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jsaenz
Joined: 09 Feb 2008
Posts: 4
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 08 May 2008 2:02 Bandgap Reference |
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| it's also possible use an voltage reference with transistors CMOS in weak inversion...the output voltage can be controlled by resistors too.
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northeast1
Joined: 21 Jun 2007
Posts: 150
Helped: 4
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| 09 May 2008 4:01 Re: Bandgap Reference |
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| firsttimedesigning wrote: |
| So I am trying generate the bias voltage of an op-amp. So far the only circuit I know that can be used to generate the bias voltage is bandgap reference. But bandgap reference can only generate a voltage that is around 1.4V. I need a bias voltage that is higher than 1.4V...What circuit should I use? |
add a buffer to generate 1.4v
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rillyxue
Joined: 03 Jan 2007
Posts: 27
Helped: 1
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| 14 May 2008 3:57 Re: Bandgap Reference |
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| use ldo is not a good way, you can use a bandgap to generate a bandgap current source , and then use this current source to generate a bias voltgae.
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chibijia
Joined: 16 Jan 2008
Posts: 19
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| 16 May 2008 18:10 Bandgap Reference |
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| how to simulation its psrr
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ppcicy
Joined: 09 May 2008
Posts: 8
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| 18 May 2008 12:01 Bandgap Reference |
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| you can use a close loop buffer .
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jsaenz
Joined: 09 Feb 2008
Posts: 4
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| 19 Jun 2008 2:33 Re: Bandgap Reference |
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| About the way to simulate the PSRR on the Bandgap , I commonly insert a sinusodal voltage source on the Vdd or GND pin (depends on PSSR+ or PSSR-), and then i measure with a .ac statement at the Vref pin the gain of this source. Normally, the worst case of this measure is when the circuitś gain is 1, therefore a unitary gain loop must be to add.
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engronger
Joined: 19 Feb 2006
Posts: 41
Helped: 1
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| 05 Aug 2008 3:58 Re: Bandgap Reference |
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i think you can still use bandgap,
the bandgap that base on current independent can get a voltage high than 1.2V
by the way, LDO is not a good idea, LDO is designed to drive large current not here.
| firsttimedesigning wrote: |
| So I am trying generate the bias voltage of an op-amp. So far the only circuit I know that can be used to generate the bias voltage is bandgap reference. But bandgap reference can only generate a voltage that is around 1.4V. I need a bias voltage that is higher than 1.4V...What circuit should I use? |
Added after 1 minutes:
you can do it as a AC sweep.
the difference only is that the input is changed to VDD or GND.
| chibijia wrote: |
| how to simulation its psrr |
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