Patent ID: 7049858
Filing Date: 2006-05-23
Classification: H03K

Abstract:
1. A switching circuit comprising: a first switching transistor having a control terminal coupled to a first input signal and having a first current carrying terminal; a first current source, providing a fixed current, coupled to the first current carrying terminal; a first isolation resistor connected in series between the first current carrying terminal and the current source, the isolation resistor reducing an in-rush current into a capacitance between the first isolation resistor and the current source to reduce distortion in an output signal of the circuit when the first switching transistor is switched, wherein the first switching transistor forms part of a differential pair of switching transistors, the circuit further comprising: a second switching transistor with a control terminal coupled to a second input signal and having a second current carrying terminal coupled to the first current carrying terminal of the first switching transistor, wherein the first switching transistor and the second switching transistor are bipolar transistors, and the first and second current carrying terminals are emitters of the first and second switching transistors; a second isolation resistor coupled in series directly between the first current carrying terminal of the first switching transistor and the second current carrying terminal of the second switching transistor; a second current source, providing a fixed current; and a third isolation resistor in series between the second current carrying terminal and the second current source.