Bi-directional amplifier having a single gain block for amplifying both forward and reverse signals

• US 6,348,837 B1
• Filed: 08/08/2000
• Issued: 02/19/2002
• Est. Priority Date: 08/08/2000
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Scientific-Atlanta Incorporated (Cisco Systems, Inc.)
• Inventors: Ibelings, Pieter
• Primary Examiner(s): Pascal, Robert
• Assistant Examiner(s): NGUYEN, KHANH V
• Application Number:
  US09/634,119
• Time in Patent Office: 560 Days
• Field of Search: 330/59, 330/126, 333/109, 348/693, 348/707
• US Class Current: 330/126
• CPC Class Codes: H03F 3/68 Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics power amplifiers using a combination of several semiconductor amplifiers H03F3/211; combinations of amplifiers using coupling networks with distributed constants H03F3/602

Abstract

An amplifier (600) includes a first terminal (605) for receiving forward signals in a first frequency band and a second terminal (655) for receiving reverse signals in a second frequency band. A single gain block (630) is coupled between the first terminal (605) and the second terminal (655) for amplifying the forward signals and the reverse signals. The forward signals, after amplification, are provided to the second terminal (655) for transmission from the amplifier (600), and the reverse signals, after amplification, are provided to the first terminal (605) for transmission from the amplifier (600). In this manner, both forward and reverse signals, which are transmitted in separate frequency bands, can be amplified by a single gain block (630).

Claims

1. An amplifier for amplifying signals, the amplifier comprising:

a first terminal for receiving forward signals in a first frequency band;

a second terminal for receiving reverse signals in a second frequency band; and

a single gain block coupled between the first terminal and the second terminal for amplifying the forward signals and the reverse signals,

wherein the forward signals, after amplification, are provided to the second terminal for transmission from the amplifier, and wherein the reverse signals, after amplification, are provided to the first terminal for transmission from the amplifier.

2. The amplifier of claim 1, further comprising:

forward path filters for isolating the forward signals, providing the forward signals to the single gain block, and routing the forward signals, after amplification, to the second terminal; and

reverse path filters for isolating the reverse signals, providing the reverse signals to the single gain block, and routing the reverse signals, after amplification, to the first terminal.

3. The amplifier of claim 1, wherein the single gain block comprises:

one input for receiving the forward signals within the first frequency band and for receiving the reverse signals within the second frequency band;

one output for transmitting the forward signals within the first frequency band to the second terminal and for transmitting the reverse signals within the second frequency band to the first terminal; and

a gain stage coupled between the one input and the one output for amplifying the forward signals within the first frequency band and the reverse signals within the second frequency band,

wherein the gain stage provides amplification at all frequencies included within the first frequency band and the second frequency band.

4. The amplifier of claim 2, wherein the forward path filters and the reverse path filters are implemented using diplex filters.

5. The amplifier of claim 2, wherein the forward path filters and the reverse path filters further comprise:

a first diplex filter including a mid-band filter and a low-band filter, the first diplex filter further including a common port coupled to the first terminal, a mid-band port, and a low-band port;

a second diplex filter including a low-band filter and a mid-band filter, the second diplex filter further including a low-band port, a mid-band port coupled to the mid-band port of the first diplex filter, and a common port coupled to an input of the single gain block;

a third diplex filter including a mid-band filter and a low-band filter, the third diplex filter further including a common port coupled to an output of the single gain block, a low-band port coupled to the low-band port of the first diplex filter, and a mid-band port; and

a fourth diplex filter including a low-band filter and a mid-band filter, the fourth diplex filter further including a mid-band port coupled to the mid-band port of the third diplex filter, a low-band port coupled to the low-band port of the second diplex filter, and a common port coupled to the second terminal.

6. An optical node for transmitting signals, the optical node comprising:

a laser receiver for converting optical signals to forward radio frequency (RF) signals and transmitting the forward RF signals downstream;

a laser transmitter for receiving reverse RF signals from upstream and converting the reverse RF signals to reverse optical signals; and

an amplifier for amplifying the forward RF signals and the reverse RF signals, the amplifier comprising;

an input terminal for receiving forward RF signals within a first frequency band from the laser receiver;

an output terminal for transmitting reverse RF signals within a second frequency band to the laser transmitter and for transmitting reverse RF signals within a third frequency band to the laser transmitter;

an input/output terminal for transmitting forward RF signals within the first frequency band, and for receiving reverse RF signals within the second frequency band and reverse RF signals within the third frequency band;

a first gain block coupled between the input terminal and the input/output terminal for amplifying the forward RF signals within the first frequency band and the reverse RF signals within the third frequency band,

wherein the forward RF signals, after amplification, are provided to the input/output terminal for transmission from the amplifier, and wherein the reverse RF signals, after amplification, are provided to the output terminal for transmission from the amplifier; and

a second gain block coupled between the input/output terminal and the output terminal for amplifying the reverse RF signals within the second frequency band,

wherein the reverse RF signals, after amplification, are provided to the output terminal for transmission from the amplifier.

7. The optical node of claim 6, wherein the first gain block comprises:

one input port for receiving the forward RF signals within the first frequency band and for receiving the reverse RF signals within the third frequency band;

one output port for transmitting the forward RF signals within the first frequency band to the input/output terminal and for transmitting the reverse RF signals within the third frequency band to the output terminal; and

a gain stage coupled between the input terminal and the input/output terminal for amplifying the forward RF signals within the first frequency band and reverse RF signals within the third frequency band,

wherein the gain stage provides amplification at all frequencies included within the first frequency band and the third frequency band.

