Wide tuning range operational transconductance amplifiers

• US 5,392,003 A
• Filed: 08/09/1993
• Issued: 02/21/1995
• Est. Priority Date: 08/09/1993
• Status: Expired due to Term

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Nag, Manbir, Heck, Joseph P.
• Primary Examiner(s): MOTTOLA, STEVEN J
• Application Number:
  US08/103,655
• Time in Patent Office: 561 Days
• Field of Search: 330/252, 330/253, 330/254, 330/258, 330/300, 330/259
• US Class Current: 330/254
• CPC Class Codes: H03F 3/45076 characterised by the way of implementation of the active amplifying circuit in the differential amplifier
• CPC Class Codes: H03F 3/45479 characterised by the way of common mode signal rejection
• CPC Class Codes: H03H 11/0422 using transconductance amplifiers, e.g. gmC filters
• CPC Class Codes: H03H 11/42 Gyrators used in frequency selective networks H03H11/08

Abstract

A wide dynamic range Operational Transconductance Amplifier (OTA) (100) includes a differential voltage to current converter (206) for converting an input voltage to a current level. A pair of programmable folded cascodes (201) are coupled to the output of the converter (206) in order to render the amplifier (100) programmable. Current sources (222 and 226) are employed to provide output sourcing current. There is also included a common mode feedback (106) for maintaining the output signal substantially and equally centered between rails of the operating voltage (208).

Claims

1. A wide dynamic range tunable Operational Transconductance Amplifier (OTA) having an output and an operating voltage, comprising:

a differential voltage to current converter, including;

an output;

at least one low noise large input swing amplifier;

at least one current source coupled to the amplifier;

a pair of programmable folded cascode stages each DC coupled to the output of the converter without utilizing additional coupling amplifiers, the folded cascode stages including;

a common base amplifier;

a programmable amplifier coupled to the common base amplifier for rendering the folded cascode stages programmable;

means for maintaining the output signal substantially and equally centered between rails of the operating voltage; and

a pair of current sources DC coupled to the pair of programmable folded cascode stages to provide variable output sourcing current.

2. An integrated low voltage wide dynamic range Operational Transconductance Amplifier (OTA), comprising:

a differential voltage to current converter;

a programmable differential folded cascode stage DC coupled to the differential voltage to current converter without additional coupling amplifiers, including;

a differential amplifier stage having a gain;

a differential current source coupled to the amplifier stage;

a differential programmable stage coupled to the amplifier stage and the current source for programming the gain of the amplifier stage and

a pair of current sources DC coupled to the programmable differential folded cascode stage.

3. The integrated low voltage wide dynamic range OTA of claim 2, further including means for maintaining the output signal substantially and equally centered between rails of the operating voltage.

4. The integrated low voltage wide dynamic range OTA of claim 2, further including a pair of current sources to provide output sourcing current.

5. The integrated low voltage wide dynamic range OTA of claim 2, wherein the differential programmable stage includes at least one transistor.

6. The integrated low voltage wide dynamic range OTA of claim 2, wherein the differential voltage to current converter comprises:

an output;

at least one low noise large input swing amplifier; and

at least one current source coupled to the amplifier.

7. An integrated gyrator, comprising:

at least one Operational Transconductance Amplifier (OTA), comprising;

a differential voltage to current converter;

a programmable differential folded cascode stage DC coupled to the differential voltage to current converter without additional coupling amplifiers, including;

a differential amplifier stage having a gain;

a differential current source coupled to the amplifier stage;

a differential programmable stage coupled to the amplifier stage and the current source for programming the gain of the amplifier stage and a pair of current sources DC coupled to the programmable differential folded cascode stage.

8. An integrated filter, comprising:

at least one gyrator operating on a low supply voltage, comprising;

at least one OTA, comprising;

a differential voltage to current converter;

a programmable differential folded cascode stage DC coupled to the differential voltage to current converter without additional coupling amplifiers, including;

a differential amplifier stage having a gain;

a differential current source coupled to the amplifier stage;

a differential programmable stage coupled to the amplifier stage and the current source for programming the gain of the amplifier stage and a pair of current sources DC coupled to the programmable differential folded cascode stage.

10. The integrated filter of claim 8, further including a pair of current sources to provide output sourcing current.

11. The integrated filter of claim 8, wherein the differential programmable stage includes at least one transistor.

9. The integrated filter of claim 9, further including means for maintaining the output signal substantially and equally centered between rails of the operating voltage.

12. A radio communication device, comprising:

a receiver for receiving radio frequency signal;

a variable bandwidth filter, comprising;

at least one gyrator operating on a low supply voltage, comprising at least one OTA, comprising;

a differential voltage to current converter;

a programmable differential folded cascode stage DC coupled to the differential voltage to current converter without utilizing addition a coupling amplifiers, including;

a differential amplifier stage having a gain;

a differential current source coupled to the amplifier stage;

a differential programmable stage coupled to the amplifier stage and the current source for programming the gain of the amplifier stage and

a pair of current sources DC coupled to the programmable differential folded cascode stage;