Mubeen Tayyab



Research Work

I received my bachelors degree in Electrical Engineering from NUST (EME College Campus) in 2011 and currently I am doing my MS in Electrical Engineering (Digital Systems and Signal Processing). I have implemented Continuous Phase modulation with turbo product codes on FPGA as Final Year Project. At AMSG I am involved in Digitally Assisted Analog Circuits (DAAC) project. Currently I am designing decimation filter for delta sigma ADC and also doing research on post processing on delta sigma converters.


Project Description

"A Continuous-Time Delta-Sigma Modulator for MEMS Applications "

Delta Sigma (Δ-Σ) modulator has become a first choice for high resolution oversampled analog to digital converter (ADC) for various bandwidths (especially low speed and low bandwidth applications) because of its programmability, scalability and its ability to integrate smoothly with digital circuits. As modern electronic devices shrink in power and size the need of transferring most of the analog functions to the digital domain for processing has become an industrial standard. To achieve this, a high resolution ADC is a necessary component of the chip.


Figure: MEMS Microphone Integrated Circuit System Model

The MEMS (Micro-Electro-MechanicalSystem) microphone is also called a microphone chip or silicon microphone. A MEMS microphone IC consists of a MEM microphone, an output amplifier (or a pre-amplifier) and a sigma-delta modulator. A lower bandwidth enables the Δ-Σ modulator to achieve higher over-sampling-ratio (OSR), which increases resolution of the A/D conversion. Δ-Σ modulators are robust and do not require high-precision analog components. At the same time, Δ-Σ ADCs offer several threads to control their performance and tune them according to the application specifications. These controlling threads are the modulator order, the over-sampling ratio and the quantizer resolution. Higher bandwidth of the MEMS microphone limits the OSR of the Δ-Σ modulator hence leaving the modulator order and the quantizer resolution as the performance-controlling threads.” (MS Thesis, Sohaib SaadatAfridi-ex lab member, 2013, NUST SEECS)
Analog to Digital converters (ADC) are very essential electronic components since they provide the interface between the digital system and analog (real) world. Delta Sigma ADCs are popular and widely used ADC because they are capable of achieving high resolution for low to medium signal bandwidths with low power consumption. The idea is to use concepts of adaptive filtering to improve the performance parameters of the Delta Sigma modulator. The objective is to use the concept of adaptive filters to improve the SNR of the system which eventually improves the effective number of bits.


Figure: Block Level Diagram of Adaptive Digital Calibration of Delta Sigma Modulator

Contact Information :

Mubeen Tayyab
Graduate Researcher
Analog Mixed Signal Group