approved: Pavan Kumar Hanumolu VCO-based ADCs have recently emerged as attractive alternative to conven­ tional Delta Sigma (ΔΣ) modulator architectures. Few salient features of a VCO­ based ADC are: 1) the quantization noise is 1 order noise shaped, 2) it is an open loop architecture, and, 3) its implementation is mostly digital in nature. Hence, they are ideally suited for oversampled data co...

Sigma Delta ADC is better than Nyquist Rate Converters as they give better Resolution with low signal bandwidth. Sigma-delta ADCs are traditionally used in audio applications ranging up to 20 KHz. ADC based on sigma-delta modulators is attractive for VLSI implementation because they are less dependent to circuit non-idealities like clock Jitter and component mismatch. However, non-idealities be...

In order to design high performance sigma-delta A/D converters, it is essential to estimate the Figure-Of-Merit in the design process. This paper describes the design of a power/performance efficient single-loop multibit sigmadelta modulator for wireless applications. Power dissipation is minimized by optimizing the architecture and by a careful design of analog circuitry. A 3 order 4-bit Σ-∆ m...

In this paper we present a method for stability analysis of high order Sigma-Delta modulators. The method is based on a parallel decomposition of the modulator. Using this presentation the general N-th order modulator could be considered as made up of N first order modulators, which interact only through the quantizer function. The decomposition helps us to extract the stability conditions of t...

This paper presents the study of an original closed-loop conditioning approach for fully-integrated convective inertial sensors. The method is applied to an accelerometer manufactured on a standard CMOS technology using an auto-aligned bulk etching step. Using the thermal behavior of the sensor as a summing function, a first order sigma-delta modulator is built. This “electrophysical” modulator...

Three-phase pwm voltage source inverters are widely employed in high performance ac drive system, active filters and uninterrupted power supply (UPS) etc.For these applications, the converter should provides good dynamic response. However the performance of the converter system largely depends on the accuracy of the applied current control strategy. The current controllers can be classified as ...

In this paper a two stage bandpass MASH (multi-stage noise shaping) sigma-delta ( Σ∆ ) modulator is presented. A resolution of 14 bits has been achieved over a 5 MHz band around an intermediate frequency (IF) of 20 MHz with a clock frequency of 80 MHz. This performance is obtained using a 6-th order bandpass Σ∆ modulator followed by a 10 bit pipeline converter. The proposed circuit has been ext...

A constant-envelope, continuous phase modulation architecture is presented in which a sigma-delta modulator is combined with an open-loop modulator. Compared to existing architectures, Σ∆ based open-loop modulation can be implemented with minimal analog circuitry. The architecture is demonstrated with a discrete implementation performing frequency modulation at a carrier frequency of 120 MHz. B...