1、JEDEC STANDARD Standard for the Measurement of Small-Signal Transistor Scattering Parameters JESD435 (Previously known as RS-435 and/or EIA-435) APRIL 1976 (Reaffirmed: April 1999, March 2009) JEDEC SOLID STATE TECHNOLOGY ASSOCIATION NOTICE JEDEC standards and publications contain material that has
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10、rlington, VA 22201-2107 or call (703) 907-7559 APRIL 1979 EIA STANDARD STANDARD FOR THE MEASUREMENT OF SMALL-SIGNAL TRANSISTOR SCATTERING PARAMETERS ELECTRONIC INDUSTRIES ASSOCIATION STANDARD RS-435 Formulated by JEDEC Solid State Products Council Recommended standarda ere rdopted by EL4 without reg
11、erd to whether or not their adoption may Involve petents on articles, materiels, or processes. BY such actton, EIA doea not UNEU my liability to any patent owner, nor does it wume nny obltgetion whatever to wea adoptlug the recommended stendards. Published by ELECTRONIC INDUSTRIES ASSOCIATION Engine
12、ering Department 2001 Eye Street, N.W., Wuhiqton, D. C. 20006 0 Electronic Industries Association 1916 All fi,hU “rnd PRICE: PREFACE The symbols and terms of this document are contained in JEDEC Publication No. 77 and are not in conflict with those in IEC Publication 147-OC. The measurement procedur
13、e.8 are similar to those published in IEC. RS-435 page1 STANDARD FOR THE MEASUREMENT OF SMALLSIGNAL TRANSISTOR SCATTERING PARAMETERS (From JEDEC Tentative Standard No. IO and Standards Proposal No. 1178, formulated by JEDEC Committee K-24 on High Frequency Sign01 Diodes and Tmnsirton and approved by
14、 the JEDEC Solid State Products Council.) 1. DEFINITIONS 1.1 Definition of the Scattering Parameters Given a two-port network as shown in Figure 1, the scattering parameters may be defined as the elements of the matrix (1 and 2)” Ql s12 s= s21 s22 associated with the linear equations bl = s11 a1 + “
15、12 a2 b2=s21 al+s22a2 where a.= - i.e., bl el/Il) - ZO *11= q a =O =Wl)+Zo 2 z =Z =z 1 2 0 (6) 812 is tbe reverse transmission coefficient with port one terminated in ZO and port two driven with a generator of impedance ZO;i.e., bl s12= - “1 a2 al = 0 = (Vo/2, z1=z2=zo (7) where V. is tbe open-circu
16、it generator voltage. 821 is the forward transmission coefficient with port two terminated in ZO and port one driven with a generator of impedance ZO; i.e., b2 “2. s21= a, =- a =O (vo12) 2 z1=z2=zo (8) 822 is the reflection coefficient (with respect to ZO) at port two with port one terminated in ZO;
17、 I.e., b2 a22= - = (V2/2) - ZO a2 a=0 1 (i2/12) + z. z1=z2=zo lbe scattering parameters of transistors are also represented by tbe following symbols: s12 - %x s21 - % s22 - sax ) where x is replaced by e, b, or c for bipolar transistors in common-emitter, common-base, or common- collector configurat
18、ion, respectively; and by a, g, or d for field-effect transistors in common-source, common- RS-435 page3 gate, or common-drain configuration, respectively. 1.2 Definition of Small-Signal Conditions Transistors are e.ssentiaBy nonlinear devices which for sufficiently small applied signals behave as l
19、inear two-ports. Small-signal conditions may, therefore, be defined as the values of the voltage and current at ports one and two below which values the transistor may be considered a linear two-port. For practical applications the following definition will he used: smaB.signal conditions are satisf
20、ied when a reduction of 50% in the amplitudes of Vl, 11, V2 or12 will not result in avariation of the ratio defined by (6), (7), (B), or (9) of more than I%.* 1.3 Definition of the Transistor Terminal Reference Planes 1.3.1 Single-Ended Azid-Leaded Packag for stripline transistors the width of the c
21、enter or stripline conductor of the tixture shall be equal to or greater than that of the transistor lead. 2.4 The location of the reference plane(s) of the input-output terminals shall be known within less than + one thousandth* of the wave length at the test frequency or 0.003 inch*, whichever is
22、greater. 2.5 Electrical contact between the transistor leads and the terminals of the mount shall be made within 0.5 mm (0.02 inch)* of the specified reference planes and should have low enough resistance to assure repeatability of the intended measurement. 2.6 For axial-leaded transistors, no porti
23、on of the input or output shall extend beyond the reference plane defined in close 1.3 and no material shall be placed in the air-gap between the seating plane of the transistor package and the reference plane of the transistor mount (see Figure 2a). 2.7 The mount insertion loss with its feedthrough
24、 shall be equal to or less than 0.3 dB + (0.05 dB/GHx) (fGHz) *. 2.0 The following suggested feedthrough comments are useful in minimizing losses and electrical dis continuities.: (a) Approximately the same material and geometry should be used as in the transmission line of the fixture. (b) In case
