LOW-NOISE AMPLIFIER WITH SEGMENTED CORE AND TUNABLE RESISTIVE FEEDBACK

Embodiments of a low noise amplifier (LNA) device and methods of operating the same are disclosed. In some embodiments, the LNA device includes an LNA input node, an LNA amplification core coupled to the LNA input node, and an LNA amplification core that includes LNA amplification segments. Each of the LNA amplification segments are configured to amplify the RF signal and are configured to be activated and deactivated. The LNA amplification core is configured to activate and deactivate the LNA amplification segments in accordance with the LNA core control input. A tunable feedback impedance is coupled between the LNA input node and the LNA amplification core. The tunable feedback impedance has a variable impedance that is set in accordance with the LNA core control input. The LNA amplification segments and the tunable feedback impedance are operated in a manner that optimizes KPIs depending on the input RF signal.

FIELD OF THE DISCLOSURE

This disclosure relates generally to low noise amplifiers (LNAs) and methods of operating the same.

BACKGROUND

In radio frequency (RF) front end circuitry, low noise amplifiers (LNAs) are commonly used to amplify wireless signals received on an antenna. As wireless technology evolves, the number and variations of wireless communications protocols increase and may encompass multiple operating modes. As such, LNAs sometimes need to be provided in high gain, medium gain, and low gain modes. Larger LNA amplification cores are advantageous in high gain modes while smaller LNA amplification cores are used in lower gain modes. Having multiple LNA amplification cores for each mode is expensive and complicated. Thus, simplified LNA cores that can operate in different modes are needed.

SUMMARY

Embodiments of a low noise amplifier (LNA) device and methods of operating the same are disclosed. In some embodiments, the LNA device includes an LNA input node, an LNA amplification core coupled to the LNA input node, and an LNA amplification core that includes LNA amplification segments. Each of the LNA amplification segments is configured to amplify the RF signal and is configured to be activated and deactivated. The LNA amplification core is configured to activate and deactivate the LNA amplification segments in accordance with the LNA core control input. A tunable feedback impedance is coupled between the LNA input node and the LNA amplification core. The tunable feedback impedance has a variable impedance that is set in accordance with the LNA core control input. Accordingly, the LNA amplification device has an LNA amplification core that has different segments that are activated depending on the gain to be used to amplify the RF signal. The tunable feedback impedance insures that regardless of which of the segments is activated, the LNA amplification device maintains essentially the same input impedance.

