Differential source follower having 6dB gain with applications to WiGig baseband filters
A differential amplifier comprising a first upper device and a first lower device series coupled between two power supplies and a second upper device and a second lower device series coupled between the two power supplies. A first DC voltage enables the first upper device and the second upper device and a second DC voltage regulates current flow in the first lower device and the second lower device. An AC signal component is coupled to the first upper device and the second lower device while the AC signal complement is coupled to the first lower device and the second upper device. A first output signal between the first upper device and the first lower device. Separate RC networks couple the AC signals to their respective device. A first and second output signal forms between the upper device and the lower device, respectively. All the devices are same channel type.
1. A differential amplifier comprising:
a first upper device and a first lower device series coupled between two power supplies;
a second upper device and a second lower device series coupled between said two power supplies;
a first DC voltage enables said first upper device and said second upper device;
a second DC voltage regulates current flow in said first lower device and said second lower device;
said first upper device and said second lower device coupled to an AC signal component;
said first lower device and said second upper device coupled to a complement of said AC signal component;
a first output signal between said first upper device and said first lower device;
a second output signal between said second upper device and said second lower device;
all said devices are same channel type;
a first RC network coupling said AC signal component to said first upper device;
a second RC network coupling said AC signal component to said second lower device;
a third RC network coupling said complement of said AC signal component to said first lower device;
and
a fourth RC network coupling said complement of said AC signal component to said second upper device, whereby
said first RC network is equivalent to said fourth RC network and said second RC network is equivalent to said third RC network.
2. The differential amplifier of claim 1 , further comprising:
said first RC network coupling said first DC voltage to said first upper device;
said second RC network coupling said second DC voltage to said second lower device;
said third RC network coupling said second DC voltage to said first lower device; and
said fourth RC network coupling said first DC voltage to said second upper device.
3. The differential amplifier of claim 2 , further comprising:
a reference current; and
a first device connected in saturation providing a load for said reference current; thereby generating said second DC voltage.
4. The differential amplifier of claim 3 , whereby
all devices are N-MOS devices.
5. The differential amplifier of claim 3 , wherein
a third, output signal is generated between said first output signal and said second output, signal.
6. The differential amplifier of claim 3 , whereby
said two power supplies are VDD and GRD.
7. The differential amplifier of claim 5 , wherein
said first output signal is the inverse of said second output signal.
8. The differential amplifier of claim 7 , wherein
said third output signal is a differential signal.
9. The differential amplifier of claim 1 , wherein
said AC signal components are coupled to said upper and lower devices by a corresponding capacitor of said corresponding RC network.