The performance of silicon amplifiers in D-band is limited by the low gain of transistors operated close to fmax. Cascode stages, yielding higher gain than a single device, are commonly preferred, but the issue is only partially alleviated. Recognizing that the common-emitter (CE) transistor limits the gain of the cascode, this work investigates the use of a local reactive feedback to trade gain for stability. Feedback shifts the CE into a conditionally-stable operating region, and enables a gain beyond its maximum available gain (MAG). Then, when the CE is combined with a common-base, by properly selecting impedance terminations, the resulting cascode displays unconditional stability with superior gain. The concept is exploited in the design of a D-band LNA in BiCMOS 55 nm technology which shows 22.8 dB gain, 130-165 GHz operating frequency and NF down to 5 dB with 40 mW power consumption. Measured results compare favorably against state of the art.

A SiGe BiCMOS D-Band LNA with Gain Boosted by Local Feedback in Common-Emitter Transistors

Piotto L.;Bilato A.;Mazzanti A.
2023-01-01

Abstract

The performance of silicon amplifiers in D-band is limited by the low gain of transistors operated close to fmax. Cascode stages, yielding higher gain than a single device, are commonly preferred, but the issue is only partially alleviated. Recognizing that the common-emitter (CE) transistor limits the gain of the cascode, this work investigates the use of a local reactive feedback to trade gain for stability. Feedback shifts the CE into a conditionally-stable operating region, and enables a gain beyond its maximum available gain (MAG). Then, when the CE is combined with a common-base, by properly selecting impedance terminations, the resulting cascode displays unconditional stability with superior gain. The concept is exploited in the design of a D-band LNA in BiCMOS 55 nm technology which shows 22.8 dB gain, 130-165 GHz operating frequency and NF down to 5 dB with 40 mW power consumption. Measured results compare favorably against state of the art.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11571/1496475
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