Multi-input amplifier with degeneration switching without the use of switches
Disclosed herein are signal amplifiers that include a plurality of switchable amplifier architectures so that particular gain modes can use dedicated amplifier architectures to provide desired characteristics for those gain modes, such as low noise figure or high linearity. The disclosed signal amplifier architectures provide tailored impedances using a degeneration block or matrix without using switches in the degeneration switching block. The disclosed signal amplifier architectures provide a plurality of gain modes where different gain modes use different paths through the amplifier architecture. Switches that are used to select the path through the amplifier architecture also provide targeted impedances in a degeneration block or matrix. The switches that select the gain path are provided in the amplifier architecture and are thus not needed or used in the degeneration block, thereby reducing the size of the package for the amplifier architecture.
1 . A variable-gain signal amplifier configured to provide a plurality of gain modes, the amplifier comprising:
an input node configured to receive an input signal;
an output node configured to provide an amplified output signal;
a plurality of active cores configured to provide a corresponding plurality of gain modes, the plurality of active cores coupled to the input node and to the output node such that there is a plurality of amplification paths between the input node and the output node corresponding to the plurality of active cores and the plurality of gain modes with a particular amplification path corresponding to a particular gain mode, each active core of the plurality of active cores configured to receive the input signal from the input node and to generate the amplified output signal at the output node with a gain characteristic corresponding to the gain mode of the amplification path;
a gain mode selector having a plurality of switches that are configured to direct the input signal along a particular amplification path of the plurality of amplification paths according to the gain mode that corresponds to the amplification path; and
a degeneration matrix having a plurality of inductance paths that are configured to provide a plurality of tailored inductances each inductance path providing a tailored inductance that corresponds to a gain mode of the plurality of gain modes, the inductance path through the degeneration matrix determined by the plurality of switches in the gain mode selector so that the degeneration matrix does not include any switches.
2 . The variable-gain signal amplifier of claim 1 wherein the input signal comprises a radio frequency signal.
3 . The variable-gain signal amplifier of claim 1 further comprising a switchable reference bias circuit configured to provide a plurality of reference bias currents so that a particular reference bias current is provided to a particular active core in a corresponding gain mode.
4 . The variable-gain signal amplifier of claim 1 wherein the gain mode selector is configured to selectively provide a bypass path that bypasses the plurality of active cores.
5 . The variable-gain signal amplifier of claim 1 wherein the plurality of tailored inductances are different from one another.
6 . The variable-gain signal amplifier of claim 1 wherein the plurality of tailored impedances are configured to provide improved linearity in the amplified output signal relative to a variable gain stage that is not coupled to the degeneration matrix with the tailored impedances.
7 . The variable-gain signal amplifier of claim 1 wherein a first tailored impedance of the plurality of tailored impedances is greater than a second tailored impedance of the plurality of tailored impedances where the first tailored impedance corresponds to a first gain mode with a gain level that is less than a gain level of a second gain mode that corresponds to the second tailored impedance.
8 . The variable-gain signal amplifier of claim 1 wherein a first active core of the plurality of active cores is configured to have a lower noise figure than a second active core of the plurality of active cores.
9 . The variable-gain signal amplifier of claim 8 wherein the second active core is configured to have a higher linearity than the first active core.
10 . The variable-gain signal amplifier of claim 9 wherein a gain level of the gain mode corresponding to the first active core is higher than a gain level of the gain mode corresponding to the second active core.
11 . The variable-gain signal amplifier of claim 1 further comprising a plurality of input nodes.
12 . The variable-gain signal amplifier of claim 11 wherein the variable-gain signal amplifier is configured to receive a plurality of input signals at the plurality of input nodes, individual received signals having frequencies within different signal frequency bands.
13 . The variable-gain signal amplifier of claim 12 wherein the variable-gain signal amplifier is configured to amplify signals received at individual input ports independent of amplification of other received signals.
14 . The variable-gain signal amplifier of claim 1 further comprising a bypass block coupled to the input node and configured to be activated in a low gain mode to provide a bypass path that does not include the plurality of active cores.
15 . The variable-gain signal amplifier of claim 1 wherein each of the plurality of active cores includes a cascode buffer coupled to an output of a gain stage.
16 . A front-end module comprising:
a packaging substrate;
a variable-gain signal amplifier implemented on the packaging substrate, the variable-gain signal amplifier including an input node configured to receive an input signal; the variable-gain signal amplifier also including an output node configured to provide an amplified output signal; the variable-gain signal amplifier also including a plurality of active cores configured to provide a corresponding plurality of gain modes, the plurality of active cores coupled to the input node and to the output node such that there is a plurality of amplification paths between the input node and the output node corresponding to the plurality of active cores and the plurality of gain modes with a particular amplification path corresponding to a particular gain mode, each active core of the plurality of active cores configured to receive the input signal from the input node and to generate the amplified output signal at the output node with a gain characteristic corresponding to the gain mode of the amplification path; the variable-gain signal amplifier also including a gain mode selector having a plurality of switches that are configured to direct the input signal along a particular amplification path of the plurality of amplification paths according to the gain mode that corresponds to the amplification path; and the variable-gain signal amplifier also including a degeneration matrix having a plurality of inductance paths that are configured to provide a plurality of tailored inductances each inductance path providing a tailored inductance that corresponds to a gain mode of the plurality of gain modes, the inductance path through the degeneration matrix determined by the plurality of switches in the gain mode selector so that the degeneration matrix does not include any switches.
17 . The front-end module of claim 16 wherein the variable-gain signal amplifier further includes a switchable reference bias circuit configured to provide independent bias currents to each active core of the plurality of active cores.
18 . The front-end module of claim 16 wherein a first active core of the plurality of active cores is configured to have a lower noise figure than a second active core of the plurality of active cores and the second active core is configured to have a higher linearity than the first active core.
19 . A wireless device comprising:
an antenna;
a filter assembly coupled to the antenna to receive signals and to direct frequency bands along selected paths; and
a variable-gain signal amplifier including an input node configured to receive an input signal; the variable-gain signal amplifier also including an output node configured to provide an amplified output signal; the variable-gain signal amplifier also including a plurality of active cores configured to provide a corresponding plurality of gain modes, the plurality of active cores coupled to the input node and to the output node such that there is a plurality of amplification paths between the input node and the output node corresponding to the plurality of active cores and the plurality of gain modes with a particular amplification path corresponding to a particular gain mode, each active core of the plurality of active cores configured to receive the input signal from the input node and to generate the amplified output signal at the output node with a gain characteristic corresponding to the gain mode of the amplification path; the variable-gain signal amplifier also including a gain mode selector having a plurality of switches that are configured to direct the input signal along a particular amplification path of the plurality of amplification paths according to the gain mode that corresponds to the amplification path; and the variable-gain signal amplifier also including a degeneration matrix having a plurality of inductance paths that are configured to provide a plurality of tailored inductances each inductance path providing a tailored inductance that corresponds to a gain mode of the plurality of gain modes, the inductance path through the degeneration matrix determined by the plurality of switches in the gain mode selector so that the degeneration matrix does not include any switches.
20 . The wireless device of claim 19 wherein the variable-gain signal amplifier further includes a switchable reference bias circuit configured to provide independent bias currents to each active core of the plurality of active cores.