| Circuit and method for controlling charge injection in radio frequency switches -> Monitor Keywords |
|
|
 
Circuit and method for controlling charge injection in radio frequency switchesRelated Patent Categories: Telecommunications, Receiver Or Analog Modulated Signal Frequency Converter, Frequency Or Phase Modulation, With Synchronized Or Controlled Local OscillatorCircuit and method for controlling charge injection in radio frequency switches description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20080076371, Circuit and method for controlling charge injection in radio frequency switches. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED UTILITY AND PROVISIONAL APPLICATIONS Claims of Priority [0001] This application is a Continuation-in-Part (CIP) of co-pending and commonly assigned U.S. patent application Ser. No. 11/520,912, filed Sep. 14, 2006, entitled "METHOD AND APPARATUS IMPROVING GATE OXIDE RELIABILITY BY CONTROLLING ACCUMULATED CHARGE" [ATTY. DOCKET NO. PER-015-CIP], which claims the benefit under 35 U.S.C. .sctn. 119 (e) of U.S. Provisional Application No. 60/718,260, filed Sep. 15, 2005; the cited application Ser. No. 11/520,912, filed Sep. 14, 2006, is a CIP of U.S. patent application Ser. No. 11/484,370, filed Jul. 10, 2006, entitled "METHOD AND APPARATUS FOR USE IN IMPROVING LINEARITY OF MOSFETS USING AN ACCUMULATED CHARGE SINK" [DOCKET NO. PER-016-PAP], pending, which claims the benefit under 35 U.S.C. .sctn. 119 (e) of U.S. Provisional Application No. 60/698,523, filed Jul. 11, 2005; the present CIP application is also a CIP of the cited U.S. patent application Ser. No. 11/484,370, filed Jul. 10, 2006, pending; and the present CIP application claims the benefit under 35 U.S.C. .sctn. 119 (e) of U.S. Provisional Application No. 60/833,562, filed Jul. 26, 2006, entitled "CIRCUIT AND METHOD FOR CONTROLLING CHARGE INJECTION IN RADIO FREQUENCY SWITCHES" [DOCKET NO. PER-018-PROV]. The present CIP application is related to co-pending and commonly assigned application Ser. No. 10/922,135, filed Aug. 18, 2004, [DOCKET NO. PER-001-CON], which issued Oct. 17, 2006 as U.S. Pat. No. 7,123,898, and is a continuation application of application Ser. No. 10/267,531, filed Oct. 8, 2002, which issued Oct. 12, 2004 as U.S. Pat. No. 6,804,502, entitled "SWITCH CIRCUIT AND METHOD OF SWITCHING RADIO FREQUENCY SIGNALS" [DOCKET NO. PER-001-PAP]. application Ser. No. 10/267,531, filed Oct. 8, 2002, which issued Oct. 12, 2004 as U.S. Pat. No. 6,804,502, claims the benefit under 35 U.S.C. .sctn. 119 (e) of U.S. Provisional Application No. 60/328,353, filed Oct. 10, 2001. The present CIP application is related to each of the applications set forth above. All of the applications and issued patents set forth above are hereby incorporated by reference herein as if set forth in full. BACKGROUND [0002] 1. Field [0003] The present teachings relate to electronic switches, and particularly to a circuit and method for controlling charge injection in semiconductor-on-insulator (SOI) radio frequency (RF) switches. [0004] 2. Description of Related Art [0005] Radio frequency (RF) switches for directing RF signals are found in many different RF devices such as televisions, video recorders, cable television equipment, cellular telephones, wireless pagers, wireless infrastructure equipment, and satellite communications equipment. As is well known, the performance of RF switches is controlled by three primary operating performance parameters: insertion loss, switch isolation, and the "1 dB compression point." The "1 dB compression point" is related to, and is indicative of, the linearity performance of an RF switch. Linearity performance is also indicated by the levels of RF signal harmonics generated by an RF switch, particularly at high RF power levels. These three performance parameters are tightly coupled, and any one parameter can be emphasized in the design of RF switch components at the expense of others. A fourth performance parameter that is occasionally considered in the design of RF switches is commonly referred to as the switching time or switching speed (defined as the time required to turn one side of a switch on and turn the other side off). Other characteristics important in RF switch design include ease and degree (or level) of integration of the RF switch, complexity, yield, return loss and cost of manufacture. [0006] Charge injection is a problem that may occur in switching circuits such as SOI RF switches. Charge injection occurs when an applied voltage, such as a gate bias voltage, is connected to a "resistively-isolated node" through a coupling capacitance. A resistively-isolated node is defined herein as a node that at some interval during operation is connected to other circuit elements only through very high resistance connections. For example, a resistively-isolated node may occur at a transistor channel node located between series-connected transistors when the transistors are in an OFF-state. The coupling capacitance through which charge injection occurs may be either a parasitic capacitance of a circuit element (e.g., gate-to-source capacitance in a transistor), or a capacitance associated with a capacitor. For example, a bias voltage applied to the gate of a transistor may be connected to a resistively-isolated source node of the transistor through the gate-to-source capacitance. In general, charge injection may be a problem for