Effects and contrasts of silicon‐on‐insulator floating‐body and body‐contacted field‐effect transistors to the design of high‐performance antenna switches

Abstract

A theoretical analysis and contrast of silicon‐on‐insulator (SOI) floating‐body (FB) and body‐contacted (BC) metal–oxide–semiconductor field‐effect transistors (FETs) including insertion loss (IL), isolation, power handling capability as well as harmonics for radio frequency switches applications, are firstly developed in detail. From the presented investigation, lower IL and smaller chip size can be obtained using FB FETs, while the BC devices are beneficial to isolation and harmonics improvement. As an experimental vehicle for the presented analysis, the high‐power single‐pole eight‐throw (SP8T) antenna switches for multi‐mode multi‐band applications, are fabricated in a partially depleted 0.18 μm SOI process based on FB and BC FETs, respectively. At 1.9 GHz, the tested IL, TR × 1 to TR × 3 isolation, and P−0.1 dB of the FB and BC SP8T switches are approximately 0.53/0.65 dB, 27.6/29.3 dB and 38.0/38.4 dBm. For the two cases, the second and third harmonics are −70.6/−75.5 and −60.4/−79.9 dBc, respectively, with a +33 dBm input power at 1.9 GHz. The experimental results strongly support the analysis that the FB FET is a preferred device in low loss or low throw‐count switching design while the BC FET is a better selection in the applications that demand high power and low harmonic.

A 0.1 to 2.7‐GHz SOI SP8T antenna switch adopting body self‐adapting bias technique for low‐loss high‐power applications

“…As a result, the total on-resistance R ON is reduced, in contrast to the one based on the conventional body bias method in Zhang et al, 13 as depicted in Figure 8. Besides, the increment of the body potential in ON state also helps a little bit to the IL improvement, thanks to its contribution to threshold decrease.…”

“…10 The term PD or fully depleted refers to the "distance" the depletion region under the gate extends into the body. As explained in our previous work, 13 the FB FET is a better option for low-loss switching applications because its FB helps in reducing the on-state resistance and substrate loss, while the BC FET is a preferred switch device in the high-power switch fields because a negative voltage could be applied to the body when the switch is in the OFF state. The body of the FB FET is floating, while the body of a BC FET may be connected to a voltage supply or source/ground.…”

“…The body of the FB FET is floating, while the body of a BC FET may be connected to a voltage supply or source/ground. 16 In this paper, the switch topology, device selection, and body self-adapting bias technique will be discussed and analyzed in detail, and the BC switch using conventional body bias method presented in Zhang et al 13 is utilized for comparison. However, the major issue of the BC FET is the conventional DC bias to the body, the additional biasing resistor, and wiring and contacts yield larger parasitic capacitance, more complex control, and even slightly larger chip size.…”

“…The body of the FB FET is floating, while the body of a BC FET may be connected to a voltage supply or source/ground. As explained in our previous work, 13 the FB FET is a better option for low-loss switching applications because its FB helps in reducing the on-state resistance and substrate loss, while the BC FET is a preferred switch device in the high-power switch fields because a negative voltage could be applied to the body when the switch is in the OFF state. However, the major issue of the BC FET is the conventional DC bias to the body, the additional biasing resistor, and wiring and contacts yield larger parasitic capacitance, more complex control, and even slightly larger chip size.…”

“…Simulated and measured harmonics single-pole 8-throw (SP8T) switches using conventional bias13 and body self-adapting bias method with a 26-dBm input power: A, second harmonics; B, third harmonics…”