RC
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For on chip IC, we have LNA at front-end, which needs input 50 Ohm match, and Power-amplifier for output 50 Ohm match. However, in between, in CMOS, we always have high impedance input/output, and we don't need to match them to 50 Ohm. Hence, when charaterize them, should we still use 50 Ohm, get the value in power and convert it back to voltage, dbV etc.? In ADS(advanced design system) from Agilent, and spectreRF from Cadence, when we doing simulation for finding IIP3, NF, etc., I always confuse whether what value of the source impedance or load impedance need to be specified? For IF block, eg. filter, can I use 50 Ohm for input (just to convert the voltage to power), and use a high impedance load at output(as the output impedance of the filter is high) ? But, how high? and will it affects the results? For RF block, should we still doing input/output matching for the internal blocks for maximum power transfer (I mean the blocks after LNA and before mixer)? For high frequency, we always talk about matching, and for low frequency, voltage is always as references. How about mixer (from high frequency to low frequency, in low-IF topology), its input is at high frequency and output at low frequency.
Thanks.
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