Measurement of Integrated PA-to-LNA Isolation on Si CMOS Chip Ryo Minami，JeeYoung Hong， Kenichi Okada，and Akira Matsuzawa Tokyo Institute of Technology, Japan Matsuzawa Matsuzawa Lab. & of Okada Lab. Tokyo Institute Technology Outline 1 • Tx leakage and problem • Evaluation of Tx leakage – Tx leakage paths – Measurement and Simulation method • Result • Conclusion 2010/12/10 R. Minami , Tokyo tech. Matsuzawa Matsuzawa Lab. & Okada Lab. Tokyo Institute of Technology Background 2 Conventionally, Power Amplifier (PA) has been implemented by compound semiconductors. • Merit – High frequency characteristic – High supply voltage • Demerit – Chip area and cost CMOS technology has been developed. CMOS transistors can provide a sufficient performance for PA design. The level of Tx leakage increases. To investigate Tx leakage paths. 2010/12/10 R. Minami , Tokyo tech. Matsuzawa Matsuzawa Lab. & Okada Lab. Tokyo Institute of Technology Tx leakage and problem 3 LNA nonlinearity FDD system Tx leakage interference signal LNA Tx leakage Rx signal received signal Tx leakage Duplexer transmitted signal PA cross modulation interference signal Rx signal intermodulation distortion • The large transmitted signal leaks to Rx input side. • Tx leakage causes IM and degrades demodulation quality. 2010/12/10 R. Minami , Tokyo tech. Matsuzawa Matsuzawa Lab. & Okada Lab. Tokyo Institute of Technology Tx leakage paths 4 The integration of the PA with other blocks increases many coupling paths. conventional single-chip LNA LNA Duplexer Duplexer PA 2010/12/10 substrate coupling PA inductor coupling wire coupling (Vdd, GND) R. Minami , Tokyo tech. Matsuzawa Matsuzawa Lab. & Okada Lab. Tokyo Institute of Technology Dicing 5 Magnetic PA LNA gnd VDD gnd VDD -+ p+ n+ -+ n+ p+ n+ p+ n+ n+ Substrate coupling and inductor coupling are generated because PA and LNA are integrated on the same chip. n+ Substrate coupling Magnetic PA LNA gnd VDD gnd VDD -+ p+ n+ -+ n+ p+ n+ n+ p+ n+ n+ Substrate coupling is blocked by physically separating the PA and LNA[1]. [1] J.Y. Hong et al., IEICE society Conference, 2009. 2010/12/10 Air gap R. Minami , Tokyo tech. Matsuzawa Matsuzawa Lab. & Okada Lab. Tokyo Institute of Technology Measurement method 6 -5dBm -5dBm Network Analyzer Network Analyzer • substrate coupling • inductor coupling • inductor coupling probe air gap probe PA LNA1 LNA2 probe LNA3 probe LNA4 PA Chip LNA2 LNA1 LNA3 LNA4 Chip absorber absorber isolation isolation[dB] S 21 (GainPA GainLNA ) couplingsubstrate dicingbefore dicingafter PA On-Chip LNA output input GLNA GPA S21 After dicing, the distance between PA and LNA is 0.74mm, 1.55mm, 2.37mm, 3.20mm. 2010/12/10 R. Minami , Tokyo tech. Matsuzawa Matsuzawa Lab. & Okada Lab. Tokyo Institute of Technology Specification of the designed PA and LNA 7 LNA PA PA LNA Technology 0.18 mm CMOS process Frequency 5 GHz VDD 3.3 V 1.8 V Gain at 5 GHz 5.5 dB 15.1 dB NF at 5 GHz Area 2010/12/10 2.7 dB 1.01mm×1.01mm 0.70mm×1.01mm R. Minami , Tokyo tech. Matsuzawa Matsuzawa Lab. & Okada Lab. Tokyo Institute of Technology Simulation method 8 Magnetic coupling simulation by HFSS (an electromagnetic field simulator) Circuit simulation with magnetic coupling effect by goldengate LNA inductor 1.8 V PA inductor 3.3 V Magnetic coupling (2.5 turn) (1.5 turn) output distance input On-chip 50 W 104mm PA LNA 0.74mm 1.55mm 2.37mm 3.20mm 160mm Assume The magnetic coupling between the inductor at PA output side and the inductor at LNA input side is the most dominant. 