Tunable transceiver front end

• US 7,269,391 B2
• Filed: 05/24/2004
• Issued: 09/11/2007
• Est. Priority Date: 03/16/2004
• Status: Expired due to Fees

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Li, Qiang (Tom), Chiu, Janice, Khorram, Shahla
• Primary Examiner(s): Anderson; Matthew D.
• Assistant Examiner(s): TRAN, TUAN A
• Application Number:
  US10/852,470
• Publication Number:
  US 20050208901A1
• Time in Patent Office: 1,205 Days
• Field of Search: 343/850, 343/795, 343/700.MS, 343/749, 343/822, 343/750, 343/852, 343860-861, 455280-284, 455289-293, 455 78- 83, 455318-328, 455330-333, 455118-126, 330116-117, 333 15- 16, 333 32- 33, 333/25, 336/200, 336/223, 336/232, 327355-357, 327/113, 327/359, 327/361, 327119-120, 327563-564
• US Class Current: 455/83
• CPC Class Codes: H03H 7/38 Impedance-matching networks
• CPC Class Codes: H03H 7/42 Networks for transforming balanced signals into unbalanced signals and vice versa, e.g. baluns
• CPC Class Codes: H04B 1/18 Input circuits, e.g. for coupling to an antenna or a transmission line coupling networks between antennas or lines and receivers independent of the nature of the receiver H03H

Abstract

A transceiver front end includes a transmit/receive (T/R) switch, a first balun, a second balun, a low noise amplifier, a power amplifier, and compensation circuitry. The T/R switch is operably coupled to an antenna for receiving inbound radio frequency (RF) signals and for transmitting outbound RF signals. The first balun includes a single ended winding and a differential winding, where the single ended winding is operably coupled to the T/R switch. The second balun includes a single ended winding and a differential winding, where the single ended winding is operably coupled to the T/R switch. The low noise amplifier is operably coupled the differential winding of the first balun. The power amplifier is operably coupled to the differential winding of the second balun. The compensation circuitry is operably coupled to the first balun to compensate for at least one of phase imbalance, amplitude imbalance, and impedance imbalance of the first balun.

Claims

1. A transceiver front end comprises:

a transmit/receive (T/R) switch operably coupled to an antenna for receiving inbound radio frequency (RF) signals and for transmitting outbound RF signals;

a first balun having a single ended winding and a differential winding, wherein the single ended winding of the first balun is operably coupled to the T/R switch;

a second balun having a single ended winding and a differential winding, wherein the single ended winding of the second balun is operably coupled to the T/R switch;

a low noise amplifier (LNA) operably coupled to the differential winding of the first balun;

a power amplifier operably coupled to the differential winding of the second balun; and

compensation circuitry operably coupled to the first balun to compensate for at least one of phase imbalance, amplitude imbalance, and impedance imbalance of the first balun, wherein the compensation circuitry includes ground compensation circuitry operably coupling one node of the single ended winding of the first balun to a circuit ground, and wherein the ground compensation circuitry includes a capacitor, a die pad, and a bond wire coupled in series between the single ended winding of the first balun and the circuit ground such that the capacitor resonates with the bond wire at frequencies of the inbound and outbound RF signals to compensate for phase imbalance of the first balun.

2. The transceiver front end of claim 1 comprises:

the capacitor including an on-chip capacitor having a first plate and a second plate, wherein the first plate of the on-chip capacitor is coupled to a first node of the single ended winding of the first balun;

the die pad coupled to the second plate of the on-chip capacitor; and

the bond wire coupling the die pad to the circuit ground, wherein the on-chip capacitor resonates with the bond wire at frequencies of the inbound and outbound RF signals to compensate for the phase imbalance of the first balun.

3. The transceiver front end of claim 1 comprises:

the die pad coupled to a first node of the single ended winding of the first balun; and

the capacitor including an off-chip capacitor having a first plate and a second plate, wherein the second plate of the off-chip capacitor is coupled to the circuit ground; and

the bond wire coupled to the die pad and the first plate of the off-chip capacitor, wherein the off-chip capacitor resonates with the bond wire at frequencies of the inbound and outbound RF signals to compensate for the phase imbalance of the first balun.

4. The transceiver front end of claim 1, wherein the compensation circuitry comprises:

a first variable capacitor having a first plate and a second plate, wherein the first plate of the first variable capacitor is coupled to a first node of the differential winding of the first balun and the second plate of the first variable capacitor is coupled to an LNA circuit ground; and

a second variable capacitor having a first plate and a second plate, wherein the first plate of the second variable capacitor is coupled to a second node of the differential winding of the first balun and the second plate of the second variable capacitor is coupled to the LNA circuit ground, wherein the first and second variable capacitors adjust for the impedance imbalance of the first balun.

5. The transceiver front end of claim 1 comprises:

second compensation circuitry coupled to the second balun to compensate for at least one of phase imbalance, amplitude imbalance, and impedance imbalance of the second balun.

6. The transceiver front end of claim 1, wherein the first balun comprises:

a center tap of the differential winding coupled to an LNA circuit ground to compensate for the amplitude imbalance of the first balun.

7. A balanced low noise amplifier (LNA) circuit comprises:

a balun having a single ended winding and a differential winding, wherein the single ended winding of the balun is operably coupled to receive inbound radio frequency (RF) signals;

a low noise amplifier operably coupled the differential winding of the balun; and

compensation circuitry operably coupled to the balun to compensate for at least one of phase imbalance, amplitude imbalance, and impedance imbalance of the balun, wherein the compensation circuitry includes ground compensation circuitry operably coupling one node of the single ended winding of the balun to a circuit ground, and wherein the ground compensation circuitry includes a capacitor, a die pad, and a bond wire coupled in series between the single ended winding of the balun and the circuit ground such that the capacitor resonates with the bond wire at frequencies of an inbound RF signal to compensate for phase imbalance of the balun.

8. The balanced LNA circuit of claim 7 comprises:

the capacitor including an on-chip capacitor having a first plate and a second plate, wherein the first plate of the on-chip capacitor is coupled to a first node of the single ended winding of the balun;

the die pad coupled to the second plate of the on-chip capacitor; and

the bond wire coupling the die pad to the circuit ground, wherein the on-chip capacitor resonates with the bond wire at frequencies of the inbound RF signals to compensate for the phase imbalance of the balun.

9. The balanced LNA circuit of claim 7 comprises:

the die pad coupled to a first node of the single ended winding of the balun; and

the capacitor including an off-chip capacitor having a first plate and a second plate, wherein the second plate of the off-chip capacitor is coupled to the circuit ground; and

the bond wire coupled to the die pad and the first plate of the off-chip capacitor, wherein the off-chip capacitor resonates with the bond wire at frequencies of the inbound RF signals to compensate for the phase imbalance of the balun.

10. The balanced LNA circuit of claim 7, wherein the compensation circuitry comprises:

a first variable capacitor having a first plate and a second plate, wherein the first plate of the first variable capacitor is coupled to a first node of the differential winding of the balun and the second plate of the first variable capacitor is coupled to an LNA circuit ground; and

a second variable capacitor having a first plate and a second plate, wherein the first plate of the second variable capacitor is coupled to a second node of the differential winding of the balun and the second plate of the second variable capacitor is coupled to the LNA circuit ground, wherein the first and second variable capacitors adjust for the impedance imbalance of the balun.

11. The balanced LNA circuit of claim 7, wherein the balun comprises:

a center tap of the differential winding coupled to an LNA circuit ground to compensate for the amplitude imbalance of the balun.