Field effect transconductance amplifiers
First Claim
1. A field effect device amplifier comprising first and second field effect devices each having source, drain and gate connections, said gate of said first field effect device being coupled to the amplifier input, said drain of said first field effect device being coupled to said source of said second field effect device and to the amplifier output, said amplifier also having means for substantially shorting said gate of said second field effect device to its said source for the intended operating frequency range of said amplifier, said field effect devices being biased to operate in a partial carrier velocity limited region, selected to provide a dependence of the output conductance of said field effect devices on drain current which approximates that of the transconductance of said field effect devices.
0 Assignments
0 Petitions
Accused Products
Abstract
Field effect transconductance amplifiers having improved linearity and noise rejection characteristics to provide an amplifier output having excellent temporal coherence with the input signal are disclosed. The amplifiers utilize a series connection of two field effect devices, actual or emulated, preferably appropriately biased in a carrier velocity limited region to maximize linearity of the output. A high level of rejection of power supply noise may be achieved by a third series field effect device. Various embodiments including high gain and power amplifier embodiments are disclosed.
76 Citations
39 Claims
- 1. A field effect device amplifier comprising first and second field effect devices each having source, drain and gate connections, said gate of said first field effect device being coupled to the amplifier input, said drain of said first field effect device being coupled to said source of said second field effect device and to the amplifier output, said amplifier also having means for substantially shorting said gate of said second field effect device to its said source for the intended operating frequency range of said amplifier, said field effect devices being biased to operate in a partial carrier velocity limited region, selected to provide a dependence of the output conductance of said field effect devices on drain current which approximates that of the transconductance of said field effect devices.
-
21. A two stage field effect device amplifier comprising first, second, third and fourth field effect devices each having source, drain and gate connections, said gate of said first field effect device being coupled to the amplifier input, said drain of said first field effect device being coupled to said source of said second field effect device, said amplifier also having means for substantially shorting said gate of said second field effect device to its said source for the intended operating frequency range of said amplifier, said first and second field field effect devices being biased to operate in a partial carrier velocity limited region, whereby the dependence of the output conductance of said first and second field effect devices on drain current is reduced to approximate that of the transconductance of said field effect devices, said gate of said third field effect device being capacitively coupled to said drain of said first field effect device, said drain of said third field effect device being coupled to said source of said fourth field effect device and to the amplifier output, said amplifier also having means for substantially shorting said gate of said fourth field effect device to its said source for the intended operating frequency range of said amplifier, said third and fourth field effect devices being biased to operate in a partial carrier velocity limited region, whereby the dependence of the output conductance of said field effect devices on drain current is reduced to approximate that of the transconductance of said field effect devices, said drain of said first and said third field effect devices being coupled together through resistive means to provide feed-forward between stages.
- 22. A field effect device amplifier comprising first, second and third field effect devices each having source, drain and gate connections, said gate of said first field effect device being coupled to the amplifier input, said drain of said first field effect device being coupled to said source of said second field effect device and to the amplifier output, said amplifier also having means for substantially shorting said gate of said second field effect device to its said source for the intended operating frequency range of said amplifier, said source of said third field effect device being coupled to said drain of said second field effect device, said gate of said third field effect device being capacitively coupled to said source of said first field effect device, said source of said first field effect device and said drain of said third field effect device each being coupled to one power supply connection.
Specification