 2 ) Low power consumption (no more than1mW ) ； ( 3 ) Simple structure and small silicon area(usually no more than 40 transistors) ； ( 4 ) Easy readoutres
13、ults with favorably digital output signal (e. g. , the frequency of asquarewave which carries the temperatureinformation) ； ( 5 ) Easy (onepoint) calib rat ion； ( 6 ) High accu racy ( in the order of 2 orless) ； ( 7 ) Compat ib ility w ith the p resen t CMO Sp rocess；Con sidering the given requ irem
14、ents, we present a new builtin temperaturesensor meeting allthe above requirements 3 Built- in thermal mon itor ing sensor Our new temperature sensoris a voltagecontrolled relaxation o scillato rbasedtemperature sensor showninFig. 1. The circuit consists of twoparts, avoltageoutput senso
15、r and arelaxation oscillator. F ig. 1 Temperature sensor designed based on a voltage2cont ro lled relaxation oscillator 3.1 Voltage-output sen sor Our voltage output sensor circuit exploits thetemperature dependence of the mosimportant parameter of theMOS transistor, namely, the t
16、hreshold voltage (V T ). The threshold voltage has anegative temperature coeff icient as: V T (T ) = V T (T 0) + a (T - T 0) (1) where a is the temperature coeff icient with atypical value of - 118mVK in CMOS 0135Lm 5Vtechnology； V T (T 0 ) is the value of the th resholdvoltage at temperatu re T0.As
17、 shown in Fig. 1, the voltage output sensoris a th reshold voltage reference cell. The pchannelt ransistors P1, P2 constitu teacurrent mirror. Thecurrent of transistor N1 is mirrored to tansistorsN 2,N 3, and N 4. The vo ltage drop on these t ran sistors isfed back to the gate of N 1. Fo r easy calc
18、ulat ing,we choose asame size of the transistorsN 2,N 3, and N 4 (BN 2= BN 3= BN 4) , and we choose approp riatesize of the othertransistors to ensure thatthe transisto rs P1, P2, N 1, N 2, N 3, and N4 are allin the state of saturation. Then the output voltagesof th is sen so r are in direct proport
19、ion to thethreshold voltage and linear with temperature andtheir values are: V H = V T (1 +2KP12KP12 - 3KN 12) = k1V T (2) V L = V T (1 +2KN 12KP12 - 3KN 12) = k2V T (3) where is determined by the ratiobetween thegatesizes of the nchannel t ran sistor N 1 and N 2, and is the ratio of the gate sizes of the pchannel transistor P1 and P2.
