Reliability of Components in Power Amplifiers Based ...

Reliability of Components in Power Amplifiers Based in MIL-HDBK-217F Standard Carlos Alexandre Gouvea da Silva and Edson Leonardo dos Santos Department of Electrical Engineering (DELT) Federal University of Paran´a (UFPR), Brazil Curitiba, Paran´a, BR 81531-980 Email: [email protected], [email protected]

Abstract—The probability of failure in electronic circuits describes the reliability of components and allows improving the efficiency use of devices and electronic systems. The objective and contribution of this work are to analyze and estimate the reliability in Power Amplifiers (PAs) for wireless communication systems. The international MIL-HDBK-217F Standard was used to estimate the reliability of components in power amplifiers circuits using the component counting method. This method is applied to each component of the electronic circuit, and then was possible to predict the failure rate. Results demonstrate that capacitors have high impact in failure ratio compared to transistors, resistors and inductors. Due to the fact of not knowing most of the technical and factory characteristics of components, the estimation process may present a challenge for reliability prediction. Keywords – Failure Rate, Power Amplifier, Reliability.

I. I NTRODUCTION Reliability can be defined as the probability of one device or system under a period of time in which the operation can be working perfectly without presents any problems. Can be also defined as the ability of a system’s product to work without failures and within specified performance limits, for one period of time, in its life cycle condition [1]. For ensure the reliability, a set of condition have to be respected such as period time of tests, environments characteristics, behavior of temperatures, and others. The reliability challenge of construct and keep the quality of systems and equipments has grown over the years, and already presents one of the most important requirements for electronic systems. Advances of technology and increased capability of manufacturing offers great opportunities for new developments in reliability engineering [2]. The advancement of technology allows the integration of components as well as decrease the physical size of electronic circuits, but some important factors such as temperature, continues to influence the operation of electronic systems. However, the temperature is not the only parameter to contribute to the decrease of reliability. Other sources that may generate failures in electronic systems, such as, deviation of components parameters, short circuit from welding process, bad contacts of connectors, electromagnetic interferences, are some examples of causes of failures. Mobile communication uses for data transmission a set of electronic system. Due to low coast, the complementary metaloxide-semiconductor (CMOS) technology has been used in

mobile devices that are powered by batteries. This condition causes a concern to create devices energetically with high level of economic consumption power. In radio communication, one of the most important devices of a radio frequency transceiver is the power amplifier (PA), due to its position on the transmitter system, immediately before the antenna. The function of a PA is to amplify a weak power signal to a strong one, without significantly distorting the signal [3]. In this context, this paper presents the reliability of a fully integrated 130 nm CMOS multimode PA presented by Santos et al. [4]. The PA reliability is measured using Military Handbook Reliability Prediction of Electronic Equipment 217F (MIL-HDBK-217F) and analyses the operation conditions. The Department of the Defense of United States of America developed this standard handbook with the assistance of the military departments, federal agencies, and industry in the USA. Every effort has been made to reflect the latest information on reliability prediction procedures [5]. The MILHDBK217F was chosen because it was one of the first global reliability standard used by both military and commercial companies. The remainder of this paper is organized as follows. Section II presents the MIL-HDBK-217F Standard and similar standards for reliability prediction. The Section III presents how the prediction was estimated. The results, comparative works and discussion are presented in Section IV. Finally, the conclusion is presented in Section V. II. MIL-HDBK-217F S TANDARD The MIL-HDBK-217F handbook is widely used in the reliability prediction of electronic systems. This standard is the result from years of information and data collection, which has allowed the creation of an official document used for many industries and factories for electronic components production. The handbook contains failure rate models for several electronic systems components, such as transistors, resistors, integrated circuits (ICs), diodes, capacitors, switches, connectors, relays, etc, taking into account factors that are considered likely to affect reliability [6]. Other methods to predict the reliability of electronic systems can be mentioned, including Bellcore/Telcordia SR332, PRISM, Naval Surface Warfare Center NSWC-06/LE10, China 299B, Nippon Telegraph and Telephone Corporation

