[hpsdr] Odyssey Active QSD Rev. A Schematic

[Lyle Johnson]

Steven Bible wrote:
> ***** High Performance Software Defined Radio Discussion List *****
> 
> Hi Alberto,
> 
> As Ahti mentioned, yes, this design is intended to drive the TI codec
> TLV320AIC31.  The codec's analog input voltage is 3.3V.  So there's actually
> a fear that it may be overdriven.  The TI codec have fully differential
> input and output, but the power supplies are all unipolar.  So hopefully the
> ISD design is a good fit for this codec (or vice versa).

Note that the input voltage range of the OPA1632 when powered by a 
single +5 supply is limited to +1.5 to +4.0 VDC, and the output range 
into a 2K load is limited to +1.9 to +3.1 VDC.

I don;t think you'll overdrive things, more worrisome is the possible 
need for a different supply voltage to get the range you want or need to 
drive the CODEC over its fuill range.

73,

Lyle KK7P

> 73,
> 
> - Steve, N7HPR
>  (n7hpr at tapr.org)
> 
> 
>> -----Original Message-----
>> From: hpsdr-bounces at hpsdr.org [mailto:hpsdr-bounces at hpsdr.org]On Behalf
>> Of Ahti Aintila
>> Sent: Friday, September 29, 2006 6:31 AM
>> To: Alberto I2PHD
>> Cc: hpsdr at hpsdr.org
>> Subject: Re: [hpsdr] Odyssey Active QSD Rev. A Schematic
>>
>>
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> On 29/09/06, Alberto I2PHD <i2phd at weaksignals.com> wrote:
>>> ***** High Performance Software Defined Radio Discussion List *****
>> , but the two opamps have their inputs biased at 2.5V and the supply
>> voltage is 5V,
>>> single-rail. Given that good sound cards can happily accepts up
>> to 4V and more of signal, isn't a design that limits its
>>> output to 2.5Vp incapable of fully exploiting the dynamic
>> offered by the sound card itself ?
>>> Wouldn't a ±15V as supply voltage be more adequate for an
>> uncompromised design ?
>>> 73  Alberto  I2PHD
>> Alberto,
>>
>> You are absolutely right, but in this case the circuit is designed for
>> a low power application using a bare CODEC circuit instead of the
>> sound card.
>>
>> In other applications I really would use ±5 V or higher supply,
>> preferably ±15 V.
>>
>> 73, Ahti OH2RZ
>>
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