Patent ID: 6335651
Filing Date: 2002-01-01
Classification: H03D

Abstract:
A mixer with a single ended input port for receiving signals, a balanced input port for receiving local signals and power and ground terminals for energizing the mixer from a low voltage power source whereby in operation, input signals received via the single ended input port and being of desired frequencies are converted to output signals with frequencies in a predetermined frequency band, the mixer comprising:a balanced mixer circuit connected with the power terminal for having energizing current conducted therethrough, connected with the balanced input port for receiving the local signals, and having a pair of input terminals for receiving substantially balanced input signals and a pair of output terminals for providing the output signals; biasing circuit including, a voltage divider having a first divider resistor connected in series with the power terminal and a first voltage tap at a junction of the first divider resistor and a second divider resistor, a third divider resistor connected in series with the ground terminal, and a second voltage tap at a junction of the second divider resistor and an active component connected in series between the second divider resistor and the third divider resistor; a differential driver circuit including a first transistor with a collector electrode connected with one of the pair of input terminals of the balanced mixer, a base electrode coupled via a capacitor to the receive signal terminal, and an emitter electrode coupled via a first resistor to the ground terminal, and a second transistor with a collector electrode connected with the other of the pair of input terminals of the balanced mixer, a base electrode coupled via a capacitor to the ground terminal, an emitter electrode coupled via a second resistor to the single ended input port transistor and, a fifth resistor connected between a second voltage tap and the base electrode of the first transistor; biasing circuit including said first and second voltage taps for providing first and second potentials, the first potential being intermediate a voltage at the power terminal and the second potential and the second potential being at least sufficiently removed from ground for causing a forward current flow between the base and emitter electrodes of the first transistor; and an impedance element connected between the single ended input port and the ground terminal.