Abstract: A FET transistor voltage-controlled oscillator is provided that includes a crossed-coupled inductor capacitor tank (LC-Tank) transistor voltage-controlled circuit having a first transistor and a second transistor, as well as a transistor frequency multiplying circuit having a third transistor and a fourth transistor. In the design, the gate of the first transistor is connected to the drain of the second transistor, and the gate of the second transistor is connected to the drain of the first transistor. Then, the source of the third transistor is connected to the source of the first transistor, and the source of the fourth transistor is connected to the source of the second transistor. Last, the gate of the third transistor is connected to the gate of the fourth transistor, and the drain of the third transistor is connected to the drain of the fourth transistor.

Abstract: A substantially temperature-independent LC-based oscillator is achieved using an LC tank that generates a tank oscillation at a phase substantially equal to a temperature null phase. The temperature null phase is a phase of the LC tank at which variations in frequency of an output oscillation of the LC-based oscillator with temperature changes are minimized. The LC-based oscillator further includes frequency stabilizer circuitry coupled to the LC tank to cause the LC tank to oscillate at the phase substantially equal to the temperature null phase.

Abstract: An oscillation maintenance circuit for a half-duplex transponder that has an LC resonant circuit, a storage capacitor and a rectifier connected to charge the storage capacitor with a rectified oscillation signal, having an end-of-burst detector providing an end-of-burst signal when the amplitude of the oscillation signal has dropped below a predetermined threshold. A clock regenerator provides a clock signal derived from the oscillation signal. Switching means controlled by the clock signal in the presence of the end-of-burst signal connect the storage capacitor with LC resonant circuit through at least one current limiting resistor during part of the period of the clock signal, in such a manner that energy is fed into the LC resonant circuit.

Abstract: An injection-locked frequency divider is provided. The injection-locked frequency divider includes a voltage control oscillator (VCO) and a mixer. The VCO includes a LC resonance tank and a negative-resistance generator for generating a differential oscillation signal including a first and a second oscillation signals. The LC resonance tank adjusts a VCO reactance and resonates for generating the differential oscillation signal. The negative-resistance generator coupled to the LC resonance tank eliminates an equivalent resistance generated by the LC resonance tank and maintains the VCO to continuously oscillate.

Abstract: A voltage-controlled oscillator comprises an inductor and a group of variable capacitance elements forming a resonance circuit. The group of variable capacitance elements includes first and second variable capacitance elements connectable in parallel and having mutually different absolute values of a ratio of control-voltage sensitivity to capacitance. The first and second variable capacitance elements both have a first end supplied with a control voltage for controlling resonance frequency of the resonance circuit and have a second end selectively connected to the inductor by a band selection signal for deciding a band in which the resonance frequency exists.

Abstract: A voltage controlled oscillator compising a distributed coupled resonator (DCR) that desirably produces a low noise signal source with reduced phase hits in comparison to a high Q resonator, such as a ceramic and SAW (Surface Acoustic Wave) resonator based oscillator.

Abstract: An integrated tunable resonance circuit is provided for providing a high-frequency output signal with a frequency dependent on a control signal, comprising a parallel resonance circuit with a first inductive element and an output for providing the high-frequency output signal, a switching unit with a controlled path, and a control terminal for switching between states, whereby the switching unit is designed to exhibit a predominantly capacitive behavior in a first state and a predominantly resistive behavior in a second state, whereby the resonance circuit is designed to drive the control terminal of the switching unit as a function of the control signal. The resonance circuit has a second inductive element which can be mutually coupled to the first inductive element, whereby the controlled path is connected parallel to the second inductive element. The invention relates furthermore to a voltage-controlled oscillator and to an integrated circuit.

Abstract: An integrated resonance circuit is provided for providing a high-frequency output signal, comprising a first output for providing a first high-frequency output signal with a first frequency and a first amplitude, a first inductive unit connected to the first output, and a first capacitive unit connected to the first output. According to the invention, a second output for providing a second high-frequency output signal with a second frequency and a second amplitude is provided, whereby the second frequency matches the first frequency and the second amplitude differs from the first amplitude, and a second inductive unit, connected to the first output and to the second output, and a second capacitive unit, connected to the second output, are provided. The invention relates furthermore to a voltage-controlled oscillator and to an integrated circuit.

