一種片外電容交叉充放電型振蕩電路設計
電子技術應用 2023年3期
曹楊,曹振吉,曹靚,趙桂林
(中國電子科技集團公司第五十八研究所,江蘇 無錫 214035)
摘要: CMOS環形振蕩器具有版圖面積小、調諧范圍大、電路簡單便于集成等優點,廣泛應用于各類電源系統及電子通信應用中。在常規的環形振蕩電路基礎上,設計了獨立的充放電控制通路,實現了一種交叉充放電型環形振蕩電路,并通過外接片外電容的方式,得到更低頻率的振蕩周期。基于0.18 μm工藝,采用HSIM工具對電路進行功能仿真,經過后端物理實現后,版圖面積為172 μm×76 μm,對電路進行提參后仿,結果表明:在3.3 V電壓及25 ℃條件下,外接10 nF接地電容時,電路獲得約1.2 ms的穩定振蕩周期。在Vcc=2.7 V~5.5 V、T=-55 ℃~125 ℃條件下,時鐘周期的最大偏移為5.83%。該電路已成功應用于某電源控制芯片中。
中圖分類號:TN432 文獻標志碼:A DOI: 10.16157/j.issn.0258-7998.223029
中文引用格式: 曹楊,曹振吉,曹靚,等. 一種片外電容交叉充放電型振蕩電路設計[J]. 電子技術應用,2023,49(3):77-81.
英文引用格式: Cao Yang,Cao Zhenji,Cao Liang,et al. An oscillator circuit with cross charge and discharge by off-chip capacitors[J]. Application of Electronic Technique,2023,49(3):77-81.
中文引用格式: 曹楊,曹振吉,曹靚,等. 一種片外電容交叉充放電型振蕩電路設計[J]. 電子技術應用,2023,49(3):77-81.
英文引用格式: Cao Yang,Cao Zhenji,Cao Liang,et al. An oscillator circuit with cross charge and discharge by off-chip capacitors[J]. Application of Electronic Technique,2023,49(3):77-81.
An oscillator circuit with cross charge and discharge by off-chip capacitors
Cao Yang,Cao Zhenji,Cao Liang,Zhao Guilin
(The 58th Research Institute, China Electronics Technology Group Corp., Wuxi 214035, China)
Abstract: CMOS Ring Oscillator has many advantages such as small layout area, large frequency range and easy integration. It is widely used in the DC-DC buck converter and electronic communication systems. On the basis of the traditional ring oscillator circuit, an independent charge and discharge control path is designed to realize a cross charge and discharge ring oscillator circuit, and a lower frequency oscillation period is obtained by externally connecting an off-chip capacitor. Based on 0.18 μm process, the circuit has been simulated with HSIM tool. After the back-end physical implementation, the layout of the oscillation occupies an area of 172 μm×76 μm. Using tools to extract parasitic parameters from the layout and conduct post-simulation, the simulation results indicates that with externally connecting an off-chip capacitor, and the power supply voltage in 3.3 V and temperature in 25℃, the oscillator has a clock period of 1.2 ms. With the power supply voltage changes in 2.7 V~5.5 V and temperature changes in -55℃~125℃, the frequency deviation is 5.83%.The circuit has been successfully applied in a power management chip.
Key words : ring oscillator;charge and discharge of capacitor;power management chip;clock
0 引言
壓控振蕩器(Voltage Controlled Oscillator, VCO)作為時鐘產生電路,作為各類通信系統的核心組成部分,被廣泛應用于鎖相環(Phase Locked Loop, PLL)、高速時鐘、數模轉換器(Analog-to-Digital Converter, ADC)等多個領域。當前主流的壓控振蕩器分為LC振蕩器和環形振蕩器。LC振蕩器通常由片上電容、電感和有源器件構成,品質因素較高,顯示出良好的相位噪聲特性,然而,調諧范圍有限、片上電感面積較大、與CMOS工藝兼容困難等問題也成為LC振蕩器的關鍵性缺陷。相比之下,環形振蕩器具有調諧范圍大、支持多相位輸出、占用面積小、電路簡單便于集成、成本低等優點,在CMOS工藝、片上系統的快速發展下,成為一種很有吸引力的選擇并被廣泛應用。
環形振蕩器是由多個延遲單元串聯形成的閉合環路,其噪聲抑制能力較差、受電源電壓影響較大,導致產生的振蕩周期并不穩定,并不適用于設計高性能環形振蕩器。因此,本文提出一種具有獨立的充放電通路、頻率可調的振蕩電路結構,分別由兩個不同的電容交叉充放電形成穩定的振蕩頻率,同時,通過外接納法級電容,突破集成片內電容約皮法級的大小限制,得到低于1 MHz的較低頻率振蕩周期。
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作者信息:
曹楊,曹振吉,曹靚,趙桂林
(中國電子科技集團公司第五十八研究所,江蘇 無錫 214035)
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