Frequency-to-digital converter based on truncated gray coding

Abstract

The present disclosure relates to frequency-to-digital converters based on truncated Gray coding. According to an embodiment, a method includes generating N phases from a ring oscillator circuit having an odd number of stages, where N is an odd integer greater than or equal to 3; encoding the N phases using a combined truncated Gray code encoder circuit to produce M truncated Gray code bits, where fewer than 2 M Gray codes are used to encode the N phases; converting the M truncated Gray code bits to binary using a Gray code to binary encoding circuit to form a binary output; and forming a first difference of the binary output.