A new technique for tuning high-Q continuous-time filters is presented. This technique is a modified version of an adaptive tuning method where the tuning signals are sinusoids generated by digital bandpass delta sigma oscillators. As will be shown, the required building blocks for the tuning system are simple. Simulation results are presented to show the feasibility of the proposed approach.

A new architecture is proposed for a single-chip digital radio receiver. This architecture has several advantages over the direct-conversion architecture that has been gaining interest for use in single-chip designs. A non-zero quadrature IF reduces the image problem and eliminates concerns about self-EMI and 1/f noise. A complex bandpass filter embedded in a delta-sigma loop allows the A/D conversion to be performed directly on the pair of quadrature outputs from the mixer.>

A methodology is presented for the design of noise and signal transfer functions for delta-sigma modulators. A computerised optimiser is used to produce maximal noise-shaping, while meeting those constraints necessary to realise a usable modulator. The design of higher-order modulators is possible, as is the design of unique noise-shaping functions such as for bandpass modulators, complex modulators, or modulators with psychoacoustically-shaped in-band noise. Optimisation of the transfer function from modulator input to output is also possible if special conditioning of the input signal is desired.>

In many applications, it is desirable to synthesize an adaptive impedance to match some "real world" system, so that when the target impedance changes, the matching impedance tracks this change and maintains a close match. In this paper we present a scheme for adaptive impedance matching formulated in the Model Reference Adaptive Systems' Control (MRAS) framework. The Model Reference adaptive controller can be implemented using Adaptive Delta-Sigma Filters to improve the performance-to-cost ratio due to their inherent oversampling. We will refer to this combined framework for adaptive impedance matching as MRAS/AIM.>