Standard Reliability Table for Semiconductor Devices (NTT Procedure), FIDES (from Latin to English: “trust”), and Reliability Data Handbook RDF 2000. The SR-332 is a model widely used in Europe by the telecommunication industry, updated for non-military organizations and non-free access [7]. PRISM tries to mitigate the limitation of HDK-217, where the main contribution of this standard is to identify that up to 78% of failure cause is not in the components, and is used for military and commercial applications. RDF 2000 or IEC 62380, are an improvement of HDK-217 with adoptions for telecommunication applications. China 299B is a reliability prediction program similar to MILHDBK-217 developed by the Chinese military. 299B includes both the component counting method and stress analysis method, also uses a number of models for various categories of electronic and electromechanical components to predict the failure. For more information about prediction methods, refer to [8].

The PA used in this work was developed with CMOS technology using GlobalFoundrie’s 130nm components. Moreover, for this reliability analysis, the same circuit presented in [4] can be represented by discrete bipolar components. Then, the HDBK-217F Standard that uses bipolar components is applied for reliability analysis of this PA and related works. The amount components used in the electronic circuit proposed by [4] are six capacitors (CF1, CF2, CF3, CF4, CG1 and CG2), two inductors (L1 and L2), one resistor (RF4), and eight transistors (T1, T2, T3, T4, T5, T6, T7, and T8). With this information, is obtained the reliability each individual component. For correct equations used from standard, was applied the main parameters described in [4], frequency operation at 2.4 GHz, consumption ranging from 171 mW (low-gain mode) to 196.2 mW (high-gain mode). Transistor reliability was used based in characteristic Bipolar Microwave RF Transistor (Frequency > 200 MHz and Power < 1Watts). The reliability πP (failures/106 hours) is defined as follows:

III. M ETHODOLOGY At first, for reliability estimation is analyzed the structure of PA schematic presented by [4]. Figure 1 shows the circuit topology of the proposed PA whereas Figure 2 shows the chip micrograph highlighting the components of the electronic circuit.

E.L. dos Santos et al.

πP = λ b · πT · πR · πS · πQ · πE ,

(1)

where λb is a base failure rate, πT is the temperature factor, πR is the power rating factor calculate by πR = Pr0.37 with Pr = 0.160 mW as the rated power, πS is the voltage stress factor from Vs = 870 mV, πQ is the quality factor (it is not specified in paper, thus the higher available value in standard was applied), and the πE is the environmental factor for GM (mobile device). The parameters values are shown in Table I.

Microelectronics Journal 70 (2017) 34–42

TABLE I PARAMETERS TRANSISTOR RELIABILITY πP [5] Parameter λb πT πR πS πQ πE

Value 0.18 variable 0.51 0.29 5.0 5.0

Fig. 2. Circuit topology of the proposed PA (bias circuitry is omitted).

Fig. 1. Circuit topology ofachieving the proposed PAand [4].high good matching

The resistor reliability λb (failures/106 hours) is defined as follows:

gain. The transistors gates are segmented in several fingers, connected in both sides to reduce the gate resistance.

Table 1 Operating modes. Mode

B3

B2

B1

Effective channel width (μm)

1 2 3 4 5 6

0 0 1 1 1 1

1 1 0 0 1 1

0 1 0 1 0 1

80 40 þ 80 ¼ 120 160 160 þ 40 ¼ 200 160 þ 80 ¼ 240 160 þ 80þ40 ¼ 280

4.1. Continuous-wave measurement results

CAPACITORSMeasurements of the PA were carried out using on-wafer probing at

(2)

where λb is the resistor (10 KΩ) style for higher value available in standard, πT is the temperature factor, πP for a dissipation not higher to 1 mW, πS = 0.71 · e1.1(S) is the power stress factor with S = 28.88 mW (14.6 dBm), πQ is the quality factor (for the higher value available in standard), and πE is the environmental factor for GM . The parameters values are shown in Table II. For capacitor, the reliability πP (failures/106 hours) is defined as follows:

