Low-Noise Amplifier Design in SiGe BiCMOS Technology

Abstract

Low-Noise Amplifiers (LNA's) for wireless applications are examined in detail demonstrating their role in a wireless receiver. LNA performance parameters namely gain; noise figure; return loss; reverse isolation; linearity; and stability are explained illustrating their impact on the system performance. A survey on reeent LNA publications is carried out. Different LNA topologies are presented and LNA implementations in silicon bipolar and SiGe HBT BiCMOS technologies are compared. Desigu and optimization techniques of inductively degenerated, tuned, cascode LNA are presented, showing the impact of bonding pads, bond wires, layout and package parasitics on LNA performance. These techniques are applied to the desigu of a single-ended and a differential LNA that target GSM specifications. The two LNA's are implemented in 0.8fim SiGe BiCMOS technology. Simulation results of the single­ ended LNA show 2 dB noise figure, 13 dB forward gain, -16 dBm iP.1dB and iiP3 of -5.4 dBu4 together with good input/output matching and 30 dB reverse isolation, while those of the differential LNA show 2 dB noise figure, 15 dB forward gain, -14.7 dBm iP.1dB and iiP3 of -4.7 dBm, with good input/output matching and 70 dB reverse isolation. Both single-ended and differential LNA's are stable and consume 13 mW and 35 mW

respectively from a 3V supply.

A new compact approach for the desigu of a dual-band LNA is devised. The proposed topology features a minimum number of devices, reducing the physical layout to its limit, thus improving cost and form factor. Band selection is controlled by three switches that guarantee good input/output matching, adequate forward gain and low noise figure. The LNA circuit is desigued and simulated in a 0.8 f1ID SiGe BiCMOS technology.