In some embodiments, a low noise amplifier (LNA) device, includes: an LNA input node for receiving a radio frequency (RF) signal; an LNA amplification core coupled to the LNA input node, wherein: the LNA amplification core includes LNA amplification segments; each of the LNA amplification segments is configured to amplify the RF signal; each of the LNA amplification segments is configured to be activated and deactivated; the LNA amplification core is configured to activate and deactivate the LNA amplification segments in accordance with an LNA core control input; and a tunable feedback impedance coupled between the LNA input node and the LNA amplification core, the tunable feedback impedance has a variable impedance that is set in accordance with the LNA core control input. In some embodiments, the variable impedance of the tunable feedback impedance is set by the LNA core control input such that an input impedance at the LNA input node is such that all inband input return loss (IRL) is better that 10 dB and inband S11for a given frequency band stays within the same quadrant of the Smith chart. In some embodiments, each LNA amplification segment of the LNA amplification segments includes: a different pair of field effect transistors (FETs), wherein the FETs in the pair of FETs are stacked; a different switch device that is coupled in shunt between the pair of FETs in the LNA amplification segment, wherein the LNA amplification segment is configured to be activated by the switch device such that the pair of FETs amplify the RF signal and is configured to be deactivated by the switch device such that the pair of FETs do not amplify the RF signal. In some embodiments, the LNA amplification core is coupled between a first node and a second node wherein, for each of the LNA amplification segments: each of the LNA amplification segments includes a different intermediary node; the switch device is coupled in shunt to the intermediary node; a first one of the pair of FETs has a first drain coupled to the first node and a first source coupled to the different intermediary node; a second one of the pair of the FETs has a second drain coupled to the intermediary node and a second source coupled to the second node. In some embodiments, a first gate of the first one of the pair of FETs in each of the LNA amplification segments is configured to receive a different bias voltage; a second gate of the second one of the pair of FETs in each of the LNA amplification segments is coupled to receive the RF input signal and is configured to receive a same bias voltage. In some embodiments, the tunable feedback impedance is connected between the first node and the LNA input node. In some embodiments, the LNA device further includes: an LNA output node that transmits the RF signal after amplification by the LNA amplification core; and an output matching impedance connected between the first node and the LNA output node. In some embodiments, the LNA device further includes a power node configured to receive a power voltage; an inductor coupled between the power node and the first node. In some embodiments, the LNA device further includes; a reference node configured to receive a reference voltage; an inductor coupled between the second node and the reference node. In some embodiments, the LNA core control input includes a control word having bits, wherein each bit of the bits in the control word determines whether a different one of the LNA amplification segments is activated or deactivated. In some embodiments, the tunable feedback impedance having a resistive device a first device terminal and a second resistive terminal; the tunable feedback impedance includes a resistive device includes resistive segments coupled between the first device terminal and the second device terminal; each resistive segment of the resistive segments includes a different resistor and a different switchable bypass path that is configured to bypass the resistor when activated and provide a resistance of the resistor between the first device terminal and the second device terminal when deactivated; each of bits is configured to cause a different one of the resistive segments to activate and deactivate the switchable bypass path for the resistive segment to thereby vary the variable impedance of the tunable feedback impedance.

In some embodiments, a low noise amplifier (LNA) device, includes: an LNA input node for receiving a radio frequency (RF) signal; an LNA amplification core coupled to the LNA input node, wherein: the LNA amplification core includes LNA amplification segments; each of the LNA amplification segments is configured to amplify the RF signal; each of the LNA amplification segments is configured to be activated and deactivated; the LNA amplification core is configured to activate and deactivate the LNA amplification segments in accordance with an LNA core control input; and a tunable feedback impedance coupled between the LNA input node and the LNA amplification core, the tunable feedback impedance has a variable impedance that is set such that an input impedance at the LNA input node is such that all inband input return loss (IRL) is better that 10 dB and inband S11for a given frequency band stays within the same quadrant of the Smith chart. In some embodiments, each LNA amplification segment of the LNA amplification segments includes: a different pair of field effect transistors (FETs), wherein the FETs in the pair of FETs are stacked; a different switch device that is coupled in shunt between the pair of FETs in the LNA amplification segment, wherein the LNA amplification segment is configured to be activated by the switch device such that the pair of FETs amplify the RF signal and is configured to be deactivated by the switch device such that the pair of FETs do not amplify the RF signal. In some embodiments, the LNA amplification core is coupled between a first node and a second node wherein, for each of the LNA amplification segments: each of the LNA amplification segments includes a different intermediary node; the switch device is coupled in shunt to the intermediary node; a first one of the pair of FETs has a first drain coupled to the first node and a first source coupled to a different intermediary node; a second one of the pair of the FETs has a second drain coupled to the intermediary node and a second source coupled to the second node. In some embodiments, a first gate of the first one of the pair of FETs in each of the LNA amplification segments is configured to receive a different bias voltage; a second gate of the second one of the pair of FETs in each of the LNA amplification segments is coupled to receive the RF input signal and is configured to receive a same bias voltage. In some embodiments, the tunable feedback impedance is connected between the first node and the LNA input node. In some embodiments, the LNA device further includes: an LNA output node that transmits the RF signal after amplification by the LNA amplification core; and an output matching impedance connected between the first node and the LNA output node. In some embodiments, the LNA core control input includes a control word having bits, wherein each bit of the bits in the control word determines whether a different one of the LNA amplification segments is activated or deactivated. In some embodiments, the tunable feedback impedance having a resistive device a first device terminal and a second resistive terminal; the tunable feedback impedance includes a resistive device includes resistive segments coupled between the first device terminal and the second device terminal; each resistive segment of the resistive segments includes a different resistor and a different switchable bypass path that is configured to bypass the resistor when activated and provide a resistance of the resistor between the first device terminal and the second device terminal when deactivated; each of the bits is configured to cause a different one of the resistive segments to activate and deactivate the switchable bypass path for the resistive segment to thereby vary the variable impedance of the tunable feedback impedance.