During layout, the PA core is placed as close as possible to theRESISTOR input and output RF pads to reduce resistance. A ground plane is placed inside and around the circuit, using all metal layers. This ground plane achieves a low resistance, which is important for noise and gain performances. MIM capacitors are distributed in a large area to ensure a stable DC power supply. ESD protection diodes are positioned close to control pads. The overall PA is laid out in a compact way to reduce access resistances, thus

INDUCTORS

λp = λb · πT · πP · πS · πQ · πE ,

room temperature. An Agilent E83612 vector network analyzer was used to measure the S-parameters of the device. The measured small-signal gain (S21) for all modes of operation of the PA is presented in Fig. 4. The results show that, at 2.4 GHz, gain ranges from 22.4 dB in mode 1–31 dB in mode 6. Fig. 5 compares the measured data to post-layout simulation. Good matching is observed, especially between 1 GHz and 3 GHz. Fig. 6 presents the measured S11 and S12 for the lowest and highest gain modes. It is observed that good input matching is obtained near 2.4 GHz with a 14.6 dB S11 for mode 6 and 22.5 dB for mode 1, along with a good isolation, represented by an S12 better than – 50 dB for both extreme modes.

TRANSISTORS

Fig. 2. Chip micrograph highlighting the components of the electronic circuit [4].

Fig. 4. Measured small-signal gain in all operating modes.

Fig. 3. Chip micrograph highlighting the reconfigurable gain stage (PPA) and the power stage (PA). 36

πP = λb · πT · πC · πV · πSR · πQ · πE ,

(3)

where λb is the capacitor type as CK Spec. MIL-C-11015, πT is the temperature factor, πC is the capacitance factor for

are 5.0, 10.0, 10.0, and 10.0. The failure rate λb1,....,4 are calculate from Eq. 1, 2, 3, and 4, with variable temperature (Tk ) for k = {20, 30, 40, ..., 140, 150}°C. The next section presents the reliability of the proposed PA.

TABLE II PARAMETERS RESISTOR RELIABILITY λb [5] Parameter λb πT πP πS πQ πE

Value 0.0037 variable 1 0.733 10.0 16.0

IV. R ESULTS AND D ISCUSSION

1.8 pF and 1 pF, πV is the voltage stress factor from voltage stage by 870 mV, πSR is the series resistance factor, πQ is the quality factor from commercial or unknown screening level, and πE is the environmental factor from environment GM . The values for capacitor reliability are shown in Table III. TABLE III PARAMETERS CAPACITOR RELIABILITY πP [5] Parameter λb πT πC πV πSR πQ πE

Value 0.00099 variable 0.54 4.4 1.0 10.0 20.0

Reliability estimation of individual components might be a hard task. Based in MIL-HDBK-217F Standard, different characteristics of each component may cause marginal interpretation about tests results. In Figure 3 it is shown the failure rate of each component for Santos et al. (2017) [4]. There is a direct influence of temperature of all components in the failure rate, whereby the higher the temperature the higher the increment in the failure rate. However, the increasing ratio is not the same for all components. Capacitor has the higher failure rate, comparing to other components, because the parameters πQ = 10 and πE = 20 have a high impact on the value of failure rate/106 hours. For temperatures above 110°C the reliability may be 10 failures in 106 hours minimum. One way to increase this condition is by reducing the πQ from 10 to less than 1 improving screening tests of the component. Unfortunately it is not possible to decrease the parameter πE because this value is specific for communication mobile.

(4)

where, λb is the base failure rate for a fixed inductor, πT is the temperature factor, πQ is the quality factor as lower, and πE is the environment quality from environment GM . The values for inductor reliability are presented in Table IV.

