Multiband matching circuit and multiband power amplifier

• US 8,487,713 B2
• Filed: 01/28/2010
• Issued: 07/16/2013
• Est. Priority Date: 01/30/2009
• Status: Expired due to Fees

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Fukuda, Atsushi, Okazaki, Hiroshi, Narahashi, Shoichi
• Primary Examiner(s): JONES, STEPHEN E
• Application Number:
  US12/695,442
• Publication Number:
  US 20100194487A1
• Time in Patent Office: 1,265 Days
• Field of Search: 333/32, 333/33
• US Class Current: 333/32
• CPC Class Codes: H03F 1/56 Modifications of input or output impedances, not otherwise provided for
• CPC Class Codes: H03F 2200/111 the amplifier being a dual or triple band amplifier, e.g. 900 and 1800 MHz, e.g. switched or not switched, simultaneously or not
• CPC Class Codes: H03F 2200/429 Two or more amplifiers or one amplifier with filters for different frequency bands are coupled in parallel at the input or output
• CPC Class Codes: H03F 2203/7209 the gated amplifier being switched from a first band to a second band
• CPC Class Codes: H03F 3/72 Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal
• CPC Class Codes: H03H 2007/386 Multiple band impedance matching
• CPC Class Codes: H03H 7/383 comprising distributed impedance elements together with lumped impedance elements
• CPC Class Codes: H03H 7/40 Automatic matching of load impedance to source impedance

Abstract

A multiband matching circuit includes a first matching unit for converting an impedance in a signal path to Z0 in a first frequency band, and a second matching unit formed of a series matching section connected at one end in series with the first matching unit in the signal path, which is a transmission line whose characteristic impedance is equal to the matching impedance Z0 or a circuit equivalent to the transmission line at least in the first frequency band, and a parallel matching section connected at one end to the signal path at the other end of the series matching section and grounded at the other end. The parallel matching section is configured to open in impedance the connection point to the signal path in the first frequency band. The series matching section and the parallel matching section are designed to match an impedance in a second frequency band with Z0.

Claims

1. A multiband matching circuit for matching an impedance Z₁(f) of a circuit element having frequency characteristics with a predetermined impedance Z0 of a system circuit in first and second frequency bands when the multiband matching circuit is disposed in a signal path between the circuit element having the impedance Z₁(f) and the system circuit having the impedance Z0, the multiband matching circuit comprising:

a first matching unit connected at one end to the circuit element and adapted to convert the impedance of the circuit element to Z0 in the first frequency band; and

a second matching unit which comprises;

a series matching section connected at one end to the other end of the first matching unit and connected at the other end to the system circuit, which is a transmission line whose characteristic impedance is equal to the impedance Z0 of the system circuit or a circuit equivalent to the transmission line at least in the first frequency band; and

a parallel matching section connected at one end to the signal path at the other end of the series matching section and grounded at the other end;

the parallel matching section being configured to open in impedance the connection point to the signal path in the first frequency band; and

the series matching section and the parallel matching section being designed to match the impedance of the circuit element with Z0 in the second frequency band,

wherein the parallel matching section comprises a first parallel block connected at one end to the signal path and a second parallel block connected at one end to the other end of the first parallel block and grounded at the other end, and

the first parallel block is configured to open in impedance at the connection point to the signal path in the first frequency band.

2. The multiband matching circuit according to claim 1, wherein the first parallel block is a parallel resonance circuit of a capacitor and an inductor, with the resonance frequency being equal to a central frequency f₁ of the first frequency band.

3. A multiband power amplifier comprising an amplification device and a multiband matching circuit according to claim 1 capable of simultaneously amplifying signals in a plurality of frequency bands.

4. A multiband matching circuit for matching an impedance Z₁(f) of a circuit element having frequency characteristics with a predetermined impedance Z0 of a system circuit in first and second frequency bands when the multiband matching circuit is disposed in a signal path between the circuit element having the impedance Z₁(f) and the system circuit having the impedance Z0, the multiband matching circuit comprising:

a first matching unit connected at one end to the circuit element and adapted to convert the impedance of the circuit element to Z0 in the first frequency band; and

a second matching unit which comprises;

a series matching section connected at one end to the other end of the first matching unit and connected at the other end to the system circuit, which is a transmission line whose characteristic impedance is equal to the impedance Z0 of the system circuit or a circuit equivalent to the transmission line at least in the first frequency band; and

a parallel matching section connected at one end to the signal path at the other end of the series matching section and grounded at the other end;

the parallel matching section being configured to open in impedance the connection point to the signal path in the first frequency band; and

the series matching section and the parallel matching section being designed to match the impedance of the circuit element with Z0 in the second frequency band,

wherein the parallel matching section comprises a second parallel block connected at one end to the signal path and a first parallel block connected at one end to the other end of the second parallel block and grounded at the other end,

the second parallel block is formed of a lumped constant element, and

the first parallel block is configured to open in impedance at the connection point to the second parallel block in the first frequency band.

5. The multiband matching circuit according to claim 4, wherein the first parallel block is a transmission line having a length equal to a quarter of the wavelength at a central frequency f₁ of the first frequency band.

