Abstract: 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.

Abstract: 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.

Abstract: An amplifier circuit comprises an input transistor Q1 with a first control electrode coupled to the input In and a first main current channel coupled to the internal node 10. An output transistor Q4 has a second control electrode coupled to the internal node 10 and a second main current channel coupled to the output Out of the amplifier. An internal transistor Q2 has a third main current channel coupled to the internal node 10. The internal transistor Q2 serves to modify the impedance at the internal node 10, but a main low-frequency gain path from the first main channel Q1 to the second control electrode does not pass through the third main current channel Q2. The internal node 10 is coupled to ground via the third main current channel Q2 and a resistive element R1 successively. The resistance value of the resistive element R1 causes poles of a transfer function of the amplifier circuit to develop an imaginary frequency (resonant) component.