The other is the design of amplifier with constant trans - conductance ( gm ) rail - to - rail input stage . when common mode input voltage changes , it provides nearly constant - gm independent of input transistor operating region ( strong , moderate or weak inversion ) , and the quiet nods of the circuit for current addition and the output stage keep unchanged 當(dāng)輸入共模電壓變化時(shí),不管它的輸入mos差分對(duì)管處于強(qiáng)反型區(qū)還是弱反型區(qū),輸入級(jí)的跨度保持不變,而且輸入級(jí)后面的電流加法電路和輸出級(jí)的靜態(tài)工作點(diǎn)也不會(huì)隨之改變。
A complementary input stage , which consists of a p - channel pair and a n - channel pair , was used in the circuit , so that the common mode input range can extend from rail to rail . a dcls is used to shift the n - transistor curve leftward to overlap the p - transistor curve properly and keep constant transconductance in the whole common mode input range 輸入級(jí)采用pmos差分輸入對(duì)和nmos輸入差分對(duì)并聯(lián)的結(jié)構(gòu),從而實(shí)現(xiàn)共模輸入范圍擴(kuò)大到電源的正負(fù)兩端,并且通過兩個(gè)源級(jí)跟隨器平移nmos輸入管跨導(dǎo)曲線,使nmos輸入管和pmos輸入管跨導(dǎo)曲線的適當(dāng)交疊,從而保持了這個(gè)輸入級(jí)的跨導(dǎo)在整個(gè)共模輸入范圍內(nèi)保持恒定。