Front-end matching amplifier
A front-end receiver includes an amplifier that has a steady gain over a wide frequency range. The disclosed amplifier adopts an architecture in which a common-source (CS) circuit stacks against a common-gate (CG) circuit. The CG circuit provides the input impedance matching while the CS circuit boosts the amplification gain. As a result, the disclosed amplifier allows the front-end receiver to break free from a tradeoff between input impedance matching and gain boosting. Moreover, the disclosed amplifier achieves power saving and noise reduction by having the CS circuit to share the same bias current with the CG circuit.
1. An integrated circuit comprising:
an input port configured to receive a radio frequency (RF) signal; and
an amplifier coupled with the input port, the amplifier including:
a common-source (CS) circuit having a gate terminal coupled with the input port, the CS circuit defining a first transconductance based on a bias current;
a common-gate (CG) circuit having a drain terminal coupled with the CS circuit and a source terminal coupled with the input port, the CG circuit defining a second transconductance based on the bias current to match an input impedance associated with the RF signal; and
an output lead coupled with the CS circuit and the CG circuit, and the output lead configured to deliver an output current.
2. The integrated circuit of claim 1 , wherein the output current is based on a sum of the first transconductance and the second transconductance.
3. The integrated circuit of claim 1 , wherein the CG circuit maintains the second transconductance at approximately one-fiftieth of an ohm over a broadband frequency range of the RF signal.
4. The integrated circuit of claim 1 , further comprising:
a cascode circuit coupled between a drain terminal of the CS circuit and the drain terminal of the CG circuit.
5. The integrated circuit of claim 1 , further comprising:
a source bias circuit coupled to the source terminal of the CG circuit, the source bias circuit configured to conduct the bias current shared by the CS circuit and the CG circuit.
6. The integrated circuit of claim 1 , wherein:
the RF signal includes a first differential signal and a second differential signal having an opposite polarity from the first differential signal;
the gate terminal of the CS circuit is coupled with the first differential signal; and
the source terminal of the CG circuit is coupled with the second differential signal.
7. The integrated circuit of claim 1 , wherein:
the RF signal includes a first differential signal and a second differential signal having an opposite polarity from the first differential signal;
the CS circuit includes a first CS transistor having a first CS gate node coupled with the first differential signal; and
the CG circuit includes a first CG transistor having a first CG source node coupled with the second differential signal.
8. The integrated circuit of claim 7 , wherein:
the CS circuit includes a second CS transistor having a second CS gate node coupled with the second differential signal; and
the CG circuit includes a second CG transistor having a second CG source node coupled with the first differential signal.
9. The integrated circuit of claim 1 , further comprising:
an attenuation circuit coupled between the input port and the source terminal of the CG circuit, the attenuation circuit including an adjustable resistor network configured to deliver an input current to the source terminal of the CG circuit.
10. The integrated circuit of claim 9 , wherein the adjustable resistor network includes
a first resistor chain configured to conduct a primary current of the input current; and
a second resistor chain diverting from the first resistor chain, and upon being selected, the second resistor chain configured to conduct a supplementary current for supplementing the first input current.
11. An amplifier for use in a radio frequency (RF) receiver configured to receive an RF signal, the amplifier comprising:
a first common-source (CS) transistor having a first CS gate node configured to sense a first differential signal of the RF signal;
a first common-gate (CG) transistor having:
a first CG drain node coupled with the first CS transistor; and
a first CG source node configured to receive a first input current driven by a second differential signal of the RF signal, the second differential signal has an opposite polarity from the first differential signal;
a second CS transistor having a second CS gate node configured to sense the second differential signal of the RF signal; and
a second CG transistor having:
a second CG drain node coupled with the second CS transistor; and
a second CG source node configured to receive a second input current driven by the first differential signal of the RF signal.
12. The amplifier of claim 11 , wherein the first CG transistor and the second CG transistor each maintains a CG transconductance at approximately one-fiftieth of an ohm over a broadband frequency range of the RF signal.
13. The amplifier of claim 11 , wherein:
the first CS transistor and the first CG transistor are configured to share a first bias current, the first CG transistor defines a first CG transconductance based on the first bias current, and the first CS transistor defines a first CS transconductance based on the first bias current;
the first CS transistor and the first CG transistor are configured to deliver a first output current based on the first CG transconductance and the first CS transconductance;
the second CS transistor and the second CG transistor are configured to share a second bias current, the second CG transistor defines a second CG transconductance based on the second bias current, and the first CS transistor defines a second CS transconductance based on the second bias current; and
the second CS transistor and the second CG transistor are configured to deliver a second output current based on the second CG transconductance and the second CS transconductance.
14. The amplifier of claim 11 , further comprising:
a first cascode transistor coupled between a first CS drain node of the first CS transistor and the first CG drain node of the first CG transistor; and
a second cascode transistor coupled between a second CS drain node of the second CS transistor and the second CG drain node of the second CG transistor.
15. The amplifier of claim 11 , further comprising:
a first bias resistor coupled to the first CG source node of the first CG transistor, the first bias resistor is configured to conduct a first bias current passing through the first CS transistor and the first CG transistor; and
a second bias resistor coupled to the second CG source node of the second CG transistor, the second bias resistor is configured to conduct a second bias current passing through the second CS transistor and the second CG transistor.
16. A front-end (FE) receiver comprising:
an antenna configured to receive a radio frequency (RF) signal; and
an amplifier coupled with the antenna, the amplifier including:
a common-source (CS) circuit defining a first transconductance based on a bias current; and
a common-gate (CG) circuit coupled with the CS circuit and defining a second transconductance based on the bias current to match an input impedance associated with the RF signal; and
an output lead coupled with the CS circuit and the CG circuit and configured to deliver an output current based on a sum of the first transconductance and the second transconductance.
17. The FE receiver of claim 16 , wherein the CG circuit maintains the second transconductance at approximately one-fiftieth of an ohm over a broadband frequency range of the RF signal.
18. The FE receiver of claim 16 , wherein:
the RF signal includes a first differential signal and a second differential signal having an opposite polarity from the first differential signal;
the CS circuit includes:
a first CS transistor having a first CS gate node coupled with the first differential signal via a first capacitor; and
a second CS transistor having a second CS gate node coupled with the second differential signal via a second capacitor; and
the CG circuit includes:
a first CG transistor having a first CG source node coupled with the second differential signal; and
a second CG transistor having a second CG source node coupled with the first differential signal.
19. The FE receiver of claim 16 , further comprising:
an attenuation circuit coupled between the antenna and the CG circuit, the attenuation circuit including an adjustable resistor network configured to deliver an input current to the CG circuit.
20. The FE receiver of claim 16 , wherein the adjustable resistor network includes
a first resistor chain configured to conduct a primary current of the input current; and
a second resistor chain diverting from the first resistor chain, and upon being selected, the second resistor chain configured to conduct a supplementary current for supplementing the first input current.