Mixer with Feedback

Abstract

A method and system for increasing the compression point of a receiver by deriving a feedback signal from mixer output signals. The feedback signal prevents the receiver from going into compression on strong out-of-band or blocking signals, while enhancing the receiver gain at the desired frequency. The desired frequency coincides with the local oscillator (LO) signal and is therefore particularly applicable for, but not limited to, homodyne receivers where selectivity can be made quite narrowband. Since the selectivity is coupled to the LO, a tunable receiver may be achieved that enables selectivity over a wide range of input frequencies.

1 . A method of providing feedback from a mixer to a preceding amplifier in a receiver, comprising:
 receiving a radio frequency signal at the radio frequency receiver;   generating a frequency translated signal from the radio frequency signal;   deriving a feedback signal from a combination of mixer output signals, the feedback signal being a function of a frequency of the radio frequency signal; and   providing the feedback signal to the preceding amplifier in the receiver.   
   
   
       2 . The method according to  claim 1 , wherein the feedback signal is derived from a feedback network connected to the mixer, the feedback network including frequency selective elements capable of separating out the feedback signal from an output of the mixer. 
   
   
       3 . The method according to  claim 2 , wherein the feedback network is a first order network. 
   
   
       4 . The method according to  claim 2 , wherein the feedback network is a higher order network. 
   
   
       5 . The method according to  claim 2 , wherein the feedback network uses single-loop feedback. 
   
   
       6 . The method according to  claim 2 , wherein the feedback network uses multiple feedback loops, and at least one feedback loop provides the feedback signal to the preceding amplifier. 
   
   
       7 . The method according to  claim 1 , wherein the mixer is a single-balanced mixer. 
   
   
       8 . The method according to  claim 1 , wherein the mixer is a double-balanced mixer. 
   
   
       9 . The method according to  claim 1 , wherein the mixer is a quadrature mixer. 
   
   
       10 . The method according to  claim 1 , wherein the preceding amplifier is a low noise amplifier and the feedback signal is provided to the low noise amplifier. 
   
   
       11 . A radio frequency receiver having a mixer feedback, the radio frequency receiver comprising:
 a low noise amplifier configured to receive a radio frequency signal, the radio frequency signal having a baseband signal carried thereon;   a mixer configured to mix the radio frequency signal with a local oscillator signal to recover the baseband signal; and   a feedback network connecting the mixer to the low noise amplifier, the feedback network providing a feedback signal to the low noise amplifier, wherein the feedback signal is a function of a frequency of the radio frequency signal.   
   
   
       12 . The receiver according to  claim 11 , wherein the feedback network includes frequency selective elements capable of separating out the feedback signal from an output of the mixer. 
   
   
       13 . The receiver according to  claim 11 , wherein the feedback network is a first order network. 
   
   
       14 . The receiver according to  claim 11 , wherein the feedback network is a higher order network. 
   
   
       15 . The receiver according to  claim 11 , wherein the feedback network comprises a single-loop feedback. 
   
   
       16 . The receiver according to  claim 11 , wherein the feedback network comprises a multiple feedback loops, and at least one feedback loop provides the feedback signal to the low noise amplifier. 
   
   
       17 . The receiver according to  claim 11 , wherein the mixer is a single-balanced mixer. 
   
   
       18 . The receiver according to  claim 11 , wherein the mixer is a double-balanced mixer. 
   
   
       19 . The receiver according to  claim 11 , wherein the mixer is a quadrature mixer. 
   
   
       20 . The receiver according to  claim 11 , wherein receiver is integrated on a single application-specific integrated circuit (ASIC). 
   
   
       21 . A radio frequency receiver having feedback from a mixer of the receiver to an input stage of the receiver, the radio frequency receiver comprising:
 an amplifier configured to receive a radio frequency signal, the radio frequency signal having a baseband signal carried thereon;   a mixer configured to mix the radio frequency signal with a local oscillator signal, the mixer having at least a high-pass output path and a low-pass output path; and   a feedback network connecting the mixer to the low noise amplifier, the feedback network providing a feedback signal from the high-pass output path to the low noise amplifier.   
   
   
       22 . The radio frequency receiver according to  claim 21 , wherein the receiver is implemented using a common-base low noise amplifier with shunt feedback and the feedback network is connected to an emitter of the low noise amplifier. 
   
   
       23 . The radio frequency receiver according to  claim 21 , wherein the receiver is implemented using a differential common-base low noise amplifier with mixer shunt feedback. 
   
   
       24 . The radio frequency receiver according to  claim 21 , wherein the receiver is implemented using a common-emitter low noise amplifier with dual loop mixer feedback. 
   
   
       25 . The radio frequency receiver according to  claim 21 , wherein the receiver is implemented using a common-emitter low noise amplifier with a higher-order mixer feedback. 
   
   
       26 . The radio frequency according to  claim 21 , wherein the feedback signal is derived from the feedback network connected to the output of the mixer, the feedback network including series connected capacitors shunting output currents of the output of the mixer. 
   
   
       27 . A method of providing feedback from a mixer to a preceding amplifier in a receiver, comprising:
 receiving a radio frequency signal at the radio frequency receiver;   generating a frequency translated signal from the radio frequency signal;   deriving a feedback signal from a combination of mixer output signals, the feedback signal being a function of a frequency of the radio frequency signal, the feedback signal operating on an instantaneous performance of the radio frequency signal, wherein the feedback signal is derived from a feedback network connected to the output of the mixer, the feedback network including series connected capacitors shunting output currents of the output of the mixer; and   providing the feedback signal to the preceding amplifier in the receiver.   
   
   
       28 . A radio frequency receiver having a mixer feedback, the radio frequency receiver comprising:
 a low noise amplifier configured to receive a radio frequency signal, the radio frequency signal having a baseband signal carried thereon;   a mixer configured to mix the radio frequency signal with a local oscillator signal to recover the baseband signal; and   a feedback network connecting the mixer to the low noise amplifier, the feedback network providing a feedback signal to the low noise amplifier, wherein the feedback signal is a function of a frequency of the radio frequency signal and operates on an instantaneous performance of the radio frequency signal and the feedback signal is derived from the feedback network connected to the output of the mixer;   wherein the feedback network including series connected capacitors shunting output currents of the output of the mixer.