Psemi Corporation

Peregrine Semiconductor Corporation

Murata Manufacturing Co., Ltd.

Texas Instruments Corporation

Simon Edward Willard

Tero Tapio Ranta

Alain Duvallet

Robert Mark Englekirk

Keith Bargroff

Abhijeet Paul

Sinan Goktepeli

Christopher C Murphy

Poojan Wagh

Kashish Pal

Befruz Tasbas

Chris Olson

Peter Bacon

Eric S Shapiro

Matt Allison

Sivakumar Kumarasamy

Ronald Eugene Reedy

Jeffrey A Dykstra

Buddhika Abesingha

Ravindranath D Shrivastava

Merlin Green

Shashi Ketan Samal

Michael J McNutt

Jean-Luc Erb

Geert Deveirman

Jay Standiford

Rajagopal Sundararaman

Kouassi Sebastien Kouassi

Kazuhiko Shibata

Shishir Ray

Methods and devices to improve the switching speed of radio frequency FET switch stacks are disclosed. The described methods and devices are based on bypassing drain-sources resistors when the FET switch stack is transitioning from an ON to an OFF state. Several implementations of the disclosed teachings are also presented.

Bypass circuitry to improve switching speed

Methods and structures for mitigating back-gate effects in a radio frequency (RF) silicon-on-insulator (SOI) substrate, RF-SOI, are presented. According to one aspect, a first implant or junction is formed in a region of a trap-rich layer (TRL) of the RF-SOI that is located below a first circuit/device to protect. The first implant or junction is fully contained within the TRL. A planar surface area of the first implant and/or junction fully contains a projection of a planar surface area of the first circuit and/or device. The first implant or junction is biased via a through BOX contact (TBC) that penetrates the BOX layer at a shallow trench isolation region formed in the RF-SOI. According to another aspect, a second implant or junction is formed in a region of the TRL below a second circuit/device. The first and second implants or junctions are disjoint and separated by an undoped region of the TRL.

Back-gate effect control via doping

Methods and devices to address body leakage current generation and bias voltage distribution associated with body leakage current in an OFF state of a FET switch stack are disclosed. The devices include charge redistribution arrangements and bridge networks to perform coupling/decoupling to/from the FET switch stack. Detailed structures of such bridge networks are also described.

RF switch stack with charge redistribution

Integrated circuits (ICs) that avoid or mitigate creation of changes in accumulated charge in a silicon-on-insulator (SOI) substrate, particularly an SOI substrate having a trap rich layer. In one embodiment, a FET is configured such that, in a standby mode, the FET is turned OFF while maintaining essentially the same Vas during an active mode. In another embodiment, a FET is configured such that, in a standby mode, current flow through the FET is interrupted while maintaining essentially the same Vas during the active mode. In another embodiment, a FET is configured such that, in a standby mode, the FET is switched into a very low current state (a 'trickle current' state) that keeps both Vand Vclose to their respective active mode operational voltages. Optionally, S-contacts may be formed in an IC substrate to create protected areas that encompass FETs that are sensitive to accumulated charge effects.

Transient stabilized SOI FETs

Various methods and circuital arrangements for biasing one or more gates of stacked transistors of an amplifier are possible where the amplifier is configured to operate in at least an active mode and a standby mode. Circuital arrangements can reduce bias circuit and stacked transistors standby current during operation in the standby mode and to reduce impedance presented to the gates of the stacked transistors during operation in the active mode while maintaining voltage compliance of the stacked transistors during both modes of operation.

Gate drivers for stacked transistor amplifiers

A transistor stack can include a combination of floating and body tied devices. Improved performance of the RF amplifier can be obtained by using a single body tied device as the input transistor of the stack, or as the output transistor of the stack, while other transistors of the stack are floating transistors. Transient response of the RF amplifier can be improved by using all body tied devices in the stack.

Body tie optimization for stacked transistor amplifier

Systems, methods, and apparatus for an improved body tie construction are described. The improved body tie construction is configured to have a lower resistance body tie exists when the transistor is 'off' (Vg approximately 0 volts). When the transistor is “on” (Vg>Vt), the resistance to the body tie is much higher, reducing the loss of performance associated with presence of body tie. Space efficient Body tie constructions adapted for cascode configurations are also described.