many types of switching circuits. In particular, charge injection is significantly deleterious to the performance properties of SOI RF switches. Further, teachings on prior art SOI RF switches do not address this problem, for reasons described in more detail hereinbelow. Consequently, a need exists for a novel circuit and method for controlling charge injection in SOI RF switches. SUMMARY [0007] A novel circuit and method for controlling charge injection in an SOI RF switch are disclosed. The SOI RF switch may comprise a plurality of switching transistors connected in series (referred to herein as "stacked" switching transistors) implemented as a monolithic integrated circuit (IC) on an SOI substrate. In one embodiment the SOI RF switch is fabricated on an Ultra-Thin-Silicon ("UTSi") substrate, also referred to herein as "silicon on sapphire" (SOS). In another embodiment, the SOI RF switch is fabricated in silicon-on-bonded wafer technology. [0008] In an embodiment according to the present disclosure, an SOI RF switch includes at least one stack comprising a plurality of switching transistors connected in a series circuit. Charge injection control elements are connected to receive injected charge from resistively-isolated nodes located between the switching transistors, and to convey the injected charge to one or more nodes that are not resistively-isolated. Optionally, the charge injection control elements may be connected to receive a control signal for switching the charge injection control elements between ON-states and OFF-states. In one embodiment, each switching transistor in a stack of the SOI RF switch has at least one charge injection control element operatively connected between a source node and a drain node of each switching transistor. [0009] In one embodiment, the charge injection control elements comprise charge injection control resistors. In another embodiment, the charge injection control elements comprise charge injection control transistors connected to receive a control signal for switching the injection control transistors between and ON-state and an OFF-state. The charge injection control transistors are operated so that they are in the ON-state when the switching transistors are in an ON-state. When the switching transistors are switched from the ON-state to an OFF-state, the charge injection control transistors are switched from an ON-state to an OFF-state after a selected delay time interval, thereby allowing the injected charge to be conveyed to the least one node that is not resistively-isolated. [0010] In one embodiment, a method for controlling charge injection includes: 1) causing charge injection to occur at resistively-isolated nodes located between the switching transistors; 2) conveying the injected charge via charge injection control elements to at least one node that is not resistively-isolated; and, 3) optionally switching the charge injection control elements from an ON-state to an OFF-state. [0011] According to one embodiment of the method for controlling charge injection, the charge injection control elements may comprise charge injection control resistors. In another embodiment, the charge injection control elements may comprise charge injection control transistors. BRIEF DESCRIPTION OF THE DRAWINGS [0012] FIG. 1A schematically illustrates an SOI RF switch circuit using stacked switching transistors. [0013] FIG. 1B illustrates the effects of charge injection in an SOI RF switch circuit using stacked switching transistors. [0014] FIG. 1C illustrates simulated data for the RF switch of FIG. 1A wherein the RF switch has recently been switched from an ON-state to an OFF-state. [0015] FIG. 2 schematically illustrates an embodiment according to the present disclosure, including a charge injection control circuit. [0016] FIG. 3 shows a schematic illustration of an embodiment according to the present disclosure, using resistors in a charge injection control circuit. [0017] FIG. 4 shows a schematic illustration of an embodiment according to the present disclosure, using transistors in a charge injection control circuit. [0018] FIG. 5 is a flow chart diagram illustrating a charge injection control method. [0019] FIG. 6A is a simplified schematic of an improved SOI NMOSFET adapted to control accumulated charge embodied as a four terminal device. Continue reading about Circuit and method for controlling charge injection in radio frequency switches... Full patent description for Circuit and method for controlling charge injection in radio frequency switches Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Circuit and method for controlling charge injection in radio frequency switches patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Circuit and method for controlling charge injection in radio frequency switches or other areas of interest. ### Previous Patent Application: Transmission interface device Next Patent Application: Reducing power dissipation using process corner information Industry Class: Telecommunications ### FreshPatents.com Support Thank you for viewing the Circuit and method for controlling charge injection in radio frequency switches patent info. IP-related news and info Results in 1.13818 seconds Other interesting Feshpatents.com categories: Electronics: Semiconductor , Audio , Illumination , Connectors , Crypto , 174 |
 * Protect your Inventions * US Patent Office filing 
PATENT INFO |
|