8. The optical node of claim 6, wherein the amplifier further comprises:

forward path filters for isolating the forward RF signals, providing the forward RF signals to the first gain block, and routing the forward RF signals, after amplification, to the input/output terminal;

first reverse path filters for isolating the reverse RF signals within the third frequency band, providing the reverse RF signals within the third frequency band to the first gain block, and routing the reverse RF signals within the third frequency band, after amplification, to the output terminal; and

second reverse path filters for isolating the reverse RF signals within the second frequency band, providing the reverse RF signals within the second frequency band to the second gain block, and routing the reverse RF signals within the second frequency band, after amplification, to the output terminal.

9. The optical node of claim 8, wherein the forward path filters, the first reverse path filters, and the third reverse path filters are implemented using diplex filters.

10. The optical node of claim 8, wherein the forward path filters, the first reverse path filters, and the third reverse path filters further comprise:

a first diplex filter including a high-band filter and a mid-band filter, the first diplex filter further including a mid-band port coupled to the input terminal, a high-band port, and a common port coupled to an input of the first gain block;

a second diplex filter including a mid-band filter and a high-band filter, the second diplex filter further including a common port coupled to an output of the first gain block, a high-band port coupled to the output terminal, and a mid-band port;

a third diplex filter including a high-band filter and a mid-band filter, the third diplex filter further including a mid-band port coupled to the mid-band port of the second diplex filter, a high-band port coupled to the high-band port of the first diplex filter, and a common port; and

a fourth diplex filter including a low-band filter and a mid/high-band filter, the fourth diplex filter further including a mid/high-band port coupled to the common port of the third diplex filter, a low-band port coupled to an input of the second gain block, and a common port coupled to the input/output terminal.

11. An amplifier for amplifying signals, the amplifier comprising:

a first terminal for receiving forward signals in a first frequency band;

a second terminal for receiving reverse signals in a second frequency band and a third frequency band;

a first gain block coupled between the first terminal and the second terminal for amplifying the forward signals within the first frequency band and the reverse signals within the third frequency band,

wherein the forward signals within the first frequency band, after amplification, are provided to the second terminal for transmission from the amplifier, and wherein the reverse signals within the third frequency band, after amplification, are provided to the first terminal for transmission from the amplifier; and

a second gain block coupled between the second terminal and the first terminal for amplifying the reverse signals within the second frequency band,

wherein the reverse signals within the second frequency band, after amplification, are provided to the first terminal for transmission from the amplifier.

12. The amplifier of claim 11, wherein the first gain block comprises:

one input port for receiving forward signals within the first frequency band and for receiving reverse signals within the third frequency band;

one output port for transmitting forward signals within the first frequency band to the second terminal and for transmitting reverse signals within the third frequency band to the first terminal; and

a gain stage for amplifying the forward signals within the first frequency band and the reverse signals within the third frequency band,

wherein the gain stage provides amplification at all frequencies included within the first frequency band and the second frequency band.

13. The amplifier of claim 11, further comprising:

forward path filters for isolating the forward signals within the first frequency band, providing the forward signals within the first frequency band to the first gain block, and routing the forward signals within the first frequency band, after amplification, to the second terminal;

first reverse path filters for isolating the reverse signals within the third frequency band, providing the reverse signals within the third frequency band to the first gain block, and routing the reverse signals within the third frequency band, after amplification, to the first terminal; and

second reverse path filters for isolating the reverse signals within the second frequency band, providing the reverse signals within the second frequency band to the second gain block, and routing the reverse signals within the second frequency band, after amplification, to the first terminal.

14. The amplifier of claim 13, wherein the forward path filters, the first reverse path filters, and the second reverse path filters are implemented using diplex filters.

15. The amplifier of claim 13, wherein the forward path filters, the first reverse path filters, and the second reverse path filters further comprise:

a first diplex filter including a low-band filter and a mid/high-band filter, the first diplex filter further including a common port coupled to the first terminal, a mid/high-band port, and a low-band port coupled to an output of the second gain block;

a second diplex filter including a mid-band filter and a high-band filter, the second diplex filter further including a common port coupled to the mid/high-band port of the first diplex filter, a high-band port, and a mid-band port;

a third diplex filter including a high-band filter and a mid-band filter, the third diplex filter further including a high-band port, a mid-band port coupled to the mid-band port of the second diplex filter, and a common port coupled to an input of the first gain block;

a fourth diplex filter including a mid-band filter and a high-band filter, the fourth diplex filter further including a common port coupled to an output of the first gain block, a mid-band port, and a high-band port coupled to the high-band port of the second diplex filter;

a fifth diplex filter including a high-band filter and a mid-band filter, the fifth diplex filter further including a high-band port coupled to the high-band port of the third diplex filter, a mid-band port coupled to the mid-band port of the fourth diplex filter, and a common port;

a sixth diplex filter including a low-band filter and a mid/high-band filter, the sixth diplex filter further including a low-band port coupled to an input of the second gain block, a mid/high-band filter coupled the common port of the fifth diplex filter, and a common port coupled to the second terminal.