# US 2014/0197714 A1 · SAW Device With Heat Efficient Temperature Controller > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0197714 A1 - Document ID: US20140197714A1 - Status: Published application - Kind: A1 - Application number: 13/741,485 - Filed: 2013-01-15 - Published: 2014-07-17 - Earliest claimed: 2013-01-15 - Assignees: Phonon Corporation - Applicants: Phonon Corporation - Inventors: Tom A. Martin; Pierre A. Dufilie - Web page: https://patentgrep.com/patent/US20140197714A1 ## CPC - H03H 9/25: Constructional features of resonators using surface acoustic waves {(devices for manipulating acoustic surface waves in general G10K11/36)} - H03H 9/02834: {of temperature influence (cut angles H03H9/02543)} - H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P) ## Abstract A surface acoustic wave (SAW) device comprising at least one heating element formed on the substrate; at least one temperature sensor having a first electric component on the substrate whose resistance varies with the temperature of the substrate and a second electric component whose resistance does not vary; and a temperature controller including an operational amplifier bonded in thermally conductive relationship to the substrate. The operational amplifier is responsive to the output of the temperature sensor to apply power to the heating element and thereby maintain the temperature of the substrate within a predetermined temperature range. The transducer, heating element, and first component are monolithically formed on the substrate, and only three electrical connections are on the substrate at voltage to off-SAW die points. ## Claims ### Claim 1 A temperature controller for a SAW device, comprising: a servo loop between a temperature sensor and a heating element, which servo loop strives to zero a bridge voltage across two input nodes of an operational amplifier by controlling the voltage across the heating element, wherein one leg of the bridge has a first, temperature dependent resistor connected to one input node and a second, temperature invariant set point resistor connected said one node; wherein the other leg of the bridge has a third, temperature dependent resistor connected to the other input node and a fourth, temperature dependent resistor connected to the other node. ### Claim 2 (depends on 1) The temperature controller of claim 1, wherein the SAW device has a piezoelectric crystal substrate and the temperature variable resistors are meander resistors carried on the substrate. ### Claim 3 (depends on 1) The temperature controller of claim 1, wherein the output end of the set point resistor is at a ground connection of the substrate. ### Claim 4 (depends on 1) The temperature controller of claim 1, wherein the operational amplifier is bonded to the substrate. ### Claim 5 (depends on 1) The temperature controller of claim 1, wherein the output of the fourth resistor and the operational amplifier are grounded to the same point of the substrate. ### Claim 6 (depends on 1) The temperature controller of claim 1, wherein the heating element is a meander resistor adhered to the substrate. ### Claim 7 (depends on 1) The temperature controller of claim 1, wherein the input ends of the first and third resistors are connected to a source voltage node and the input end of the heating element is connected to the source voltage node. ### Claim 8 (depends on 1) The temperature controller of claim 1, wherein the output end of the fourth resistor and a ground lead from the amplifier are connected to a common ground terminal that is off the substrate. ### Claim 9 (depends on 7) The temperature controller of claim 7, wherein the source voltage node is connected to a voltage source that is off the substrate. ### Claim 10 (depends on 1) The temperature controller of claim 1, wherein the first, temperature dependent resistor is connected at its output end to input node and the second, temperature invariant set point resistor is connected at its input end to said one node; and the third, temperature dependent resistor is connected at its output end to the other input node and the fourth, temperature dependent resistor is connected at its input end to the other node. ### Claim 11 (depends on 1) The temperature controller of claim 1, wherein the first, temperature dependent resistor is connected at its input end to input node and the second, temperature invariant set point resistor is connected at its output end to said one node; and the third, temperature dependent resistor is connected at its output end to the other input node and the fourth, temperature dependent resistor is connected at its input end to the other node. ### Claim 12 A surface acoustic wave (SAW) device comprising: a piezoelectric crystal substrate; a working surface of the substrate capable of transmitting acoustic waves along an acoustic channel; at least one transducer formed on said working surface for inducing said waves to travel along said channel and for receiving said waves; at least one heating element formed on the substrate; at least one temperature sensor having an output which varies with a temperature of said substrate, said temperature sensor including a first electric component formed on said substrate whose resistance varies with the temperature of said substrate and a second electric component whose resistance does not vary; a temperature controller including an operational amplifier bonded in thermally conductive relationship to the substrate, said operational amplifier responsive to the output of said temperature sensor to apply power to said heating element to maintain the temperature of said substrate within a predetermined temperature range; wherein the transducer, heating element, and first component are monolithically formed on the substrate; and only three electrical connections are on the substrate at voltage to off-SAW die points, for providing the function of temperature control with the substrate. ### Claim 13 (depends on 12) The SAW device of claim 12, wherein the temperature sensor comprises a voltage divider bridge having bridge output nodes and the controller comprises a servo loop between the temperature sensor and the heating element, which servo loop strives to zero the bridge voltage across said two nodes which are also two input nodes of the operational amplifier by controlling the voltage across the heating element, wherein one leg of the bridge has a first, temperature dependent resistor constituting said first component connected to one input node and a second, temperature invariant set point resistor constituting said second component connected said one node; wherein the other leg of the bridge has a third, temperature dependent resistor connected to the other input node and a fourth, temperature dependent resistor connected to the other node. ### Claim 14 (depends on 13) The SAW device of claim 13, wherein the output end of the set point resistor is at a ground connection of the substrate; and the output of the fourth resistor and the operational amplifier are grounded to the same point of the substrate. ### Claim 15 (depends on 13) The temperature controller of claim 13, wherein the input ends of the first and third resistors are connected to a source voltage node and the input end of the heating element is connected to the source voltage node. ### Claim 16 (depends on 13) The temperature controller of claim 13, wherein the output end of the fourth resistor and a ground lead from the amplifier are connected to a common ground terminal that is off the substrate. ### Claim 17 (depends on 15) The temperature controller of claim 15, wherein the source voltage node is connected to a voltage source that is off the substrate. ### Claim 18 (depends on 13) The temperature controller of claim 13, wherein the first, temperature dependent resistor is connected at its output end to input node and the second, temperature invariant set point resistor is connected at its input end to said one node; and the third, temperature dependent resistor is connected at its output end to the other input node and the fourth, temperature dependent resistor is connected at its input end to the other node. ### Claim 19 (depends on 13) The temperature controller of claim 13, wherein the first, temperature dependent resistor is connected at its input end to input node and the second, temperature invariant set point resistor is connected at its output end to said one node; and the third, temperature dependent resistor is connected at its output end to the other input node and the fourth, temperature dependent resistor is connected at its input end to the other node.