SCIENTISTS

LC FILTERS DESIGN

2007-11-03T07:15:00.000-07:00

THIS FILTERS TUTORIALS SITE

This chapter lc filters is the most interesting tutorial of all for newcomers to radio design. Without a thorough grasp of lc filters you will never fully understand the ramifications of receiver and transmitter design.
Here you should gain a full understanding of the selection and design basics for lc filters. These lc filters topics cover everything necessary for your continued understanding of radio design and transmitter design.
It is absolutely imperative you fully understand the basic terms capacitance, chokes, impedance, inductance, "Q", reactance, resonance and toroids to complete these very comprehensive tutorials.
LOW PASS FILTERS:

We will start with low pass filters (LPF) because they are the basis of other filter designs. High pass or band pass filters are often simply transformations from low pass filter designs. It is simply two L networks added together.
HARMONIC TRAP FILTERS:

With the addition of one small component, a capacitor, we can transform a low pass filter into a filter with near infinite attenuation at a designed trap frequency. I call this an "harmonic trap filter".
BAND PASS FILTERS:

LC Band pass filters are usually LC filters containing resonator combinations of inductance and capacitance which are designed mathematically to respond to design frequencies while rejecting all other out of band frequencies. Because LC bandpass filters have inherent limitations these statements should not be taken too literally.
CONVENIENT FILTER SOFTWARE PROGRAM:

This LC and crystal filter software was written by Neil Heckt of Almost All Digital Electronics as an aid for filter designers to simply plug in various filter parameters and hey presto! there is your finished design. I will present you with the design example of a crystal filter of the crystal ladder filters variety as designed on my evaluation copy of the downloaded software.
HIGH PASS FILTERS:

Assuming you have mastered the design of low pass LC filters we will now proceed to the design of a high pass filters. A high pass filter is simply the transformation of a low pass filter. Just as one high pass filter design example, we will say we need a five pole butterworth filter with a cut off frequency Fc at 2000 Khz. That is we want to pass all frequencies above 2000 Khz but attenuate those below 2000 Khz, that is the function of a high pass filter.
IF AMPLIFIER BAND PASS FILTERS:

IF amplifier filters are LC resonator stages separated by individual stages of amplification. The principle is called synchronously tuned filters stages. In IF amplifier filters there can be any number of resonators per individual stage.
ACTIVE BAND PASS FILTERS:

Active bandpass filters are simply filters constructed by using operational amplifiers as active devices configured to simulate inductors or what are known as "gyrators". Active bandpass filters are used largely at audio frequencies where otherwise the size of the inductor would become prohibitive. The are many different types of active filters including high pass, low pass, band reject and there are numerous responses including multiple feedback bandpass (MFBP), dual-amplifier bandpass (DABP) and, state variable bi-quad all pole circuits. Interestingly all known filter responses such as Butterworth and Chebyshev may be synthesised.
Buy Lancaster's Active Filter Cookbook - Don Lancaster
NARROW BAND PASS FILTERS:

Narrow band filters are filters where the fractional bandwidth is extremely small in a relative sense. My personal definition of a narrow band filter is where the narrow band filter has a fractional bandwidth NOT exceeding 1%. A filter with a bandwidth of 200 Khz ( ± 100 Khz ) centred around 7100 Khz would represent a bandwidth of about 2.86% Here I present a very detailed design of a Butterworth narrow band filter.
ANTENNA PRE-SELECTOR FILTERS:

I'm asked every so often to produce a page on antenna pre-selector filters. An antenna pre-selector filter is nothing more than a narrow band filter, a topic already covered at some length on another page. Some confusion results because the narrow band filter topic contains no provision for variable tuning. There are several reasons for this. Contrary to your immediate impressions I find no particular benefit in introducing variable tuning to an antenna pre-selector filter. I can see a number of drawbacks however.

Embedded system

2007-10-19T01:35:00.000-07:00

Projects in multiprocessor systems-on-chips (MPSoCs):

* Video architectures.
* Networks-on-chips.
* Code compression.
* Low-power design.
* Embedded software.
* Secure processors.

MPSoC resources:

* The MPSoC workshop.
* Our edited volume on MPSoCs.

Video Architectures

We have developed new architectures for high-performance video processing, both for our smart camera application and for other video applications. With Vijaykrishnan of Penn State, we studied the power and performance properties of motion estimation algorithms.

Selected papers:

* Shengqi Yang, Wayne Wolf, and N. Vijaykrishnan, "Search speed and power driven integrated software and hardware optimizations for motion estimation algorithms," in Proceedings, International Conference on Multimedia and Exhibition, IEEE, 2004.
* Wayne Wolf, Tiehan Lv, and I. Burak Ozer, "An architectural design study for a high-speed smart camera," in Proceedings, 4th Workshop on Media and Streaming Processors, IEEE, 2002.
* Jason Schlessman and Wayne Wolf, "Leakage power considerations for processor array-based vision systems," in Proceedings, SASIMI 04, 2004.

