微波電路期中報告

1. 微波電路期中報告 論文研討: A High Efficiency and Low Rx-Noise Three Power ModePower Amplifier for W-CDMA Handsets 作者： Katsuya Kato Naoko Matsunaga Kenichi Horiguchi Morishige Hieda and Kazutomi Mori Mitsubishi Electric Corporation 5-1-1 Ofuna, Kamakura, Kanagawa, 247-8501 Japan 報告人: 碩研電子一甲 MA130117 陳偉中 Southern Taiwan University Department of Electronic Engineering

2. Abstract • This paper presents a high efficiency and lowReceive-band noise power ( Rx-Noise ) three power mode poweramplifier for W-CDMA handsets. • The number of Switches inoutput matching circuit and bypass circuit are reduced to realizehigh efficiency in high-power mode operation. • Our developed amplifier achieves 28.25dBm of high output power with power added efficiency (PAE) ashigh as 40% in the high power mode, 17.0 dBm with 23% ofPAE in the middle power mode, and 7.0 dBm with 13% in thelow power mode. Proceedings of APMC 2012, Kaohsiung, Taiwan, Dec. 4-7, 2012

3. PROPOSED SWITCHING BYPASS STAGE POWER AMPLIFIER • The amplifier consists ofhigh-frequency power transistors (M1, M2 and M3) whichare switched by switches (SWs) corresponding to the HPM,MPM and LPM. • In the conventional circuit, the transistor M2 and M3,switches SW4 and SW5 are on in the HPM. The transistorM2 and, switches SW2 and SW3 are on in the MPM. Thetransistor M1 and, switches SW1, SW2 and SW3 are on inthe LPM. • In the proposed circuit, transistor M2 and M3, switchesSW4 are on in the HPM. In HPM, SW6 is also on, and thusM2 operates as a feedback amplifier. The transistor M2 and,switches SW2 are on in the MPM. The transistor M1 and,switches SW1, SW2 are on in the LPM. In MPM and LPM,SW6 is off, and thus the feedback circuit of M2 is disabled. • First, connected point between bypasscircuit and output circuit is changed from output of theamplifier to corrector of M3 in the proposed circuit. Second,the feedback circuit with a switch is employed to the firststagetransistor (M2) in the proposed circuit. Fig. 1. Block diagram of the conventional stage bypass poweramplifier Fig. 2. Block diagram of the proposed stage bypass power amplifier Proceedings of APMC 2012, Kaohsiung, Taiwan, Dec. 4-7, 2012

4. PERFORMANCE IMPROVEMENT • A. HPM Efficiency Improvement • Shows simulated impedances Za and Zb in MPM. • The impedance Za is nearly short in the conventional circuitconfiguration. • The signal from bypass circuit leaks tomatching network 6 in the LPM and MPM without SW5.Therefore, the output switch SW5 must to be employed in theconventional circuit configuration. • On the other hand, theimpedance Zb is enough high without the output switch in theproposed circuit configuration. Therefore, the output switch isnot necessary in the proposed circuit configuration. Fig. 3. Simulated impedances Za and Zb in the MPM Proceedings of APMC 2012, Kaohsiung, Taiwan, Dec. 4-7, 2012

5. Shows output circuit loss versus gate width of theoutput switch SW5 in Fig. 1. The output circuit loss ofproposed circuit configuration is also shown in Fig.4. • Thesimulated output circuit loss of 0.80 dB was obtained withgate width of 3.8mm in the conventional circuitconfiguration. • Therefore, theproposed circuit configuration can be reduced output loss by0.15 dB in the HPM. Therefore, we can improve HPMefficiency in the proposed circuit configuration. Fig. 4. Simulated results circuit loss versus gate width of outputswitch SW5 in the conventional circuit configuration and thesimulated output circuit loss of proposed circuit configuration. Proceedings of APMC 2012, Kaohsiung, Taiwan, Dec. 4-7, 2012

