Correction of duty-cycle distortion in communications and other circuits

Abstract

Abstract A typical occurrence in communication circuits, such as transmitters and receivers, is the internal transfer of a sequence of pulses, known as a clock signal, from an amplifier to a digital circuit. For proper operation, it is critical that the digital circuit accurately comprehends the clock signal. However, in some communications circuits a phenomenon called duty-cycle distortion—that is, a distortion of the apparent duration of the pulses in clock signals—causes the digital circuit to read the clock signals as having a longer or shorter duration than intended. Accordingly, the inventors devised unique circuitry for correcting or preventing this distortion. One exemplary circuit uses a voltage divider, comprising a pair of transistors, to set the DC or average voltage of the clock signals input to the digital circuit at a level approximating the logic threshold voltage of the digital circuit. In another example, a feedback circuit drives the DC or average voltage of signals input to the digital circuit to match a reference voltage that is substantially equal to the logic threshold voltage. In both examples, equating the DC or average voltage of the clock signals to the logic threshold voltage of the digital circuit reduces or prevents duty-cycle distortion.

Inventors

• 👤 Eric Douglas Groen
• 👤 Charles Walter Boecker

Bibliographic Details