Transistor Resistor Capacitor Inductor

25

Failure rate/10 6 hours

λ p = λ b · πT · πQ · πE ,

Reliability of components

30

Finally, for inductor reliability λp (failures/106 hours) is defined as follows:

20

15

10

5

TABLE IV PARAMETERS INDUCTOR RELIABILITY λp [5] Parameter λb πT πQ πE

0 20

n X

Value 0.00003 variable 3.0 12.0

Ni · πQi · λbi ,

60

80

100

120

140

160

Temperature in °C

Fig. 3. Failure rate/106 for each component with capacitor.

Equations 1, 2, 3 and 4 present individual reliability for each component, however not for PA component. PA reliability estimate is based in components counter method and defined as follows: λ=

40

(5)

i=1

where, n is the maximum number of components categories, Ni is the amount of i-th component, πQi is the quality factor of i-th component, and λbi is the failure rate of i-th component. As our scenario is fixed with i = 1, ..., 4 respectively for amount of transistor, resistor, capacitor and inductor components, the N1,...,4 are 8, 6, 2, and 1. The values of πQ1,...,4

Figure 4 shows the failure rate without capacitor. There is a small chance of failure occurrence for inductor component, which can be less than one failure for any temperature. Transistor and resistor may present similar failures during the operation for any temperature, however around 125°C transistor presents more failures than resistor. Santos et al. (2017) [4] present a performance comparison between the proposed PA with another works. Using the same methodology described above, reliability is verified by counting the number of components of each work as shown in Table V. Each work was verified based in the component counting method, thus it was possible to estimate the failure rate for each PA. Results are presented in Figure 5, note that the PA the worst result in reliability is [11], and best are [15] and

Reliability of components

6

Transistor Resistor Inductor

Failure rate/10 6 hours

5

4

3

2

1

0 20

40

60

80

100

120

140

160

: T (°C)

Fig. 4. Failure rate/106 for each component without capacitor. TABLE V R ELATION OF COUNT COMPONENTS BY OTHER WORKS . Component Capacitor Resistor Inductor Transistor

[9] 2 0 3 8

[10] 2 2 1 7

[11] 6 8 7 16

[12] 4 3 2 5

[13] 5 2 3 15

[14] 3 1 1 4

[15] 4 0 5 4

[10]. This condition can be explained because in [11] there are six capacitors, and as described previously, has a high impact in reliability. However, [10] presents better reliability only between 100 to 150°C, as well as [15] only between 20 and 100°C. Reliability of comparative works

3000

Failure rate/10 6 hours

2500

2000

Santos et al. (2017) [4] Yoon et al. (2010) [9] Wen and Sun (2010) [10] An et al. (2009) [11] Montes et al. (2014) [12] Wu et al. (2005) [13] Chironi et al. (2013) [14] Meshkin et al. (2010) [15]

1500

1000

500

0 20

40

60

80

100

120

140

160

: T (°C)

Fig. 5. Reliability of Comparative Works

V. C ONCLUSION This paper presented the evaluation reliability of a proposed PA by [4] using the component counting method from the MIL-HDBK-217F Standard. The temperature was analyzed and showed worst reliability for higher temperature from 20°C to 150°C. Results show that capacitor presents a high impact in PA reliability, followed by transistor, resistor and inductor. However, the transistor or resistor may have differences accuracy for specific temperature of operation. The

