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Converting dBm to Watts

In the field of electrical engineering, power is most often specified in dBm–not Watts.  This brief post talks about how to convert between dBm and Watts and what the dBm unit means. A complete explanation of the decibel and log / linear conversions for many units (including dBm) can be found in The Decibel article. dBm and Watts Conversion Notice that the equations are for mW (milliwatts), not Watts.  That’s because the dBm is a unit based on the mW.  Converting to mW to W is...

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The Decibel

The Decibel

The decibel (dB) is one of the most widely used measurement units in electrical engineering, but is a common source of misunderstanding for unfamiliar engineers. Fundamentally, the dB is a ratio, but the concept the decibel is also used to describe absolute quantities, of which power is the most common example. This article will cover: Definition of the Decibel When to Use 10log10 or 20log10 Why Engineers Use the Decibel Common Decibel Units Used in Electrical...

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Power Spectral Density in MATLAB

Power Spectral Density in MATLAB

All real systems contain noise from various sources, be it from thermal noise, intentional or unintentional interference, cross-talk, etc. It’s important that we understand how to specify and model noise in our designs. A noise concept that seems to come up often as a question to me is how to accurately evaluate the power spectral density in MATLAB, where the thermal noise floor specification given in dBm/Hz. This article will discuss modeling thermal noise in MATLAB: Thermal Noise...

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Modeling a DDS in MATLAB

Modeling a DDS in MATLAB

Over the last few decades, we’ve seen the analog components of electronic systems slowly shrink as digital electronics take over that space. One important component driving that evolution is the direct digital synthesizer (DDS) chip. Because the DDS is not an analog device, there are some nuances derived from the quantized digital implementation that need to be considered in a design. For this, and maybe hundreds of other reasons, you may want to simulate or model a DDS in MATLAB. This...

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Verilog Counter

Verilog Counter

Counters are a principle part of nearly every FPGA design, facilitating time tracking in logic circuits by counting clock cycles. I’m going to discuss Verilog counter construction, and I also want to share a very practical counter tip that I picked up from a colleague many years back: count backwards. This article will cover the following concepts: Counter Concepts Verilog Implementation Synthesis Considerations Typical Uses For a VHDL counter, see our corresponding counter article with...

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Verilog Shift Register

Verilog Shift Register

Shift registers are a fundamental part of nearly every FPGA design, allowing the ability to delay the flow of data and examine previous values in the architecture pipeline. This article will cover the following concepts: Shift Register Concepts Verilog Implementation Synthesis Considerations Typical Uses For a VHDL shift register, see our corresponding shift register article with example code and VHDL specific tips.   Shift Register Concepts A shift register is a series of connected...

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