Amplification circuit

摘要

An amplification circuit (100) comprising a first filter (102) and an LNA (110). The first filter (102) comprising an input (104) for receiving an input signal; a first differential output (106); and a second differential output (108). The first filter (102) has a differential mode of operation for frequencies in its pass-band (706, 806) and a common mode of operation for frequencies outside its pass-band (706, 806), and may be an acoustic wave filter. The LNA (110) comprising a first differential input (112) connected to the first differential output (106) of the first filter (102); a second differential input (114) connected to the second differential output (108) of the first filter (102); and an output (116) for providing an amplified output signal.

主权项

1. An amplification circuit comprising:
a first surface acoustic wave (SAW) filter comprising:
an input for receiving an input signal;a first differential output; anda second differential output; wherein the first filter has a differential mode of operation for frequencies in its pass-band and a common mode of operation for frequencies outside its pass-band; and further having: a first magnitude transfer function from the input of the first filter to the first differential output of the first filter; a second magnitude transfer function from the input of the first filter to the second differential output of the first filter; a first phase transfer function from the input of the first filter to the first differential output of the first filter; and a second phase transfer function from the input of the first filter to the second differential output of the first filter; and wherein the difference between the first magnitude transfer function and the second magnitude transfer function for frequencies outside the pass-band of the first filter is less than a first threshold value of 3 dB; the difference between the first phase transfer function and the second phase transfer function for frequencies outside the pass-band of the first filter is less than a second threshold value of 40°; the difference between the first phase transfer function and the second phase transfer function for frequencies inside the pass-band of the first filter is less than a third threshold value of 20° away from 180° an LNA comprising:
a first differential input connected to the first differential output of the first filter;a second differential input connected to the second differential output of the first filter; andan output for providing an amplified output signal.