What are the advantages of differential circuits in RF signal chain applications?

Dec 17,2024
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When it comes to communication systems, differential circuits always provide better performance than single ended circuits - they have higher linearity, resistance to common mode interference signals, and so on. Today we will talk about the four major advantages of differential circuits in RF signal chain applications.

Using differential circuits can achieve higher signal amplitudes than using single ended circuits.

At the same power supply voltage, differential signals can provide twice the amplitude of single ended signals, and they can also provide better linearity and SNR performance.

Figure 1. Differential output amplitude

Differential circuits have good anti-interference properties against external EMI and interference from nearby signals.

This is because the received useful signal voltage doubles, and the impact of noise on tightly coupled wiring is theoretically the same, they cancel each other out.

The EMI generated by differential signals is often low

This is because the change in signal level (dV/dt or dI/dt) generates opposite magnetic fields, which cancel each other out again.

Differential signals can suppress even order harmonics

The following shows an example of continuous wave (CW) passing through a gain module.

When using a single ended amplifier, as shown in Figure 2, the output can be expressed as Formula 1 and Formula 2.