Efficient CMOS amplifier with increased transconductance

• US 5,721,500 A
• Filed: 02/07/1996
• Issued: 02/24/1998
• Est. Priority Date: 02/07/1996
• Status: Expired due to Term

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Karanicolas, Andrew N.
• Primary Examiner(s): Callahan, Timothy P.
• Assistant Examiner(s): LAM, TUAN THIEU
• Application Number:
  US08/597,776
• Time in Patent Office: 748 Days
• Field of Search: 327/560-563, 327/103, 327/113, 327/114, 327/356, 327/358, 327/359, 327/105, 330/264, 330/265, 330/270
• US Class Current: 327/113
• CPC Class Codes: H03D 2200/0033 Current mirrors
• CPC Class Codes: H03D 2200/0043 Bias and operating point
• CPC Class Codes: H03D 2200/0084 Lowering the supply voltage and saving power
• CPC Class Codes: H03D 7/125 with field effect transistors
• CPC Class Codes: H03D 7/1441 using field-effect transistors H03D7/145 takes precedence
• CPC Class Codes: H03D 7/1458 Double balanced arrangements, i.e. where both input signals are differential
• CPC Class Codes: H03D 7/1483 comprising components for selecting a particular frequency component of the output
• CPC Class Codes: H03F 1/0261 with control of the polarisation voltage or current, e.g. gliding Class A
• CPC Class Codes: H03F 2200/294 the amplifier being a low noise amplifier [LNA]
• CPC Class Codes: H03F 2200/372 Noise reduction and elimination in amplifier
• CPC Class Codes: H03F 3/345 with field-effect devices H03F3/347 takes precedence

Abstract

An RF IC having an improved transconductance comprises a first active device of a first conductance type having a gate, a drain and a source and a second active device of a second conductance type having a gate, a drain and a source. The second active device is coupled in series with the first active device. The gate of the first active device is coupled to the gate of the second active device. A current reuse circuit is coupled to the first active device and the second active device wherein a current flowing from the drain of the first active device is reused in the second active device. Whereby transconductance is increased without an increased current utilization and without an increase in noise.

Claims

1. An RF IC having an improved transconductance, the device comprising:

a first active device of a first conductivity type having a first transconductance, a gate, a drain and a source;

a second active device of a second conductivity type having a second transconductance, a gate, a drain and a source, said second active device coupled in series with said first active device and said gate of said first active device is coupled to said gate of said second active device;

a current reuse circuit is coupled to said first active device and said second active device wherein a current flowing from said drain of said first active device is reused in said second active device;

a low pass filter coupled between said current reuse circuit and said drain of said first active device and said drain of said second active device;

whereby a total transconductance of said first and second transconductances is increased without an increased current utilization and without an increase in noise.

2. The device as recited in claim 1 wherein said first active device is an pMOS device.

3. The device as recited in claim 1 wherein said second active device is a nMOS device.

5. The device as recited in claim 1 wherein said current reuse circuit further comprises a current mirror and a bias reference current to set a bias current for said first active device and said second active device.

6. The device as recited in claim 1 further comprising a capacitor coupled from said source of said first active device to a first voltage potential.

4. The device as recited in claim I wherein said current reuse circuit steers current into said first active device and said second active device.

7. An RF LNA IC having an improved transconductance, the device comprising:

a first active device of a first conductivity type having a first transconductance, a gate, a drain and a source;

a second active device of a second conductivity type having a second transconductance, a gate, a drain and a source, said second active device coupled in series with said first active device and said gate of said first active device is coupled to said gate of said second active device;

a current reuse circuit is coupled to said first active device and said second active device wherein a current flowing from said drain of said first active device is reused in said second active device;

a low pass filter coupled between said current reuse circuit and said drain of said first active device and said drain of said second active device;

whereby a total transconductance of said first and second transconductances is increased without an increased current utilization and without an increase in noise.

8. The device as recited in claim 7 wherein said first active device is an pMOS device.

9. The device as recited in claim 7 wherein said second active device is a nMOS device.

10. The device as recited in claim 7 wherein said current reuse circuit steers current into said first active device and said second active device.

11. The device as recited in claim 7 wherein said current reuse circuit further comprises a current mirror and a bias reference current to set a bias current for said first active device and said second active device.

12. The device as recited in claim 7 further comprising a capacitor coupled from said source of said first active device to a first voltage potential.

13. An RF mixer having an improved transconductance, the device comprising:

a first active device of a first conductivity type having a first transconductance, a gate, a drain and a source;

a second active device of a second conductivity type having a second transconductance, a gate, a drain and a source, said second active device coupled in series with said first active device and said gate of said first active device is coupled to said gate of said second active device;

a current reuse circuit is coupled to said first active device and said second active device wherein a current flowing from said drain of said first active device is reused in said second active device;

a low pass filter coupled between said current reuse circuit and said drain of said first active device and said drain of said second active device;

whereby a total transconductance of said first and second transconductances is increased without an increased current utilization and without an increase in noise.

14. The device as recited in claim 13 wherein said first active device is an pMOS device.

15. The device as recited in claim 13 wherein said second active device is a nMOS device.

16. The device as recited in claim 13 wherein said current reuse circuit steers current into said first active device and said second active device.

17. The device as recited in claim 13 wherein said current reuse circuit further comprises a current mirror and a bias reference current to set a bias current for said first active device and said second active device.