In some embodiments, a method of providing low noise amplification to a radio frequency (RF) signal, includes: receiving a low noise amplifier (LNA) core control input; performing one or more of (a) activating one or more LNA amplification segments in an LNA amplification core in accordance with the LNA core control input, and (b) deactivating one or more of the LNA amplification segments in the LNA amplification core in accordance with the LNA core control input to provide activated set of one or more of the LNA amplification segments; tuning a variable impedance of a tunable feedback impedance coupled between an LNA input node and the LNA amplification core in accordance with the LNA core control input; receiving the RF signal at the LNA input node; and amplifying the RF signal with the activated set of one or more LNA amplification segments.

In some embodiments, a user element includes a low noise amplifier (LNA) device, the LNA includes: an LNA input node for receiving a radio frequency (RF) signal; an LNA amplification core coupled to the LNA input node, wherein: the LNA amplification core comprises LNA amplification segments; each of the LNA amplification segments is configured to amplify the RF signal; each of the LNA amplification segments is configured to be activated and deactivated; the LNA amplification core is configured to activate and deactivate the LNA amplification segments in accordance with an LNA core control input; and a tunable feedback impedance coupled between the LNA input node and the LNA amplification core, the tunable feedback impedance has a variable impedance that is set in accordance with the LNA core control input.

DETAILED DESCRIPTION

FIG.1is a low noise amplifier (LNA) device100, in accordance with some embodiments.

In some embodiments, the LNA device100is provided in a front-end module of a user equipment (not explicitly shown), such as a smartphone, tablet, or laptop. The LNA device100have several modes of operation that correspond to the modes of operation of front-end circuitry of the user equipment. Each mode of operation of the LNA device has different key performance indicators (KPIs) for optimal performance in the user equipment. The KPIs include: gain, noise figure, linearity (IIP3), and current consumption. In some embodiments, the LNA device100is configured to keep input return loss (IRL) and output return loss (ORL) substantially constant. The LNA device100is configured to tune its KPIs for better performance within the user equipment. More specifically, the LNA device100gives a better system performance by trading off different KPIs at different modes by using a segmented LNA core and countering the change in IRL using resistive feedback, as explained in further detail below.

The LNA device100is configured to amplify a radio frequency (RF) signal104. In some embodiments, the RF signal104is a receive signal received from an antenna (not explicitly shown) of the user equipment. The LNA device100is configured to provide low noise amplification to the RF signal104. After amplification by the LNA device100, the amplified RF signal105is transmitted to downstream circuitry so as to demodulate the amplified RF signal and extract data from the output RF signal105.

InFIG.1, the LNA device100includes an LNA input node RFin and an LNA output node RFout. The LNA device100is configured to receive the RF signal104at the LNA input node RFin and output the amplified RF signal105from the LNA output node RFout. The LNA device100also includes an LNA amplification core102, a tunable feedback impedance106, a power terminal108, an output matching impedance109, an inductor110, an inductor112and a capacitor114.

