How to connect a microphone ( piezo sensor) to the psoc?

[Anonymous]

Hi,

   

 I my application I am using a piezo element as a microphone.

   

I need to amlify and process it but I have 2 problems:

   

1. How to make a charge mode amplifier using an internal Op-amp (single supply ).

   

2. How to interface the mic with the chip.

       

Please help...

   

Anna 

[Anonymous]

 For scope I am using a Hantek 6022BE , it is a usb scope.

   

In this configuration the DC is not gained because of the feedback capacitor.

   

Yes 10K it is no enough for the piezo... I need additional stage before biasing.

   

Will post here when I will find the solution:)

[ETRO_SSN583]

My apologies, completely missed fdbk Cap. Blind as a bat.

       

Regards, Dana.

[ETRO_SSN583]

Found a piezo, got these results -

                       

Got ~ 1 V pk-pk out of PGA.

       

Regards, Dana.

[EvPa_264126]

 You'd need an amp with several MΩ input impedance.
See here:  Amplifying sound from a microphone 
PSoC amplifiers  seems unable to provide such an input impedance.

[ETRO_SSN583]

The input Z of the prior posted circuit is ~10 M.

       

Regards, Dana.

[ETRO_SSN583]

@pavloven,

       

The DC input R of an OpAmp is its input V / Ibias, NI case. At room temp spec is

   

10 pA, so thats a Rin of ~ 100 G Ohms. The Inv case its the input R used to

   

set G.

       

This of course is not Zin, thats influenced by stray C and GBW of OpAmp. LaPlace

   

methods can derive that.

       

Regards, Dana.

[EvPa_264126]

 I'm not sure that CYPRESS subscribe to a value of 10 pA.
I would prefer an external amplifier.

[ETRO_SSN583]

Thats a datasheet typical spec. But even if it was 1 uA hot, which

   

makes it a very poor OpAmp if that was the case, it would still

   

equate to 1 M ohm at 1 V.

       

You can google "cmos leakage" and there are many papers, process, IEEE,

   

on this topic. Leakage in CMOS is complex, surface state leakage, turnoff

   

leakage, PN junction leakage........not to mention PCB leakage and manufactuing

   

related stuff.

       

ieeexplore.ieee.org/xpl/login.jsp

       

Regards, Dana.

[Anonymous]

 Hi ,

   

Thanks for the advise!

   

maybe do you know what is the problem:

       

I cann`t compile it:(

[ETRO_SSN583]

Intesteingly enough the datasheet API description does not

   

show the _n_ naming convention (maybe a bug) -

               

For now you can jsut set its properties to high power by double clicking

   

component and it will start up in high power.

       

Regards, Dana.

[Anonymous]

 and not to write anything in the main.c?

   

it will work this way?

[Anonymous]

 I is no working  ... opamp3 and opamp4 not working

   

I am opening  a tech support....:(

[ETRO_SSN583]

Yes, when you set the component properties, unless you change them in code, they remain

   

at the settings you gave them in the component properties.

       

What part number are you using, regarding the OpAmps ? Some parts only have 2

   

OpAmps.

       

Regards, Dana.

[Anonymous]

 The problem solved after restarting the program ! 🙂

   

Do you know how can I cancel/ shift back tha phase shifting of Inverting amp?

   

I have a one working amp  with a lot of noise and phase shifting....

   

Now I am making a filters and learning how can I get the signal out (after filtering and amplification ) from the psoc to some speakers....

[Anonymous]

 the evidance

[ETRO_SSN583]

Do you know how can I cancel/ shift back tha phase shifting of Inverting amp?

       

Do you want to change the amp from inverting to non inverting ? If so you could use

   

multiplexors to effect a topology change.

       

Regards, Dana.