maxswell
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serdes,I/O,ADC,EEPRO M
Posts: 3
china,guangdong,zhuhai
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hi all,i recently use pss+pnoise (source method & time method) to analysis very simple sample/hold circuit. and get a confusion result. switch frequency is just 2.5MHz, sample/hold cap is just 2pf, switch mos is just nmos, input voltage is dc voltage。 when i include flicker noise of MOS, and plot pnoise spectrum with source method, pnoise spectrum has very very high spur at 10MHz in surprise, and also has a high spur at 100MHz, when i disable flicker noise effect, these two spur frequency points disappea. when i plot pnoise spectrum with time method (enable flicker noise effect), i also find 10MHz and 100MHz spur during mos switch disconnect phase, so i am confused by these spur, because when mos switch disconnect (that is to say hold phase), output voltage should appear no noise , at lease, switch mos flicke noise should have no effect on output voltage, and during hold phase, there is no current flow through mos switch and cap ,flicker noise should disappear? is it wrong? The same phenomenon appear in the paper 《SIMULATION AND ANALYSIS OF NOISE IN SWITCHED CAPACITOR AMPLIFIER CIRCUITS 》,but the author have no explain
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