The LNA amplification core102is configured to receive the RF signal104from the LNA input node RFin. The LNA amplification core102is coupled between a node116and a node118. In this embodiment, the node116operates as a feedback node. More specifically, the tunable feedback impedance106is connected between the node116and the LNA input node RFin. The capacitor114is connected between the LNA input node RFin and the input node120of the LNA amplification core102. The LNA amplification core102is configured to amplify the RF signal104, wherein the amplified RF signal105is then output from the node116. The power terminal108is configured to receive a power voltage Vdd. In some embodiments, the power voltage Vdd is a regulated power voltage. In some embodiments, the power voltage Vdd is a power source voltage from a power source (e.g., battery). The inductor110is coupled between the power node108and the node116. The inductor110blocks RF signal to the power terminal108. The inductor112is connected between the node118and a reference node122. The reference node122is configured to receive a reference voltage. In this embodiment, the reference node122is a ground node and the reference voltage is a ground voltage. The inductor112block RF signals to the reference node122. Inductors110and112are also part of the frequency match of the LNA device100.

When the RF signal104at the LNA input node RFin has low input power, the LNA amplification core102is configured to operate with a high gain and low noise figure. The high gain and low noise figure are important KPIs for overall system performance. When the RF signal104at the LNA input node RFin has high input power, the LNA amplification core102is configured to operate with a low gain. Low gain is important in maintaining low current consumption and high IIP3, which are more important KPIs for overall system performance in this situation. In some embodiments, a KPI is an input signal power range, wherein the input signal power range is from a thermal noise floor to about −10 dBm. In some embodiments, another example of a KPI is a gain range, wherein the gain range is from 21 dB to −15 dB. In some embodiments, a KPI is an Idd range, wherein the Idd range is from 15 mA to 2 mA. However, it should be noted that these are simply exemplary and that the KPIs may depend strongly on application and ADC ranges. Exemplary KPIs are listed above.

In order to provide a single LNA device that simultaneously meets all KPIs at both high and low gain modes, the LNA amplification core102of the LNA device100is segmented and the LNA device100includes the tunable feedback impedance106. The segmentation of the LNA device100allows the LNA device100to switch from high to low gain modes. However, switching from high to low gain modes can change the input impedance of the LNA device100as seen at the LNA input node RFin. Accordingly, the tunable resistive feedback is tuned in the different modes so as to maintain the input impedance at the LNA input node RFin substantially the same in the different modes of operation.

InFIG.1, the LNA amplification core102includes LNA amplification segments130A,130B,130C. The LNA amplification core102includes three LNA amplification segments130A,130B,130C. In other embodiments, the LNA amplification core102includes two or more LNA amplification segments. Each of the LNA amplification segments130A,130B,130C are configured to be activated and deactivated. In higher gain modes, more of the LNA amplification segments130A,130B,130C are activated and for lower gain modes less of the LNA amplification segments130A,130B,130C are activated. In one embodiment, there are gains states 0-9. For gain states 0-2, all of the LNA amplification segments130A,130B,130C are active. For gain state 3-4, the LNA amplification segments130A,130B are active and the LNA amplification segment130C is deactivated. For gain states 5-7, the LNA amplification segment130B is active and the LNA amplification segments130A,130C are deactivated.

The LNA amplification segment130A includes a common gate field effect transistor (FET)132A and a common source FET134A. InFIG.1, the common gate FET132A and the common source FET134A are each N-channel FETs (NFETs). A gate of the common gate FET132A is configured to receive a bias gate voltage VG2. The drain of the common gate FET132A is coupled to the node116. A source of the common gate FET132A is coupled to an intermediary node136A. A drain of the common source FET134A is coupled to the intermediary node136A. A source of the common source FET134A is coupled to the node118. The gate of the common source FET134A is coupled through the capacitor114to the LNA input node RFin to receive the RF signal104at the input node120. The gate of the common source FET134A is also configured to receive a bias voltage VG1. A switch device138A is connected in shunt to the intermediary node136A. Accordingly, in response to the switch device138A being closed, the LNA amplification segment130A is deactivated. In response to the switch device138A being opened, the LNA amplification segment130A is activated.

