Transimpedance Amplifier Circuit

• US 20160261246A1
• Filed: 09/26/2014
• Published: 09/08/2016
• Est. Priority Date: 10/25/2013
• Status: Active Grant

• Current Assignee: Nippon Telegraph and Telephone Corporation, Ntt Electronics Corporation (Nippon Telegraph and Telephone Corporation)
• Original Assignee: Nippon Telegraph and Telephone Corporation, Ntt Electronics Corporation (Nippon Telegraph and Telephone Corporation)
• Inventors: KOIZUMI, Hiroshi, NOGAWA, Masafumi, TOBAYASHI, Masatoshi, ENDO, Masahiro
• Granted Patent: US 9,853,618 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H03F 2200/408 the output amplifying stage of an amplifier comprising three power stages
• CPC Class Codes: H03F 2203/45142 At least one diode being added at the input of a dif amp
• CPC Class Codes: H03F 2203/45212 the differential amplifier being designed to have a reduced offset
• CPC Class Codes: H03F 2203/45288 Differential amplifier with circuit arrangements to enhance the transconductance
• CPC Class Codes: H03F 3/082 with FET's H03F3/085 takes precedence
• CPC Class Codes: H03F 3/087 with IC amplifier blocks H03F3/085 takes precedence
• CPC Class Codes: H03F 3/45179 using MOSFET transistors as the active amplifying circuit H03F3/45278 takes precedence
• CPC Class Codes: H03F 3/45475 using IC blocks as the active amplifying circuit
• CPC Class Codes: H03F 3/45744 by offset reduction
• CPC Class Codes: H03F 3/45968 by offset reduction
• CPC Class Codes: H03G 3/3052 in bandpass amplifiers (H.F. or I.F.) or in frequency-changers used in a (super)heterodyne receiver H03G3/32, H03G3/34 take precedence
• CPC Class Codes: H03G 3/3084 in receivers or transmitters for electromagnetic waves other than radiowaves, e.g. lightwaves H03G3/32, H03G3/34 take precedence
• CPC Class Codes: H04B 10/58 Compensation for non-linear transmitter output
• CPC Class Codes: H04B 10/6931 Automatic gain control of the preamplifier

Abstract

A transimpedance amplifier circuit (1) includes an amplifier (22) that amplifies a received signal, an automatic gain control (AGC) circuit (2) that controls the amplification gain of the amplifier by a first time constant in accordance with the level of the received signal, and a first selection circuit (25) that selects the first time constant from a plurality of predetermined values. This can simultaneously implement a short time constant of an AGC function necessary to instantaneously respond to a burst signal and a long time constant of the AGC function necessary to obtain a satisfactory bit error rate (BER) characteristic in a continuous signal by an inexpensive and compact circuit arrangement.

Claims

1. A transimpedance amplifier circuit comprising:

an amplifier that amplifies a received signal;

an automatic gain control circuit that controls an amplification gain of the amplifier by a first time constant in accordance with a level of the received signal; and

a first selection circuit that selects the first time constant from a plurality of predetermined values.

2. The transimpedance amplifier circuit according to claim 1, wherein the first selection circuit changes, based on a control signal, at least one of a resistance value of a resistive element and a capacitance value of a capacitive element which decide a value of the first time constant.

3. The transimpedance amplifier circuit according to claim 1, wherein the first selection circuit includes:

a plurality of resistive elements or a plurality of capacitive elements included in the automatic gain control circuit; and

a first switch element connected in series or parallel with at least some of the plurality of resistive elements or the plurality of capacitive elements and turned on or off based on the control signal to change one of the resistance value of the resistive element and the capacitance value of the capacitive element which decide the value of the first time constant.

4. The transimpedance amplifier circuit according to claim 3, wherein the first switch element comprises a MOS transistor, and

the control signal is applied to a gate terminal of the MOS transistor.

5. The transimpedance amplifier circuit according to claim 3, wherein the control signal of the first switch element is a logic signal of at least 2 bits, and

the first switch element switches the first time constant between a plurality of predetermined discrete values in accordance with a value of the logic signal.

6. The transimpedance amplifier circuit according to claim 1, further comprising a received signal detection circuit that detects the received signal and outputs a first control signal when a continuous reception time of the received signal exceeds a predetermined time,

wherein the first selection circuit selects, based on the first control signal, a longer time constant for the first time constant from at least two predetermined-values.

7. The transimpedance amplifier circuit according to claim 6, wherein the received signal detection circuit outputs a second control signal upon detecting a loss of the received signal, and

the first selection circuit selects, based on the second control signal, a shorter time constant for the first time constant from at least two predetermined-values.

8. The transimpedance amplifier circuit according to claim 1, further comprising:

an automatic offset control circuit that outputs a differential signal based on an output of the amplifier and controls an offset amount of the differential signal by a second time constant; and

a second selection circuit that selects the second time constant from a plurality of predetermined values.

9. The transimpedance amplifier circuit according to claim 8, wherein the second selection circuit changes, based on a control signal, at least one of a resistance value of a resistive element and a capacitance value of a capacitive element which decide a value of the second time constant.

10. The transimpedance amplifier circuit according to claim 8, wherein the second selection circuit includes:

a plurality of resistive elements or a plurality of capacitive elements included in the automatic offset control circuit; and

a second switch element connected in series or parallel with at least some of the plurality of resistive elements or the plurality of capacitive elements and turned on or off based on the control signal to change one of the resistance value of the resistive element and the capacitance value of the capacitive element which decide the value of the second time constant.

11. The transimpedance amplifier circuit according to claim 10, wherein the second switch element comprises a MOS transistor, and

the control signal is applied to a gate terminal of the MOS transistor.

12. The transimpedance amplifier circuit according to claim 10, wherein the control signal of the second switch element is a logic signal of at least 2 bits, and

the second switch element switches the second time constant between a plurality of predetermined discrete values in accordance with a value of the logic signal.

13. The transimpedance amplifier circuit according to claim 8, further comprising a received signal detection circuit that detects the received signal and outputs a first control signal when a continuous reception time of the received signal exceeds a predetermined time,

wherein the second selection circuit selects, based on the first control signal, a longer time constant for the second time constant from at least two predetermined-values.

14. The transimpedance amplifier circuit according to claim 13, wherein the received signal detection circuit outputs a second control signal upon detecting a loss of the received signal, and

the second selection circuit selects, based on the second control signal, a shorter time constant for the second time constant from at least two predetermined-values.