I was playing around with a double balanced mixer the yesterday. In an attempt to understand how the thing worked, (I could find no good explanations on the web.) I made a little spice file. (To be attached later to thread.) This worked fine. I then replaced the two transformers with opposite polarity voltage sources at one half the amplitude, and kept the series inductance. This doesn=92t work nearly as well! The transformers are doing something that I don=92t understand. (I find transformers a bit mysterious in general.)
Any help would be appreciated,
George H.
LTspice file without transformers below.
Version 4 SHEET 1 880 680 WIRE 320 -64 160 -64 WIRE 416 -64 320 -64 WIRE 528 -64 464 -64 WIRE 160 -48 160 -64 WIRE 528 -48 528 -64 WIRE 320 -32 320 -64 WIRE 416 -32 416 -64 WIRE 320 48 320 32 WIRE 320 48 256 48 WIRE 416 48 416 32 WIRE 464 48 464 -64 WIRE 464 48 416 48 WIRE 528 64 528 32 WIRE 160 80 160 32 WIRE 528 160 528 144 WIRE 768 160 528 160 WIRE 160 192 160 160 WIRE 160 192 -96 192 WIRE 528 192 528 160 WIRE 768 192 768 160 WIRE -96 208 -96 192 WIRE 160 208 160 192 WIRE 768 288 768 272 WIRE 528 304 528 272 WIRE -96 320 -96 288 WIRE 160 320 160 288 WIRE 320 320 320 48 WIRE 416 320 416 48 WIRE 320 400 320 384 WIRE 320 400 160 400 WIRE 416 400 416 384 WIRE 416 400 320 400 WIRE 256 432 256 48 WIRE 528 432 528 384 WIRE 528 432 256 432 FLAG -96 320 0 FLAG 768 288 0 SYMBOL ind2 176 -64 M0 WINDOW 0 84 20 Right 2 WINDOW 3 102 61 Right 2 SYMATTR InstName L2 SYMATTR Value 100=B5 SYMATTR Type ind SYMBOL voltage 160 64 R0 WINDOW 123 0 0 Left 2 WINDOW 39 -157 61 Left 2 WINDOW 3 -195 24 Left 2 SYMATTR SpiceLine Rser=3D10 SYMATTR InstName V1 SYMATTR Value SINE(0 1 100k) SYMBOL ind2 176 304 M0 SYMATTR InstName L3 SYMATTR Value 100=B5 SYMATTR Type ind SYMBOL diode 400 -32 R0 SYMATTR InstName D1 SYMATTR Value 1N4148 SYMBOL diode 400 320 R0 SYMATTR InstName D2 SYMATTR Value 1N4148 SYMBOL diode 336 384 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D3 SYMATTR Value 1N4148 SYMBOL diode 336 32 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D4 SYMATTR Value 1N4148 SYMBOL ind2 512 400 M180 WINDOW 0 61 71 Left 2 WINDOW 3 57 35 Left 2 SYMATTR InstName L5 SYMATTR Value 100=B5 SYMATTR Type ind SYMBOL ind2 512 48 M180 WINDOW 0 40 108 Left 2 WINDOW 3 41 73 Left 2 SYMATTR InstName L6 SYMATTR Value 100=B5 SYMATTR Type ind SYMBOL voltage 528 48 R0 WINDOW 123 0 0 Left 2 WINDOW 39 92 72 Left 2 WINDOW 0 79 13 Left 2 WINDOW 3 77 47 Left 2 SYMATTR SpiceLine Rser=3D10 SYMATTR InstName V2 SYMATTR Value SINE(0 .5 10k) SYMBOL res -80 304 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R3 SYMATTR Value 1k SYMBOL res 784 288 R180 WINDOW 0 -39 78 Left 2 WINDOW 3 -47 33 Left 2 SYMATTR InstName R4 SYMATTR Value 1k SYMBOL voltage 160 304 R180 WINDOW 123 0 0 Left 2 WINDOW 39 59 24 Left 2 WINDOW 0 94 80 Left 2 WINDOW 3 45 50 Left 2 SYMATTR SpiceLine Rser=3D10 SYMATTR InstName V3 SYMATTR Value SINE(0 1 100k) SYMBOL voltage 528 288 R180 WINDOW 123 0 0 Left 2 WINDOW 39 -157 15 Left 2 WINDOW 0 -87 81 Left 2 WINDOW 3 -192 47 Left 2 SYMATTR SpiceLine Rser=3D10 SYMATTR InstName V4 SYMATTR Value SINE(0 .5 10k) TEXT -320 416 Left 2 !.tran 400u