Capacitance coupled isolation amplifier and method

A method of operating isolation amplifier circuitry to produce an isolated output signal, the isolation amplifier circuitry including electrically floating circuitry for receiving and operating upon the differential input voltage, said method comprising the steps of:

• a. producing a first signal having a triangular wave shape;
• b. capacitively coupling a first portion of said first signal to an electrically floating power supply circuit;
• c. producing an electrically floating D C voltage difference by means of the electrically floating power supply;
• and
• d. applying said electrically floating D C voltage difference to the electrically floating circuitry.

A method of operating amplifier circuitry to amplify a differential input signal applied to first and second inputs of the amplifier circuitry to produce an output signal which is isolated from the differential input signal, the first input having a floating ground voltage level thereon, the amplifier circuitry including

• i. comparator circuitry having first and second inputs coupled, respectively, to the first and second inputs of the amplifier circuitry and also having first and second outputs, the comparator circuitry being electrically floating,
• ii. power supply circuitry for supplying electrical power to the comparator circuitry, the power supply circuitry also being electrically floating, and
• iii. demodulator circuitry coupled to the first and second outputs of the comparator circuitry to demodulate a pulse width modulated output produced at the first and second outputs of the comparator circuitry, the demodulator circuitry having an output at which the output signal of the amplifier circuitry is produced,
• said method comprising the steps of:
• a. producing a triangular waveform signal;
• b. capacitively coupling a portion of said triangular waveform signal to the power supply circuitry to provide operating power for the power supply circuitry;
• c. capacitively coupling a portion of said triangular waveform signal to a first conductor, the first conductor being electrically coupled to one of the first and second input nodes of the amplifier circuitry, hereby superimposing the portion of the triangular waveform signal capacitively coupled to the first conductor onto the differential input voltage;
• d. producing a pulse width modulated output signal between the first and second outputs of the comparator circuitry in response to said superimposing, said pulse width modulated output signal representing the magnitude of the differential input signal;
• and
• e. demodulating the pulse width modulated output signal to produce the output signal of the amplifier circuitry, the output signal of the amplifier circuitry being an amplified version of the differential output signal and being isolated from the differential input signal.