Networks-on-chips

Networks-on-chips are structured interconnect for systems-on-chips. We studied wave pipelining as a NoC technique and showed that it can save energy as well as run faster. With Joerg Henkel and Srimiat Chakradar of NEC, we developed application-specific architectures for networks-on-chips.

Selected papers:

1. J.Henkel, W.Wolf, and S.Chakradhar, "On Chip Networks: A scalable communication-centric embedded system design paradigm," in Procedings, VLSI Design 2004, IEEE, 2004.
2. J. Xu, W. Wolf, T. Lv, J. Henkel, and S. Chakradhar, "A case study in networks-on-chip design for embedded video," in Proceedings, DATE 04, IEEE Computer Society Press, 2004.
3. Jiang Xu and Wayne Wolf, "A wave-pipelined on-chip interconnect structure for networks-on-chips," in Proceedings, Hot Interconnects 2003, IEEE, 2003.

Code Compression

We have studied code compression algorithms and architectures for many years. Most recently, we have concentrated on code compression for VLIW architectures. We developed profile-driven methods that selectively compress code. We also showed how to use LZW-style algorithms for code compression by making use of variable-sized blocks.

Selected papers:

1. C. H. Lin, W. Wolf, and Y. Xie, "LZW-based code compression for embedded systems," in Proceedings, DATE 04, IEEE Computer Society Press, 2004.
2. Yuan Xie, Wayne Wolf, and Haris Lekatsas, "Profile-driven code compression," in Proceedings, DATE '03, IEEE Computer Society Press, 2003, pp. 462-467.
3. Yuan Xie and Wayne Wolf, "Code compression for VLIW using variable-to-fixed coding," in Proceedings, ISSS 2002, IEEE, 2002.

Low-Power Design

We developed a bus encoding technique that reduces power consumption and can be efficiently implemented. This method uses dictionary encoding, so it does not have to transmit the code words even though they are derived from the data being transmitted.

Selected papers:

* Tiehan Lv, Joerg Henkel. Haris Lekatsas, and Wayne Wolf, "A dictionary-based en/decoding scheme for low-power data busses," IEEE Transactions on VLSI Systems, 11(5), October 2003, pp. 943-951.

Secure Processors

We developed a new approach to the design of microprocessors that are resistant to power attacks. A power attack analyzes power supply dynamic behavior to interpret events within the processor, taking advantage of the fact that different operations take different amounts of energy. We use dynamic voltage and frequency scaling to hide the energy consumption of microprocessor operations:

(c) 2005 IEEE

Our approach makes processor activity less visible with no significant energy consumption penalty and a modest performance penalty. Dynamic voltage frequency scaling is well-known and commercially available so this technique is applicable today.

Selected papers:

* Shengqi Yang, Wayne Wolf, Vijaykrishnan Narayanan, Dimitrios Serpanos, and Yuan Xie, "Power-attack resistant cryptosystem design: a dynamic voltage and frequency switching approach," in Proceedings, DATE '05 Designers Forum, 2005.

2007-10-16T05:22:00.000-07:00

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MP3 / Ipod Accessory

2007-10-15T04:33:00.000-07:00

MP3 / Ipod Accessory

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Power Supplies Section

2007-10-14T01:24:00.000-07:00

Power Supplies Section

This is a Regulated 0-30 V DC Power Supply manufactured by me in small numbers, 0-30V 5A and 5V -5A. It had a Switching Preregulator. This keeps the Vce across Transistor Bank at the Back of Instrument, at the lowest possible level, in order to keep them Cool. When Vce and Ic both are more in a Power transistor it will get heated more, then the efficiency of power supply is low.The Output had both Constant Current Control and Constant Voltage Control. The CC control is also a Short circuit protection. The Output was protected from outside voltages damaging output circuits even when equipment is switched off. The back panel is a finned anodized black aluminum heat sink with many transistors.I looked for the circuits to scan them, i could not find it. I made-n-sold quite a few of them years ago. All of them work well even today as i over-rated most components. The cabinet was Steel for EMI-RFI Immunity, it was painted with Stipple Matt Powder Coating, the Cabinet maker had just learnt to give such a finish to his boxes. Some circuit ideas of others.
Power Supply Adjustable 30
3-30 V/2.5 A Stabilized power supply
Small Variable power Supply
Build A 10 Amp 13.8 Volt Power Supply
Bench Top Power Supply, 30V - 10amp
40A Power Supply Unit