High-speed high-bandwidth VCO (Voltage Controlled Oscillator) delay unit with rail-to-rail voltage regulating range

Abstract

The invention discloses a high-speed high-bandwidth delay unit circuit with a rail-to-rail voltage regulating range, which is applied to a high-speed voltage controlled oscillator (VCO). Compared with the traditional symmetrical load difference delay unit, the delay unit provided by the invention is mainly improved in the following three points that: (1) a control voltage is used for simultaneously controlling PMOS (P-channel Metal Oxide Semiconductor) tubes and NMOS (N-channel Metal Oxide Semiconductor) tubes to realize the regulation of the working frequency of the VCO in the rail-to-rail range; (2) two PMOS tubes connected by a diode are changed into cross coupling connection, so that the working efficiency of the VCO is increased; and (3) a tail current source is omitted, so that the design complexity is reduced. A ring VCO formed by cascading the improved delay units has the characteristics of wide control voltage regulating range, high working efficiency, high bandwidth and goodlinearity.

Description

technical field [0001] The invention mainly relates to the design field of a frequency synthesizer, a clock recovery circuit and a voltage-controlled oscillator (VCO) in a phase-locked loop, in particular to a delay unit circuit applied to a high-speed voltage-controlled oscillator (VCO). Background technique [0002] Voltage-controlled oscillator (VCO), as an adjustable signal source whose oscillation frequency can change with the applied control voltage, is widely used in modern communication systems, especially in phase-locked loop, clock recovery In circuits such as frequency synthesis and frequency synthesis, it is a key component that affects the performance of the entire system. In integrated circuits, the research on VCOs implemented by CMOS technology mainly focuses on two types: LC resonators and RC ring oscillators. Among them, LC resonators have better noise performance, but it is more difficult to integrate on-chip inductors in standard CMOS technology. The CMO...

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Problems solved by technology

Since this structure adjusts the equivalent resistance of the symmetrical load by controlling the PMOS transistor to adjust the operating frequency of the VCO, and the gate voltage can only turn on the PMOS transistor in a certain range, the control voltage outside this range will not be able to modulate the delay unit. load resistance, so that the oscillation frequency of the VCO cannot be modulated, and the ring oscillator formed by cascading the delay units cannot work in the rail-to-rail range. Figure 9 The change trend of the load resistance is given when the control voltage Vcont changes from 0V to 1.8

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