# US 7,609,113 B2 · Constant current bias circuit and associated method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,609,113 B2 - Document ID: US7609113B2 - Status: Granted - Kind: B2 - Application number: 11/599,932 - Filed: 2006-11-15 - Published: 2008-05-15 - Granted: 2009-10-27 - Earliest claimed: 2006-11-15 - Assignees: TriQuint Semiconductor, Inc. - Inventors: William H. Davenport - Web page: https://patentgrep.com/patent/US7609113B2 ## CPC - H03F 3/3432: {with bipolar transistors} - H03F 1/30: Modifications of amplifiers to reduce influence of variations of temperature or supply voltage {or other physical parameters (in differential amplifiers H03F3/45479)} - H03F 1/302: {in bipolar transistor amplifiers (H03F1/303, H03F1/305, H03F1/307 take precedence)} - H03F 3/19: with semiconductor devices only - H03F 3/24: of transmitter output stages - H03F 2200/18: the bias of the gate of a FET being controlled by a control signal - H03F 2200/447: the amplifier being protected to temperature influence - H03F 2200/451: the amplifier being a radio frequency amplifier - H03F 2200/75: the amplifier stage being a common source configuration MOSFET - H03F: AMPLIFIERS ## Abstract A constant current bias circuit and associated method is disclosed. The constant current bias circuit comprises an output stage for amplifying a radio frequency (RF) signal, wherein the output stage is operably coupled with a voltage. The constant current bias circuit further comprises a bias circuit operably coupled with the output stage for generating a substantially constant current bias to the output stage. The constant current bias circuit still further comprises a plurality of bias transistors operably coupled with the voltage and the output stage. ## Claims ### Claim 1 A constant current bias circuit, comprising: an output stage operably coupled with a first voltage, for amplifying a radio frequency (RF) signal; and a bias circuit operably coupled with the output stage, wherein the bias circuit comprises: a first bias transistor having a base and a collector, the collector of the first bias transistor operably coupled with a second voltage through a first impedance element; a second bias transistor having a base, a collector, and an emitter, the base of the second bias transistor operably coupled with the collector of the first bias transistor, the collector of the second bias transistor operably coupled with the second voltage, and the emitter of the second bias transistor operably coupled with a ground through a second impedance element; a third bias transistor having a base and a collector, the base of the third bias transistor operably coupled with the base of the first bias transistor and with the emitter of the second bias transistor; and a fourth bias transistor having a base, a collector, and an emitter, the base of the fourth bias transistor operably coupled with the collector of the first bias transistor, the collector of the fourth bias transistor operably coupled with the second voltage through a third impedance element, and the emitter of the fourth bias transistor operably coupled with the collector of the third bias transistor. ### Claim 2 (depends on 1) The circuit of claim 1, further comprising: a diode operably coupled between the collector of the first bias transistor and the first impedance element, wherein the base of the second and fourth bias transistors are operably coupled between the diode and the first impedance element; and a fourth impedance element operably coupled between the collector of the first bias transistor and the second voltage. ### Claim 3 (depends on 1) The circuit of claim 1, wherein the diode is a first diode, the bias circuit further comprises a second diode operably coupled between the base of the first bias transistor and the ground. ### Claim 4 (depends on 1) The circuit of claim 1, wherein the base of the third bias transistor is operably coupled through a fifth impedance element to the second voltage. ### Claim 5 (depends on 1) The circuit of claim 1, wherein the bias circuit further comprises: a fifth bias transistor having a collector and an emitter, the collector of the fifth bias transistor is operably coupled with the base of the third bias transistor; and a sixth impedance element operably coupled between the emitter of the fifth bias transistor and the ground. ### Claim 6 (depends on 5) The circuit of claim 5, wherein the fifth bias transistor further comprises a base, the base of the fifth bias transistor capable of being controlled by an external bias control. ### Claim 7 (depends on 6) The circuit of claim 6, wherein the external bias control provides for setting a predetermined output power of the output stage. ### Claim 8 (depends on 1) The circuit of claim 1, wherein the output stage comprises an output transistor having a base and a collector, the base of the output transistor operably coupled with the constant current bias circuit, and the collector of the output transistor operably coupled with the first voltage. ### Claim 9 (depends on 1) The circuit of claim 1, wherein the second voltage is a battery voltage. ### Claim 10 (depends on 9) The circuit of claim 9, wherein the first voltage is a battery voltage. ### Claim 11 (depends on 9) The circuit of claim 9, wherein the voltage is a regulated voltage. ### Claim 12 (depends on 1) The circuit of claim 1, wherein the constant current bias circuit is fabricated in Gallium Arsenide (GaAs). ### Claim 13 A wireless device comprising: a transmitter for transmitting RF signals, the transmitter comprising: an output power amplifier stage; and a bias circuit operably coupled with the output power amplifier stage, wherein the bias circuit comprises: a first bias transistor having a base and a collector, the collector of the first bias transistor operably coupled through a first impedance element to a voltage; a second bias transistor having a base, a collector, and an emitter, the base of the second bias transistor operably coupled with the collector of the first bias transistor, the collector of the second bias transistor operably coupled with the voltage, and the emitter of the second bias transistor operably coupled through a second impedance element to a ground; a third bias transistor having a base and a collector, the base of the third bias transistor operably coupled with the base of the first bias transistor and to the emitter of the second bias transistor; and a fourth bias transistor having a base, a collector, and an emitter, the base of the fourth bias transistor operably coupled with the collector of the first bias transistor, the collector of the fourth bias transistor operably coupled through a third impedance element to the voltage, and the emitter of the fourth bias transistor operably coupled with the collector of the third bias transistor; and a battery connected to the transmitter of the wireless device. ### Claim 14 (depends on 13) The wireless device of claim 13, wherein the bias circuit further comprises: a diode operably coupled between the collector of the first bias transistor and the first impedance element, wherein the base of the second and fourth bias transistors are operably coupled between the diode and the first impedance element; and a fourth impedance element operably coupled between the collector of the first bias transistor and the voltage. ### Claim 15 (depends on 13) The wireless device of claim 13, wherein the diode is a first diode, the bias circuit further comprises a second diode operably coupled between the base of the first bias transistor and the ground. ### Claim 16 (depends on 13) The wireless device of claim 13, wherein the base of the third bias transistor is operably coupled through a fifth impedance element to the battery. ### Claim 17 (depends on 13) The wireless device of claim 13, wherein the bias circuit further comprises: a fifth bias transistor having a base, a collector, and an emitter, the collector of the fifth bias transistor operably coupled with the base of the third bias transistor; and a sixth impedance element operably coupled between the emitter of the fifth bias transistor and the ground, wherein the base of the fifth bias transistor is capable of being controlled by an external bias control. ### Claim 18 (depends on 13) The wireless device of claim 13, wherein the output power amplifier stage comprises an output transistor having a base and a collector, the base of the output transistor operably coupled with the bias circuit, and the collector of the output transistor operably coupled with the battery.