基于可編程非線性補(bǔ)償?shù)男逼码妷喊l(fā)生器

摘" 要： 恒定斜率的線性斜坡電壓經(jīng)過電容后，可以生成小于1 nA的校準(zhǔn)電流，而電流的穩(wěn)定性很大程度上取決于斜坡電壓發(fā)生器的性能。文中提出一種基于可編程非線性補(bǔ)償?shù)男逼码妷喊l(fā)生器，采用可控電流源對電容進(jìn)行充電，獲取非線性補(bǔ)償信號，并結(jié)合多個(gè)模擬開關(guān)實(shí)現(xiàn)兩個(gè)相同通道的交替補(bǔ)償，從而生成更加平滑的斜坡電壓。與過去基于兩個(gè)數(shù)模轉(zhuǎn)換器的斜坡電壓發(fā)生器相比，所提發(fā)生器大大縮短了補(bǔ)償時(shí)間，擴(kuò)展了斜率的可調(diào)范圍；同時(shí)，通過電容充電生成的線性斜坡克服了數(shù)模轉(zhuǎn)換器補(bǔ)償信號非線性的問題。實(shí)驗(yàn)結(jié)果表明，所提的基于電容充電非線性補(bǔ)償方法的斜坡電壓發(fā)生器在斜率控制和斜坡平滑性方面的表現(xiàn)均優(yōu)于數(shù)模轉(zhuǎn)換器的補(bǔ)償方法，并且經(jīng)過電容充電非線性補(bǔ)償后的斜坡電壓平滑性相對提升了80.4%。

關(guān)鍵詞： 斜坡電壓發(fā)生器； 非線性補(bǔ)償； 模擬開關(guān)； 可控電流源； 數(shù)模轉(zhuǎn)換器； 電容充放電

中圖分類號： TN782?34" " " " " " " " " " " " " " "文獻(xiàn)標(biāo)識碼： A" " " " " " " " " " " 文章編號： 1004?373X（2025）04?0045?07

A ramp voltage generator based on programmable nonlinear compensation

LIU Zhicun， FU Yaqiong， QIAN Lushuai， CHEN Le

（College of Mechanical and Electrical Engineering， China Jiliang University， Hangzhou 310018， China）

Abstract： A linear ramp voltage with constant slope can generate the calibration current of less than 1 nA after passing by the capacitor. The stability of the current largely depends on the performance of the ramp voltage generator. A slope voltage generator based on programmable nonlinear compensation is proposed， which uses the controllable current source to charge the capacitor， obtains nonlinear compensation signals， and combines multiple analog switches to achieve alternating compensation of two identical channels， thereby generating a smoother slope voltage. In comparison with the slope voltage generator based on two analog?to?digital converters in the past， it can greatly shorten the compensation time and expand the adjustable range of slope. The linear slope generated by capacitor charging overcomes the problem of nonlinearity in the compensation signal of the analog?to?digital converter. The experimental results show that the proposed slope voltage generator based on the non?linear compensation method of capacitor charging proposed in this paper can perform better than the compensation method of the analog?to?digital converter in terms of slope control and slope smoothness. After non?linear compensation by means of capacitor charging， the smoothness of the ramp voltage is relatively improved by 80.4%.

Keywords： ramp voltage generator; nonlinear compensation; analog switch; controlled current source; digital to analog converter; capacitor charge?discharge

0" 引" 言

線性斜坡電壓經(jīng)過電容后可以產(chǎn)生1 nA以下的電流，這對于校準(zhǔn)皮安計(jì)等小電流檢測儀器具有重要意義[1]。該方法的核心部件是斜坡電壓發(fā)生器，其斜坡的平滑程度決定了輸出電流的穩(wěn)定性。低溫電流比較儀（CCC）電橋是目前最準(zhǔn)確的測阻儀器[2]。然而，電流正負(fù)換向的操作導(dǎo)致了瞬時(shí)電流“跳躍”，這將造成電橋工作不穩(wěn)定。斜坡電壓發(fā)生器同樣是解決這一問題的關(guān)鍵[3?5]。

文獻(xiàn)[6]使用單個(gè)16位的數(shù)模轉(zhuǎn)換器（DAC）直接產(chǎn)生斜坡電壓。……