The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Simulators >> Circuit Simulators >> Simulating a PolyPhase Filter in SpectreRF
https://designers-guide.org/forum/YaBB.pl?num=1065477504

Message started by jstenger on Oct 6^th, 2003, 2:58pm

Title: Simulating a PolyPhase Filter in SpectreRF
Post by jstenger on Oct 6^th, 2003, 2:58pm

How do I simulate a polyphase filter with SpectreRF and take advantage of the Direct Plot features available in ADE?

That is, how do I generate a 90 degree phase shift of a signal over a wideband frequency range, with unity gain? The purpose of this is to do Noise Figure and IPN calculations with ADE from SpectreRF results.

Here is the background information to assist in answering this question.

For those not familiar, a polyphase filter (complex filter) requires In-Phase and Quadrature inputs. The basic idea is to design a low-pass filter and cross-couple the I and Q channels to each other through the appropriate impedances. The end result is a low-pass filter shifted in frequency to the desired IF (intermediate frequency). One benefit of this architecture is the image suppression at the negative IF.

Thank You,

Title: Re: Simulating a PolyPhase Filter in SpectreRF
Post by Ken Kundert on Oct 8^th, 2003, 12:58am

In transient or PSS, you specify quadrature inputs using the sinephase argument

Vi (i 0) vsource type=sine freq=FREQ ampl=1 sinephase=0
Vq (q 0) vsource type=sine freq=FREQ ampl=1 sinephase=90

FREQ would be a design variable that you could sweep.

For small signal analysis, you could use the phase or pacphase parameter

Vi (i 0) vsource mag=1 phase=0
Vq(q 0) vsource mag=1 pahse=90

-Ken