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aaron_do

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Re: How to block RF signal?
Reply #15 - Nov 19^th, 2013, 10:18pm

Hi,

you can use a -ve charge pump. It requires a ring oscillator an the charge pump itself. Why do you need a minimum number of components? You're in the wrong design age if you're worried about complexity. Problem is it needs to be on as long as you want to enable/disable, so power consumption is an issue.

I still don't get why you're so keen on using PMOS...

Aaron

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there is no energy in matter other than that received from the environment - Nikola Tesla

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shaikss_rf

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Re: How to block RF signal?
Reply #16 - Nov 19^th, 2013, 10:27pm

aaron_do wrote on Nov 19^th, 2013, 10:18pm:

Hi,

you can use a -ve charge pump. It requires a ring oscillator an the charge pump itself. Why do you need a minimum number of components? You're in the wrong design age if you're worried about complexity. Problem is it needs to be on as long as you want to enable/disable, so power consumption is an issue.

I still don't get why you're so keen on using PMOS...

Aaron

I am not worried about circuit complexity. I am worried about power consumption. Since it is a passive tag and it harvests energy, whatever power I harvest, some of the harvested energy is utilized for Chargepump and other devices.

Even I am not keen about PMOS. As u said, it is PMOS or NMOS, I need voltage source. The only Q is who wil provide the voltage.

During energy harvesting, Rf input signal is in the order of few mV and the control voltage for NMOS SPDT switch is more than the peak of the RF input.

I am thinking of using a start-up circuit to generate required voltage for SPDT switch. Once I get some voltage, then I can enable/disable the switching scheme.

Pls correct me if I am wrong.

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shaikss_rf Junior Member Offline Posts: 22	Re: How to block RF signal? Reply #17 - Nov 20^th, 2013, 1:50am Hi, I have one basic query. For NMOS, bulk is connected to Vss and PMOS is connected to Vdd. In case of ac signals, RF signal goes negative. In such scenarios, the most negative voltage is the negative peak of RF signal. How should the bulk connected in such scenarios?
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aaron_do Senior Fellow Offline Posts: 1398	Re: How to block RF signal? Reply #18 - Nov 20^th, 2013, 1:57am I think you should try reading my earlier replies. I told you the answer several times. Aaron
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shaikss_rf

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Re: How to block RF signal?
Reply #19 - Nov 20^th, 2013, 2:26am

aaron_do wrote on Nov 20^th, 2013, 1:57am:

I think you should try reading my earlier replies. I told you the answer several times.

Aaron

Sorry for repeatedly asking the same.
I understood your point - Pull-up or down to either S/D terminal.
But though I do, pull-up /down, I see bulk current.

Earlier, when I connected bulks to ground, I could see bulk current of 200uA. So, I thought of nullifying it. I tried to do pull up/down, but no significant result.

Not getting how to solve.

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shaikss_rf

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Re: How to block RF signal?
Reply #20 - Nov 20^th, 2013, 2:40am

shaikss_rf wrote on Nov 20^th, 2013, 2:26am:

aaron_do wrote on Nov 20^th, 2013, 1:57am:

I think you should try reading my earlier replies. I told you the answer several times.

Aaron

Sorry for repeatedly asking the same.
I understood your point - Pull-up or down to either S/D terminal.
But though I do, pull-up /down, I see bulk current.

Earlier, when I connected bulks to ground, I could see bulk current of 2uA. So, I thought of nullifying it. I tried to do pull up/down, but no significant result.

Not getting how to solve.

This is how bulk currents are...

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7.png

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