Multi-standard Σ - Δ Modulator for GSM/WCDMA Applications

Abstract

This paper reports the design of multi-standard sigma delta modulator with low power consideration. It uses the cascaded methodology for modulator design to reduce power dissipation and single feedback system has been used to provide higher stability. The concept of oversampling and noise shaping is used in the design of modulator to increase Signal to Noise Ratio (SNR). The OP-AMP designed has a gain of 62 dB and phase margin of 72° to make the design stable. The second order sigma delta modulator designed can be used for either GSM or WCDMA applications at a sampling frequency of 5 MHz and 20 MHz, respectively. The bandwidth of the signal considered for GSM and WCDMA is 200 KHz and 2 MHz, respectively. The SNR and dynamic range obtained for GSM is 82 dB and 71 dB, respectively, and for WCDMA the same is 62 dB and 54 dB, respectively. The multi-standard modulator is designed in standard 180 nm CMOS technology at a power supply of 1.8 V and the total power consumed is 4.867 mW.

Keywords:

• CMOS
• Common mode feedback
• Comparator
• GSM
• Integrator
• Multi-standard
• OPAMP
• WCDMA
• Σ - Δ Modulator

Additional information

Notes on contributors

Durshee Sharma

Durshee Sharma received B.E. in Electronics and Telecommunication from Shri Shankaracharya College of Engineering and Technology Bhilai, India in 2009 and M.Tech in VLSI from Indian Institute of Technology Guwahati in 2011. She is currently working as Sr. Software Engineer in Samsung India Software Operations Pvt. Ltd. Bangalore, India. Her area of interest is low power - low voltage analog and digital circuit design.

E-mail: [email protected]

Roy Paily

Roy Paily received the B.Tech. degree in electronics and communication engineering from the College of Engineering, Trivandrum, India, in 1990; the M.Tech. degree from the Indian Institute of Technology Kanpur, Kanpur, India, in 1996; and the Ph.D. degree from the Indian Institute of Technology Madras, India, in 2004; all in semiconductor devices. Currently, he is a Professor with the Department of Electronics and Electrical Engineering, Indian Institute of Technology Guwahati, India where he joined in 2004 as an Assistant professor. His research interests include very large-scale integrated circuits and microelectromechanical systems and devices.

E-mail: [email protected]