2010/12/10 R. Minami , Tokyo tech. Matsuzawa Matsuzawa Lab. & Okada Lab. Tokyo Institute of Technology Simulation result 9 -40 Gain of PA and LNA -60 S21[dB] -80 -100 -120 0.74mm 2.37mm -140 1.55mm 3.2mm -160 0 1 2 3 4 5 6 7 8 9 10 Frequency[GHz] • Gain of PA and LNA are shown at 5 GHz • S21 depends on the distance between PA and LNA 2010/12/10 R. Minami , Tokyo tech. Matsuzawa Matsuzawa Lab. & Okada Lab. Tokyo Institute of Technology Measurement result S21 [dB] noise floor or thermal noise 10 -40 sim.: dotted -60 probe coupling meas.: solid -80 -100 -120 0.74mm 2.37mm -140 1.55mm 3.2mm -160 0 Assume 1 2 3 4 5 6 frequency[GHz] 7 8 • Under 3 GHz – Thermal noise from the resistance of LNA – Noise floor of the network analyzer • Around 5 GHz – Noise floor of the network analyzer with gain • Over 8 GHz – Probe coupling exists. 2010/12/10 R. Minami , Tokyo tech. 9 10 Matsuzawa Matsuzawa Lab. & Okada Lab. Tokyo Institute of Technology Noise floor and probe coupling ● Probe coupling ● Noise floor -5dBm Network Analyzer -5dBm 3cm probe 11 probe open(=S21) Network Analyzer 0.98mm,1.8mm,2.62mm,3.45mm probe 2cm probe coupling(=S21) 0.3mm absorber absorber Noise floor S21 with 3 cm distance between probes and 2cm distance between probe and absorber Probe coupling S21 with 4 patterns of probe distance and 0.3mm distance between probe and absorber 2010/12/10 R. Minami , Tokyo tech. Matsuzawa Matsuzawa Lab. & Okada Lab. Tokyo Institute of Technology Probe coupling problem 12 ● The case of measuring chip coupling signal probe PA probe LNA signal Chip GND Signal flows into the chip. absorber ● The case of measuring probe coupling probe coupling signal probe 0.3mm absorber 2010/12/10 R. Minami , Tokyo tech. This is the worst case of probe coupling. Matsuzawa Matsuzawa Lab. & Okada Lab. Tokyo Institute of Technology Thermal noise from the resistance of LNA 13 -5dBm Network Analyzer (a): noise calculation point × On-Chip LNA PA input output GPA k: 1.38*10-23 [J/K] T: 300 [K] GLNA B: 10 [Hz] Cable loss:2 [dB] Noisethermal [ dB] 10Log(kTB) NFLNA GainLNA Losscable NAout 2010/12/10 R. Minami , Tokyo tech. Matsuzawa Matsuzawa Lab. & Okada Lab. Tokyo Institute of Technology Result of error analysis (higher and lower side) 14 S21&Thermal noise [dB] -40 0.74mm probe couping noise floor NA noise thermal -60 -80 -100 -120 -140 -160 0 1 2 3 7 6 5 4 frequency[GHz] • Under 3 GHz – Noise floor of the network analyzer • Over 8 GHz – Probe coupling exists. 2010/12/10 R. Minami , Tokyo tech. 8 9 10 Matsuzawa Matsuzawa Lab. & Okada Lab. Tokyo Institute of Technology Result of error analysis (middle section) -40 sim.: dotted meas.: solid -60 GPA+GLNA S21 [dB] -80 -100 -120 0.74mm 1.55mm 2.37mm 3.2mm noise floor -140 -160 0 1 2 3 4 5 6 7 frequency[GHz] 8 9 10 • Around 5 GHz – Noise floor of network analyzer with gain noisefloor(5GHz) GainPA GainLNA 80dB 2010/12/10 R. Minami , Tokyo tech. Matsuzawa Matsuzawa Lab. & Okada Lab. Tokyo Institute of Technology 15 Comparison of coupling data at 5 GHz 16 -40 Isolation [dB] -50 • The isolation value of inductor coupling is affected by the noise floor of the NA over 1.8mm distance between PA and LNA. inductor coupling -60 simulation -70 -80 -90 -100 noise floor -110 -120 1 2 distance[mm] • Total isolation value becomes smaller than that of the duplexer over 0.4mm • Substrate coupling is the most dominant factor in Tx leakage. 2010/12/10 3 4 -40 Duplexer isolation -50 Isolation [dB] 0 -60 all Tx leakage -70 inductor coupling substrate coupling -80 -90 -100 -110 -120 0 R. Minami , Tokyo tech. 1 2 3 distance[mm] Matsuzawa Matsuzawa Lab. & Okada Lab. Tokyo Institute of Technology 4 Conclusion 17 • Substrate coupling is the most dominant factor in Tx leakage for Si substrate. • Total isolation value becomes smaller than that of the duplexer over 0.4mm distance between PA and LNA. • Error sources in measurement are noise floor of the network analyzer and probe coupling. 2010/12/10 R. Minami , Tokyo tech. Matsuzawa Matsuzawa Lab. & Okada Lab. Tokyo Institute of Technology 18 Thank you for your attention! 2010/12/10 R. Minami , Tokyo tech. Matsuzawa Matsuzawa Lab. & Okada Lab. Tokyo Institute of Technology
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