A low power monolithic AGC with automatic DC offset cancellation for direct conversion hybrid CDMA transceiver used in telemetering

The monolithic integration can be made possible with the advantages of direct conversion techniques. However, DC offset and flicker noise become critical to the system. In this paper we propose a wide tuning range AGC with an effective automatic DC offset cancellation. The proposed AGC is specifically designed for direct conversion hybrid CDMA system operating at 2.4 GHz used in telemetering applications. The AGC was fabricated using TSMC 0.35 um double poly process. The circuit achieves a 80 dB continuous gain tuning range, [-30 dB, 50 dB], with 40 dB dynamic range for differential output voltage set to 500 mV/sub pp/ and a THD better than 30 dBc. The AGC is powered by 3 V with 7 mW power consumption.

[1]  Asad A. Abidi,et al.  A CMOS variable gain amplifier for a wideband wireless receiver , 1998, 1998 Symposium on VLSI Circuits. Digest of Technical Papers (Cat. No.98CH36215).

[2]  C.D. Hull,et al.  A direct-conversion receiver for 900 MHz (ISM band) spread-spectrum digital cordless telephone , 1996, 1996 IEEE International Solid-State Circuits Conference. Digest of TEchnical Papers, ISSCC.

[3]  J. M. Khoury,et al.  On the design of constant settling time AGC circuits , 1998 .

[4]  S.A. Sanielevici,et al.  A 900 MHz transceiver chipset for two-way paging applications , 1998, 1998 IEEE International Solid-State Circuits Conference. Digest of Technical Papers, ISSCC. First Edition (Cat. No.98CH36156).

[5]  Francois Krummenacher,et al.  A 4-MHz CMOS Continuous-Time Filter with On-Chip Automatic Tuning , 1987, ESSCIRC '87: 13th European Solid-State Circuits Conference.

[6]  Behzad Razavi,et al.  RF Microelectronics , 1997 .