Hi Jeferson,
below a comparison between differential and single ended driver topology.
Differential (Push-Pull) Driver Topology
How it works:
The matching network is connected to a H-bridge push pull driver stage. Both outputs are actively driven: when one goes high, the other goes low, and vice versa. This creates a differential signal across the matching network and antenna.
Benefits:
Double the Voltage Swing:
The voltage across the matching network and antenna is the difference between the two outputs. If each output swings between 0 and VDD(_DR), the antenna sees a swing of 2*VDD(_DR) (from +VDD(_DR) to −VDD(_DR).
The result is a higher magnetic field strength, which improves NFC communication range and reliability.
Improved Power Efficiency:
For the same supply voltage, you get more power delivered to the antenna and less power is wasted in the driver, as both sides are actively driven.
Better Common-Mode Noise Rejection:
Differential signals are less susceptible to common-mode noise (e.g., power supply noise, external EMI). This improves signal integrity and reduces the risk of communication errors.
Higher Sensitivity:
A differential signal is present on the two RFI pins resulting in twice the input voltage and higher sensitivity.
Drawbacks:
BOM:
Bigger BOM, higher costs
Single-Ended Driver Topology
How it works:
One end of the antenna is driven by the push pull driver, the other push pull driver can be connected to another antenna. The voltage swing across the antenna is limited to VDD(_DR)
Benefits:
Dual Antenna operation:
Two single ended antennas can be connected to most of the ST25R products. The two antennas can be operated time-multiplexed (one after the other).
Reduced BOM:
Only the half amount of components used compared to the differential antenna topology.
Drawbacks:
EMI:
Possible common mode EMI issues due to lack of differential signal.
Please let us know if you have further questions.
BR Travis
