Wideband coupled input impedance matching LNA architecture
Circuits and methods for a radio frequency amplifier, such as an LNA, that include a wideband coupled input impedance matching network. One embodiment includes a first inductor coupled between a first terminal and a first node, the first terminal couplable to a degeneration terminal of an amplifier core; a second inductor coupled between a second terminal and either the first node or a second node, the second terminal couplable to an input terminal of the amplifier core; a third inductor coupled between the first node and a third terminal, the third terminal couplable to a reference potential; and, in a variant embodiment, a fourth inductor coupled between the second node and a fourth terminal, the fourth terminal couplable to the reference potential; wherein the first inductor and the second inductor are mutually coupled. Some embodiments allow multiple modes to allow tradeoffs of gain versus linearity and NF characteristics.
1. A wideband coupled input impedance matching network including:
(a) a first inductor coupled between a first terminal and a first node, the first terminal configured to be coupled to a degeneration terminal of an amplifier core;
(b) a second inductor coupled between a second terminal and the first node, the second terminal configured to be coupled to an input terminal of the amplifier core; and
(c) a third inductor coupled between the first node and a third terminal, the third terminal configured to be coupled to a reference potential;
wherein the first inductor and the second inductor are mutually coupled.
2. The invention of claim 1 , wherein the mutual coupling of the first inductor and the second inductor is negative.
3. The invention of claim 1 , wherein the mutual coupling of the first inductor and the second inductor is positive.
4. The invention of claim 1 , wherein the amplifier core, the first inductor, and the second inductor are co-fabricated on an integrated circuit die.
5. The invention of claim 1 , wherein the amplifier core is fabricated on an integrated circuit die, and the first inductor and the second inductor are located external to the integrated circuit die.
6. The invention of claim 1 , wherein the first inductor comprises a plurality of parallel inductances.
7. The invention of claim 1 , wherein the first inductor and the second inductor comprise mutually coupled segments of an integrated circuit transformer coil.
8. The invention of claim 1 , wherein the first inductor comprises a first selectable inductance coupled in series with a second selectable inductance.
9. The invention of claim 8 , wherein the second inductor and the first selectable inductance are mutually coupled in a first selectable state, and the second inductor and a series sum of the first and second selectable inductances are mutually coupled in a second selectable state.
10. The invention of claim 1 , further including a series inductor coupled between the input terminal of the amplifier core and a radio frequency input terminal of the amplifier core, wherein the second terminal of the wideband input impedance matching network is configured to be coupled to the input terminal of the amplifier core through the series inductor.