25、of stripline packages the physical dimensions should be the same as that of the space which the transistor will occupy. Leads should have sufficient length and should have widths slightly narrower than both the fixture and feedthrough transmission lines. RS-435 Page 5 3. THE MEASURING SYSTEMS FOR SC
26、ATTERING PARAMETERS 3.1 General The measuring system must provide a means for applying bias to the transistor under test. Thebias system must be such as not to influence the accuracy of the measurements. The signal applied by the measuring system to the transistor must be bvfficiently small to satis
27、fy the small-signal conditions defined in 1.2. In addition, any spurious signals which might appear at the transistor terminals and, in particular the local oscillator feedthrough when a superheterodyne receiver is used, must be kept at least 30 dB* below the applied desired signal. 3.2 Input and Ou
28、tput Source Match Ideally, the measurement of scattering parameters would require that system source and load impedances at the two-port-reference planes be precisely equal io ZO, the defining reference impedance. In practice, these impedances must satisfy the following conditions: Input Source Matc
29、h: I I zl-zo rl = z1 +zo 40dB* 3.4 Transmission lines may be used to make connection between the transistor mount and the measuring system. These lines may include adjustable-length sections for phase compensation. However, the SWR created by residual reflections in the lines must not exceed 1.01 +
30、(O.OI/GH,) (fGH 2. Slotted sections where the unknown is compared to a characteristic impedance using voltage rations; and 3. Reflectometers, including network analyzers, where power levels and phase are compared to a reference signal assuming an impedance reference. In general, over the range of co
31、ncern, reflection coefficients can be measured1 to 0.01 and phase angles to lo/s mm using typical equipment and techniques (see Figures 3 and 4). Using the best equipment and technique this can be improved to 0.001 and O.l”/smm ( see Figures 5 and 6). 3 Using either typical or the best equipment, at
32、tenuation or gain can be measnred to 0.2 dB+ O.O1smn (in dB): The phase angle of attenuation can be measured to lo + (O.Ol/dB) (smn indB). See Figures 7 and 8. For low power levels these are degraded as shown in Table I. A summary of error verats power level using optimum and typical equipment and t
33、echniques is shown in this table. lhe effect of power level on the test terminals can be estimated as follows. Noise and detector sensitivity will be the primary limiting factors on the measurement at low power levels. While detectors can be im- proved in sensitivity at the expense of response time
34、and cost, typical detectors used for measurements have sensitivities of about -80 dBm. The slottedline or reflectometer has about 20 dB coupling in the probe or directional coupler giving roughly -60 dBm sensitivity. A typical generator will have about 10 dBm output decoupled by pads or power splitt
35、ers by around 1OdB providing roughly 1 mW to the teat terminals. The 60 dBdifference then allows a sensitivity of 60 dBin return loss or 0.0003 in p, which is about the beat found in practice. This is subject to considerable variation but can serve as a general limitation. Not all of the error at lo
36、w reflection coefficients is due to noise limitation so the power level can probably be reduced by 10 dB before the general 0.01 limit given above is exceeded. The bridge circuit is usually limited by errors other than noise at low reflections but a similar treatment will show that for 0.01 error in
37、 p, the bridge will require about -1OdBm on the test terminals. At lower signal levels, the slotted line with the generator feeding the probe appears most practicaL2 With such a system it is possible to obtain errors as low as 0.003 in p and 0.1 m phase angle at 8 GHz using -50 dBm on the test termi
38、nals (see Figures 5 and 6). 4 RS-435 Page 7 a rigorous error analysis would not be feasible for the following reasons: 1. 2. 3. 4. Insufficient data is available on the various instruments, particularly the interaction of phase and magnitude values and errors. Some instruments measure the parameters
39、 of two ports under matched conditions, others under open - and short-circuit conditions, and others approximate these conditions to different degrees. Thus, they cannot be directly compared. For comparison, errors should be given for the same quantity while different instruments measure variously:
40、impedances, scattering parameters, reflection coefficients, or standing wave ratios. While the above quantities are mathematically related, four independent measurements are required to describe the two port device. These four complex measured values and their errors interact in the transformation.
