How to make a I/Q modulator?

[yuhohang]

iq modulator sige

Dear All
Is it possible use discrete components to make a I/Q modulator?

 

[flatulent]

Yes

Yes it certainly is possible. Your problem will be matching components for making the carrier feed through initially low and stay low over temperature and time.

 

[dd22]

This is depend on what kind of modulation you need.

 

[ttosolee]

hi, yuhohang

this may usful document from mini circuit.
I&Q and QPSK Modulators/Demodulators: most often asked questions

 

[toonafishy]

You need two mixers, a 90 degree phase network. But I would expect pretty poor carrier/sideband supression since the circuit must be very balanced.

 

[jwei363]

re

theoretically,you can make all ic by discrete componets.but why not use ICs?

 

[adolfchen]

Dear All
Is it possible use discrete components to make a I/Q modulator?

You should tell us clearly what kind of modulation you need.
Maybe there are existing ICs to fit in with your requirement.

 

[martin]

Any example for pi/4 - DQPSK modem ? "Mini" circuits is preferred!
thanks!

 

[riz_aj]

IQ

Get modulator IC. A\t\m\e\l has a few for pi/4 DQPSK, so does R\F\M\D and A\n\a\l\o\g d\e\v\i\c\e\s

h**p:\\www.atmel.com
h**p:\\www.rfmd.com
h**p:\\www.analog.com

 

[BigBoss]

It's obviously possible to make a IQ Modulator.

There will be 8 transistor for full differential Gilbert cell and " Current Transducer " to control the currents of the each pairs.

But some pitfalls may ocur . You may not provide the symmetricity and if
there become 15-20 degree phase error , at the output this will return back with poor sideband rejection and LO rejection.
Instead of this , using ready-to use IQ modulator is more efficient.
Philips SA 900 is very useful Transmit IQ Modulator.
Datasheet and App. report are attached here.


GL

 

[martin]

please send me documents about IQ modulator

Hi, BigBoss
can you me send me " design" documents about IQ modulator ?

 

[Needbias]

how to measure accurately a IQ mixer?

A new question:how to measure a IQ mixer's amplitude and phase error accurately?

Now I should design a 9~10GHz IQ mixer,the IF is DC to 100MHz.
As I know,The HP 8753C or HP 8753D's freq offset mode can be used to measure the phase track of IQ mixer,but this network analyses's can not be used up to 6 GHz.whoever know any other method to measure it accurately?

 

[Wacko2000]

What frequency range do you need?

There are a lot of good integrated circuits available at this moment which are good enough for most applications.

Take for example Analog Devices, Maxim etc.

 

[Wacko2000]

I mean with above posting something like:
Why making your own I/Q mod with discrete components when cheap and good IC's exists.

Otherwise build your own with some Mini Circuit components if you call that 'discrete'

regards

 

[trifilinux]

Dear All
Is it possible use discrete components to make a I/Q modulator?

Hi, I am designing one using SiGe Bicmos technology, if you are interested don't hesitate to ask more information.

Trifilinux

 

[prd]

I want to test baseband circuit.
Modulator has baseband IQ output and Demodulator receive 10.8 MHz input.
Are there any IC match or how to test it anyway.
The only idea I get is to build IQ modulator to output at 10.8MHz
Do you have any idea?

prd

 

[IICCEE]

you may use the easy way of R/C and C/R to get the 45degrees and -45degrees phase and using the diode as a MIX.