Concurrent multi-band low noise amplifier architecture

Abstract

The present invention relates to a concurrent multi-band amplifiers and to a monolithic, concurrent multi-band low noise amplifier (LNA). The inventive LNA includes a three-terminal active device, such as a transistor with a characteristic transconductance, g m , disposed on a semiconductor substrate. The active device has a control input terminal, an output terminal, and a current source terminal. The amplifier also includes an input impedance matching network system, Z in , and an output load network. Z in simultaneously and independently matches the frequency-dependent input impedance of the three-terminal active device to a predetermined characteristic impedance at two or more discrete frequency bands. The output load network simultaneously provides a voltage gain, A v , to an input signal at the amplifier input at each of the two or more discrete frequency bands.

We claim:  
     
         1 . A concurrent multi-band amplifier having an input and output, comprising: 
 (a) a three-terminal active device with a characteristic transconductance, g m , and having a control input terminal, an output terminal, and a current source terminal;    (b) an input impedance matching network system, Z in , that simultaneously and independently matches the frequency-dependent input impedance of the three-terminal active device to a predetermined characteristic impedance at two or more discrete frequency bands; and    (c) an output load network that simultaneously provides a voltage gain, A v , to an input signal at the amplifier input at each of the two or more discrete frequency bands.    
     
     
         2 . A monolithic, concurrent multi-band low noise amplifier (LNA) having an input and output, comprising: 
 (a) a three-terminal active device with a characteristic transconductance, g m , and having a control input terminal, an output terminal, and a current source terminal, the device being disposed on a semiconductor substrate;    (b) an input impedance matching network system, Z in , that simultaneously and independently matches the frequency-dependent input impedance of the three-terminal active device to a predetermined characteristic impedance at two or more discrete frequency bands while minimizing the noise associated with the active device; and    (c) an output load network, Z L , that simultaneously provides a voltage gain, A v , to an input signal at the LNA input at each of the two or more discrete frequency bands.    
     
     
         3 . The multi-band LNA of  claim 2 , wherein the input impedance matching network system is defined by the equation, Z in =Z 1 +Z 2 +Z 3 +Z 4 +Z 5,  and wherein: 
 (i) Z 1  is a first two-terminal, frequency-dependent, impedance network disposed between the input of the active device and ac-ground and defined by the equation:     Z   1   =Z   g   +Z   gs   +Z′   s   +g   m    Z′   s   Z   gs,      wherein Z g  is a series impedance disposed between the LNA input and the control input terminal of the active device, Z gs  is the impedance between the control input and current source terminals and Z′ s  is the sum of the impedance between the current source terminal of the active device and ac-ground, Z s , and the intrinsic current source-to-bulk impedance, Z bs ;    (ii) Z 2  is a second two-terminal, frequency-dependent, impedance network disposed between the input of the active device and ac-ground and defined by the equation:     Z   2   =Z′   L   +Z   ƒ,      wherein Z′ L  is the sum of the load impedance between the output and ac-ground, Z L , and the intrinsic output terminal-to-bulk impedance, Z bd , and Z ƒ  is the feedback between the output terminal and control input terminal;    (iii) Z 3  is a third two-terminal, frequency-dependent, impedance network disposed between the input of the active device and ac-ground and defined by the equation:     Z   3 =[1+ Z   ƒ   /Z′   L   ]/g   mb,      wherein g mb  is the bulk effect transconductance;    (iv) Z 4  is a fourth two-terminal, frequency-dependent, impedance network disposed between the input of the active device and ac-ground and defined by the equation:                   Z   4     =       1       g   m     -     g     m                 b           ·     (       Z   f       Z   L   ′       )     ·         Z   gs     +       Z   s   ′          (     1   +       g   m          Z   gs         )           Z   gs           ;   and                     (v) Z 5  is a fifth two-terminal, frequency-dependent impedance network disposed between the input of the active device and ac-ground, which is the intrinsic control terminal-to-bulk impedance, Z gb .    
     
     
         4 . The multi-band LNA of  claim 3 , wherein Z f  and Z gb  are neglected, thereby simplifying the input impedance matching network system to Z in =Z 1 .  
     
     
         5 . The LNA of  claim 4 , further having a characteristic noise factor, F, approximated by the equation:  
       
         
           
             
               
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                               ( 
                               
                                 
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                                   Z 
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       and wherein Z in  is matched to the predetermined characteristic impedance and F is minimized by setting Z gs, +Z′ s +Z g =0 for the center frequency of each of the two or more discrete frequency bands.  
     
