Resonant loop resistive FET mixer

• US 5,263,198 A
• Filed: 11/05/1991
• Issued: 11/16/1993
• Est. Priority Date: 11/05/1991
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Geddes, John J., Bauhahn, Paul E.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): VO, NGUYEN THANH
• Application Number:
  US07/788,072
• Time in Patent Office: 742 Days
• Field of Search: 455/325, 455/326, 455/323, 455/330, 455/327, 455/333, 307/579
• US Class Current: 455/325
• CPC Class Codes: H03D 2200/0074 using a resistive mixer or a passive mixer
• CPC Class Codes: H03D 2200/009 Reduction of local oscillator or RF leakage
• CPC Class Codes: H03D 7/125 with field effect transistors
• CPC Class Codes: H03D 9/0658 by means of semiconductor devices having more than two electrodes
• CPC Class Codes: H04B 1/28 the receiver comprising at least one semiconductor device having three or more electrodes

Abstract

A mixer includes a local oscillator (LO) matching network having an LO input port, an RF matching network also having an input port and an IF filter which provides an IF output from the mixer. A FET having a gate, drain and source operates at the center of the mixer. A resonant loop is connected between the drain and gate of the FET. The gate of the FET is connected to an output of the LO matching network. The drain of the FET is connected to an output of the RF matching network. The source of the FET is connected to an input of the IF filter. The resonant loop may incorporate a DC blocking capacitor which does not function as part of the resonant loop, but which serves to block DC allowing the drain and gate of the FET to be biased independently.

Claims

1. A resonant loop resistive mixer apparatus comprising:

means for operating as a field effect transistor (FET) having a source, a drain and a gate;

means for operating as a local oscillator (LO) matching network including an LO port and having an output connected to the FET gate;

means for operating as an RF matching network including an RF port and having an output connected to the FET drain;

means for operating as a resonant loop connected between the FET drain and gate; and

means for operating as an IF filter having an input connected to the FET source; and

wherein the FET includes internal capacitances and the resonant loop means comprises a length of transmission line selected to resonate with the internal FET capacitances so as to provide RF port to LO port isolation of greater than about 15 dB.

2. The apparatus of claim 1 wherein the FET means comprises a GaAs Metal Semiconductor Field Effect Transistor (MESFET).

3. The apparatus of claim 1 wherein the resonant loop means further includes a DC blocking capacitor.

4. The apparatus of claim 1 further comprising:

a. a gate bias decoupling network means connected to the FET gate; and

b. a drain bias decoupling means connected to the FET drain. means for operating as an IF filter having an input connected to the FET source; and

wherein the FET includes internal capacitances and the resonant loop means comprises a length of transmission line selected to resonate with the internal FET capacitances so as to provide RF port to LO port isolation of greater than about 15 dB.

5. A resonant loop resistive mixer apparatus comprising:

a field effect transistor (FET) having a source, a drain and a gate wherein the FET comprises a GaAs Metal Semiconductor Field Effect Transistor (MESFET);

a local oscillator (LO) matching network having an output connected to the FET gate;

an RF matching network having an output connected to the FET drain;

a resonant loop connected between the FET drain and gate wherein the resonant loop means further includes a DC blocking capacitor;

an IF filter having an input connected to the FET source;

a gate bias decoupling network means connected to the FET gate; and

a drain bias decoupling means connected to the FET drain; and

wherein the FET includes internal capacitances and the resonant loop means comprises a length of transmission line selected to resonate with the internal FET capacitances so as to provide RF port to LO port isolation of greater than about 15 dB.

6. A resonant loop resistive mixer apparatus comprising:

a field effect transistor (FET) having a source, a drain and a gate wherein the FET comprises a GaAs Metal Semiconductor Field Effect Transistor (MESFET);

a local oscillator (LO) providing an LO signal;

a local oscillator matching network including an LO port coupled to receive the LO signal and having an output connected to the FET gate;

an RF signal generator providing an RF signal;

an RF matching network including an RF port coupled to receive the RF signal and having an output connected to the FET drain;

a resonant loop connected between the FET drain and gate wherein the resonant loop means further includes a DC blocking capacitor;

an IF filter having an input connected to the FET source;

a gate bias decoupling network means connected to the FET gate; and

a drain bias decoupling means connected to the FET drain; and

wherein the FET includes internal capacitances and the resonant loop means comprises a length of transmission line selected to resonate with the internal FET capacitances so as to provide RF port to LO port isolation of greater than about 15 dB at LO frequencies above about 32 GHz and below about 36 GHz.

7. A resonant loop resistive mixer apparatus comprising:

means for operating as a field effect transistor (FET) having a source, a drain and a gate;

means for operating as a local oscillator (LO) matching network including an LO port and having an output connected to the FET gate;

means for operating as a radio frequency (RF) matching network including an RF port and having an output connected to the FET drain;

means for operating as a resonant loop connected between the FET drain and gate, wherein the FET includes internal capacitances and the resonant loop means comprises an inductance selected to resonate with the internal FET capacitances so as to increase RF port to LO port isolation; and

means for operating as an intermediate frequency (IF) filter having an input connected to the FET source.

8. A resonant loop resistive mixer apparatus comprising:

a field effect transistor (FET) having a source, a drain and a gate;

a local oscillator (LO) matching network having an output connected to the FET gate;

an RF matching network having an output connected to the FET drain;

a resonant loop connected between the FET drain and gate, wherein the FET includes internal capacitances and the resonant loop comprises an inductance selected to resonate with the internal FET capacitances so as to increase RF port to LO port isolation; and

an IF filter having an input connected to the FET source.

9. A resonant loop resistive mixer apparatus comprising:

a transistor having first, second and third terminals;

a local oscillator (LO) matching network having an output connected to the first terminal;

a radio frequency (RF) matching network having an output connected to the second terminal;

a resonant loop connected between the first and second terminals, wherein the transistor has an internal capacitance and the resonant loop comprises an inductance selected to resonate with the internal transistor capacitance; and

an intermediate frequency (IF) filter having an input connected to the third terminal.