Mixer-B

The schematic of Mixer-B is shown in Fig. 3-35. As indicated by arrow1, the on-chip inductor is for input matching. Using Marchand balun to transform the single LO signal to differential pair, the balance is less dependent to process variation. The layout is shown in Fig. 3-36 where the chip size is 0.9*1.46 um².

Fig. 3-35. The schematic of Mixer-B.

Fig. 3-36. The layout of Mixer-B. Chip size 0.9*1.46 um².

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As shown in Fig. 3-37, by using the on-chip inductor for input matching, the RF port return loss is under -10dB for 8.5~17GHz. In Fig.3-38 and Fig.3-39 are the LO and IF ports’ return loss, and shown the return loss is under -10dB for the desired bandwidth.

Fig. 3-37. RF port return loss for RF signal band 8.5~17GHz.

Fig. 3-38. LO port return loss for a fixed LO frequency at 17.5GHz.

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Fig. 3-39. IF port return loss for IF band 0.5~9GHz.

The conversion gain is shown in Fig.3-40,and the gain variation is less than 3dB for the RF bandwidth. The three corner (TT、FF、SS) are simulated under the same current consumption, and the three conversion gains are acceptable.

Fig. 3-40. Conversion gain versus RF frequency with LO at 17.5GHz.

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The isolation from RF port to IF port is shown in Fig.3-41, and the isolation is -30dB in RF bandwidth. It means that the lower out of RF band signal has 30dB rejection ratio to IF port. This can release the loading of the filters connected to the mixer.

Fig. 3-41. Isolation of RF port to IF port.

Table 3-42. The summary of Mixer-B.

Simulation

Process CMOS 0.18um

RF Bandwidth 8.5~17 GHz Supply Voltage(V) 1.8

IF Bandwidth 0.5~9 GHz RF input return loss < -10 (dB) LO input return loss < -15 (dB) IF input return loss < -10 (dB) Conversion Gain 7 dB (dB) RF to IF Isolation < -30 dB (dB)

Power (mW) 37

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3.4 Reference

[1] L. A. MacEachern, T. Manku, .A charge-injection method for Gilbert cell biasing,.

IEEE Canadian Conference on Electrical and Computer Engineering, vol. 1, pp.

365.367, May 1998.

[2] M. L. Schmatz, U. Lott, W. Baumberger, W. Baechtold, .Novel design topology for ultra low power down converters with broadband ob chip matching network,.

IEEE Trans. Microwave Theory Techniques, vol. 43,no. 12, pp. 2946.2951, Dec.

1995.

[3] S. J. Mahon, et. al, .Broadband integrated millimeter-wave up- anddown-converter GaAs MMICs,. IEEE Trans. Microwave Theory Techniques, vol. 54, no. 5, pp.

2050.2060, May 2006.

[4] T. T. Hsu, C. N. Kuo, .Low power 8-GHz ultra-wideband active balun,. IEEE 2006 Topical Meeting on Silicon Monolithic Integrated Circuits inRF systems, pp.

365.368, Jan. 2006.

[5] R. Hu, .Wide-band matched LNA design using transistor's intrinsic gate-drain capacitance,. IEEE Trans. Microwave Theory Techniques, vol. 54,no. 3, pp.

1277.1286, March 2006.

[6] B. W. Lee, D. S. Park, S. S. Park, M. C. Park, .Design of new three-line balun and its implementation using multilayer configuration,. IEEETrans. Microwave Theory Techniques, vol. 54, no. 4, pp. 1405.1414, April2006.

[7] W. M. Fathelbab, M. B. Steer, .New classes of miniaturized planar baluns,. IEEE Trans. Microwave Theory Techniques, vol. 53, no. 4, pp.1211.1220, April 2005.

[8] T.-Y. Yang, H.-K. Chiou, .A 16.46 GHz mixer using broadband multilayer balun in 0.18-um CMOS technology,. IEEE Microwave Wireless Comp .Lett., vol. 17, no. 7, pp. 534.536, July 2007.

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[9] N. Marchand, .Transmission-line conversion transformers,. Electronics, vol. 17, no. 12, pp. 142.145, Dec. 1944.

[10] K. S. Ang, I. D. Robertson .Analysis and design of impedance-transforming planar Marchand baluns,. IEEE Trans. Microwave Theory Techniques, vol. 49, no. 2, pp. 402.406, Feb. 2001.

[11] C. T. Fu, C. N. Kuo, .3.11-GHz CMOS UWB LNA using dual feedback for broadband matching,. 2006 IEEE Radio Frequency Integrated Circuits Symposium, pp. 53.56, June. 2006.

[12] B. Gilbert, .The MICROMIXER: a highly linear variant of the Gilbert mixer using a bisymmetric class-AB input stage,. IEEE J. Solid-State Circuits, vol. 32, pp.

1412.1423, Sep. 1997.

[13] S. C. Tseng, C. C. Meng, C. H. Chang, C. K. Wu, G. W. Huang,. Monolithic broadband Gilbert micromixer with an integrated Marchand balun using standard silicon IC process,. IEEE Trans. Microwave Theory Techniques, vol. 54, no. 12, pp.

4362.4371, Dec. 2006.

[14] K. W. Hamid, A. P. Freundorfer, Y. M. M. Antar, .A monolithic double-balanced circuit conversion mixer with an integrated wideband passive balun,. IEEE J.

Solid-State Circuits, vol. 40, no. 3, pp. 622.629, March 2005.

