US 12,483,449 B2
Passive equalizer
Siamak Delshadpour, Phoenix, AZ (US); and Alexander Wayne Sheldon, Gilbert, AZ (US)
Assigned to NXP USA, Inc., Austin, TX (US)
Filed by NXP USA, Inc., Austin, TX (US)
Filed on Jan. 31, 2023, as Appl. No. 18/162,337.
Prior Publication US 2024/0259238 A1, Aug. 1, 2024
Int. Cl. H04L 25/03 (2006.01); H04L 25/02 (2006.01)
CPC H04L 25/03885 (2013.01) [H04L 25/0272 (2013.01); H04L 25/03031 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A passive equalizer circuit, comprising:
an input configured to receive an input signal having an input frequency band;
a transfer function circuit configured to transform the input frequency band into an output frequency band; and
an output configured to be coupled to an active equalizer circuit and carry an output signal having the output frequency band;
wherein the transfer function circuit includes a variable impedance circuit configured to adjust a mid-band frequency gain of the output signal;
wherein the variable impedance circuit includes a first variable capacitor (C4) having a variable capacitance in parallel with the active equalizer circuit;
wherein the first variable capacitor adjusts a set of mid-band frequency gains of the output frequency band;
wherein the first variable capacitor is in parallel with a first resistor (R4) having a resistance and in series with a second resistor (R3) having a resistance; and
wherein the second resistor (R3) is coupled to the output.