ChetanGK
Newbie level 6
Hi everyone,
In continuation of my old question:
https://www.edaboard.com/showthread.php?388562-Down-conversion-Mixer
I am planning to design a fully differential amplifier as a front end amplifier for my sensor application which later drives a passive mixer followed by a passive LPF. I am new to system-level design. Please help me out
1. I know I have to drive a resistive load as voltage mode passive mixer will have switches which imposes ON resistance (switches) which is very low. This resistance will load my opamp and reduces the DC gain. My question is should I design the mixer first and get to know the exact input impedance of the mixer?
2. I read a few papers and Textbooks (Jacob Baker and Razavi) which uses Class AB as an output buffer to drive resistive loads. Is it possible to use Source follower (only 1 CMFB loop) as the output buffer instead of Class AB (needs 2 CMFB loops and also needs floating current source)? And please do suggest output buffer topology.
Fews specifications are Open loop DC gain - 70dB, Capacitive Load (feedback cap) - 3pF, GBW - 150MHz, Closed-loop gain around is 3 to 6dB, Resistive load (unknown as of now), no constraint on power and the critical parameter is noise.
Please let me know your suggestions and thanks in advance.
In continuation of my old question:
https://www.edaboard.com/showthread.php?388562-Down-conversion-Mixer
I am planning to design a fully differential amplifier as a front end amplifier for my sensor application which later drives a passive mixer followed by a passive LPF. I am new to system-level design. Please help me out
1. I know I have to drive a resistive load as voltage mode passive mixer will have switches which imposes ON resistance (switches) which is very low. This resistance will load my opamp and reduces the DC gain. My question is should I design the mixer first and get to know the exact input impedance of the mixer?
2. I read a few papers and Textbooks (Jacob Baker and Razavi) which uses Class AB as an output buffer to drive resistive loads. Is it possible to use Source follower (only 1 CMFB loop) as the output buffer instead of Class AB (needs 2 CMFB loops and also needs floating current source)? And please do suggest output buffer topology.
Fews specifications are Open loop DC gain - 70dB, Capacitive Load (feedback cap) - 3pF, GBW - 150MHz, Closed-loop gain around is 3 to 6dB, Resistive load (unknown as of now), no constraint on power and the critical parameter is noise.
Please let me know your suggestions and thanks in advance.
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