6. B. Rx-Noise Improvement • Rx-noise and Txgain decreases with the decrease of feedback resistance. Thefeedback resistance is determined to 900 ohms to meet thetarget Tx gain of 28.5dBm, where Rx-noise is improved to -137.4 dBm/Hz by 1dB. • On the other hand, the feedbackcircuit cannot be employed to realize Tx gain in MPM andLPM. Therefore, the SW6 in the Fig2 is employed in thefeedback circuit and is controlled to activate the feedbackcircuit only in the HPM to suppress the Rx-noise in HPM. Fig. 5. Simulated results of Rx noise and Tx Gain versus feedbackresistance Proceedings of APMC 2012, Kaohsiung, Taiwan, Dec. 4-7, 2012

7. MEASUREMENT RESULT • (a) and (b) shows the measured PAE and Gainversus output power, respectively. The supply voltage is 3.4V, and the input signal is W-CDMA signal at 1.95 GHz. • Gainof 27.8 dB, PAE of 40.0% and ACLR of -41.3 dBc with anoutput of 28.25 dBm in the HPM. • Gain of 16.3 dB, PAE of23.1% and ACLR of -48.0 dBc with an output of 17.0 dBm4733B1-04are achieved in the MPM. • Gain of 10.4 dB, PAE of 13.7%and ACLR of -41.0 dBc with an output of 7.0 dBm areachieved in the LPM. Fig. 6.Measurement result of proposed circuit at 1950 MHz, WCDMAsignal and Vcc=3.4 V. (a) PAE versus output power, (b)Gain versus output power. Proceedings of APMC 2012, Kaohsiung, Taiwan, Dec. 4-7, 2012

8. PAE in HPM and LPM was improved with keeping the PAEin MPM in the proposed circuit. In addition, the Rx-noise of-136 dBm/Hz (190 MHz offset) is achieved at output powerof 28.25 dBm. Table 1. Measured PAE and Rx-noise of the proposed circuitcompared with and the conventional circuit Proceedings of APMC 2012, Kaohsiung, Taiwan, Dec. 4-7, 2012

9. CONCLUSION • In this paper, we proposed the three power mode poweramplifier for W-CDMA handsets. The number of switches inoutput matching circuit and bypass circuit were reduced torealize high efficiency in the HPM operation by changing theconnected point between bypass circuit and output circuit ofthe final-stage amplifier. • The switching feedback circuit wasapplied to the first-stage amplifier to achieve low noise • performance in Rx-band. • The PA achieved 40% of PAE at28.25 dBm in the HPM, 23% of PAE at 17.0 dBm in the • MPM and 13% of PAE at 7.0 dBm in the LPM, whilesatisfying ACLR of less than -40 dBc under the measurementcondition of 1.95 GHz W-CDMA (R99) modulated signaland 3.4 V supply voltage. • Good Rx-noise characteristics of -136 dBm/Hz (190 MHz offset) at 28.25 dBm is achieved byusing the switching feedback circuit. Proceedings of APMC 2012, Kaohsiung, Taiwan, Dec. 4-7, 2012

10. 參考文獻 [1] Teeter, D. A., et al.: Average Current Reduction in(W)CDMA Power Amplifiers, IEEE Radio FrequencyIntegrated Circuits Symposium Digest, 429–432 (2006) [2] Hau, G., et al.: Multi-Mode W-CDMA Power AmplifierModule with Improved Low-Power Efficiency using Stage-Bypass, IEEE Radio Frequency Integrated CircuitsSymposium Digest, 163–166 (2010) Proceedings of APMC 2012, Kaohsiung, Taiwan, Dec. 4-7, 2012

11. 心得 這篇報告中，他們有提出三種功率模式下功率輸出匹配電路和旁通電路放大器W-CDMA，從輸出匹配電路和旁通電路的開關數量減少，在HPM操作中來實現高效率的通過而改變旁通電路和輸出電路的最後階段的放大器之間的連接點。