# uV to dBuV Calculator

This tool helps convert from μV (microvolt) to dBµV (deciBel microvolt).

Note that μV is a positive number that represents the root-mean-square (RMS) voltage and it cannot be less than zero.

## Formula

dBµV = 20*Log10(µV)

The same formula applies when converting either quantity scaled by distance (e.g. per-meter)

dBµV/m = 20*Log10(µV/m)

## Background

Volt (unit of potential difference and of electromotive force). It is defined as:

“the potential difference between two points of a conducting wire carrying a constant current of 1 ampere, when the power dissipated between these points is equal to 1 watt.” – Reference Bureau International des Poids et Mesures

1 µV or microvolt = 10-6 Volt = 0.000001 Volt

also

1 Volt = 106 microvolt = 1000000 microvolt

The dB or deciBel scale is a very convenient representation for large numbers and allows for easy multiplication of two linear quantities. dB can be used to represent a ratio of power or voltage.

dBuV (like dBm) is an absolute quantity. It is the voltage level in dB referenced to 1 microvolt. Note that there is no consideration of impedance.

### Where are µV and dBµV used?

Both uV and dBuV are used in the field of Electromagnetic Compatibility in the measurement of conducted emissions. Conducted emissions refers to noise generated by an electronic device and transferred to another electronic device via cables, PCB traces, power and ground planes, or parasitic capacitance.

Conducted emissions must be kept low or they can propagate through cables to other devices, causing electromagnetic interference. This can cause devices to malfunction.

FCC specifies limits on these emissions as shown in the table below. The frequency range varies from 150 kHz to 30 MHz.

The picture below shows a plot of emissions from a power amplifier module. The red line indicates the limits while the black plot represents the actual measurement.

The y-axis of the plot shows dBuV values ranging from 20 to 80 dBuV.

On a linear scale (using this calculator) that would be 10 uV to 10000 uV – a large range of values. Representing this range is much easier on a dB scale. Hence the reason to convert from uV to dBuV.

### Where are uV/m and dBuV/m used?

uV/m or microvolt-per-meter is used by the FCC to specify radiated emission limits for RF equipment at a 3-meter distance from the source.

The first three columns of the following table of Radiated Emissions Limit is from [1]. The calculator is used to find the dBuV/m equivalent value