Any text book/AppNotes about SiGe circuit design?

[yolande_yj]

Hi,

I am farmiliar with CMOS and I have learned BJT. Now I want to learn circuit design in SiGe, any suggestion about how to start and reading materials?

Thanks

 

[truebs]

Re: Any text book/AppNotes about GeSi circuit design?

Start off with any Basic Electronics Book ,for eg. by Halkias ,
Or if you are working for specific area such as RF try RF circuit Design books.

Both these group of books are available in our forum.
You can search at Ebook upload/download forum.

Also try to learn by doing and making some hobby projects.
To get a better and clear picture you can also spend time with simulators like Pspice where you can see the affect of your design parameters.

Wish you all the best on this Journey !!!

 

[yolande_yj]

Any text book/AppNotes about GeSi circuit design?

Thanks.
Actually what I want to know is the difference between SiGe and CMOS/BJT IC design. I have designed LNA and Mixer in CMOS. Now it is likely that I need to change to a new process using SiGe. I don't have much time to go over very basic knowledge. I hope I can make use of my CMOS/ BJT knowledge to do a fast switch to SiGe.

Materials like these will be very helpful:
1. Review of GeSi;
2. Transistors characteristic in SiGe;
3. ......

I just started reading the process spec, it seems that the SiGe is like a BiCMOS process with better performance. I have read some SiGe design examples in RF books, it seems that they are doing BJT circuit design. Other than the better performance, I cann't see much difference.

 

[Mazz]

Any text book/AppNotes about GeSi circuit design?

You're right yolande_yj
from the designer point of view there is no much difference using conventional bipolar or SiGe (it's only the addition of Germanium in the base, to incease performances). For futher details you can download: Wiley SiGe Heterojunctio Bipolar Transistors - Ashbum available on this forum

 

[yolande_yj]

Thanks Mazz, I've got good info from this forum.

 

[dsjomo]

(1) For bias network design, the main difference is that HBT needs base bias current. While CMOS acts as open at its gate node.

(2) For LNA, HBT has better characteristic to simutaneously power and noise matching, but its linearity is poorer than CMOS while its gm is larger than CMOS.

(3) For Mixer, the flicker noise is smaller in HBT, and the LO swing to full swing the quad of Gilbert Cell is lower than the quad composed of CMOS.

(4) Normally SiGe process is a kind a BiCMOS process, CMOS devices are available, too. The characteristic of HBT is resemble to BJT. SiGe process has many adventage over CMOS, so many company choose SiGe for their RF front-end circuit, then integrate the whole transmitter and baseband using SYSTEM-IN-CHIP(SIP) package.

(5) HBT device is not scalable.

 

[cmosbjt]

You can get a rough idea about SiGe by reading the chapter of "Si/SiGe HBT technology" of the following book, it is a good review about SiGe.

 

[Mazz]

I agree with dsjomo for all except than
(5) HBT device is not scalable -> In a lot of advanced foundries you'll have scalable devices.
I hope it can help
Mazz

 

[dsjomo]

Thanks for Mazz's acknowledgment. About the point (5), here I have to describe it more specifically.

While in CMOS circuit, we design the (W/L) ratio for each transistor. But in BJT circuit, we design the paralleling device quantity (M) for each BJT. "Scaling" in BJT means to change the Length or Width of emitter area. If we doubles the area of emitter, the characteristics is not fully predictable. So the foundry provides several different dimension device models, the designer has to parallel the given device model several times if he needs a larger dimension device.

So the accuracy of a small device is important, otherwise after paralleled, the summed error is large.

Am i right??

 

[Mazz]

Usually you have the possibility to change the emitter lenght in a continous way, while paralleling more transistors is allowed, of course.
I hope it can help
Mazz