Study And Design Of Bandpass Sigma Delta Modulator

Considerable research effort in the field of microelectronics pushes towards the realization of fully monolithic, chiefly digital, RF transceivers - with the ultimate objective being the implementation of small, inexpensive, low power communication devices that are robust, testable, and capable of handling multiple communications standards. The goal of monolithic implementation has led to zero-IF architectures and the others. Lots of problems limit their usefulness, however, resulting in digital IF receiver in which the key block is the band-pass sigma delta modulator. Based on the basic principles of sigma delta modulator, the design method of band-pass sigma delta modulator is researched systematically including structures, resonator and circuit modules. And a single-bit fourth-order band-pass sigma delta modulator with low voltage and low power is designed.As the basic design fundamentals of band-pass sigma delta modulator, the quantization noises of the Nyquist ADC, over-sampling ADC and sigma delta are discussed. Low-pass and band-pass sigma delta modulator are analyzed. Then, the performance parameters and simulation methods are introduced, and the macro-model simulation method is proposed. The structures of the band-pass sigma delta modulator are researched. The suitable structures are found out by the deep analysis of six classes of modulators. On the ground of that, discrete time single loop one-bit band-pass sigma delta modulators are discussed and two improved structures are proposed.The resonator is researched duo to its importance in band-pass sigma delta modulator. Different switched-capacitor resonators are studied and the double-delay resonator is found to be the best candidate for a high quality resonator, in which the double sampling Salo resonator has lowest power. So a lot of attentions are paid to it and its non-idealities are analyzed. In order to overcome image component of the double sampling resonator, an improved resonator is presented.Then the circuit design techniques of band-pass modulator are studied, such as switch, amplifier, comparator and internal DAC. Also, a new bootstrapped switch and an improved amplifier is presented. In addition, a class AB latched comparator is discussed and optimized. On the basis of above research, a single-bit forth-order band-pass modulator is designed in 0.35μm CMOS technology. The design process is as follow: First, the power consumption...