High resolution, large multiplication factor digitally-controlled frequency multiplier

摘要

A frequency multiplier circuit generates an supplemental high-frequency timing signal from a single, low-frequency current-controlled oscillator (CCO). The current-controlled oscillator (CCO) generates a controlled discharge current and a controlled bias current which are controlled in parallel to substantially eliminate inaccuracies in a characteristic frequency-current curve of the current-controlled oscillator. The frequency multiplier circuit generates a high-frequency timing signal using the digitally-controlled CCO and avoids the usage of a phase-locked loop (PLL) technique. Specifically, a frequency multiplier includes a current-controlled oscillator having a plurality of input lines connected to receive a digital current select signal and having an output terminal connected to carry a timing signal at a current-controlled oscillator frequency fCCO set in accordance with the current select signal. The frequency multiplier further includes a control circuit having a first timing input terminal connected to the current-controlled oscillator output terminal to receive the current-controlled oscillator frequency fCCO, output lines connected to the current-controlled oscillator digital current select input lines, a second timing input terminal connected to receive a timing signal at a reference frequency fREF, and a plurality of input lines connected to receive a programmable frequency multiplication factor.