H-Mode mixer

Mixer Transformers

The following 1:4 and 1:1 transformers have been tested with the H-Mode mixer circuit:

For these tests the FSA3157 has been used with a fundamental frequency squarer based on the 74AC04 in stead of the divide by two 74AC74M squarer used in the switch tests.

IMD

It is interesting to see how the Minicircuits 1:4 and 1:1 transformers used in the H-Mode mixer behave with respect to IMD.

In this test 2 cascaded transformers are used and the IIP3 is measured while going from 50 to 200 and back to 50 ohms.

Transformer IIP3 (dBm) @ +6dBm input
Band	TT4-1A	T4-1	FT37-43	ADTT4-1	ADTT1-1	T1-1T	ADTT1-6	ADT1-6T	TT1-6	T1-6T	ADT1-1WT	TW-2A2T
160	43,4	40,2	43,7	45,7	44,2	40,7	49,7	48,7	48,9	49,4	42,1	52,4
80	46,1	43,8	49,6	51,1	47,8	44,8	54,6	53,8	53,3	54,3	49,1	53,1
40	51,4	48,4	53,6	56,4	54,4	53,4	54,9	53,9	53,9	54,1	58,1	54,4
30	52,6	51,6	54,1	52,6	52,6	51,1	49,4	49,6	49,9	50,4	53,6	50,6
20	49,1	49,1	50,1	49,4	48,1	49,1	48,4	47,9	48,4	48,9	51,6	47,6
17	50,5	50,0	51,5	50,5	48,8	49,0	48,3	48,0	49,0	49,5	52,0	47,5
15	49,3	49,3	49,6	50,8	48,8	49,3	47,8	49,1	48,8	49,6	52,1	47,8
12	47,6	48,4	48,9	48,4	46,9	47,4	44,4	45,6	45,4	46,1	50,4	48,1
10	45,4	46,4	46,2	45,4	43,4	43,7	43,9	42,7	42,7	44,2	48,6	47,2
6	43,0	44,2	43,7	44,2	41,2	42,5	39,0	40,0	40,2	40,2	43,5	45,2

All transformers do > +40dBm on all bands (almost), but the best transformer in this test seems to be the ADTT4-1. Things are more complicated when the transformers are applied in the H-Mode mixer as it turned out. All these transformers are tested with the FSA3157 mixer.

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