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US 5,859,559 AGranted
Mixer structures with enhanced conversion gain and reduced spurious signals
AssigneeRaytheon Company
InventorsBo S. Hong, Lloyd F. Linder, Erick M. Hirata, Don C. Devendorf
Life of this patent
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Abstract
Mixer structures are described which include a current mirror for insertion of trickle currents to an input differential amplifier and an output interface for coupling an output differential amplifier to an output port. The current mirror trickle currents improve the mixer's conversion gain and third-order intercept point and the current mirror introduces them without introducing spurious signals. The output interface couples mixer currents to the output port while isolating the output port from power-supply spurious signals.
Claims19
A mixer, comprising:
- an input differential amplifier having a first input port and first and second output paths;
- an output differential amplifier having first and second differential pairs in which inputs of said differential pairs are cross-coupled to form a second input port and outputs of said differential pairs are cross-coupled to form an output port;
- an isolation amplifier coupling said first and second output paths of said input differential amplifier to said output differential amplifier;
- and
- an active current source generating trickle currents and coupled to supply said trickle currents to said first and second output paths;
- wherein said active current source is a current mirror configured to supply said first and second trickle currents to said first and second output paths and wherein said current mirror includes:
- first, second and third current transitors which each have first and seocnd current terminals that are responsive to a control terminal, wherein the first current terminals of said first, second and third current transistors are coupled together, the control terminals of said first, second and third current transistors and the seocnd current terminal of said first current transistor are coupled together, and the second current terminals of said second and third transistors are coupled respectively to said first and second output paths;
- and
- a current source coupled to said second current terminal of said first current transistor;
- said trickle currents enhancing the conversion gain of said mixer between said first and second input ports and said output port.
7 more elements
A mixer, comprising:
- an input differential amplifier having a first input port and first and second output paths;
- an output differential amplifier having first and second differential pairs in which inputs of said differential pairs are cross-coupled to form a second input port and outputs of said differential pairs are cross-coupled to form an output port;
- an isolation amplifier coupling said first and second output paths of said input differential amplifier to said output differential amplifier;
- an active current source generating trickle currents and coupled to supply said trickle currents to said first and second output paths;
- and
- an output interface inserted between said output differential amplifier and said output port, said output interface having an active load coupled to said cross-coupled collectors of said output differential amplifier and further having a current conveyor inserted between said active load and said output port and configured to convey currents to said output port which are representative of currents in said active load;
- wherein said active load includes first and second load transistors coupled to said cross-coupled outputs of said differential pairs;
- and
- said current conveyor includes:
- first and second output transistors coupled to said output port and respectively arranged in cascode relationships with said first and second load transistors;
- and
- first and second output resistors coupled to said output port;
- said trickle currents enhancing the conversion gain of said mixer between said first and second input ports and said output port.
10 more elements
A mixer, comprising:
- an input differential amplifier having a first inupt port and first and second output paths;
- an output differential amplifier having first and second differential pairs of transistors in which common emitters of said differential pairs are coupled to said first and second output paths, inputs of said differential pairs are cross-coupled to form a second input port and outputs of said differential pairs are cross-coupled to form an output port;
- a current source that generates trickle currents and is arranged to introduce said trickle currents into said first and second output paths;
- and
- an active load that generates mixing currents and is arranged to couple said mixing currents to said cross-coupled outputs of said output differential amplifier.
2 more elements
A mixer comprising:
- an input differential amplifier having a first input port and first and second output paths;
- an output differential amplifier coupled to said first and second output paths, said output differential amplifier having first and second differential pairs in which inputs of said differential pairs are cross-coupled to form a second input port and outputs of said differential pairs are also cross-coupled;
- an isolation amplifier that couples said first and second output paths to said output differential amplifier;
- an output interface having an active load coupled to said cross-coupled collectors of said output differential amplifier and further having a current conveyor which defines an output port and which is configured to convey currents to said output port which are representative of currents in said active load;
- and
- a current source generating trickle currents and coupled to supply said trickle currents to said first and second output paths wherein said current source includes a current mirror configured to supply said first and second trickle currents to said first and second output paths.
3 more elements
A mixer, comprising:
- an input differential amplifier having a first input port and first and second output paths;
- an output differential amplifier having first and second differential pairs of transistors in which inputs of said differential pairs are cross-coupled to form a second input port and outputs of said differential pairs are cross-coupled to form an output port;
- an isolation amplifier coupling said first and second output paths of said input differential amplifier to said output differential amplifier;
- a current mirror that generates first and second trickle currents and respectively introduces said first and second trickle currents into said first and second output paths;
- and
- an active load that generates mixing currents and is arranged to couple said mixing currents to said cross-coupled outputs of said output differential amplifier.
3 more elements
A mixer, comprising:
- an input differential amplifier having a first input port and first and second output paths;
- an output differential amplifier having first and second differential pairs in which inputs of said differential pairs are cross-coupled to form a second input port and outputs of said differential pairs are cross-coupled;
- an isolation amplifier coupling said first and second output paths of said input differential amplifier to said output differential amplifier;
- a current mirror configured to supply first and second trickle currents to said first and second output paths;
- and
- an output interface having an active load coupled to said cross-coupled collectors of said output differential amplifier and further having a current conveyor which defines an output port and which is configured to convey currents to said output port which are representative of currents in said active load;
- wherein said current mirror includes:
- first, second and third current transistors which each have first and second current terminals that are responsive to a control terminal, wherein the first current terminals of said first, second and third current transistors are coupled together, the control terminals of said first, second and third current transistors and the second current terminal of said first current transistor are coupled together, and the second current terminals of said second and third transistors are coupled respectively to said first and second output paths;
- and
- a current source coupled to said second current terminal of said first current transistor.
7 more elements
Dependencies are inferred from the claim text.