The LNA amplification segment130B includes a common gate FET132B and a common source FET134B. InFIG.1, the common gate FET132B and the common source FET134B are each N-channel FETs (NFETs). A gate of the common gate FET132B is configured to receive a bias gate voltage VG3. The drain of the common gate FET132B is coupled to the node116. A source of the common gate FET132B is coupled to an intermediary node136B. A drain of the common source FET134B is coupled to the intermediary node136B. A source of the common source FET134B is coupled to the node118. The gate of the common source FET134B is coupled through the capacitor114to the LNA input node RFin to receive the RF signal104at the input node120. The gate of the common source FET134B is also configured to receive the bias voltage VG1. A switch device138B is connected in shunt to the intermediary node136B. Accordingly, in response to the switch device138B being closed, the LNA amplification segment130B is deactivated. In response to the switch device138B being opened, the LNA amplification segment130B is activated.

The LNA amplification segment130C includes a common gate FET132C and a common source FET134C. InFIG.1, the common gate FET132C and the common source FET134C are each NFETs. A gate of the common gate FET132C is configured to receive a bias gate voltage VG4. The drain of the common gate FET132C is coupled to the node116. A source of the common gate FET132C is coupled to an intermediary node136C. A drain of the common source FET134C is coupled to the intermediary node136C. A source of the common source FET134C is coupled to the node118. A gate of the common source FET134C is coupled through the capacitor114to the LNA input node RFin to receive the RF signal104at the input node120. The gate of the common source FET134C is also configured to receive a bias voltage VG1. A switch device138C is connected in shunt to the intermediary node136C. Accordingly, in response to the switch device138C being closed, the LNA amplification segment130C is deactivated. In response to the switch device138C being opened, the LNA amplification segment130C is activated.

Each of the LNA amplification segments130A,130B,130C includes a different pair of the FETs (132A,134A), (132B,134B), (132C,134C). The FETs (132A,134A), (132B,134B), (132C,134C) are stacked since the source of the FETs (132A,132B,132C) are coupled to the drain of the FETs (134A,134B,134C). The different switch device (138A,138B,138C) is coupled in shunt between the pair of the FETs (132A,134A), (132B,134B), (132C,134C) in the LNA amplification segment130A,130B,130C. For each of the LNA amplification segments130A,130B,130C, the LNA amplification segment130A,130B,130C is configured to be activated by the switch device (138A,138B,138C) such that the pair of FETs (132A,134A), (132B,134B), (132C,134C) amplify the RF signal102and is configured to be deactivated by the switch device (138A,138B,138C) such that the pair of the FETs (132A,134A), (132B,134B), (132C,134C) do not amplify the RF signal104. In this manner, different LNA amplification segments130A,130B,130C can be activated and deactivated to amplify the RF signal104. As such, for each of the LNA amplification segment130A,130B,130C, the LNA amplification segment130A,130B,130C is configured to be activated by the switch device138A,138B,138C such that the pair of the FETs (132A,134A), (132B,134B), (132C,134C) amplify the RF signal104and is configured to be deactivated by the switch device138A,138B,138C such that the pair of the FETs (132A,134A), (132B,134B), (132C,134C) do not amplify the RF signal104.

Each of the LNA amplification segments130A,130B,130C includes the different intermediary node136A,136B,136C. The switch device138A,138B,138C of each of the LNA amplification segments130A,130B,130C is coupled in shunt to the intermediary node136A,136B,136C. The FET132A,132B,132C of each of the LNA amplification segments130A,130B,130C has a drain coupled to the node116and first source coupled to the intermediary node136A,136B,136C of the LNA amplification segments130A,130B,130C. The FET134A,134B,134C of each of the LNA amplification segments130A,130B,130C has a drain coupled to the intermediary node136A,136B,136C of the LNA amplification segments130A,130B,130C and a source coupled to the node118. A gate of the FET132A,132B,132C of each of the LNA amplification segments130A,130B,130C is configured to receive a different bias voltage VG2, VG3, VG4. A gate of the FET134A,134B,134C of each of the LNA amplification segments130A,130B,130C is coupled to receive the RF signal104and is configured to receive the same bias voltage VG1.

