Intrinsic safety isolation with capacitive coupling

An apparatus comprising:

• a printed circuit board having a thickness that complies with an intrinsic safety physical separation specification;
• a first pair of capacitive plates disposed on opposite sides of the printed circuit board and arranged to form a first capacitor having an insulating layer of the printed circuit board forming a dielectric material for the first capacitor;
• a second pair of capacitive plates disposed on opposite sides of the printed circuit board and arranged to form a second capacitor having the insulating layer of the printed circuit board forming a dielectric material for the second capacitor;
• a modulator coupled to the first and second capacitors, the modulator being configured to receive an input signal having an input signal frequency and provide a modulated signal having a frequency that is higher than the input signal, wherein the modulator includes an oscillation circuit that is configured to oscillate when the input signal is in a low state;
• and
• a demodulator coupled to the first and second capacitors, the demodulator being configured to detect the modulated signal and provide a demodulated signal:
• having the input signal frequency.