Abstract: A carrier generator for generating a carrier at a frequency of interest in a wireless communications system comprises an oscillator exhibiting a first impedance, the oscillator comprising an energy storage tank configured to generate a periodic signal, the energy storage tank including at least one inductor and at least one capacitor, and an amplifier coupled with the energy storage tank, the amplifier being configured to amplify an amplitude of the periodic signal, an antenna exhibiting a second impedance smaller than the first impedance, and a network coupled between the oscillator and the antenna, the network including at least one inductor or at least one capacitor and being configured to provide a third impedance such that a resultant impedance of the second impedance and the third impedance as viewed from the oscillator toward the antenna is large enough to facilitate the oscillator to generate the carrier at the frequency of interest.

Abstract: The invention relates to a proximity switch, particularly an inductive proximity switch, with an oscillator having an at least partly self-compensated feedback network influenceable by a target to be detected, as well as an oscillator amplifier.

Abstract: Provided is a voltage-controlled oscillator (VCO) using an LC resonator circuit which includes a first resonance circuit in which two serially connected varactor diodes and an inductor are connected in parallel, a second resonance circuit in which one or more inductor L1 and one or more capacitor C1 are connected in parallel, the second resonance circuit being serially connected to a port of the first resonance circuit, and a third resonance circuit in which one or more inductor L2 and one or more capacitor C2 are connected in parallel, the third resonance circuit being serially connected to the other port of the first resonance circuit.

Abstract: A phase lock loop (PLL) includes a calibration loop for calibrating a tank circuit for capacitance variation through process variations of manufacturing an integrated circuit including the PLL. A capacitance profile for setting the frequency of the PLL at a process comer is stored. At power up, or after an idle time, a calibration is performed at two frequencies. The capacitances of operating the phase lock loop at the two frequencies are determined and stored. During a frequency change, the capacitance of operating the PLL is determined from the capacitance profile and stored capacitances. The capacitance of the PLL is presumed to change linearly with frequency and the two stored capacitances are used to determine a difference capacitance at the selected frequency by linear interpolating between the two stored capacitances, which is added to the capacitance in the capacitance profile at the selected frequency to generate an operating capacitance.

Abstract: A programmable filter for LC tank voltage controlled oscillator (VCO) and a design structure for a programmable filter for LC tank VCO. The programmable filter includes a proportional control comprising a plurality of capacitance biased by different input voltages and an integral control comprising a filter element with a capacitance C1 and a set of capacitance biased by a voltage output of the filter element.

Abstract: An oscillator controller has a phase frequency detector that compares a reference signal and a frequency-divided signal and outputs a phase difference signal; a charge pump; a loop filter that filters the phase error signal output from the charge pump and outputs an oscillation frequency controlling voltage; a voltage-controlled oscillator; a first counter that counts the number of waves of the reference signal to a desired number and outputs a first flag signal; a second counter that counts the number of waves of the frequency-divided signal to the desired number and outputs a second flag signal; a first comparator that compares the first flag signal and the second flag signal and outputs a frequency comparison signal; and a control circuit that controls the voltage-controlled oscillator, the first counter, the second counter and the frequency divider by outputting signals thereto.

Abstract: A voltage-controlled oscillator has an oscillation frequency controlled through a voltage applied across ends of a variable-capacitance element. The voltage-controlled oscillator has a frequency control bias circuit which applies to a first end of the variable-capacitance element a voltage for frequency control according to a control voltage, a first current source which generates a first current according to the control voltage, a second current source which generates a second current according to temperature, independent of the control voltage, a converting resistor which converts a current, obtained by adding together the first and second currents, into a voltage, and a temperature compensation bias circuit which applies to the second end of the variable-capacitance element a voltage for temperature compensation according to the voltage produced by the converting resistor.

Abstract: The disclosure relates to an electronic circuit including at least one first and one second differential pair each including a plurality of transistors. All the transistors of said first and second differential pair are included in a single well.

Abstract: Disclosed are embodiments of a voltage controlled oscillator (VCO) capable of non-volatile self-correction to compensate for process variations and to ensure that the center frequency of the oscillator is maintained within a predetermined frequency range. This VCO incorporates a pair of varactors connected in parallel to an inductor-capacitor (LC) tank circuit for outputting a periodic signal having a frequency that is proportional to an input voltage. A control loop uses a programmable variable resistance e-fuse to set a compensation voltage to be applied to the pair of varactors. By adjusting the compensation voltage, the capacitance of the pair of varactors can be adjusted in order to selectively increase or decrease the frequency of the periodic signal in response to a set input voltage and, thereby to bring the frequency of that periodic signal into the predetermined frequency range.

Abstract: Disclosed are embodiments of a voltage controlled oscillator (VCO) capable of non-volatile self-correction to compensate for process variations and to ensure that the center frequency of the oscillator is maintained within a predetermined frequency range. This VCO incorporates a pair of varactors connected in parallel to an inductor-capacitor (LC) tank circuit for outputting a periodic signal having a frequency that is proportional to an input voltage. A control loop uses a programmable variable resistance e-fuse to set a compensation voltage to be applied to the pair of varactors. By adjusting the compensation voltage, the capacitance of the pair of varactors can be adjusted in order to selectively increase or decrease the frequency of the periodic signal in response to a set input voltage and, thereby to bring the frequency of that periodic signal into the predetermined frequency range.

Abstract: An ILO circuit has a plurality of oscillator stages which are coupled to one another by means of a “tank lock” coupling. The coupling leads to an improved synchronization of the individual oscillator stages and thus to a reduced phase noise. Any desired LC oscillator topology can be used, not just the topology with PMOS and NMOS transistors. It is also possible to use SOI transistors, that is to say transistors formed on an SOI substrate. The bulk terminals of the transistors may be coupled not only to a supply voltage but, for example, also to a center potential, a reference voltage source, to ground, in floating fashion and/or to the source terminal.

Abstract: The capacitance of the capacitor with the constant capacitance is equivalently reduced in the capacitance of a resonant capacitor in a voltage control oscillator to increase the variable amount of the capacitance of the resonant capacitor, and to expand an oscillation frequency range. There are provided a differential negative conductance generator circuit having two resonation nodes for differential output, a differential resonant circuit having a variable capacitance that is controlled by voltage control and an inductance connected in parallel to each other, and a differential negative impedance circuit. A resonant circuit and a negative impedance circuit are connected between the resonation nodes. The capacitor with the constant capacitance that occurs between the resonation nodes is reduced by the negative impedance of the negative impedance circuit.

Abstract: A voltage controlled oscillator has an amplifier circuit which includes an inductor and a variable capacitance element, and outputs an oscillation signal of an oscillation frequency corresponding to an oscillation frequency control voltage supplied to the variable capacitance element; and a power supply circuit which supplies an operation current to the amplifier circuit, wherein by changing the operation current outputted from the power supply circuit in a state where the oscillation frequency control voltage is fixed to a desired value, a value of the operation current at which the oscillation frequency of the oscillation signal takes a value in the vicinity of a maximum value, is extracted, and the extracted value of the operation current is set as a value of the operation current outputted from the power supply circuit.

Abstract: Disclosed are circuits and methods to control the amplitude of a signal generated by a VCO.

Abstract: System and method for increasing the frequency tuning range of a RF/microwave LC oscillator. An electronic communications device includes a controller to regulate the operation of the electronic communications device, a modem coupled to the controller, a radio frequency unit coupled to the controller and to the modem, an oscillator coupled to the controller and to the radio frequency unit, and an amplifier coupled to the radio frequency unit. The oscillator produces a timing and reference signal for the radio frequency unit based on control information from the controller. The oscillator includes a multi-tap inductor that may controllably alter its effective inductance to change the timing and reference signal provided to the radio frequency unit.

Abstract: A self-biasing negative transconductance LC oscillator that uses self-biasing circuitry to regulate a current source that feeds negative transconductance circuitry and direct current (DC) bias circuitry to apply a DC bias between control inputs and outputs of the negative transconductance circuitry is disclosed. A current source setpoint is based on the voltage swing of the oscillator, which can then be controlled by the DC power supply that powers the oscillator. In one embodiment of the present invention, the negative transconductance circuitry includes a pair of p-type metal oxide semiconductor (PMOS) cross-coupled field effect transistors (FETs), which have a limit applied to their gate to source voltages. Limiting the gate to source voltages of the FETs limits the percentage of the oscillation cycle that the FETs spend in the triode region and thus reduces the noise contribution of the FETs and allows for less power consumption for a given noise requirement.

