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Full-automatic gain control (AGC) crystal oscillator realizing low noise rejection and high power supply rejection (PSR)

A high power supply suppression, crystal oscillator technology, applied in power oscillators, electrical components, etc., can solve problems such as high phase noise, and achieve the effect of ensuring low noise

Inactive Publication Date: 2013-01-02
苏州本然微电子有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantage of existing crystal oscillators with automatic gain control (AGC) is that they have high phase noise

Method used

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  • Full-automatic gain control (AGC) crystal oscillator realizing low noise rejection and high power supply rejection (PSR)
  • Full-automatic gain control (AGC) crystal oscillator realizing low noise rejection and high power supply rejection (PSR)
  • Full-automatic gain control (AGC) crystal oscillator realizing low noise rejection and high power supply rejection (PSR)

Examples

Experimental program
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Effect test

Embodiment 1

[0016] Embodiment 1: as figure 2 Shown is a low-noise fully automatic gain control high power supply suppression crystal oscillator, PMOS transistor M2, PMOS transistor M3, NMOS transistor M5, NMOS transistor M6 and resistor R2, resistor R3 form a bias current generator. A typical implementation is that the NMOS transistors M5 and M6 are selected to have the same size, so that the same current flows into the PMOS transistor M2, which also flows into the resistor R2. Therefore I = VGS2 / R3. The bias current generated in this way is reflected to the NMOS transistor M4, and the NMOS transistor M4 provides the bias current to the PMOS main oscillator transistor M1. In order to get a proper internal bias current, the PMOS main oscillator tube M1 needs to have a large enough gain to overcome the loss of the crystal (typical gain value is three times or more than the loss of the crystal), the oscillator will start to oscillate the crystal, the capacitor C1 and C2 set the frequenc...

Embodiment 2

[0017] Embodiment 2: as image 3 A low-noise full-automatic gain control high-power-suppressed crystal oscillator is shown. The bias current generated from the bias current generator unit is input into the NMOS transistor M7 and reflected to the NMOS transistor M4, which will set the Determine the bias current of the main oscillator tube M1 and the gain in the gain circuit. When the oscillator starts to oscillate, the gate node of the NMOS transistor M7 is driven by the capacitor C5 to AC couple the oscillation signal. Through the same class AB amplifier of the above-mentioned NMOS transistor M7, the DC voltage at the gate node of the NMOS transistor M7 is controlled according to the amplitude of the oscillator signal. This DC voltage is applied to the gate node of the NMOS transistor M4 after the low-pass filter of the resistor R5 and the capacitor C6. The current of the NMOS transistor M4 is adjusted accordingly to improve the gain of the transconductance circuit. As ab...

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Abstract

The invention discloses a full-automatic gain control (AGC) crystal oscillator realizing low noise rejection and high power supply rejection (PSR). The AGC crystal oscillator comprises a crystal oscillator circuit, a gain circuit and a bias current generator which is controlled by the oscillation amplitude to generate a bias current. The bias current generator controlled by the oscillation amplitude provides a feedback path for the crystal oscillator, and therefore, the full-automatic gain control (AGC) oscillator is formed. With the setting of the appropriate gain, the AGC crystal oscillator achieves the aims of low noise rejection and high power supply rejection (PSR).

Description

technical field [0001] The invention relates to a crystal oscillator, in particular to a crystal oscillator with low noise automatic gain control and high power supply suppression. Background technique [0002] In the past few years, the development of communication technology has made remarkable progress. Digital modulation techniques are widely used, such as Time Division Multiple Access (TDMA) and Code Division Multiple Access (CDMA). With the rapid development of these communication methods, systems with intensive communication transmission need to implement modulation techniques to reduce the number of similar carrier frequencies. spacing and modulation bandwidth. Frequency stability of oscillators is becoming more and more important in contemporary technology. The existing crystal oscillator (XO) schematic is shown in figure 1 shown. However, crystal oscillators (XOs) have been used as frequency reference sources in electronic systems for decades. Such oscillators ...

Claims

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Application Information

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IPC IPC(8): H03B5/04
Inventor 刘斌陈克恭王树一
Owner 苏州本然微电子有限公司
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