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Can i use a inductor based on a gyrator for RFIC

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Advark

Advark

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high frequency gyrator

Hi i have a doubt can i use a active inductor based on a gyrator for RFIC
 

gyrator bandpass filter

What is "RFIC" ?
Is it an IC for RF frequencies ?
OK, I´guess it is !
In this case, a general answer is: Of course, why not ?
Or, what is your probable concern ?
 

gyrator inductor design

Well, as you know a gyrator can be inplemented with OTAs, my questions what characteristics must have this OTAS in order to use this inductor for GHz applications for example
 

gyrators vs inductors

This is not easy to answer - or with other words: It is easy !
The OTAs should have a high frequency capabilty - as high as possible.
Does this help ? Probably not ! But what could be the answer to such a general question ?
One additional comment: L-simulation with GIC-blocks (gyrators) normally is used for highpass filters only (sometimes for bandpass filters).
 

gyrator vs inductor

hi
I haven't practically tried to build a simulated inductor myself but from what I have heard I dont think it will be practical for RF operations, since you will need opamps with frequency response range (to the range of 100s of MHz). I dont think such opamps will be easily available, but of course it depends on what resources are available at your location.
Do try to find out more first. Please let me know too if you find something useful.
:)
 

gyrator lc

mahaju said:
hi
you will need opamps with frequency response range (to the range of 100s of MHz). I dont think such opamps will be easily available, but of course it depends on what resources are available at your location.
:)
Click to expand...

Don´t forget that also transconductor stages with high frequency capabilty (OTA´s) can be used in principle. But watch the restriction for GIC stages (gyrators): The should be referenced to ground potential (all inductors of the reference circuit to be grounded)
 

passive gyrator

An inductor is

1. Noiseless
2. Does not consume energy
3. Cancel capacitive loads at a specific frequency
4. Getting smaller at high frequency, so easier

If you want to built active filters it is more useful to use standard filter approaches using, Gm-C or active RC.

I have seen that out off band blocking reduction filtering is getting competitive. There the rejection is some 10% from the band away and any 10dB is a huge improvement for blocking.
 

38.9mhz low pass filter

Advark said:
Hi i have a doubt can i use a active inductor based on a gyrator for RFIC
Click to expand...

Of course u can. And u don't need to use opamps to generate the inductor. There are plenty of papers discussing this issure.

But if ur application requires low noise and high linearity, u'd better use passive inductor.
 

high frequency op-amp gyrator

Hello!

I am trying to replace a classic LC circuit with a gyrator or any active inductor ( so that I get rid of the passive inductor ).

The problem is that I want to use the circuit for high frequences. To be more specific, I want to use it as a filter that only allows a 38.9 Mhz frequency to pass and stops all the others.

Is there a way to do it? Is the noise ratio good? Is it possible to get a schematic?

Will I be banned for asking so many questions? :)

Thank you all in advance for your time.
 

gyrator active c inductor

Active inductors (active circuits with inductive behaviour in the frequency region of interest) have been realized up to GHz. Apparently they are an interesting alternative to on-chip passive inductors in terms of occupied area.

You have to find out if they are also a meaningful technique for your application. In VHF band, most likely simple analog building blocks (differential pairs, gm cells) or individual transistors should be used for C-to-L transformation rather than OP. As already mentioned, usual active filter topologies may be considered as well.
 

uses of gyrator

foxclab01 said:
I am trying to replace a classic LC circuit with a gyrator or any active inductor ( so that I get rid of the passive inductor ).
The problem is that I want to use the circuit for high frequences. To be more specific, I want to use it as a filter that only allows a 38.9 Mhz frequency to pass and stops all the others.
Is there a way to do it? Is the noise ratio good? Is it possible to get a schematic?
Click to expand...

I understand, that you are going to design an active bandpass filter centered at 38.9 MHz.
As FvM has mentioned, the gyrator principle (using an active GIC block) is only one of several alternatives which exist to build RC-active band pass filters. To select one of these alternatives is not quite easy as all the circuits have different pro´s and con´s and a decision normally should take into account several aspects:
Filter order (bandwidth), pole frequency, sensitivity to passive and active parasitics, gain requirements, discrete or IC realization, opamp or OTA or CC, power consumption, single/dual supply, parts count, cost, tuning capabilities, ......(something else ?). To find the best compromize is very time consuming.
Are there special reasons for you to stick to the gyrator principle ?
 

active power gyrator

The whole problem is this :

I am creating a TV receiver and demodulator. I have figured out the schematic that I attach. But I want to replace the 2 LC circuits that filter the video and audio with some active circuit ( not necessarily gyrators ).

The reason for this is that the LC circuits need a variable inductor and it is very difficult to find or create one. Also, there is this general rule that says "the less inductors, the better!!".

On the other hand, the passive LC circuit seems to have a better behavior as a filter ( more accurate ).

Please tell me what to do.

Also, if someone knows a completely different way to create a TV receiver-demodulator that WORKS ( mine is not working yet!!! ) I will be more than happy to see the schematic !!

Thank you all in advance for your time.
 

gyrator filter schematic

foxclab01 said:
........I have figured out the schematic that I attach. But I want to replace the 2 LC circuits that filter the video and audio with some active circuit ( not necessarily gyrators ).
...................
On the other hand, the passive LC circuit seems to have a better behavior as a filter ( more accurate ).
Click to expand...

1.) For my opinion, it is not possible to propose an alternative solution to your filtering problem unless the internal impedances at the input/output pins of the LC circuits are known.

2.) .. the passive LC circuit seems to have a better behavior as a filter
What does this mean ? What means "better" ? Please, be more sprecific !
 

gyrator rf

I found and bought this variable inductor


http://5cc.isocomponents.com/Public/search_inventory_results.aspx?keyword=5cce

and I solved the problem. Thank you all !!

Added after 2 minutes:

Now I want to improve my device, by creating a TV receiver, both for analog and digital signals.

To be more specific, I want to :

1. Replace the can tuner ( uv1316 ) with a silicon one ( e.g. tda8275 ). Is there any application circuit example for a chip tuner?

2. Create a circuit for both analog and digital TV, which I just cannot do it !! Maybe if I put tda10048 instead of tda8341 and tba120U, but I have no clue how the circuit will be.

Can anyone please help me?

Thank you all in advance for your time.
 

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