Compact Architecture for Multipath Low Noise Amplifier

Abstract

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.

What is claimed is: 
     
         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.