Diplexer design program

The Windows ® program
for diplexer design and analysis

Current revision is 2.10; revision history is at the bottom of this page

This program expedites the design of lumped-element diplexers using the lowpass/highpass topology.

Here are the highlights of this program:
  • To design and analyze the lowpass/highpass type of diplexer, the program accepts for its inputs the crossover frequency, the order, the passband ripple and the system impedance.

  • To design and analyze the bandpass/bandstop type of diplexer, the program accepts the lower and upper bandedges along with the order, the passband ripple and the system impedance.

  • See the schematic drawn on the screen including component values.

  • On the Plot screen, you can "tune" the crossover frequency (or the bandedges), the passband ripple and the order and get instant feedback regarding how those items affect the transmission to the two ports as well as the return loss looking into the common port.

  • Click on the Print button and send the data plot and the schematic to the printer using a very high resolution - presentation quality - plotting system (not just a screen dump).

  • Diplexer generates nice schematic [.ASC] files for LTspice. This enables an arbitrary input signal to be applied to the input to see the voltage and current stresses on the individual components.
    (Tonne Software has no connection with Linear Technology Corporation.)

  • On exiting the program the current design is saved to enable a simplified program restart.

Here are screen dumps from the program illustrating some of the outputs to the screen. Click on them to see larger versions; use your browser's BACK button to return.
Click to see large design page
Click to see large plot image

Updated to 2.10 - complete rewrite of the user interface for both the lowpass/highpass type and the bandpass/bandstop type

Updated to 2.09 - allow the user to enter up to five marker frequencies

Updated to 2.08 - lowered minimum-allowed crossover frequency to go as low as .1Hz to allow determining normalized (one ohm, one radian/second) values

Updated to 2.07 - added LTspice schematic routine to Bandpass/Bandstop version

Updated to 2.06 - added LTspice schematic routine to Highpass/Lowpass version

Updated to 2.05 - extended frequency range to 10 Hz-10GHz

Updated to 2.04 - added bandpass/bandstop topology.

Updated to 2.03 - added plotting for return loss.

Updated to 2.02 - added plotting for transmission. This also allowed the tuning of various items to be added.

Released as 2.01 - December 2005