High frequency analog-to-digital converter

Claim 1

A high frequency analog-to-digital converter for an analog signal comprising, in combination: signal generating means for producing a sinusoidal sampling reference signal at a frequency and amplitude always greater than the maximum anticipated frequency and amplitude of an analog signal to be converted; reset means connected to receive the reference signal for producing a reset pulse in each cycle thereof; and threshold means including a plurality of threshold units each unit having subtracting means adapted to receive the analog signaL and connected to receive the sinusoidal reference signal for providing output difference signals indicative of an amplitude difference between the analog and reference signals, and including first and second resistors having their one ends connected in common and their other ends receiving respectively the analog and sinusoidal reference signals, and wherein the resistances of said first and second resistors is selected to provide a greater peak current of the reference signal through said second resistor than the anticipated peak current of the analog signal through said first resistor, and sampling means connected to receive the difference signals and the reset pulse for producing parallel output signals indicative of a peak amplitude of respective ones of the difference signals between adjacent reset pulses, and including a third resistor having its one end connected in common to said first and second resistors and its other end to a d.c. signal, and a diode unit connected to an input to the one ends of said resistors and providing the threshold unit output signal, the duration between the reset pulses being preselected to include the time of the peak amplitude of all anticipated frequencies of the difference signals.