Electronic filter

About: Electronic filter is a research topic. Over the lifetime, 13207 publications have been published within this topic receiving 93063 citations. The topic is also known as: filter.

A digitally programmable switched-capacitor universal active filter/oscillator

Abstract: A universal second-order switched-capacitor filter section has been fabricated on an NMOS chip. The device can perform all five basic filter types as well as a sine wave oscillator without external components, while requiring only an external clock. The filter type is determined by selecting one or more of three input pins. The filter response is determined by ten external programming pins which may be either digitally controlled or hard wired.

A Nanopower Biopotential Lowpass Filter Using Subthreshold Current-Reuse Biquads With Bulk Effect Self-Neutralization

Abstract: A nanopower CMOS 4th-order lowpass filter suitable for biomedical applications is presented. The filter is formed by cascading two types of subthreshold current-reuse biquadratic cell. Each proposed cell is capable of neutralizing the bulk effect that induces the passband attenuation. The nearly 0-dB passband gain can thus be maintained, while the entire filter circuit remains compact and power-efficient. Designed for electrocardiogram detection as an example of application, the filter prototype has been fabricated in a 0.35 $\mu \text{m}$ CMOS process occupying 269 $\mu \text{m}\,\,\times $ 383 $\mu \text{m}$ chip area. Measurements verify that the filter can operate from a 1.5-V single supply and consumes 5.25 nW, while providing a cutoff frequency of 100 Hz and input-referred noise of $39.38~\mu \text{V}_{\mathrm {rms}}$ . The intermodulation-free dynamic range of 51.48 dB is obtained from a two-tone test of 50 and 60 Hz input frequencies. Compared with state-of-the-art nanopower lowpass filters using the most relevant and reasonable figure of merit, the proposed filter ranks the best.

Method and apparatus for providing input EMI filtering in power supplies

Abstract: A power supply electromagnetic interference (EMI) filter circuit and technique In one embodiment, a method of filtering EMI in a power supply includes rectifying an AC signal from an AC source, smoothing the rectified AC signal with a bulk storage capacitor to provide a DC output as an input to a power conversion circuit and filtering the EMI generated by the power conversion circuit from reaching the AC source by using the bulk capacitor and one or more inductors in combination with the AC source capacitance as an EMI filter In one embodiment the method also includes the use of one or more of the inductors as a fusing element

Time-Interval Measurement Based on SAW Filter Excitation

Abstract: This paper deals with a novel time-interval measurement method that makes use of a surface acoustic wave (SAW) filter as a time interpolator. The method is based on the fact that a transversal SAW filter excited by a short pulse can generate a well-defined finite signal with highly suppressed spectra outside a narrow frequency band. If the responses to two excitations are sampled at clock ticks, they can be precisely reconstructed from a finite number of samples and then compared to determine the time interval between the two excitations. As a first step of a more comprehensive discussion of the method, the time-interpolation error caused by deterministic effects has been analyzed in this paper. It has been shown that the mean square of the interpolation error is limited by the upper bound, which is proportional to the relative energy of aliasing distortion and inversely proportional to the square of the filter center frequency. The upper bound has been compared to the results obtained from the simulation based on a linear-phase transversal filter. The RMS error resulting from the simulation exactly follows the slope of the theoretical upper bound, and it is approximately four times smaller than that. The described method excels in time interpolation efficiency since the time interpolation error relative to clock period is small; in other words, accurate measurement can be achieved even with a relatively low clock frequency. This has been practically demonstrated in a time-interval counter, which provides precision of 7-ps RMS using a clock frequency as low as 16.4 MHz. It results from the analysis that using state-of-the-art elements in the interpolator, the deterministic interpolation error on the order of 0.1 ps can be achieved.

6 MVA five-level hybrid converter for windpower

Abstract: For the further improvement of today's full converter systems for windpower applications a 6 MVA converter prototype has been developed. It is utilizing the ANPC5L topology as inverter on the grid-side and the simple 2-quadrant ANPC3L topology as rectifier for a permanent magnet synchronous generator (PMG). ANPC stands for Active Neutral Point Clamped, which is the base for the derivation of multiple topologies, i.e. 3-, 5- and higher levels. The ANPC5L converter is realized as a hybrid converter based on IGCT (Integrated Gate Commutated Thyristor) presspack devices and IGBT (Insulated Gate Bipolar Transistor) modules. The ANPC5L is modulated at 2 kHz. The IGCTs, used as inner switches, are operated at fundamental frequency, which allows a substantial reduction in silicon size. To meet the harmonic limits of the IEEE 519 no additional passive filter is required. To fulfill the more stringent VDEW requirements a simple LC filter is implemented. On the permanent generator side a simplified 2-quadrant 3 level converter (2Q-ANP3L), with 50% less turn-off switches than in a conventional NPC converter, is used. The operation of this simple topology with a discontinuous modulation allows the adjustment of the power factor of the permanent magnet synchronous generator for all operation conditions. The 6 MVA converter has been designed, built and tested in the power lab. The dimensions of the 6 MVA converter prototype, represents one of the most compact designs achieved for windpower applications today.