On Wednesday 05 July 2006 17:20, Vasile Surducan wrote:
> On 7/5/06, Wouter van Ooijen <wouter@voti.nl> wrote:
> > > The input signal is 20v peak-to-peak (-10v to +10v)  ac 14Mhz
> > > rf signal.
> > > and i want to shift it to ( -15v to +5v ).  I looking for a
> > > way to do it
> > > without using additional power supply.
> >
> > a suitable transformer, with the 0 of the secondaryt at -5V?
> +10v - (-10V) = 20V swing
> +5V - (-15V) = 20V swing too
> Pass the signal via a capacitor and fixe the DC level at the right
> value(ie  -5V).
> The question is how you've get 20Vpp/14Mhz RF signal (meaning sinusoidal)
> and what you're doing with it.
> Vasile

Thanks for your replies, 
The actual problem is ,  i am modifying a rf transceiver board (rf id) , for 
more power. There is low power transceiver ic (TI S67 00) on the board, which 
do all the modulation and demodulation (only for low power output).
I need to modify it to get more power output and more range for rf id tag.
I added a power amplifier on transmitter path. 

For the receiver path, the rx pin of IC is limited to 5V, so i need to 
attenuate the rx signal, without losing the data on its envelope. direct 
resistance attenuation will affect the signal strength (envelope). so i 
thought of  shifting down the signal and feeding it to the IC.

I am trying the methods you suggested. Thanks.

regards,
palani.

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