ANALYSIS AND DESIGN OF A 4th ORDER BANDPASS SIGMA DELTA MODULATOR FOR GSM COMMUNICATIONS STANDARD |
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| J.J. Ocampo Hidalgo, A. Garcia Ortiz, L. D. Kabulepa, M. Glesner |
- Abstract:
- This work addresses the design of a 4th order bandpass sigma delta modulator (BPSDM) for IF AD converters suitable for second generation cellular standards such as GSM. The resonator architecture of a BPSDM can be derived from the transfer characteristic of a lowpass modulator by means of mathematical transformations. It can be observed that each transformation results in a different cascade of resonators (COR). Therefore different values of performance metrics like SNR, dynamic range, robustness against circuit non-idealities and SFDR can be expected. Behavioral simulations at the architectural level were carried out to find the COR that best meets the requirements imposed by the GSM communications standard and minimizes requirements of the sub-circuits used in the chosen architecture. A BPSDM was designed and sent to fabrication, using a 0.3 µm, double polysilicon, triple metal, N-well CMOS technology. Simulation results are showing that the proposed prototype reaches a SNR of 85 dB and a sampling rate of 80 MHz.
- Keywords:
- bandpass sigma delta modulators and IF digitization
- Download:
- IMEKO-TC4-2002-027.pdf
- DOI:
- -
- Event details
- IMEKO TC:
- TC4
- Event name:
- TC4 Conference and Workshop 2002
- Title:
- 4th International Conference on Advanced A/D and D/A Conversion Techniques and their Applications (together with 7th IMEKO TC4 Workshop on ADC Modelling and Testing)
- Place:
- Prague, CZECH REPUBLIC
- Time:
- 26 June 2002 - 28 June 2002