41、The input reflection coefficient of a twoport, rl, is related to the scattering parameters by l rl=sll+ s12 s21 FL l- s22 rL where rL is the reflection coefficient of the load Therefore, if the two port is terminated in a matched impedance rL=o and then the power incident on a two-port, PI, is hl” p
42、1=Z 01 0 - 11 I 2, where Z o1 is the input impedance of the two-port. RS435 Page 8 The transmitted power, P2, is p2+L 02 (1 -jQJ2 where Zo2 is the output impedance of the two-port. The ratio of P2/P1 as would be measured by a reflectometer or ratio meter ia p2 ZOl lb212 -= (1 -Iq2) p1 Z021al 12 (I +
43、,I 2, For the case where the input and output are matched and the terminal planes are at the same impedance p2 P212 q-= (7 =ls2112 Approximate comparison of the methods can be obtained by letting 8 =r r- 1 RN- 1 mm mm z-z_ 1 Or r+ 1 RN+1 RRO R .Ro where r is the SWR and RN is the normalized resistan
44、ce, R/R0 This is true only if the two-port is terminated in a matched load which is purely resistive. 51 Then RS-435 page9 Test Power 10-3w 10-01 0.01 0.01 0.01 0.01 loIS mm lo/S mm lo/s mm 1 O/s mm 1 o/e mm lo/S mm 0.2 dB+ 0.01s dB mn 0.2dB+o.1s dB mn lo + (O.l/dB) (smn in dB) lo + (lo/ 0.0006 - 5
45、k 3 s 0.0004 - I 0 I I I I , 0 0.2 0.4 0.6 0.0 1.0 REFLECTION COEFFICIENT PI*, MINIMUM MEASUREMENT ERROR MAGNITUDE ERROR FIGURE 5 RS-435 Page 17 0.0 0.7 z 0.6 2 ii 0.5 I - I I I I I . I/ 86th REFLEiTOMETER 1GHt SLOnED LINE . . 1. . . 0.2 OHr BRIDGE 0 I I I I 0 0.2 0.4 0.6 0.8 1.0 REFLECTION COEFFICI
46、ENT r%, MINIMUM MEASljREMENT ERROR PtlA.$G ERROR FIGURE 6 RM35 Page 18 a.4 / 0 0 0 - 0.3 NETWRK MEASUREMENI ANALYZER 0 I I I I 0, 10 20 #) 40 ATTENUATION m 6AlN IN dBi sm MEASUREMENT ERROR AMPLITUDE OF ATTENUATKm FIGURE 7 RS-435 Page 19 0 0 0 0 l+(O.l/db) S 0 0 ,.,/- / AVERAGE OF 20 MEASUREMENTS I I I I 1 -, WA *A _ 0 IO 20 3v 9v 00 ATTENUATION OR GAIN IN dB d s, MEASUREMENT ERROR PHase of mmm FIGURE 8
