Oscillator, negative resistance circuit and its oscillating method

Abstract

An oscillator, comprising an LC tank circuit and a negative resistance circuit. The negative resistance circuit is coupled to the LC tank circuit and comprises a pair of transistors and a pair of voltage drop generators. The transistors have first terminals and second terminals, wherein the first terminals are cross-coupled to the second terminals thereof. The voltage drop generators are respectively coupled between the first and second terminals of the transistors.

Description

technical field [0001] The present invention relates to an oscillator, and more particularly to an oscillator including a voltage drop generator which improves its output swing, a negative resistance circuit and an oscillating method thereof. Background technique [0002] FIG. 1A is a circuit diagram of a basic voltage controlled oscillator (VCO) 100 , which includes an LC tank 110 , negative resistance circuits 120 and 130 and a current source 140 . The negative resistance circuits 120 and 130 respectively include cross coupled bipolar junction transistors (BJT) and metal-oxide-semiconductor (MOS) transistors. The collectors C1 and C2 of the BJTs Q1 and Q2 of the negative resistance circuit 120 are coupled to the LC tank 110 , and the drains of the MOS transistors of the negative resistance circuit 130 are also coupled to the LC tank 110 . The emitter of the BJT is grounded, and the source of the MOS transistor is coupled to the current source 140 . [0003] Figure 1B and...

AI Technical Summary

Problems solved by technology

For example, when the V B2C2 =0.5V, the bipolar junction transistor Q2 will enter a saturated state, and when any bipolar junction transistor enters a saturated state, the voltage-controlled oscillator cannot work normally

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