Square-root Domain Filters Research Articles

A low-voltage square-root domain n-th order multifunction FLF filter topology

A novel n-th order Follow the Leader Feedback (FLF) multifunction low-voltage filter topology, realized by employing the concept of Square-Root Domain (SRD) filtering, is introduced in this manuscript. The realization of the SRD filter topology is achieved by utilizing the corresponding FLF conventional topology and performing a transposition into SRD, through an appropriate set of complementary operators. As a design example, a 5th-order SRD FLF filter has been designed and its performance has been evaluated through simulation results, where the most important performance factors have been considered.

Switched-Current Filters Revisited: Square-Root Domain Sampled-Data Filters

In this brief, the well-known switched-current (SI) filtering technique is revisited using the concept of the square-root domain (SRD) filtering. It is proved that SI filters are a subclass of the SRD filters, where sampled-data signal processing is performed. This is achieved by considering typical lossless and lossy SRD sampled-data integrator configurations, using a set of complementary SRD operators which are based on the quadratic I-V relationship of MOS transistor operated in the saturation. Circuit examples are given, where linear-domain integrator and third-order filter configurations were derived using appropriate SRD sampled-data building blocks

Design of Square-Root Domain Filters

In this paper, a square-root domain band-pass filter and biquad filter which are based on the MOSFET square law are proposed. Both of the square-root domain filters operated at 2.5 V supply voltage are constituted by current mirrors, current-mode square-root circuits and capacitors. The circuits presented have been simulated and fabricated using 0.25 ? m CMOS process. Both of simulation and measured results which are in good agreement indicate that the center frequency f0 is not only attainable at megahertz frequencies but also tunable electronically. The proposed circuits have the merits of high frequency operation, tuneability, low power supply voltage operation, low third order intermodulation distortion and low total harmonic distortion.

1.5 V tunable Square-Root Domain filter

A novel approach to the design of low-voltage CMOS Square-Root Domain filters is presented. It is based on the large-signal behaviour of a well-known class-AB linear transconductor. A first-order filter is built employing three such transconductors, featuring simplicity and compactness. Measurement results for an experimental prototype in 0.8 µm CMOS validate the technique proposed. The filter operates with a single supply voltage of 1.5 V and can be tuned in more than one decade.