[15] S. A. Maas, .A GaAs MESFET mixer with very low intermodulation,. IEEE Trans. Microwave Theory Techniques, vol. mtt-35, no. 4, pp. 425. 429, Apr. 1987.

[16] R. A. Pucel, D. Masse, .Performance of GaAs MESFET mixers at X band,. IEEE Trans. Microwave Theory Techniques, vol. mtt-24, no. 6, pp. 351.360, June 1976.

[17] H. Ma, S. J. Fang, F. Lin, K. S. Tan, .A high performance GaAs MMIC upconverter with an automatic gain control amplifier,. 19th Annual Gallium Arsenide Integrated Circuit Symposium, pp. 232.235, Oct. 1997.

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[18] R. H. Lee, et. al., .Circuit techniques to improve the linearity of an up-conversion double balanced mixer with an active balun,. 2005 Asia Pacific Microwave Conference (APMC), vol. 2, pp. 4.7, Dec. 2005.

[19] Chin-Shen Lin; Pei-Si Wu; Mei-Chao Yeh; Jia-Shiang Fu; Hong-Yeh Chang;

Kun-You Lin; Huei Wang; ”Analysis of Multiconductor Coupled-Line Marchand Baluns for Miniature MMIC Design”, Microwave Theory and Techniques, IEEE Transactions on olume 55, Issue 6, Part 1, June 2007 Page(s):1190 - 1199 [20] Choonsik Cho; Gupta, K.C.,”A new design procedure for single-layer and two-layer three-line baluns”, Microwave Theory and Techniques, IEEE Transactions on lume 46, Issue 12, Part 2, Dec. 1998 Page(s):2514 - 2519

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Chapter 4

Conclusion and Future Work

4.1 Conclusion and Future Work

The thesis mainly contains two circuits; one is transformer feedback LNA, and the other is wide IF band down-converting mixer. For LNA, using transformer feedback to achieve input matching can eliminate the noise of input port. Because the transformer feedback can simply the input-matching schematic and thus only the noise of input transistor exist. Form the simulated results the noise figure of the proposed LNA is 3dB from 10~18GHz with 17dB voltage gain. However the simulated results need the measured results to verify and the 37.6mW power consumption can be further minimized. Besides, the input impedance of transformer feedback still need accurately development since for high frequency, the transistor’s parasitic capacitor Cgd can no longer be ignored in derivation of input impedance.

For the wide IF band down-converting mixer, two components still need to be further analyzed; one is the balun’s input impedance and the other is mixer core.

Mentioned in [1], the S-parameter of Marchand balun is as follows, and the matrix derived with the assumption that the two coupled lines have electric length θ=90⁰ is valid only for the central frequency. When using Marchand balun in wideband application, the wideband S-parameter of Marchand balun is needed. Since Marchand balun is composed of two quarter-λ coupled lines, analysis of a single coupled line for wide band is approachable. Then using ABCD matrix multiplication of two single coupled lines can form the matrix of Marchand balun.

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where k is the coupling factor and Z1、Z2 are balanced and unbalanced ports’ source impedance.

For mixer core, the Gilbert cell is often simplified as a switch, and LO signal is modulated the switch by switching on-off. However the Gilbert cell is not perfectly switching on-off, and the modeling of Gilbert cell as a square function can be further improved. This aspect is proposed in [2] by Abidi, and in [2] two switching models is presented; one is hard switching and the other is soft switching. The difference between hard switching and soft switching is the LO signal modeled as square or sine wave and the model will affect the white noise of mixer. Moreover it is suspect that the model may affect the conversion gain and IF bandwidth. In 1978[3], the conversion matrix for diode proposed by Kerr can solve the conversion gain of diode-mixer. In 1976[4], active FET nonlinear model was proposed and used conversion matrix to solve the FET-mixer. In 1987[5], Stephen A. Mass proposed a GaAs MESFET mixer with low intermodulation, and he claimed that using a passive MESFET as a time-varying linear resistor can realize a non-intermodulation mixer.

Therefore analyzing and modeling the passive MOSFET under large signal modulated is challenging and then using conversion matrix to solve the mixer is expected.

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4.2 Reference

[1] S. C. Tseng, C. C. Meng, C. H. Chang, C. K. Wu, G. W. Huang,. Monolithic broadband Gilbert micromixer with an integrated Marchand balun using standard silicon IC process,. IEEE Trans. Microwave Theory Techniques, vol. 54, no. 12, pp.

4362.4371, Dec. 2006.

[2] Hooman Darabi and Asad A. Abidi, Fellow, IEEE,” Noise in RF-CMOS Mixers:

A Simple Physical Model”, IEEE TRANSACTIONS ON SOLID STATE CIRCUITS, VOL. 35, NO. 1, JANUARY 2000

[3] DANIEL N. HELD, MEMBER, IEEE, AND ANTHONY R. KERR, ASSOCIATE MEMBER, IEEE, “Conversion Loss and Noise of Microwave and Millimeter Wave Mixers: Part l—Theory”, IEEE TRANSACTIONS ON MICROWAVE THEORY AND TSCHNIQUES, VOL. MTT-26, NO. 2, FEBRUARY 1978

[4] ROBERT A. PUCEL, SENIOR MEMBER, IEEE, DANIEL MASSE, MEMBER, IEEE, AND RICHARD BERA, “Performance of GaAs MESFET Mixers at X Band”, IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL.

MTr-24, NO. 6, JUNE 1976

[5] STEPHEN A. MAAS, MEMBER, IEEE, “A GaAs MESFET Mixer with Very Low Intermodulation”, IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. MTT-35, NO. 4, APRIL 1987

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