     
         6 . The LNA of  claim 5 , wherein the predetermined characteristic impedance and thus g m Z′ s Z gs  equals 50 ohms.  
     
     
         7 . The LNA of  claim 5 , wherein the voltage gain, A v , is defined by the equation 
         A   v   =−Z   L   /Z′   s . 
     
     
         8 . The LNA of  claim 7 , wherein the output load network is a multi-resonant load circuit disposed between the output of the three-terminal device and ac-ground that provides the voltage gain of the device at each of the discrete frequency band.  
     
     
         9 . A monolithic, concurrent dual-band low noise amplifier (LNA) having an input and output, comprising: 
 (a) a three-terminal active device with a characteristic transconductance, g m , and having a control input terminal, an output terminal, and a current source terminal, the device being disposed on a semiconductor substrate;    (b) an input impedance matching network system, Z in , associated with the active device that simultaneously and independently matches the frequency-dependent input impedance of the active device to a predetermined characteristic impedance at two discrete frequency bands, and defined by the equation:     Z   in   =Z   g   +Z   gs   +Z′   s   +g   m    Z′   s   Z   gs ,    wherein Z g  is a series impedance disposed between the LNA input and the control input terminal of the active device, Z gs  is the impedance between the control input and current source terminals, and Z′ s  is the sum of the impedance between the current source terminal of the active device and ac-ground, Z s , and the intrinsic current source-to-bulk impedance, Z bs , and    (c) an output load network, Z L , that simultaneously provides a voltage gain, A v , to an input signal at the LNA input at each of the two discrete frequency bands.    
     
     
         10 . The LNA of  claim 9 , wherein Z g +Z gs +Z′ s =0 and g m  Z′ s Z gs  equals the predetermined characteristic impedance.  
     
     
         11 . The LNA of  claim 10 , wherein the characteristic impedance and thus Z in  =50 ohms.  
     
     
         12 . The LNA of  claim 11 , wherein Z g  is a parallel LC network wire bonded to the input of the three terminal device and Z′ s  is an inductor.  
     
     
         13 . The LNA of  claim 12 , wherein the output load network, Z L , is a series LC branch in parallel with a parallel LC tank.  
     
     
         14 . A concurrent dual band LNA, having an input and an output that operates simultaneously at 2.45 GHz and 5.25 GHz center frequency bands, comprising: 
 (a) a CMOS transistor disposed on a semiconductor substrate and having a gate, g, a drain, d, a source, s, and a characteristic transconductance, g m,      (b) an input impedance network, Z in , that simultaneously and independently matches the frequency-dependent input impedance of the transistor to a 50 ohm characteristic impedance at center frequencies of 2.45 GHz and 5.25 GHz, and defined by the equations:     Z   in   =Z   g   +Z   gs   +Z′   s   +g   m    Z′   s   Z   gs , =50Ω  and Z   g   +Z   gs   +Z′   s =0     wherein: 
 (i) Z g  is an input parallel resonator having a capacitor in parallel with an inductor, disposed between the LNA input and gate and with a wire bonded to the gate,  
 (ii) Z gs  is the impedance between the gate and source, and  
 (iii) Z′ s  is an inductor disposed between the source and AC ground; and  
   (c) an output load network, Z L , that simultaneously provides a voltage gain, A v , to an input signal at the LNA input at the 2.45 GHz and 5.25 GHz center frequencies, wherein the output load network, Z L , is a series LC branch circuit, in parallel with a parallel LC tank circuit.    
     
     
         15 . The concurrent dual band LNA of  claim 14 , wherein: 
 the input parallel resonator is an approximately 0.9 pF capacitor in parallel with an approximately 2.7 nH inductor with the wire boding having an approximate inductance value of 3 nH,    Z′ s  is an approximately 0.7 nH inductor,    the series LC branch circuit is an approximately 240 fF capacitor in series with an approximately 9.8 nH inductor, and    the parallel LC tank circuit is an approximately 2.3 nH inductor in parallel with the inherent parasitic inductance of the active device.    
     
     
         16 . A method of concurrently amplifying a multi-band input signal with a three-terminal active device, including: 
 simultaneously and independently matching the frequency dependent, input impedance of the three terminal active device to a predetermined characteristic input impedance at two or more discrete frequency bands; and    simultaneously providing a voltage gain to the input signal at each of the two or more discrete frequency bands.    
     
     
         17 . The method of  claim 16  further including: 
 simultaneously minimizing the noise associated with of the impedance-matched input signal at each of the two or more discrete frequency bands.