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This video is part of a series that demonstrates the Genesys integrated board flow. Products
featured include Genesys Core, WhatIF Frequency Planner, Spectrasys System Architecture Design,
M/Filter Microstrip Filter Synthesis Tool, and Momentum GX Planar 3D Electromagnetic
simulator. Now we would like to show a Genesys integrated board flow demo by designing a
dual band 802.11 Wi-Fi receiver. We’re going to use WhatIF to find a spur-free IF, use
Spectrasys to analyze the system, synthesize in RF filter from within Spectrasys, and then
perform a Momentum GX EM analysis on the filter.
The 802.11 design is a dual band at 2.4 and 5.4 GHz, with 10 MHz and 50 MHz bandwidths.
We will start out by using WhatIF spur-free IF synthesis. The first thing we want to do
in our design is determine a spur-free IF. And to do this, we’re going to use the WhatIF
Frequency Planner.
I’ve opened up Genesys to a blank schematic screen. And you can see the workspace tree
is on the left, and this is like our project manager. The button on the far left is the
New Item button. If you click on that and scroll down to Synthesis and then “Add WhatIF
Frequency Planner.” I’m going to use the factory default values and the default name.
And when I click Okay, it opens up the WhatIF screen, and this is the Properties screen.
And you can see there are three tabs: Settings, Inputs, and Type.
In the first settings tab, we’re going to select the number of mixers, and I want to
select two, since it’s a dual-band design. The IF is going to be at the mixer output,
as it’s a down converter. The spurious order – I’m going to select – we can go up
to 20, but I’m going to select 10, which is 5 x 5 spurs. The amplitude range is 100
dB, which means that we’re going to look at spurs down to -100 below our IF.
And then we’re going to look at all intermediate frequencies. When I click on the Input tab,
this is where you enter the parameters for each of your mixers. And you can see the two
mixers on the left. I’m going to click on Mixer 1. And I select whether I want a sum
or difference, and whether I want a low-side or high-side LO. I’m going to select low-side.
And my center frequency for the first mixer is going to be 2450. My RF bandwidth is going
to be 100. My IF bandwidth is going to be 10. And my input drive level is going to be
20, with an LO drive level of 10.
So, then I click on Mixer 2, and it allows me to enter the properties for Mixer 2. I’m
going to use the same difference in low-side LO. But my RF center frequency is going to
be 5350. My RF bandwidth is going to be 300. My IF bandwidth is going to be 50. My input
drive level is going to be -35, and LO, again, is 10.
And then the next tab is the Type tab. This is where you select the mixer types. And the
selections are either a double- balanced mixer, where if you click on the Advanced tab, you
can enter in the parameters, such as forward voltage and diode balance. Or you can use
these intermod tables.
And we actually have – if you click on this ellipsis button, it will open up our libraries,
and we have a number of different manufacturers’ libraries that are built in. I’m going to
select the Hittite Library, and I’ve preselected the HMC218S8. I just double-click on it, and
it adds it in.
And for Mixer 2, I’m going to do the same – use the same mixer. So after we have
everything completed – the inputs – you just click the Apply button. And as you can
see – I’m going to close the window or move the window, so you can see a little bit
better – and expand – it brings up a graph that shows the mixers, spurs, and the level
along the X-axis is the IF frequencies. And along the Y-axis, the spur output levels relative
to IF and dBc.
And if you hover over these, you can see this is from Mixer 1; it’s a 1 x 3 spur. The
blue ones are from Mixer 1. The red spurs shown are from Mixer 2, and it tells you that’s
a 2 x 4 spur. And you can even right-click on these and add what we call an info balloon,
which will retain the data. And you can see the green lines, if I hover over them, are
spur-free areas.
So we have a spur-free area starting at about 672, and then another one about 1517. And
I’d like maybe an IF a little bit lower in frequency. So what you can do is come back,
click on any of these tabs, and change parameters to see if maybe we can come up with some different
spur-free areas. So, I’m going to click on Mixer 2, and I’m going to check and see
if maybe high-side will work. So I can switch to high-side. Click Apply. And immediately,
you see we have some new spur-free areas.
But there are none that are really lower in frequency down here. So, I can see that I
have a spur here at about -81, and there are no other spurs higher than that. So, if I
go back to my Settings tab and change – let’s say I can handle spurs down to -80,
if I put in 80, then you can see that we now have a spur-free area, starting from about
212 MHz to 423 MHz, and this is in the range that I really wanted to put my IF. And I can
live with spurs down to -80.
That concludes Part 1 of the Genesys Flow video. Please continue to Part 2 of the Genesys
Flow video to continue this series.