6. A multiband matching circuit for matching an impedance Z₁(f) of a circuit element having frequency characteristics with a predetermined impedance Z0 of a system circuit in first to N-th frequency bands (N≧

3, central frequencies f₁>

f₂>

. . . >

f_N) when the multiband matching circuit is disposed in a signal path between the circuit element having the impedance Z₁(f) and the system circuit having the predetermined impedance Z0, the multiband matching circuit comprising;

a first matching unit connected at one end to the circuit element and adapted to convert the impedance of the circuit element to Z0 in the first frequency band; and

m-th matching units (m=2, 3, . . . , and N) each comprising;

a series matching section connected at one end to the other end of the (m−

1)-th matching unit, which is a transmission line whose characteristic impedance is equal to the impedance Z0 of the system circuit or a circuit equivalent to the transmission line at least in each of the first to (m−

1)-th frequency bands; and

a parallel matching section connected at one end to the signal path at the other end of the series matching section and grounded at the other end;

the other end of the series matching section of the N-th matching unit being connected to the system circuit;

the parallel matching section of the m-th matching unit being configured to open in impedance at the connection point to the signal path in the first to (m−

1)-th frequency bands; and

the series matching section and the parallel matching section of the m-th matching unit being designed to match the impedance of the circuit element with Z0 in the m-th frequency band,

wherein the parallel matching section of the m-th matching unit comprises a first parallel block connected at one end to the signal path and a second parallel block connected at one end to the other end of the first parallel block and grounded at the other end, and

the first parallel block is configured to open in impedance at the connection point to the signal path in each of the first to (m−

1)-th frequency bands.

7. The multiband matching circuit according to claim 6, wherein the first parallel block is a parallel resonance circuit of a capacitor and an inductor, with the resonance frequency being greater than or equal to the central frequency f_m−

1 of the (m−

1)-th frequency band and smaller than or equal to the central frequency f₁ of the first frequency band.

8. The multiband matching circuit according to claim 6, wherein the first parallel block is a series connection of m−

1 parallel circuits of capacitors and inductors, with the resonance frequencies being the central frequencies f₁, f₂, . . . , and f<sub>m−

1</sub> of the first to (m−

1)-th frequency bands, respectively.

9. A multiband matching circuit for matching an impedance Z₁(f) of a circuit element having frequency characteristics with a predetermined impedance Z0 of a system circuit in first to N-th frequency bands (N≧

3, central frequencies f₁>

f₂>

. . . >

f_N) when the multiband matching circuit is disposed in a signal path between the circuit element having the impedance Z₁(f) and the system circuit having the predetermined impedance Z0, the multiband matching circuit comprising;

a first matching unit connected at one end to the circuit element and adapted to convert the impedance of the circuit element to Z0 in the first frequency band; and

m-th matching units (m=2, 3, . . . , and N) each comprising;

a series matching section connected at one end to the other end of the (m−

1)-th matching unit, which is a transmission line whose characteristic impedance is equal to the impedance Z0 of the system circuit or a circuit equivalent to the transmission line at least in each of the first to (m−

1)-th frequency bands; and

a parallel matching section connected at one end to the signal path at the other end of the series matching section and grounded at the other end;

the other end of the series matching section of the N-th matching unit being connected to the system circuit;

the parallel matching section of the m-th matching unit being configured to open in impedance at the connection point to the signal path in the first to (m−

1)-th frequency bands; and

the series matching section and the parallel matching section of the m-th matching unit being designed to match the impedance of the circuit element with Z0 in the m-th frequency band,

wherein the parallel matching section of the m-th matching unit comprises a second parallel block connected at one end to the signal path and a first parallel block connected at one end to the other end of the second parallel block and grounded at the other end,

the second parallel block is formed of a lumped constant element, and

the first parallel block is configured to open in impedance at the connection point to the second parallel block in each of the first to (m−

1)-th frequency bands.

10. The multiband matching circuit according to claim 9, wherein the first parallel block is a transmission line whose length is greater than or equal to a quarter of the wavelength at the central frequency f₁ of the first frequency band and smaller than or equal to a quarter of the wavelength at the central frequency f_m−

1 of the (m−

1)-th frequency band.

11. A multiband matching circuit for matching an impedance Z₁(f) of a circuit element having frequency characteristics with a predetermined impedance Z0 of a system circuit in two frequency bands of first to N-th frequency bands (N≧

3) when the multiband matching circuit is disposed in a signal path between the circuit element having the impedance Z₁(f) and the system circuit having the impedance Z0, the multiband matching circuit comprising;

a first matching unit connected at one end to the circuit element and adapted to convert the impedance of the circuit element to Z0 in one of the first to m-th (m≧

2) frequency bands; and

a second matching unit which comprises;

a series matching section connected at one end to the other end of the first matching unit and connected at the other end to the system circuit, which is a transmission line whose characteristic impedance is equal to the impedance Z0 of the system circuit or a circuit equivalent to the transmission line at least in the one of the first to m-th frequency bands; and

a parallel matching section connected at one end to the signal path at the other end of the series matching section and grounded at the other end;

the parallel matching section being configured to open in impedance at the connection point to the signal path in the one of the first to m-th frequency bands; and

the series matching section and the parallel matching section being designed to match the impedance of the circuit element with Z0 in one of (m+1)-th to N-th frequency bands,

wherein the parallel matching section comprises a first parallel block, which is a variable device, connected at one end to the signal path, and a second parallel block, which is a variable device, connected at one end to the other end of the first parallel block and grounded at the other end, and

the first parallel block is configured to open in impedance at the connection point to the signal path in the one of the first to m-th frequency bands.

12. The multiband matching circuit according to claim 11, wherein the first parallel block is a parallel resonance circuit of a variable capacitor and an inductor.