The LNA output node RFout transmits the amplified RF signal105after amplification by the LNA amplification core102. The output matching impedance109is connected between the node116and the LNA output node RFout. The output matching impedance109is configured to provide an impedance to match the impedance of the LNA device100at the LNA output node RFout to the load impedance at the LNA output node RFout. In some embodiments, the output match also varies. However, the output match is primarily used for tuning the LNA device100to different frequency bands. Nevertheless, some minor changes to ORL can be obtained if needed.

The LNA device100is configured to receive an LNA core control input140. The LNA amplification segments130A,130B,130C are activated and deactivated in accordance with the LNA core control input140. In some embodiments, the LNA core control input140corresponds to different modes of the front-end circuitry that the LNA device100has put in. Thus, the LNA amplification segments130A,130B,130C are activated and deactivated in accordance to what mode the front-end circuitry is operating in.

As the different LNA amplification segments130A,130B,130C are activated and deactivated, the input impedance at the RF input terminal RFin can change. The tunable feedback impedance106has a variable impedance that is set by the LNA core control input140such that the input impedance at the LNA input node RFin stays substantially equal regardless of which of the LNA amplification segments130A,130B,130C that are activated and deactivated. How this is met practically is application dependent. In some embodiments, the IRL as a dot in the smith chart is best, the smaller the area the better and within the same quadrant. The IRL ofFIG.6Bis better than the IRL ofFIG.6A. In some embodiments, the base value for variance of the input impedance depends on an input filter impedance. All inband IRL (|dB|) are better than 10 dB and inband S11for a given frequency band stays within the same quadrant of the Smith chart. Additionally, in some embodiments, inband S11in smith chart for a given frequency band should overlay as much as possible across gain states. The node116is therefore a feedback node as the tunable feedback impedance106is connected between the node116and the LNA input node RFin.

InFIG.1, the tunable feedback impedance106includes a variable resistive device142and a capacitor144connected in series. The variable resistive device142has a variable resistance that can be varied in order to vary the variable impedance of the tunable feedback impedance106. In this embodiment, the capacitor144is a fixed capacitor. In other embodiments, the capacitor is a variable capacitor with a variable capacitance that can be varied. The impedance can also be variable using components in a combination of series and shunt configuration which a combination of fixed and variable components. In other embodiments, the tunable feedback impedance106includes a fixed or a variable impedance. Furthermore, in other embodiments, the tunable feedback impedance106may have any arrangement suitable for matching the input impedance.

FIG.2is an LNA amplification core200, in accordance with some embodiments.

InFIG.2, the LNA core control input140(SeeFIG.1) is a control word that includes three bits Segm<2>, Segm<1>, Segm<0>. Each of the three bits Segm<2>, Segm<1>, Segm<0> is received by a different one of the switch devices202A,202B,202C. With regard to the switch device202A, the switch device202A is an NFET. A drain of the switch device202A is connected to the intermediary node136A. When the bit Segm<2> is in a low voltage state, the switch device202A is deactivated. When the bit Segm<2> is in a high voltage state, the switch device202A is activated. In this manner, the LNA amplification segment130A is activated and deactivated depending on the voltage state of the bit Segm<2>.

With regard to the switch device202B, the switch device202B is a NFET. A drain of the switch device202B is connected to intermediary node136B. When the bit Segm<1> is in a low voltage state, the switch device202B is deactivated. When the bit Segm<1> is in a high voltage state, the switch device202B is activated. In this manner, the LNA amplification segment130B is activated and deactivated depending on the voltage state of the bit Segm<1>.

