EMRFD Message Archive 9066

Message Date From Subject
9066 2013-09-04 07:37:41 Ashhar Farhan musings about Chris' Mixer Musings
chris and others,

i am looking at split-ring mixer topology from chris' paper titled Mixer Musings available in emrfd group's file sections.

if i were to merge T1 and T2 into a single transformer such we have two pairs of diodes in different directions, then the topology would reduce to that of a standard doubly-balanced diode ring mixer.

for those who are too lazy to read the article, the idea is to remove the active devices from signal paths to improve the IP3.

now, consider an implementation of this as follows: we just use a regular doubly balanced diode mixer with two transformers T1 and T2. We inject the T1 with Local Oscillator and the RF signal into the primary of T2. Now, effectively for one half of the cycle, two diodes diodes will switch on and for the other half of the cycle, the other two diodes will switch on. In effect, these diodes alternatively ground one of the two secondary ends of T2, achieving commutation.

does that mean that this particular configuration (injection LO into T1 primary, RF signal into T2 primary and taking the IF out of T2's center tap) has better performance than any other configuration?

- farhan