Voltage Controlled Oscillator for Rail-to-Rail Input Voltage Range

Abstract

The invention discloses a voltage-controlled oscillator capable of achieving a track-to-track input voltage range. The voltage-controlled oscillator comprises a current-controlled oscillator and a voltage-current converter formed by a voltage-current converting control circuit, a first bias voltage circuit, a current source and a synchronization resistor. The voltage-current converting control circuit comprises an operation amplifier and a converting control output circuit, the operation amplifier can achieve track-to-track input, a reverse input end of the operation amplifier is connected with a control end of the converting control output circuit, an output end of the operation amplifier is connected with the input end of the converting control output circuit, an output end of the converting control output circuit is connected with an input end of the first bias voltage circuit, an output end of the first bias voltage circuit is connected with an input end of the current source, and an output end of the current source is connected with a power supply end of the current-controlled oscillator. The voltage-controlled oscillator is mainly used in a circuit of a phase-locked loop.

Description

technical field [0001] The invention relates to a voltage-controlled oscillator (VCO) in a phase-locked loop, in particular to a rail-to-rail (Rail-to-Rail) input voltage range voltage-controlled oscillator circuit. technical background [0002] Phase-Locked Loop (Phase-Locked Loop) is a technology that uses the principle of feedback control to achieve frequency and phase synchronization. Its function is to synchronize the clock output by the PLL with an external reference clock. When the frequency or phase of the reference clock changes, the phase-locked loop will detect this change and adjust the output frequency and phase through its internal feedback system until it is re-synchronized. This synchronization is called "phase-locked". Using frequency multiplication, frequency division and other frequency synthesis, modulation and demodulation, and clock recovery techniques of the phase-locked loop, a multi-frequency, high-stability, and low-noise clock output signal can be ...

AI Technical Summary

Problems solved by technology

Since the working range is between 1.5V and 3.3V, if Vctrl fails to enter this working range for some reasons, such as when the PLL is powered on (Start-up), Vctrl may be very low, in this case VCO will be Lose the ability to track changes in the reference clock CKref, making the PLL unable to work properly

Images