With regard to the switch device202C, the switch device202C is an NFET. A drain of the switch device202C is connected to intermediary node136C. When the bit Segm<0> is in a low voltage state, the switch device202B is deactivated. When the bit Segm<0> is in a high voltage state, the switch device202C is activated. In this manner, the LNA amplification segment130C is activated and deactivated depending on the voltage state of the bit Segm<0>.

FIG.3is a variable resistive device300, in accordance with some embodiments.

The variable resistive device300is configured to provide a variable resistance. More specifically, the variable resistive device300has a first device terminal P1and a second resistive terminal P2. The resistive device300has resistive segments302,304,306,308coupled between the first device terminal P1and the second device terminal P2. The resistive segment302includes the resistor R1and is connected to the first resistive terminal P1. The resistive segment304is connected between the resistive segment302and the resistive segment306. The resistive segment306is connected between the resistive segment304and the resistive segment308. The resistive segment308is connected to the second resistive terminal P2.

With respect to the resistive segments304,306,308, each of the resistive segments304,306,308includes a different resistor R2, R3, R4, and a different switchable bypass path310,312,314. The switchable bypass path310includes a FET that is configured to receive the bit Segm<2> (See alsoFIG.2.) so that the FET is activated and deactivated in accordance with the bit Segm<2>. In response to the FET in the switchable bypass path310being turned on, a resistance of the resistor R2is bypassed. In response to the FET in the switchable bypass path310being activated, a resistance of the resistor R2is provided between the resistive terminals P1, P2.

The switchable bypass path312includes a FET, wherein the FET is configured to receive the bit Segm<1> (See alsoFIG.2.) so that the FET is activated and deactivated in accordance with the bit Segm<1>. In response to the FET in the switchable bypass path312being turned on, a resistance of the resistor R3is bypassed. In response to the FET in the switchable bypass path312being activated, a resistance of the resistor R3is provided between the resistive terminals P1, P2.

The switchable bypass path314includes a FET that is configured to receive the bit Segm<0> (See alsoFIG.2.) so that the FET is activated and deactivated in accordance with the bit Segm<0>. In response to the FET in the switchable bypass path314being turned on, a resistance of the resistor R4is bypassed. In response to the FET in the switchable bypass path312being activated, a resistance of the resistor R4is provided between the resistive terminals P1, P2. By utilizing the control word bits Segm<2>, Segm<1>, Segm<0> to introduce or bypass the resistances R2, R3, R4, the resistance of the resistive device300is varied in accordance to which LNA amplification segments130A,130B,130C are activated and deactivated.

In some embodiments, control of the segmented LNA amplification core200and the variable resistive device300(i.e., tunable feedback impedance300) is done using the same control bits segm<2>, segm<1>, segm<0> or by using different control bits Ina_segm<2>, Ina_segm<1>, Ina_segm<0>, fb_segm<2>, fb_segm<1>, fb_segm<0> from the control system802(SeeFIG.8). In other embodiments, the number of control bits used for the segmented LNA amplification core200and the variable resistive device300are different.

FIG.4andFIG.5are Smith Charts that shows the effect of using resistive feedback to re-align IRL in the LNA amplification device100as a result of a change of number of the active LNA amplification segments130A,130B,130C, in accordance with some embodiments.

The reference IRL for best matching to the receive filter is with all of the LNA amplification segments130A,130B,130C active (here G2 mode). G3 mode disables a number of segments of the LNA amplification segments130A,130B,130C, and the IRL moves ‘out’ in the Smith chart. Thus, matching to the receive filter changes between G2 and G3, which changes transfer function of the receive filter, which again may degrade the system performance. By adding resistive feedback, the IRL can be re-aligned very close to the reference IRL. Thus, recreating a good match to the receive filter and restoring good system performance. G5 mode (SeeFIG.5) disables more of the LNA amplification segments130A,130B,130C and the IRL moved further out in the Smith Chart. As the shift in the IRL from an even smaller LNA core is greater, then a smaller resistance is needed to re-align the IRL.

FIG.6AandFIG.6Bare Smith Charts wherein the LNA is used in 3 steps and, in G0-G2 modes, all of the LNA amplification segments130A,130B,130C are active, in G3-G4 modes, some of the LNA amplification segments130A,130B,130C are active, and, in G5-G7 modes, one of the LNA amplification segments130A,130B,130C is active. As shown, with the tunable feedback impedance106, the IRL becomes centered at the same area of the smith chart enabling a much-improved match to the receive filter.

FIG.7is a flow diagram700of a method of providing low noise amplification to the RF signal104, in accordance with some embodiments.

In some embodiments, the flow diagram700is performed by the LNA device100shown inFIG.1. The flow diagram700includes blocks702-708. Flow begins at the block702.

At the block702, an LNA core control input is received. An example of the LNA core control input is the LNA core control input140inFIG.1. Flow then proceeds to the block704.

At the block704, one or more of (a) activating one or more LNA amplification segments in an LNA amplification core in accordance with the LNA core control input, and (b) deactivating one or more of the LNA amplification segments in the LNA amplification core in accordance with the LNA core control input is performed to provide activated set of one or more of the LNA amplification segments. An example of the LNA amplification core is the LNA amplification core104shown inFIG.1. An example of the LNA amplification segments is the LNA amplification segments130A-130C inFIG.1. Flow then proceeds to the block706.

At the block706, a variable impedance of a tunable feedback impedance coupled between an LNA input node and the LNA amplification core in accordance with the LNA core control input. An example of the LNA input node is the LNA input node RFin shown inFIG.1. An example of the tunable feedback impedance is the tunable feedback impedance106inFIG.1. Flow then proceeds to the block708.

At the block708, an RF signal is received at the LNA input node. Flow then proceeds to the block710.

At the block710, the RF signal is amplified with the activated set of one or more LNA amplification segments.

With reference toFIG.8, the concepts described above may be implemented in various types of user elements800, such as mobile terminals, smart watches, tablets, computers, navigation devices, access points, and like wireless communication devices that support wireless communications, such as cellular, wireless local area network (WLAN), Bluetooth, and near field communications.

The user element800will generally include a control system802, a baseband processor804, transmit circuitry806, receive circuitry808, antenna switching circuitry810, multiple antennas812, and user interface circuitry814. In a non-limiting example, the control system802may be a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC). In this regard, the control system802may include at least a microprocessor(s), an embedded memory circuit(s), and a communication bus interface(s). The receive circuitry808receives radio frequency signals via the antennas812and through the antenna switching circuitry810from one or more base stations. A low noise amplifier and a filter cooperate to amplify and remove broadband interference from the received signal for processing. Downconversion and digitization circuitry (not shown) will then downconvert the filtered, received signal to an intermediate or baseband frequency signal, which is then digitized into one or more digital streams using analog-to-digital converter(s) (ADC).

The baseband processor804processes the digitized received signal to extract the information or data bits conveyed in the received signal. This processing typically comprises demodulation, decoding, and error correction operations, as will be discussed in greater detail below. The baseband processor804is generally implemented in one or more digital signal processors (DSPs) and application specific integrated circuits (ASICs).

For transmission, the baseband processor804receives digitized data, which may represent voice, data, or control information, from the control system802, which it encodes for transmission. The encoded data is output to the transmit circuitry806, where a digital-to-analog converter(s) (DAC) converts the digitally encoded data into an analog signal and a modulator modulates the analog signal onto a carrier signal that is at a desired transmit frequency or frequencies. A power amplifier will amplify the modulated carrier signal to a level appropriate for transmission and deliver the modulated carrier signal to the antennas812through the antenna switching circuitry810. The multiple antennas812and the replicated transmit and receive circuitries806,808may provide spatial diversity. Modulation and processing details will be understood by those skilled in the art.