A system to generate a gated spread spectrum carrier in a radio frequency isolated circuit, the system comprising: an input circuit (100, 300, 400) comprising: a gated voltage-controlled oscillator, VCO, (104, 404) to receive a digital gate signal (102, 402) and, when gated on upon assertion of the digital gate signal, to generate complementary first and second differential signals forming the spread spectrum signal to be transmitted across an RF-passing isolation barrier; a low-pass filter to receive the first and second differential signals (414a, 414b) from the gated VCO and generate low-pass filtered differential signals (418a, 418b); a demodulator to receive the low-pass filtered differential signals (418a, 418b) and to generate an output signal that is high if the frequency of the low-pass differential signal formed by the low-pass filtered differential signals is below a predetermined frequency and low if said frequency is above the predetermined frequency; a delaying bidirectional ramp generator to receive the output signal, the output signal to ramp a voltage control signal in either a positive or a negative direction and to generate a sawtooth waveform as the voltage control signal to be received into a voltage control input of the gated VCO; and an output circuit comprising a high-pass filter to receive third and fourth differential signals (428a, 428b) corresponding to the transmitted first and second differential signals from the RF-passing isolation barrier; wherein the RF-passing isolation barrier disposed between the input circuit and the output circuit protects the input circuit and the output circuit from common mode voltage differences and transients. an input circuit (100, 300, 400) comprising: a gated voltage-controlled oscillator, VCO, (104, 404) to receive a digital gate signal (102, 402) and, when gated on upon assertion of the digital gate signal, to generate complementary first and second differential signals forming the spread spectrum signal to be transmitted across an RF-passing isolation barrier; a low-pass filter to receive the first and second differential signals (414a, 414b) from the gated VCO and generate low-pass filtered differential signals (418a, 418b); a demodulator to receive the low-pass filtered differential signals (418a, 418b) and to generate an output signal that is high if the frequency of the low-pass differential signal formed by the low-pass filtered differential signals is below a predetermined frequency and low if said frequency is above the predetermined frequency; a delaying bidirectional ramp generator to receive the output signal, the output signal to ramp a voltage control signal in either a positive or a negative direction and to generate a sawtooth waveform as the voltage control signal to be received into a voltage control input of the gated VCO; and an output circuit comprising a high-pass filter to receive third and fourth differential signals (428a, 428b) corresponding to the transmitted first and second differential signals from the RF-passing isolation barrier; a gated voltage-controlled oscillator, VCO, (104, 404) to receive a digital gate signal (102, 402) and, when gated on upon assertion of the digital gate signal, to generate complementary first and second differential signals forming the spread spectrum signal to be transmitted across an RF-passing isolation barrier; a low-pass filter to receive the first and second differential signals (414a, 414b) from the gated VCO and generate low-pass filtered differential signals (418a, 418b); a demodulator to receive the low-pass filtered differential signals (418a, 418b) and to generate an output signal that is high if the frequency of the low-pass differential signal formed by the low-pass filtered differential signals is below a predetermined frequency and low if said frequency is above the predetermined frequency; a delaying bidirectional ramp generator to receive the output signal, the output signal to ramp a voltage control signal in either a positive or a negative direction and to generate a sawtooth waveform as the voltage control signal to be received into a voltage control input of the gated VCO; and an output circuit comprising a high-pass filter to receive third and fourth differential signals (428a, 428b) corresponding to the transmitted first and second differential signals from the RF-passing isolation barrier; wherein the RF-passing isolation barrier disposed between the input circuit and the output circuit protects the input circuit and the output circuit from common mode voltage differences and transients.