A dual-mode broadband voltage-controlled oscillator

Abstract

The invention provides a dual-mode broadband voltage controlled oscillator which comprises two voltage controlled oscillator parts working at a high frequency band and a low frequency band respectively, wherein each voltage controlled oscillator part comprises an inductor, two variable capacitors, a negative resistance circuit, a switch variable capacitor array, a switch capacitor array, and a switch tail current source array. In each voltage controlled oscillator part, the inductor is connected between two output ends of the voltage controlled oscillator part; one end of each variable capacitor is connected with control voltage, and the other end of each variable capacitor is connected with bias voltage through a blocking capacitor and a resistor; the negative resistance circuit is formed by a cross-coupled NMOS (n-channel metal oxide semiconductor) pair and a cross-coupled PMOS (p-channel metal oxide semiconductor) pair; the switch variable capacitor array is controlled by digital control words, and used for controlling the tuning range of each tuning curve; the switch capacitor array is controlled by the digital control words; the maximum capacitance in the switch capacitor array and the switch variable capacitor array codetermines the starting point of each tuning curve; the switch tail current source array is controlled by the digital control words and the control voltage together, and used for generating tail current; and the tail current is in direct proportion to output swing amplitude of the voltage controlled oscillator part. The oscillator is stable in output swing amplitude, and wider in tuning range.

Description

technical field [0001] The invention relates to the technical field of radio frequency integrated circuits, in particular to a dual-mode broadband voltage-controlled oscillator. Background technique [0002] With the development of wireless communication technology, more and more communication standards require receivers to cover a wider frequency range, which undoubtedly poses a higher challenge to the design of voltage-controlled oscillators. Tuning range, power consumption, phase noise, and tuning gain are the basic specifications for a VCO in a receiver. [0003] For broadband voltage-controlled oscillators, a design difficulty is to keep the tuning gain low. An ideal VCO whose output frequency ω out and control voltage V TUNE The relationship can be expressed as: [0004] ω out = ω 0 +K VCO V TUNE (1) [0005] Among them, ω 0 is the center frequency, K VCO is the tuning gain. [0006] Control voltage V TUNE It will inevitably be affected by the front-stage ...

AI Technical Summary

Problems solved by technology

[0012] When the start-up conditions are met, if the output swing of the VCO is too large, it will enter the voltage limit region, which will not only affect the phase noise but also waste current

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