component counting method may be a hard task, due to several specifications in the standard, where each component may be under different operating circumstances. A comparison between several papers is analyzed confronted with the paper of [4]. These results show that this paper may present better reliability than three papers and worst than other three papers. For the better PA referred on [15] and [10], both can be great but for specific temperatures. As the reliability was estimated using the component counting method, it is suggested for future works to compare the reliability with other models such as Telcordia and perform the reliability estimation using the parameters Mean Time to Repair (MTTR) and Mean Time Between Failures (MTBF) from the time cycle during the operation of PA for an extensive time. From there, it is possible to determine the fraction availability (A) or unavailability (U) of PA as a unique component. R EFERENCES [1] K. C. Kaput, M. Pecht. Reliability engineering. John Wiley & Sons, 2014. [2] E. Zio, ”Some Challenges and Opportunities in Reliability Engineering,” in IEEE Transactions on Reliability, vol. 65, no. 4, pp. 1769-1782, Dec. 2016. [3] M. Rios, E. L. Santos, B. Leite, L. Lolis, A. Mariano, ”Linearity characterization of a CMOS Power Amplifier for IEEE 802.15.4, IEEE 802.11n and LTE signals”, XXII Iberchip Workshop, Florianpolis, 2016. [4] E. L. Santos, M. A. Rios, L, Schuartz, B. Leite, L. A. Lolis, E. G. Lima, and A. A. Mariano, A fully integrated CMOS power amplifier with discrete gain control for efficiency enhancement. Microelectronics Journal, v.70, pp.34-42, 2017. [5] Handbook, Military Standardization. MIL-HDBK-217F. Reliability Prediction of Electronic Equipment, US Department of Defense, 1991. [6] K. Choudhary and P. Sidharthan, ”Reliability prediction of Electronic Power Conditioner (EPC) using MIL-HDBK-217 based parts count method,” 2015 International Conference on Computer, Communication and Control (IC4), Indore, pp. 1-4, 2015. [7] L. Zhou, R. Cao, C. Qi and R. Shi, ”Reliability prediction for smart meter based on Bellcore standards,” 2012 International Conference on Quality, Reliability, Risk, Maintenance, and Safety Engineering, Chengdu, 2012, pp. 631-634. [8] B. Foucher, J. Boullie, B. Meslet, and D. Das, A review of reliability prediction methods for electronic devices. Microelectronics reliability, v. 42, n. 8, 2002, pp. 1155-1162. [9] Y. Yoon, H. Kim, K. H. An, J. Kim, C. H. Lee and J. Laskar, ”A fullyintegrated dual-mode tunable CMOS RF power amplifier with enhanced low-power efficiency,” The 40th European Microwave Conference, Paris, 2010, pp. 982-985. [10] J. C. Wen and L. L. Sun, ”A variable gain and output power CMOS PA with combination switch controls,” 2010 10th IEEE International Conference on Solid-State and Integrated Circuit Technology, Shanghai, 2010, pp. 111-113. [11] K. H. An et al., ”A 2.4 GHz Fully Integrated Linear CMOS Power Amplifier With Discrete Power Control,” in IEEE Microwave and Wireless Components Letters, vol. 19, no. 7, pp. 479-481, July 2009. [12] L. A. A. Montes, K. Raja, F. Wong and M. Je, ”An efficient power control scheme for a 2.4GHz class-E PA in 0.13-m CMOS,” 2014 IEEE Ninth International Conference on Intelligent Sensors, Sensor Networks and Information Processing (ISSNIP), Singapore, 2014, pp. 1-4. [13] L. Wu, U. Basaran, R. Tao, M. Berroth and Z. Boos, ”A 2 GHz CMOS dB-linear programmable-gain amplifier with 51 dB dynamic range,” 2005 European Microwave Conference, Paris, 2005, pp. 4 pp.-1566. [14] V. Chironi, B. Debaillie, S. D’Amico, A. Baschirotto, J. Craninckx and M. Ingels, ”A Digitally Modulated Class-E Polar Amplifier in 90 nm CMOS,” in IEEE Transactions on Circuits and Systems I: Regular Papers, vol. 60, no. 4, pp. 918-925, April 2013. [15] R. Meshkin, A. Saberkari and M. Niaboli-Guilani, ”A novel 2.4 GHz CMOS class-E power amplifier with efficient power control for wireless communications,” 2010 17th IEEE International Conference on Electronics, Circuits and Systems, Athens, 2010, pp. 599-602.