High linearly WiGig baseband amplifier with channel select filter
View Patent ↗A circuit comprises a Sallen-Key filter, which includes a source follower that implements a unity-gain amplifier; and a programmable-gain amplifier coupled to the Sallen-Key filter. The circuit enables programmable gain via adjustment to a current mirror copying ratio in the programmable-gain amplifier, which decouples the bandwidth of the circuit from its gain settings. The programmable-gain amplifier can comprise a differential voltage-to-current converter, a current mirror pair, and programmable output gain stages. The Sallen-Key filter and at least one branch in the programmable-gain amplifier can comprise transistors arranged in identical circuit configurations.
1. A WiGig baseband signal-processing circuit comprising:
a Sallen-Key filter comprising a source follower that implements a unity-gain amplifier; and
a programmable-gain amplifier coupled to the Sallen-Key filter, the circuit configured to provide programmable gain via adjustment to a current mirror copying ratio in the programmable-gain amplifier to decouple bandwidth of the circuit from its gain settings.
2. The WiGig baseband signal-processing circuit recited in claim 1 , wherein the programmable-gain amplifier comprises a differential voltage-to-current converter, a current mirror pair, and programmable output gain stages.
3. The WiGig baseband signal-processing circuit recited in claim 1 , configured to function as at least one of a low-pass filter, a high-pass filter, and a band-pass filter.
4. The WiGig baseband signal-processing circuit recited in claim 1 , wherein the source follower comprises a first plurality of transistors arranged in a first circuit configuration, and at least one branch within the programmable-gain amplifier comprises at least a second plurality of transistors arranged in at least a second circuit configuration, the at least second circuit configuration identical to the first circuit configuration.
5. The WiGig baseband signal-processing circuit recited in claim 4 , wherein the first and the at least second plurality of transistors have the same unit device sizes and current densities.
6. The WiGig baseband signal-processing circuit recited in claim 1 , comprising a fabrication layout that comprises a uniform array of unit devices.
7. A method for manufacturing a baseband signal-processing circuit, comprising:
employing a source follower in a Sallen-Key filter to provide unity gain; and
coupling a programmable-gain amplifier to the Sallen-Key filter to provide programmable gain via adjustment to a current mirror copying ratio in the programmable-gain amplifier, thereby decoupling bandwidth of the circuit from its gain settings.
8. The method of claim 7 , wherein the source follower comprises an active device and a load device.
9. The method of claim 8 , further comprising providing for controlling a DC level of an input signal to the Sallen-Key filter to ensure adequate headroom of at least one of the load device and devices in a current-mirror pair in the programmable-gain amplifier.
10. The method recited in claim 7 , wherein the programmable-gain amplifier comprises a differential voltage-to-current converter and programmable output gain stages.
11. The method recited in claim 7 , wherein the Sallen-Key filter is configured to function as at least one of a low-pass filter, a high-pass filter, and a band-pass filter.
12. The method recited in claim 7 , wherein the source follower comprises a first plurality of transistors arranged in a first circuit configuration, and at least one branch within the programmable-gain amplifier comprises at least a second plurality of transistors arranged in at least a second circuit configuration, the at least second circuit configuration identical to the first circuit configuration.
13. The method recited in claim 12 , wherein the first and the at least second plurality of transistors have the same unit device sizes and current densities.
14. The method recited in claim 12 , wherein each of the source follower and the programmable-gain amplifier comprises a fabrication layout comprising a uniform array of unit devices.
15. A method of operating a circuit, comprising:
controlling bandwidth of the circuit via a Sallen-Key filter comprising a source follower that implements a unity-gain amplifier; and
controlling gain of the circuit via adjustment to a current mirror copying ratio in a programmable-gain amplifier coupled to the Sallen-Key filter, wherein the bandwidth of the circuit is decoupled from its gain settings.
16. The method recited in claim 15 , wherein controlling gain further comprises adjusting a resistor ratio.
17. The method recited in claim 15 , wherein the programmable-gain amplifier comprises a differential voltage-to-current converter, a current mirror pair, and programmable output gain stages.
18. The method recited in claim 15 , further comprising employing a load device to provide a DC bias to operate the source follower.
19. The method recited in claim 18 , wherein the DC bias is controllable to ensure adequate headroom of at least one of the load device and a device in a current-mirror pair in the programmable-gain amplifier.
20. The method recited in claim 15 , further comprising controlling a DC bias input to the programmable-gain amplifier to adjust headroom of devices that provide the current mirror copying ratio.