This is due to the fact that each transistor in a cmos circuit is actually made from a pmos transistor and an nmos transistor
Compared with the similar research results , the weighted control ic here has the following characteristics : ( 1 ) the circuit structure is simpler ; ( 2 ) the chip ' s fabrication is compatible with standard cmos process ; ( 3 ) n - mosfets with high w / l ratio and short channels are used for weighting and output to reduce the insertion loss ; ( 4 ) the weighting factor varies in a relatively wide range with the controlling signals ; ( 5 ) input and output impedance approach 50 in low frequency ( e . g . 50mhz ) , while in higher frequency they slightly deviate from 50 , hence the energy reflection lower than 0 . 1 ; ( 6 ) it completes the functions of sampling , weighting , controlling and summing of high frequency analog signals
A switch ic for analog signal processing is designed and implemented , which can fulfill the functions of sampling , weighting , controlling and summing of high frequency analog signals . the circuit consists of three parts : four channel analog switches , a voltage reference and the control circuitry . each analog switch is comprised of two high - transconductance n - mosfets with high w / l ratio , which realize the fine tuning and coarse tuning of the input signal respectively
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