BACKGROUND

All wireless mobile devices (DECT, GSM, 3G, LTE, WiMax, Wi-Fi 802.11 n/ac, ULE 802.11ah etc.) including low noise amplifiers (LNAs) and Voltage Control Oscillators (VCOs) require stable over process tank resonant circuits—which are tank resonant circuits that are stable despite process variations.

FIG. 1illustrates a prior art amplifier topology10with a CRTMOM (an inter-digitated metal-oxide-metal multi-finger capacitor formed by multiple metal layers) C14at the input. Capacitor C14and inductor L15are coupled in parallel to each other between first input port IN_P11and second input port IN_N19.

The first input port IN_P11is connected to first transistor T112of a first output circuit that also includes a first resistor R114, and a first output port OUT_P13.

The second input port IN_N19is connected to second transistor T218of a second output circuit that also includes a second resistor R217and a second output port OUT_N16.

FIG. 2illustrates a simulation of a CRTMOM capacitor based amplifier topology simulation results over process variation. The simulation illustrates substantial difference in the response of the circuit at the presence of process variations. InFIG. 2—the X-axis represents the frequency band in GHz and Y-axis represents the amplitude response (voltage gain) in dB of the amplifier over the frequency band.

InFIG. 2M34is an amplifier amplitude response related to the slow-slow (ss) process variation corner with maximum voltage gain of 31.44 dB at 2.43 GHz. M35is an amplifier amplitude response related to the typical-typical (tt) process variation corner with maximum voltage gain of 34.1 dB at 2.49 GHz. M36is an amplifier amplitude response related to the fast-fast (ff) process variation corner with maximum voltage gain of 36.27 dB at 2.53 GHz.

There is a need to control and compensate frequency drifts over the process variation, especially for the Low Power CMOS process.

