Analog duty cycle replicating frequency converter for PWM signals

An analog, duty cycle replicating frequency converter extracts duty cycle information from an input, pulse width modulated signal and generates an output pulse width modulated signal of the same duty cycle at a different frequency without regard to the frequency of the input signal. It uses bipolar transistor based circuitry, adaptable to an application specific integrated circuit, to derive voltages representing the on-time and period durations of the input signal, convert these voltages to currents representing the logarithms thereof, generate a voltage representing the difference between the currents, exponentially convert the voltage to a current representing the duty cycle and control an oscillator to generate an output pulse width modulated signal at a predetermined frequency with the duty cycle of the input signal.