Phase quadrature signal generator having a variable phase shift network

A variable phase shift network for a phase quadrature signal generator comprising:

• a first NPN transistor having a base terminal, a collector terminal and an emitter terminal, the base terminal of the first NPN transistor being adapted to receive a first differential signal, the collector terminal of the first NPN transistor being adapted to receive a reference voltage, and the emitter terminal of the first NPN transistor being adapted to produce a first quadrature output signal;
• a second NPN transistor having a base terminal, a collector terminal and an emitter terminal, the base terminal of the second NPN transistor being adapted to receive a second differential signal that is 180.degree. out of phase with respect to the first differential signal, the collector terminal of the second NPN transistor being adapted to receive the reference voltage, and the emitter terminal of the second NPN transistor being adapted to produce a second quadrature output signal that is 180.degree. out of phase with respect to the first quadrature output signal;
• a third NPN transistor having a base terminal, a collector terminal and an emitter terminal, the base terminal of the third NPN transistor being adapted to receive the first differential signal, the collector terminal of the third NPN transistor being adapted to receive the reference voltage, and the emitter terminal of the third NPN transistor being adapted to produce a first quadrature input signal that is in substantially a phase quadrature relationship with respect to the first quadrature output signal;
• a fourth NPN transistor having a base terminal, a collector terminal and an emitter terminal, the base terminal of the fourth NPN transistor being adapted to receive the second differential signal, the collector terminal of the fourth NPN transistor being adapted to receive the reference voltage, and the emitter terminal of the fourth NPN transistor being adapted to produce a second quadrature input signal that is 180.degree. out of phase with respect to the first quadrature input signal and that is substantially in a phase quadrature relationship with respect to the second quadrature output signal;
• a first capacitor having a first terminal and a second terminal, the first terminal of the first capacitor being coupled to the emitter terminal of the first NPN transistor, the second terminal of the first capacitor being coupled to the emitter terminal of the fourth NPN transistor;
• second capacitor having a first terminal and a second terminal, the first terminal of the second capacitor being coupled to the emitter terminal of the second NPN transistor, the second terminal terminal of the second capacitor being coupled to the emitter terminal of the third NPN transistor;
• a first fixed current source having a first terminal and a second terminal, the first terminal of the first fixed current source being coupled to coupled to the emitter terminal of the third NPN transistor, the second terminal of the first fixed current source being coupled to a circuit ground;
• a second fixed current source having a first terminal and a second terminal, the first terminal of the second fixed current source being coupled to coupled to the emitter terminal of the fourth NPN transistor, the second terminal of the second fixed current source being coupled to the circuit ground;
• and
• a variable current controller having a first terminal and a second terminal, the first terminal of the variable current controller being coupled to the emitter terminal of the first NPN transistor and being adapted to control current in the first NPN transistor to vary an emitter resistance in the first NPN transistor, the second terminal of the variable current controller being coupled to the emitter terminal of the second NPN transistor and being adapted to control current in the second NPN transistor to vary an emitter resistance in the second NPN transistor, the variable current controller being adapted to control the emitter resistance in the first NPN transistor and the emitter resistance in the second NPN transistor to adjust the phase quadrature relationship between the second quadrature output signal and the second quadrature input signal and to adjust the phase quadrature relationship between the first quadrature output signal and the first quadrature input signal.

A radiotelephone comprising:

• an antenna;
• a transmitter coupled to the antenna;
• and
• a receiver coupled to the antenna,
• wherein at least one of the transmitter and the receiver further comprises:
• a phase quadrature signal generator for producing a first quadrature input signal, a second quadrature input signal, a first quadrature output signal and a second quadrature output signal responsive to receiving a first differential input signal and a second differential input signal, the phase quadrature signal generator comprises:
• a variable phase shift network comprising:
• a first NPN transistor having an emitter resistance;
• a second NPN transistor having an emitter resistance;
• and
• a variable current controller being adapted to control current in the first NPN transistor and current in the second NPN transistor to vary the emitter resistance in the first NPN transistor and the emitter resistance in the second NPN transistor, respectively, to adjust a phase quadrature relationship between the first quadrature input signal and the first quadrature output signal and to adjust a phase quadrature relationship between the second quadrature input signal and the second quadrature output signal.