>Hi, > >I'm looking for a copy of the following document. > >"Parametric frequency divider basics. (technical note )" > >>From the Microwave Journal Sept 1 1989. > >Can anyone help? > >Thanks, > >Corby > >Abstract below. > >>>>Since the introduction of half octave bandwidth microwave frequency >dividers and full octave models, parametric frequency dividers have found >applications in many microwave systems. >General Description >The parametric frequency divider is constructed using two varactor diodes >in a resonant circuit. These diodes are biased slightly forward under >normal operation. The input signal capacitively is coupled into the >matching network for the two diodes, where it drives both of the diodes >in phase. Due to the modulation of the varactor's capacitance at the >input frequency f, a subharmonic resonance is set up in the diode pair at >half of the input frequency, f/2. [1] This signal appears across both of >the varactor diodes, but at 180[degrees] out of phase with each other. It >is possibly, by using a balun connected to both diodes, to cancel the >input signal f. However, by observing the signal on one of the diodes in >the time domain, it can be seen that balancing is unnecessary. This >signal appears as a negative impulse train with a period of f/2, with a >positive maximum at the varactor's turn-on threshold voltage of 0.7 V. An >electrical schematic diagram of a typical divider is shown in Figure 1.
Corby, If you use LTspice, this may be what you are looking for. The basic circuit is courtesy Phil Hobbs in the newsgroup sci.electronics.design. I improved it by changing varactor D2 to a schottky diode. This increased the output amplitude slightly and reduced the harmonic distortion. You can easily change it back to see the original. I verified it runs on a virgin copy of LTspice. If you have problems, pleae let me know. You can download LTspice at http://www.linear.com/designtools/software/ It is free. Mike Here is the circuit file: Version 4 SHEET 1 880 680 WIRE 416 32 272 32 WIRE 464 32 416 32 WIRE 512 32 464 32 WIRE 512 48 512 32 WIRE 272 64 272 32 WIRE 416 96 416 32 WIRE -16 144 -32 144 WIRE 64 144 -16 144 WIRE 192 144 144 144 WIRE 272 144 272 128 WIRE 272 144 192 144 WIRE -32 160 -32 144 WIRE 512 160 512 128 WIRE 512 176 512 160 WIRE 272 192 272 144 WIRE -32 256 -32 240 WIRE 272 272 272 256 WIRE 416 272 416 160 WIRE 416 272 272 272 WIRE 512 272 512 256 WIRE 512 272 416 272 WIRE 416 304 416 272 FLAG 416 304 0 FLAG -32 256 0 FLAG -16 144 Vin FLAG 192 144 R1D1 FLAG 464 32 Tank FLAG 512 160 L1R2 SYMBOL varactor 256 64 R0 SYMATTR InstName D1 SYMATTR Value KV1471 SYMBOL cap 400 96 R0 SYMATTR InstName C1 SYMATTR Value 1000p SYMBOL ind2 496 32 R0 SYMATTR InstName L1 SYMATTR Value 10µ SYMATTR Type ind SYMBOL res 48 160 R270 WINDOW 0 32 56 VTop 2 WINDOW 3 0 56 VBottom 2 SYMATTR InstName R1 SYMATTR Value 100 SYMBOL voltage -32 144 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value SINE(5 10 3e6 1u) SYMBOL res 496 160 R0 SYMATTR InstName R2 SYMATTR Value 5R SYMBOL schottky 288 256 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D2 SYMATTR Value BAT54 SYMATTR Description Diode SYMATTR Type diode TEXT 88 0 Left 2 !.tran 0 30u 25u 10n TEXT 88 -24 Left 2 ;'Hobbs Halver Improved MRM Here is the plot file: [Transient Analysis] { Npanes: 4 { traces: 1 {524291,0,"V(tank)"} X: ('µ',1,0,5e-007,5e-006) Y[0]: (' ',1,-1,0.2,1) Y[1]: ('_',0,1e+308,0,-1e+308) Volts: (' ',0,0,1,-1,0.2,1) Log: 0 0 0 GridStyle: 1 }, { traces: 2 {524290,0,"V(vin)"} {524294,0,"V(r1d1)"} X: ('µ',1,0,5e-007,5e-006) Y[0]: (' ',0,-6,2,16) Y[1]: ('_',0,1e+308,0,-1e+308) Volts: (' ',0,0,0,-6,2,16) Log: 0 0 0 GridStyle: 1 }, { traces: 1 {34603013,0,"I(D2)"} X: ('µ',1,0,5e-007,5e-006) Y[0]: ('m',0,-0.005,0.005,0.05) Y[1]: ('_',0,1e+308,0,-1e+308) Amps: ('m',0,0,0,-0.005,0.005,0.05) Log: 0 0 0 GridStyle: 1 }, { traces: 2 {34603012,0,"I(D1)"} {34603015,0,"I(L1)"} X: ('µ',1,0,5e-007,5e-006) Y[0]: ('m',0,-0.028,0.004,0.016) Y[1]: ('_',0,1e+308,0,-1e+308) Amps: ('m',0,0,0,-0.028,0.004,0.016) Log: 0 0 0 GridStyle: 1 } } _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
