Patent ID: 7046044
Filing Date: 2006-05-16
Classification: H03F

Abstract:
1. The first stage of a preamplifier circuit, comprising: a first differential pair of amplifying transistors and a second differential pair of amplifying transistors; the bases of the first differential pair of amplifying transistors being capacitively coupled to the first side of an input through a first capacitor; the bases of the second differential pair of amplifying transistors being capacitively coupled to the second side of an input through a second capacitor; a first current loop and a second current loop; the first current loop comprised of a first resistor, a first transistor switch and a second resistor; the first resistor and second resistor having the same value; the second current loop comprised of a third resistor, a second transistor switch and a fourth resistor; the third resistor and fourth resistor having the same value; the first current loop being coupled to the bases of said first differential pair of amplifying transistors; the second current loop being coupled to the bases of said second differential pair of amplifying transistors; a third transistor switch being coupled across the bases of the first differential pair of amplifying transistors; a fourth transistor switch being coupled across the bases of the second differential pair of amplifying transistors; and the first current loop and second current loop operable to equalize the charges upon the first transistor and second transistor.