Butted body contact for SOI transistor and amplifier circuit

FET designs that exhibit low leakage in the presence of the edge transistor phenomenon. Embodiments includes nFET designs in which the work function Φof the gate structure overlying the edge transistors of the nFET is increased by forming extra P+ implant regions within at least a portion of the gate structure, thereby increasing the Vt of the edge transistors to a level that may exceed the Vt of the central conduction channel of the nFET. In some embodiments, the gate structure of the nFET is modified to increase or 'flare' the effective channel length of the edge transistors relative to the length of the central conduction channel of the FET. Other methods of changing the work function Φof the gate structure overlying the edge transistors are also disclosed. The methods may be adapted to fabricating pFETs by reversing or substituting material types.

Low leakage FET

Systems, methods, and apparatus for an improved protection from charge injection into layers of a device using resistive structures are described. Such resistive structures, named s-contacts, can be made using simpler fabrication methods and less fabrication steps. In a case of metal-oxide-semiconductor (MOS) field effect transistors (FETs), s-contacts can be made with direct connection, or resistive connection, to all regions of the transistors, including the source region, the drain region and the gate.

S-contact for SOI

Methods and devices to address the undesired DC voltage distribution across switch stacks in OFF state are disclosed. The disclosed devices include charge control elements that sample the RF signal to generate superimposed voltages at specific points of the switch stack biasing circuit. The provided voltages help reducing the drooping voltages on drain/source/body terminals of the transistors within the stack by supplying the current drawn by drain/source terminals of the stacked transistors and/or by sinking the body leakage current exiting the body terminals of such transistors. Methods and techniques teaching how to provide proper tapping points in the biasing circuit to sample the RF signal are also disclosed.

RF switch stack with charge control elements

Electronic circuits and methods encompassing an RF switch comprising a plurality of series-coupled (stacked) integrated circuit (IC) SOI MOSFETs having a distributed back-bias network structure comprising groups of substrate contacts coupled to a bias voltage source through a resistive ladder. The distributed back-bias network structure sets the common IC substrate voltage at a fixed DC bias but resistively decouples groups of MOSFETs with respect to RF voltages so that the voltage division characteristics of the MOSFET stack are maintained. The distributed back-bias network structure increases the voltage handling capability of each MOSFET and improves the maximum RF voltage at which a particular MOSFET is effective as a switch device, while mitigating loss, leakage, crosstalk, and distortion. RF switches in accordance with the present invention are particularly useful as antenna switches.

Distributed FET back-bias network

A high-voltage switching device that can be fabricated in a standard low-voltage process, such as CMOS, and more specifically SOI CMOS. Embodiments include integrated circuits that combine, in a unitary structure, a FET device and an integrated, co-fabricated modulated resistance region (MRR) controlled by one or more Voltage-Drop Modulation Gates (VDMGs). The VDMGs are generally biased independently of the gate of the FET device, and in such a way as to protect each VDMG from excessive and potentially destructive voltages. In a first embodiment, an integrated circuit high voltage switching device includes a transistor structure including a source, a gate, and an internal drain; an MRR connected to the internal drain of the transistor structure; at least one VDMG that controls the resistance of the MRR; and a drain electrically connected to the MRR. Each VDMG at least partially depletes the MRR upon application of a bias voltage.

High voltage switching device

A positive-logic FET switch stack that does not require a negative bias voltage, exhibits high isolation and low insertion/mismatch loss, and may withstand high RF voltages. Embodiments include a FET stack comprising series-coupled positive-logic FETs (i.e., FETs not requiring a negative voltage supply to turn OFF), series-coupled on at least one end by an 'end-cap' FET of a type that turns OFF when its Vis zero volts. The one or more end-cap FETs provide a selectable capacitive DC blocking function or a resistive signal path. Embodiments include a stack of FETs of only the zero Vtype, or a mix of positive-logic and zero Vtype FETs with end-cap FETs of the zero Vtype. Some embodiments withstand high RF voltages by including combinations of series or parallel coupled resistor ladders for the FET gate resistors, drain-source resistors, body charge control resistors, and one or more AC coupling modules.

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Irvine, CA, United States of America

Simon Edward Willard