![](http://datasheet.mmic.net.cn/180000/74017_datasheet_11250435/74017_8.png)
CX74017
On the Direct Conversion Receiver
8
Skyworks Solutions, Inc., Proprietary and Confidential
101735A
Preliminary Data Subject to Change
July 20, 2001
constellation diagram. In DCR systems however, the IQ
matching is not as critical as in image-rejection architectures.
Rather, it is only important insofar as the accuracy of the
modulation is concerned.
Analog and digital (DSP based) calibration and adaptation
methods have been described so as to correct for these
imbalances, for example in [15].
101735A 14_071801
I
Q
gain
imbalance
ideal
constellation
Figure 14. IQ Demodulator Imperfections (Gain Imbalance)
101735A 15_071801
I
Q
phase
imbalance
Figure 15. IQ Demodulator Imperfections (Phase Imbalance)
Conclusion
The direct conversion receiver is an attractive yet challenging
receiving technique. It has recently been applied successfully to
devices such as pagers, mobile phones, PC and internet
wireless connectivity cards, satellite receivers etc. in a variety of
process technologies and increasing integration levels. It is
poised to appear in many more applications in the near future.
References
[1]
L. Lessing, “Man of High Fidelity: Edwin Howard
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[2]
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[3]
D.G. Tucker, “The Synchrodyne”, Electronic Engng, 19, p.
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[4]
D.G. Tucker, “The History of the Homodyne and the
Synchrodyne”, Journal of the British Institution of Radio
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[5]
A.A. Abidi, “Direct-Conversion Radio transceivers for
Digital Communications”, IEEE Journal of Solid-State
Circuits, vol. 30, no. 12, December 1995.
[6]
B. Razavi, “Design Considerations for Direct-Conversion
Receivers”, IEEE Transactions on Circuits and Systems-II:
Analog and Digital Signal Processing, vol. 44, no. 6, June
1997.
[7]
S.J. Franke, “ECE 353 – Radio Communication Circuits”,
Department of Electrical and Computer Engineering,
University of Illinois, Urbana, 1994.
[8]
B. Razavi, “RF Microelectronics”, Prentice Hall, Upper
Saddle River, NJ, 1998.
[9]
J.C. Rudell et al., “Recent Developments in High
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University, 1997.
[11] R. Hartley, “Single-Sideband Modulator”, U.S. Patent no.
1666206, April 1928.
[12] D.K. Weaver, “A Third Method of Generation and
Detection of Single Sideband Signals”, Proceedings of the
IRE, vol. 44, p. 1703-1705, December 1956.
[13] I.A.W. Vance, “Fully Integrated Radio Paging Receiver”,
IEE Proc., vol. 129, no. 1, p. 2-6, 1982.
[14] P.R. Gray, R.G. Meyer, “Analysis and Design of Analog
Integrated Circuits”, Third edition, John Wiley & Sons,
New York, 1993.
[15] J.K. Cavers, M. W. Liao, “Adaptive Compensation for
Imbalance and Offset Losses in Direct Conversion
Transceivers”, IEEE Transactions on Vehicular
Technology, vol. 42, p. 581-588, November 1993.