On 7/5/06, Palaniappan C wrote: > On Wednesday 05 July 2006 17:20, Vasile Surducan wrote: > > On 7/5/06, Wouter van Ooijen 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. Oh boy. I like mistic solutions. Where did you heard about any solution of killing only the carier and keeping the modulated signal amplitude? This is possible only after demodulation. If you have 20Vpp on 50 or 75 ohm line, you're killing the receiver. Take a look in the spec, any receiver even the cheap one must be able to receive at least at -60dBm. Vasile -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist