# US 2013/0154556 A1 · Dc-dc converter, power receiving device, and power feeding system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0154556 A1 - Document ID: US20130154556A1 - Status: Published application - Kind: A1 - Application number: 13/711,961 - Filed: 2012-12-12 - Published: 2013-06-20 - Earliest claimed: 2011-12-16 - Assignees: Semiconductor Energy Laboratory Co., Ltd. - Inventors: Kei TAKAHASHI; Koichiro Kamata; Misako Miwa; Shuhei Maeda - Web page: https://patentgrep.com/patent/US20130154556A1 ## CPC - H02M 3/156: with automatic control of output voltage or current, e.g. switching regulators - G05F 3/08: wherein the variable is DC - H02J 50/12: of the resonant type - H02J 7/42: with electronic devices having internal batteries, e.g. mobile phones - H02J 50/80: involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices - H02M 1/0022: {the disturbance parameters being input voltage fluctuations} - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) - G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY ## Abstract A circuit capable of keeping input impedance constant is provided. Further, a circuit which can contribute to improvement in power feeding efficiency in power feeding by a magnetic resonance method is provided. A voltage (a former voltage) proportional to a direct-current voltage input to a DC-DC converter from the outside and a voltage (a latter voltage) proportional to a current input from the outside are detected, and the ratio of the former voltage and the latter voltage are held constant. Accordingly, input impedance can be kept constant. Further, impedance conversion is performed in the DC-DC converter. Thus, even when the battery in which power feeding is performed exists on an output side of the DC-DC converter, input impedance can be kept constant. Consequently, power can be supplied to a power receiving device including the DC-DC converter and the battery with high power feeding efficiency by a magnetic resonance method. ## Claims ### Claim 1 A DC-DC converter comprising: a load; a first circuit comprising a first resistor; a second circuit comprising an instrumentation amplifier; a third circuit comprising an error amplifier; and a first switch, wherein one end of the load is electrically connected to one end of the first resistor and a first input terminal of the instrumentation amplifier, wherein the other end of the load is electrically connected to a second input terminal of the instrumentation amplifier and one end of the first switch, wherein the other end of the first resistor is electrically connected to a first input terminal of the error amplifier, wherein the second circuit is electrically connected to a second input terminal of the error amplifier, and wherein the third circuit is electrically connected to the first switch. ### Claim 2 (depends on 1) The DC-DC converter according to claim 1, wherein the first circuit is configured to output a first voltage proportional to an input voltage input to the DC-DC converter to the third circuit, wherein the second circuit is configured to output a second voltage proportional to a current generated in the load to the third circuit, and wherein the third circuit is configured to hold a ratio of the first voltage and the second voltage constant. ### Claim 3 (depends on 1) The DC-DC converter according to claim 1, further comprising a second resistor in the first circuit, wherein the one end of the first resistor is electrically connected to a first input node of the DC-DC converter, wherein the other end of the first resistor is electrically connected to one end of the second resistor, and wherein the other end of the second resistor is electrically connected to a second input node of the DC-DC converter. ### Claim 4 (depends on 1) The DC-DC converter according to claim 1, further comprising a second switch, wherein the other end of the first switch is electrically connected to one end of the second switch and a first output node of the DC-DC converter, and wherein the other end of the second switch is electrically connected to a second output node of the DC-DC converter. ### Claim 5 (depends on 1) The DC-DC converter according to claim 1, further comprising a comparator in the third circuit, wherein the comparator is electrically connected to the error amplifier. ### Claim 6 (depends on 1) The DC-DC converter according to claim 1, wherein the first switch is a transistor. ### Claim 7 (depends on 1) The DC-DC converter according to claim 1, further comprising a charge and discharge unit, wherein the charge and discharge unit is provided between a first output node of the DC-DC converter and a second output node of the DC-DC converter. ### Claim 8 (depends on 1) A power receiving device comprising: a first coil; a rectifier circuit electrically connected to the first coil; the DC-DC converter according to claim 1, the DC-DC converter being electrically connected to the rectifier circuit; and a battery electrically connected to the DC-DC converter. ### Claim 9 (depends on 8) A power feeding system comprising: a power transmitting device comprising: a power supply; and a second coil electrically connected to the power supply, and the power receiving device according to claim 8. ### Claim 10 A DC-DC converter comprising: a load; a first circuit comprising a first resistor; a second circuit comprising an instrumentation amplifier; a third circuit comprising an error amplifier; a first switch; and a diode, wherein one end of the load is electrically connected to one end of the first resistor and a first input terminal of the instrumentation amplifier, wherein the other end of the load is electrically connected to a second input terminal of the instrumentation amplifier and one end of the first switch, wherein the other end of the first resistor is electrically connected to a first input terminal of the error amplifier, wherein one end of the diode is electrically connected to the other end of the first switch, wherein the second circuit is electrically connected to a second input terminal of the error amplifier, and wherein the third circuit is electrically connected to the first switch. ### Claim 11 (depends on 10) The DC-DC converter according to claim 10, wherein the first circuit is configured to output a first voltage proportional to an input voltage input to the DC-DC converter to the third circuit, wherein the second circuit is configured to output a second voltage proportional to a current generated in the load to the third circuit, and wherein the third circuit is configured to hold a ratio of the first voltage and the second voltage constant. ### Claim 12 (depends on 10) The DC-DC converter according to claim 10, further comprising a second resistor in the first circuit, wherein the one end of the first resistor is electrically connected to a first input node of the DC-DC converter, wherein the other end of the first resistor is electrically connected to one end of the second resistor, and wherein the other end of the second resistor is electrically connected to a second input node of the DC-DC converter. ### Claim 13 (depends on 10) The DC-DC converter according to claim 10, further comprising a second switch, wherein the other end of the first switch is electrically connected to one end of the second switch and a first output node of the DC-DC converter, and wherein the other end of the second switch is electrically connected to a second output node of the DC-DC converter. ### Claim 14 (depends on 10) The DC-DC converter according to claim 10, further comprising a comparator in the third circuit, wherein the comparator is electrically connected to the error amplifier. ### Claim 15 (depends on 10) The DC-DC converter according to claim 10, wherein the first switch is a transistor. ### Claim 16 (depends on 10) The DC-DC converter according to claim 10, further comprising a charge and discharge unit, wherein the charge and discharge unit is provided between a first output node of the DC-DC converter and a second output node of the DC-DC converter. ### Claim 17 (depends on 10) A power receiving device comprising: a first coil; a rectifier circuit electrically connected to the first coil; the DC-DC converter according to claim 10, the DC-DC converter being electrically connected to the rectifier circuit; and a battery electrically connected to the DC-DC converter. ### Claim 18 (depends on 17) A power feeding system comprising: a power transmitting device comprising: a power supply; and a second coil electrically connected to the power supply, and the power receiving device according to claim 17.