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Design >> RF Design >> pss and pnoise in harmonic-reject mixer
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Message started by Mak on Nov 10^th, 2007, 11:10pm

Title: pss and pnoise in harmonic-reject mixer
Post by Mak on Nov 10^th, 2007, 11:10pm

Dear all experts,

I am designing a direct-downconversion harmonic-reject mixer with input freq of 0.7 GHz.

The LO freq is 2.8GHz, and I use it to generate a 700MHz I/Q LO through divison by 4 and the 3-path harmonic-reject technique with gains: 1: sqrt(2):1 to reject the 3th and 5th harmonics.

I find diffcult in convergence in doing the PSS with "flexible balance".

The RF source is set to DC while the LO source is set to sine.

my questions are:

beat frequency use 2.8 GHz or 0.7 GHz?

oversampling factor is what?

number of harmonics should be what? 10, or 400, else?

I use moderate in accuracy

Title: Re: pss and pnoise in harmonic-reject mixer
Post by pancho_hideboo on Nov 11^th, 2007, 9:07pm

Hi.

Your question is not design issue but usage of EDA tool.
So please post to "The Designer's Guide Community Forum » Simulators » RF Simulators".

Although I have SpectreRF, I don't use SpectreRF for RF circuit simulation mainly since I have ADSsim and GoldenGate of Agilent in RFDE.
But I can give some comments as general opinion.

Quote:

I am designing a direct-downconversion harmonic-reject mixer with input freq of 0.7 GHz.
The LO freq is 2.8GHz, and I use it to generate a 700MHz I/Q LO through divison by 4
and the 3-path harmonic-reject technique with gains: 1: sqrt(2):1 to reject the 3th and 5th harmonics.
I find diffcult in convergence in doing the PSS with "flexible balance".
The RF source is set to DC while the LO source is set to sine.

Why don't you use shooting-PSS since your current simulation is involved with only one large fundamental frequency(0.7GHz) ? :-?
However you will have to use HB-QPSS after all since you have to evaluate IP2 and IP3. :P

Quote:

beat frequency use 2.8 GHz or 0.7 GHz?

Fundamental frequency must be 0.7GHz.

Quote:

oversampling factor is what?

In HB analysis in ADS, I will set oversampling factor as 4 or 8 since frequency divider is included.
Maybe in SpectreRF, you have to set tstab parameter appropriately in addition to setting oversampling factor.

Quote:

number of harmonics should be what? 10, or 400, else?

What is the reason why you think 400 is reasonable ?
In HB Analysis, number of harmonics is orders of fundamental tone.
So I recommend harms >= 20 or harms >= 32 since 5*2.8=20*0.7, 8*2.8=32*0.7.