# US 2014/0197828 A1 · High frequency switch > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0197828 A1 - Document ID: US20140197828A1 - Status: Published application - Kind: A1 - Application number: 14/119,573 - Filed: 2012-06-12 - Published: 2014-07-17 - Earliest claimed: 2011-06-17 - Assignees: Mitsubishi Electric Corporation - Inventors: Miki Kagano; Kazuya Makabe; Tomokazu Ogomi; Takahito Nakanishi; Tadashi Minobe; Takashi Ito - Web page: https://patentgrep.com/patent/US20140197828A1 ## CPC - H03F 3/45: Differential amplifiers (differential sense amplifiers G11C7/062) - G01D 5/145: {influenced by the relative movement between the Hall device and magnetic fields (see G01R33/06)} - G01R 33/09: Magnetoresistive devices - H03F 3/45179: {using MOSFET transistors as the active amplifying circuit (H03F3/45278 takes precedence)} - H03F 3/45475: {using IC blocks as the active amplifying circuit} - H03F 2200/411: the output amplifying stage of an amplifier comprising two power stages - H03F 2200/78: A comparator being used in a controlling circuit of an amplifier - H03F 2203/45512: the FBC comprising one or more capacitors, not being switched capacitors, and being coupled between the LC and the IC - H03F 2203/45514: the FBC comprising one or more switched capacitors, and being coupled between the LC and the IC - H03F 2203/45521: the FBC comprising op amp stages, e.g. cascaded stages of the dif amp and being coupled between the LC and the IC - H03F 2203/45528: the FBC comprising one or more passive resistors and being coupled between the LC and the IC - H03F 2203/45534: the FBC comprising multiple switches and being coupled between the LC and the IC - H03F 2203/45536: the FBC comprising a switch and being coupled between the LC and the IC - H03F 2203/45594: the IC comprising one or more resistors, which are not biasing resistor - H03F 2203/45728: the LC comprising one switch - H03F: AMPLIFIERS - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract When a switch is set to off, and a switch is set to on, the voltage of a SigOut terminal is stabilized with a reference voltage, and a bias voltage is applied to a capacitor. Changing the switch from on to off, with the bias voltage retained in the capacitor, a detection signal which is input via a SigIn terminal is amplified with the reference voltage as a reference, and an amplified signal is output from the SigOut terminal. ## Claims ### Claim 1 An amplifier comprising: a first resistor; a first operational amplifier into which an input signal is input into an inverting input terminal via the first resistor from a signal input terminal; a second resistor, one end of which is connected to the inverting input terminal of the first operational amplifier and the other end of which is connected to the output terminal of the first operational amplifier; a second operational amplifier into which a prescribed reference voltage is input into the non-inverting input terminal and the output terminal is connected to the non-inverting input terminal of the first operational amplifier; a first capacitor, one end of which is connected to the inverting input terminal of the second operational amplifier and the other end of which is connected to the output terminal of the second operational amplifier; a first switch, one end of which is connected to the inverting input terminal of the second operational amplifier and the other end of which is connected to the output terminal of the second operational amplifier; a third resistor and a second switch connected in series, one end of which is connected to the output terminal of the first operational amplifier and the other end of which is connected to the inverting input terminal of the second operational amplifier; and, a control circuit for receiving input of amp control signals and switching the first switch and the second switch on and off in a prescribed order based on the amp control signals; wherein through the switching process of the control circuit, the first operational amplifier amplifies the input signal with the reference voltage as a reference and an amplified signal is output from a signal output terminal connected to the output terminal of the first operational amplifier. ### Claim 2 (depends on 1) The amplifier according to claim 1, further comprising: a fourth resistor and a third switch connected in series, one end of which is connected to the output terminal of the first operational amplifier and the other end of which is connected to the inverting input terminal of the second operational amplifier; wherein the control circuit switches the first switch, the second switch and the third switch on and off in a prescribed order based on the amp control signals. ### Claim 3 (depends on 1) The amplifier according to claim 1, further comprising: a third switch for switching the connection between the output terminal of the first operational amplifier and the signal output terminal on and off; and a fourth switch, one end of which is connected between the signal input terminal and the first resistor and the other end of which is connected between the third switch and the signal output terminal; wherein the control circuit switches the first switch, the second switch, the third switch and the fourth switch on and off in a prescribed order based on the amp control signals. ### Claim 4 (depends on 1) The amplifier according to claim 1, further comprising: a fourth resistor and a third switch connected in series, one end of which is connected to the output terminal of the first operational amplifier and the other end of which is connected to the inverting input terminal of the second operational amplifier; a fourth switch for switching the connection between the output terminal of the first operational amplifier and the signal output terminal on and off; and a fifth switch, one end of which is connected between the signal input terminal and the first resistor and the other end of which is connected between the fourth switch and the signal output terminal; wherein the control circuit switches the first switch, the second switch, the third switch, the fourth switch and the fifth switch on and off in a prescribed order based on the amp control signals. ### Claim 5 (depends on 1) The amplifier according to claim 1, further comprising a second capacitor connected in parallel with the second resistor. ### Claim 6 (depends on 1) The amplifier according to claim 1, wherein the switch positioned between the output terminal of the first operational amplifier and the inverting input terminal of the second operational amplifier is a complementary switch including a P-type MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) and an N-type MOSFET. ### Claim 7 (depends on 1) A signal processing device comprising: a conveyance route on which a detectable body is conveyed; multiple detection elements for detecting a prescribed physical quantity that changes depending on the detectable body, and outputting a detection signal the voltage of which changes in accordance with changes in the prescribed physical quantity; a detector for detecting entry of the detectable body into the conveyance route, and outputting a detection signal indicating the absence or presence of entry of the detectable body into the conveyance route; a reading control circuit for outputting an amp control signal and a channel control signal the signal levels of which change based on the detection signal; channel amplifiers respectively connected to the detection elements and possessing the amplifier of claim 1, for amplifying the detection signal by switching the switches provided in the amplifiers on and off in a prescribed order based on the amp control signals, and outputting an amplified signal; a parallel-series converter for respectively amplifying, converting to serial and outputting as a serial signal the amplified signals output by prescribed channel amplifiers based on the channel control signals; a differential amplifier for amplifying and outputting the difference between the serial signal and a prescribed signal; and a digital signal processor for converting the output signal of the differential amplifier to a digital signal and accomplishing a prescribed signal process. ### Claim 8 (depends on 7) The signal processing device according to claim 7, wherein: the parallel-series converter amplifies, converts to serial and outputs as the serial signal the amplified signal output by the channel amplifiers respectively connected to the detection elements containing at least a portion of the conveyance route in the detection region; and the differential amplifier amplifies and outputs the difference between the serial signal and the amplified signal output by the channel amplifiers connected to the detection element not containing any portion of the conveyance route in the detection region. ### Claim 9 (depends on 7) The signal processing device according to claim 7, wherein: the parallel-series converter amplifies, converts to serial and outputs as the serial signal the amplified signal output by the channel amplifiers respectively connected to the detection elements containing at least a portion of the conveyance route in the detection region; and the differential amplifier amplifies and outputs the difference between the serial signal and a prescribed voltage value. ### Claim 10 (depends on 7) The signal processing device according to claim 7, wherein: the parallel-series converter amplifies, converts to serial and outputs as the serial signal the amplified signal output by the channel amplifiers respectively connected to the detection elements containing at least a portion of the conveyance route in the detection region; and when the detection element not including any portion of the conveyance route in the detection region exists, the differential amplifier amplifies and outputs the difference between the serial signal and a prescribed voltage value or the amplified signal output by the channel amplifier connected to that detection element, and when a detection element not including any portion of the conveyance route in the detection region does not exist, the differential amplifier amplifies and outputs the difference between the serial signal and a prescribed voltage value. ### Claim 11 (depends on 1, 2, 3, 4, 5, 6, 7) The signal processing device according to claim 7, wherein the parallel-series converter possesses the amplifier according to any one of claims 1 to 6, and respectively amplifies, converts to serial and outputs as the serial signal the amplified signals output by the channel amplifiers by switching the switches provided in the amplifier on and off in a prescribed order based on the amp control signals. ### Claim 12 (depends on 7) The signal processing device according to claim 7, wherein the gain of the channel amplifiers is larger than the gain of the differential amplifier and the gain of the parallel-series converter.