Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

How to reduce the I and Q mismatch?

Status
Not open for further replies.

dinesh agarwal

Full Member level 3
Joined
Oct 20, 2007
Messages
151
Helped
4
Reputation
8
Reaction score
1
Trophy points
1,298
Location
Hyderabad India
Activity points
2,074
there is a amplitude mismatch of about 100mV.

the output is at 2.4 Ghz

how to reduce this amplitude mismatch

what is the reason once the circuit is symetical
 

vfone

Advanced Member level 5
Joined
Oct 10, 2001
Messages
5,292
Helped
1,549
Reputation
3,099
Reaction score
1,156
Trophy points
1,393
Activity points
33,538
Re: I and Q mismatch

I/Q Amplitude mismatch appear if:
- Unbalance in the RF splitter used to divide the incoming RF signal equally between the I and Q paths which may introduce gain differences.
- The quadrature 90° phase-splitter used to generate the I and Q Local-Oscillator (LO) signals that drive the I and Q channel mixers may not be exactly 90°. Furthermore, there might be differences in conversion losses between the output ports of the I and Q channel mixers.
- Amplitude mismatch appear also if the filters and ADCs in the I and Q paths are not perfectly matched.
 

GVVIN

Advanced Member level 4
Joined
Apr 11, 2008
Messages
110
Helped
21
Reputation
42
Reaction score
3
Trophy points
1,298
Activity points
2,048
Re: I and Q mismatch

Use 1% tolerant components in Both I and Q paths. If you dont have 1% components measure each component and put equal value components in both paths.

regards
GV
 

yashiro32

Member level 1
Joined
Sep 5, 2007
Messages
38
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,288
Activity points
1,501
Re: I and Q mismatch

What kind of effects will result when I and Q are mismatch ?
 

RFCMOS

Full Member level 2
Joined
May 5, 2005
Messages
144
Helped
20
Reputation
40
Reaction score
0
Trophy points
1,296
Location
France
Activity points
1,971
Re: I and Q mismatch

HI,

mainly EVM degradation
 

jecyhale

Advanced Member level 1
Joined
Feb 19, 2008
Messages
403
Helped
54
Reputation
108
Reaction score
8
Trophy points
1,298
Location
China
Activity points
3,001
Re: I and Q mismatch

yashiro32 said:
What kind of effects will result when I and Q are mismatch ?

If I and Q are mismatch, the image rejection will be reduce.
When amplitude mismatch increase 0.5dB the image rejection will reduce 5~10dB.
 

DDavid

Full Member level 5
Joined
Apr 6, 2006
Messages
305
Helped
49
Reputation
98
Reaction score
27
Trophy points
1,308
Activity points
2,986
Re: I and Q mismatch

Hi,

please review the following paper!

David
 

symsnowfairy

Junior Member level 1
Joined
May 6, 2008
Messages
18
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Location
Germany
Activity points
1,393
I and Q mismatch

"Unbalance in the RF splitter used to divide the incoming RF signal equally between the I and Q paths"
How does the RF splitter divide I and Q?
 

Bhanumurthy

Full Member level 5
Joined
Jun 18, 2008
Messages
255
Helped
34
Reputation
68
Reaction score
20
Trophy points
1,298
Location
Subcontinent
Activity points
2,743
Re: I and Q mismatch

Hi,
For the RF splitter to split the data into I and Q channels, a clock should be used as one of the inputs to the RF splitter.
bye
Bhanumurthy.
 

GVVIN

Advanced Member level 4
Joined
Apr 11, 2008
Messages
110
Helped
21
Reputation
42
Reaction score
3
Trophy points
1,298
Activity points
2,048
Re: I and Q mismatch

Bhanu,
could you pls provide more details (datasheet) of this special RF splitter which splits into I and Q

Regards
GV
 

Bhanumurthy

Full Member level 5
Joined
Jun 18, 2008
Messages
255
Helped
34
Reputation
68
Reaction score
20
Trophy points
1,298
Location
Subcontinent
Activity points
2,743
Re: I and Q mismatch

GVVIN,
The details abt the special RF splitter can be found in the text book"Principles of Communications-Fundamentals through Advanced" by Wayne Tomasi.
bye
Bhanumurthy
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top