Receiver sensitivity is the strength of the weakest signal that a radio receiver can detect and demodulate. It is typically specified in dBm, Watt or microvolt.

It is also referred to as **Minimum Detectable Signal (MDS)**.

**How to Calculate Receiver Sensitivity**

Use this tool is used to calculate the sensitivity. Enter the following:

- Temperature
- Bandwidth
- Receiver Noise Figure
- Signal to Noise ratio required to achieve the desired performance

**Receiver Sensitivity Formula**

**Receiver Sensitivity = 10 * log _{10} (kTB/(1 mW))**

**+ NF + SNR**

Where

**T**– Temperature**B**– Bandwidth**k**– Boltzmann’s Constant**1.380649 × 10**^{-23}m^{2}kg s^{-2}K^{-1}**NF**– Noise Figure**SNR**– Signal-to-Noise ratio (sometimes referred to as Carrier-to-Noise Ratio)

Receiver sensitivity can also be expressed as a function of Noise Floor:

**Receiver** **Sensitivity = Receiver Noise Floor + SNR**

**Noise Figure**

Noise figure degrades the receiver sensitivity. Typically a low noise amplifier can be used to improve or lower the minimum detectable signal level.

**Signal-to-Noise Ratio**

As the complexity of the modulation increases the required SNR increases as well. Frequency Modulation (FM) signals for instance require lower SNR than Bluetooth which is a more complex digital waveform.

**Temperature**

As the operating temperature increases, the noise power increases. This degrades the receiver sensitivity

**Bandwidth**

The larger the bandwidth, the higher the noise power in the band of interest. This in turn degrades the receiver sensitivity.

**Example Receiver Sensitivity Calculation**

At:

- Room temperature 27
^{o}C or 300 K, - Signal bandwidth of 25 kHz,
- Receiver noise figure of 5 dB,
- Required SNR of 4 dB,

results in a receiver sensitivity or minimum detectable signal level of -121 dBm.

In other words, a signal has to be at least -121 dBm to be demodulated by the receiver.

**Bluetooth Receiver Sensitivity**

Bluetooth signal has a bandwidth of 1 MHz and requires SNR of 15 dB for a Bit error rate of 0.1%.

Bluetooth requires that compliant devices must be able to achieve a minimum Receiver Sensitivity of -70 dBm. Using the calculator above, the noise figure can be as high as 29 dB.

In practice however the noise figure can be designed to be 8 dB or less. In this scenario the receiver will be able to detect a signal as low as -90 dBm.

**Related Calculators**

Use the following to convert from dBm to: