Compact Architecture for Multipath Low Noise Amplifier
Methods and devices used in mobile receiver front end to support multiple paths and multiple frequency bands are described. The presented devices and methods provide benefits of scalability, frequency band agility, as well as size reduction by using one low noise amplifier per simultaneous outputs. Based on the disclosed teachings, variable gain amplification of multiband signals is also presented.
The present application is related to U.S. Pat. No. 9,941,849 issued Apr. 10, 2018, entitled “Programmable Optimized Band switching LNA for Operation in Multiple Narrow-Band Frequency Ranges”, application Ser. No. 15/616,824 filed Jun. 7, 2017, entitled “LNA with Variable Gain and Switched Degeneration Inductor”, U.S. Pat. No. 9,973,149 issued May 15, 2018, entitled “Source Switched Split LNA”, and application Ser. No. 15/846,055 filed Dec. 18, 2017, entitled “Switchless Multi Input Stacked Transistor Amplifier Tree Structure”, all incorporated herein by reference in their entirety.
BACKGROUND Technical FieldThe present disclosure is related to low noise amplifiers (LNA), and more particularly to methods and apparatus used in mobile receiver front end to support multiple paths and multiple frequency bands.
BackgroundLow noise amplifier (LNA) front end circuits for mobile communication continue to increase in complexity requiring support for multiple frequency bands and for multiple amplifier paths active at the same time (carrier aggregation and/or dual connectivity). As an example, in the Long Term Evolution (LTE) standard, carrier aggregation is used to increase the bandwidth. Such carrier aggregation may comprise various operation modes such as intra-band continuous/non-continuous carrier aggregation and inter-band carrier aggregation. As a result, receivers supporting these various modes are needed. At the same time, RF front end suppliers are pushed to make design changes rapidly while reducing device size and cost. In other words, demand for reducing the size and manufacturing costs of mobile communication equipment is ever increasing while miniaturization of such equipment has become an essential design requirement.
SUMMARYMethods and devices taught in the present disclosure address the challenging and conflicting design requirements described in the previous section. The described methods and devices provide LNA designs allowing for easier modifications of the band inputs and the number of supported outputs. Such methods and devices aim to reduce the device size by essentially using one LNA per simultaneous outputs.
According to a first aspect of the present disclosure, a radio frequency (RF) receiver is provided comprising: a plurality of current gain blocks; and a plurality of output loads; wherein: (i) each current gain block is selectively connected to one or more output loads of the plurality of the output loads; (ii) a current gain block of the plurality of current gain blocks is configured to: receive an input signal; generate one or more amplified signals corresponding to the input signal, and (iii) an output load of the plurality of output loads is configured to receive corresponding one or more amplified signals and to generate corresponding one or more output signals.
According to a second aspect of the present disclosure, a method of amplifying a signal with a spectrum comprising multiple frequency bands is provided comprising: providing one or more current gain blocks; providing one or more output loads; connecting each gain block of the one or more current gain blocks to one or more output loads; amplifying at least one signal corresponding to one or more frequency bands of the multiple frequency bands to generate one or more amplified signals, and driving at least one output loads of the one or more output loads using the one or more amplified signals to generate at least one or more amplified output signals.
According to a third aspect of the present disclosure, a radio frequency (RF) receiver front end is provided comprising: a plurality of band filters corresponding to one or more frequency bands representing an input signal; one or more band switches; one or more current gain blocks connecting each a corresponding band switch of the one or more band switches to one or more output loads; wherein: each band switch is configured to select at least one frequency band filter of the plurality of band filters; a current gain block corresponding to the band switch is configured to selectively tune into the at least one frequency band of the one or more frequency bands; the at least one frequency band filter of the one or more frequency band filters receives the input signal to generate a filtered signal; the current gain block is configured to receive the filtered signal to generate one or more amplified signals; and the one or more output loads are configured to receive the one or more amplified signals and to generate corresponding one or more output signals.
The term “current gain block” is referred herewith to an electronic circuit that amplifies an input signal thereby generating current to drive an output load.
The term “folded architecture” is referred herewith to an LNA architecture using a combination of negative metal oxide (NMOS) and positive metal oxide (PMOS) transistors in current gain and load stages to provide support for smaller available power supply voltage headroom imposed by design requirements.
DescriptionMethods and devices in accordance with the present disclosure are presented, providing LNA designs allowing for easier modifications of the band inputs and the number of supported outputs. Such methods and devices:
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- offer band agility, covering as many bands as possible with one LNA
- aim toward size reduction by using one LNA per simultaneous outputs
- support step-variable gain for low Noise Figure (NF) in high gain states and high linearity in low gain states.
With further reference to
With further reference to
A combination of
With reference to
With reference to current gain block (gm1) of
With continued reference to
where the term “Re” represents the real part and ω is an angular frequency. The above-mentioned formula may be used to set a desired gain and impedance adapted for a given frequency band. As mentioned previously, each current gain block (gm1, . . . , gm6) may be designed to have various states corresponding to various frequency bands. Depending on the receiver requirement, one of such frequency bands may be chosen to be tuned into. For a different application, different parameter values may be used to support a potentially new and different frequency band.
Referring to
Referring back to
As described previously, the teachings of the present disclosure provide methods and devices for supporting step-variable gain for low Noise Figure (NF) in high gain states and high linearity in low gain states.
A number of embodiments of the invention have been described. It is to be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, some of the steps described above may be order independent, and thus can be performed in an order different from that described. Further, some of the steps described above may be optional. Various activities described with respect to the methods identified above can be executed in repetitive, serial, or parallel fashion.
It is to be understood that the foregoing description is intended to illustrate and not to limit the scope of the invention, which is defined by the scope of the following claims, and that other embodiments are within the scope of the claims. (Note that the parenthetical labels for claim elements are for ease of referring to such elements, and do not in themselves indicate a particular required ordering or enumeration of elements; further, such labels may be reused in dependent claims as references to additional elements without being regarded as starting a conflicting labeling sequence).
Claims
1. A radio frequency (RF) receiver comprising:
- a plurality of current gain blocks; and
- a plurality of output loads;
- wherein: (i) each current gain block is selectively connected to one or more output loads of the plurality of the output loads; (ii) a current gain block of the plurality of current gain blocks is configured to: receive an input signal; generate one or more amplified signals corresponding to the input signal, and (iii) an output load of the plurality of output loads is configured to receive corresponding one or more amplified signals and to generate corresponding one or more output signals.
2. The RF receiver of claim 1, wherein the plurality of current gain blocks and the plurality of output loads are implemented on a same chip or die.
3. The receiver of claim 1, wherein:
- the plurality of current gain blocks are tunable;
- the input signal corresponds to one or more frequency bands; and
- the current gain block of the plurality of current gain blocks is further configured to tune into the one or more frequency bands.
4. The RF receiver of claim 3, wherein the output loads are tunable supporting a second frequency band including a combination of the one or more first frequency bands supported by corresponding current gain blocks.
5. The RF receiver of claim 1, wherein each current gain block of the plurality of current gain blocks comprises:
- one or more gain transistors;
- a first variable capacitor coupled across gate and source of a gain transistor of the one or more gain transistors;
- one or more cascode transistors coupling the one or more gain transistors to corresponding one or more output loads of the plurality of output loads; and
- drains of the one or more cascode transistors are connectable to a power supply via an RF choke.
6. The RF receiver of claim 1, wherein each current gain block of the plurality of current gain blocks comprises:
- one or more gain transistors;
- a first variable inductor coupling sources of the one or more gain transistors to a first reference voltage or ground;
- one or more cascode transistors coupling the one or more gain transistors to corresponding one or more output loads of the plurality of output loads; and
- drains of the one or more cascode transistors are connectable to a power supply via an RF choke.
7. The RF receiver of claim 5, wherein each current gain block of plurality of current gain blocks further comprises a first variable inductor coupling sources of the one or more gain transistors to a first reference voltage or ground.
8. The RF receiver of claim 7, wherein a combination of the variable capacitor and the variable inductor is used to tune a corresponding current gain block to a corresponding one or more frequency bands.
9. The RF receiver of claim 8, wherein a combination of the variable capacitor and the variable inductor is used to set a desired gain and impedance adapted to the corresponding one or more frequency bands.
10. The RF receiver of claim 7, wherein the output loads comprise:
- an RF choke; and
- a transistor stack coupling the cascode transistors to a second variable inductor coupled to a second reference voltage or ground;.
11. The RF receiver of claim 7, wherein the output loads comprise an RF choke; and
- a transistor stack and a second variable capacitor;
- wherein the second variable capacitor couples the transistor stack to output terminals of the output load;
12. The RF receiver of claim 11, wherein:
- the transistor stack couples the cascode transistors to a second variable inductor coupled to a second reference voltage or ground; and
- a combination of the second variable conductor and the second variable capacitor is used for tuning purposes.
13. The RF receiver of claim 12, wherein the transistor stack comprises PMOS transistors.
14. The RF receiver of claim 13, configured to receive bias voltages via gates of the cascode transistors.
15. The RF receiver of claim 14, wherein the cascode transistors are configured to be in ON or OFF states in correspondence with applied bias voltages.
16. The RF receiver of claim 15, wherein each output load is configured to receive an amplified signal from only one of corresponding current gain blocks of the plurality of current gain blocks.
17. The RF receiver of claim 1, wherein at least one current gain block of the plurality of current gain blocks is different from all other current gain blocks of the plurality of gain blocks.
18. The RF receiver of claim 1, wherein all current gain blocks of the plurality of current gain blocks are the same.
19. The RF receiver of claim 1, wherein each current gain block of the plurality of current gain blocks is different from any other gain block of the plurality of current gain blocks.
20. The RF receiver of claim 7, wherein at least one of the current gain blocks of the plurality of current gain blocks has a variable gain.
21. The receiver of claim 12, further comprising a first switch and a second switch configured to control a signal through the current gain block wherein:
- the first switch is coupled across a combination of the gain transistors and the cascode transistors;
- the second switch couples an input terminal to an output terminal;
- in a first gain state, the first switch is closed and the second switch is open, thereby bypassing the one or more gain transistors, and creating a first signal path from the input terminal to the output terminal through the transistor stack;
- in a second gain state, the first switch is open and the second switch is open, thereby bypassing the stacked transistors and creating a second signal path from the input terminal to the output terminal via a combination of the one or more gain transistors and the one or more cascode transistors; and
- in a third state, the first switch is open and the second switch is closed, thereby creating a third path directly from the input terminal to the output terminal without amplification.
22. The receiver of claim 12, further comprising a first switch and a second switch configured to control a gain of the current gain block wherein:
- the first switch is coupled across a combination of the gain transistors and the cascode transistors,
- the second switch is coupled across the stacked transistors;
- in a first state, the first switch is closed, and the second switch is open, thereby creating a first signal path from the input terminal to the output terminal through the stacked transistors;
- in a second state, the first switch is open and the second switch is closed, thereby bypassing the stacked transistors and creating a second signal path from the input terminal to the output terminal via a combination of the one or more gain transistors and the one or more cascode transistors; and
- in a third state, the first switch and the second switch are closed, thereby bypassing the stacked transistors and the gain transistors and creating a third signal path from the input terminal to the output terminal.
23. A method of amplifying a signal with a spectrum comprising multiple frequency bands:
- providing one or more current gain blocks;
- providing one or more output loads;
- connecting each gain block of the one or more current gain blocks to one or more output loads;
- amplifying at least one signal corresponding to one or more frequency bands of the multiple frequency bands to generate one or more amplified signals, and
- driving at least one output loads of the one or more output loads using the one or more amplified signals to generate at least one or more amplified output signals.
24. The method of claim 23, wherein the one or more amplified output signals comprises two or more amplified output signals.
25. A radio frequency (RF) receiver front end comprising:
- a plurality of band filters corresponding to one or more frequency bands representing an input signal;
- one or more band switches;
- one or more current gain blocks connecting each a corresponding band switch of the one or more band switches to one or more output loads;
- wherein: each band switch is configured to select at least one frequency band filter of the plurality of band filters; a current gain block corresponding to the band switch is configured to selectively tune into the at least one frequency band of the one or more frequency bands; the at least one frequency band filter of the one or more frequency band filters receives the input signal to generate a filtered signal; the current gain block is configured to receive the filtered signal to generate one or more amplified signals; and the one or more output loads are configured to receive the one or more amplified signals and to generate corresponding one or more output signals.
Type: Application
Filed: Sep 19, 2018
Publication Date: Mar 19, 2020
Inventor: Jonathan James Klaren (San Diego, CA)
Application Number: 16/135,965