Abstract: A VCO device is described that has pre-compensation. Digitally switchable compensation capacitors are selectively activated to adjust operation of the VCO to mitigate undesirable operational effects. In some example embodiments, the digitally switchable compensation capacitors of the VCO are adjusted to compensate for the effects of activating (from a quiescent state) an output buffer driven by the VCO.

Abstract: The new RTD-HBT differential oscillator circuit topology is proposed. At the nodes of the inductors and varactors in the conventional differential oscillator topology, each the RTD is attached to increase the magnitude of the negative conductance, which results in performance improvement in both the RF output power and phase noise. And, the differential sinusoidal voltage waveform which is essential for the wireless communication system are generated. In addition, the DC power consumption RTD-HBT differential oscillator circuit is similar to the conventional HBT differential oscillator due to the small DC power consumption performance of the RTD.

Abstract: A digitally controlled oscillator device includes a programming input, a selection input and an oscillator core with a first capacitive element which is frequency determining and programmable. The first capacitive element is coupled to the programming input that receives a first data word by which an oscillating frequency of the oscillator device is programmed with a predetermined frequency step size. The oscillator device further includes a selection unit for selecting a mode which is coupled to the selection input that receives a mode selection signal. The mode is selectable from a plurality of modes depending on the mode selection signal and each mode from the plurality of modes is characterized by a predetermined frequency step size. The digitally controlled oscillator device also includes a deattenuation amplifier.

Abstract: An integrated circuit design for differential variable capacitors uses an integration method to integrate an integrated circuit having differential variable capacitors as a whole, and takes the parasitic effect into consideration for the manufacturing process to lower the circuit inaccuracy and reduce the chip size effectively. Such arrangement lowers the manufacturing cost, identifies the quality of loading quality of the overall variable capacitance during the manufacture, and further controls the quality of loading capacity of the overall variable capacitance effectively. Furthermore, this invention does not need to reposition for the symmetrical position of the coils, and thus giving a very precise positioning to reduce the level of difficulty for the manufacture.

Abstract: A system for reducing phase-noise in a resonant tank circuit. The system includes a single-electron device configured to inject a single electron into the oscillator circuit tank circuit. The system further includes a synchronizer coupled to the single-electron device and configured to cause the single-electron device to inject the single electron into the resonant tank circuit at a phase based on an extreme (maximum or minimum) electrical characteristic output of the resonant tank circuit.

Abstract: A voltage controlled oscillator including an inductor circuit including inductors 101, 102, a variable capacitance circuit 110 having variable capacitance elements 111, 112 changing a capacitance according to a voltage difference between two terminals thereof and having capacitive elements 113, 114 cutting a DC component, a negative resistance circuit including cross-coupled oscillating transistors 103, 104, and a time-switched level shift circuit 108 for shifting a reference voltage to two or more levels in a predetermined period. A connection point A of the variable capacitance elements is supplied with a control voltage Vt controlling an oscillation frequency, and connection points B, C of the variable capacitance elements and the capacitive elements are supplied with a reference voltage Vref output from the time-switched level shift circuit 108 via resistors 115, 116.

Abstract: An oscillator device includes a resonator including a coil and a capacitor connected to the coil in parallel; and an oscillator connected to the resonator. Electric waves are emitted from the coil to at least one receiving antenna of the receiver while the oscillator device changes position and direction over time. The coil has an outer diameter and a total length which is approximately the same as the outer diameter.

Abstract: An LC tack structure. The structure, including a set of wiring levels on top of a semiconductor substrate, the wiring levels stacked on top of each other from a lowest wiring level nearest the substrate to a highest wiring level furthest from the substrate; an inductor in the highest wiring level, the inductor confined within a perimeter of a region of the highest wiring level; and a varactor formed in the substrate, the varactor aligned completely under the perimeter of the region of the highest wiring level. The structure may additionally include an electric shield in a wiring level of the set of wiring levels between the lowest wiring level and the highest wiring level. Alternatively, the inductor includes a magnetic core and alternating electrically non-magnetic conductive metal coils and magnetic coils around the core.

Abstract: An oscillator circuit for a sensor, with a tuned circuit and an operational amplifier, the electrical oscillation of the tuned circuit is capable of being tapped between a first terminal and a second terminal of the tuned circuit, and the first terminal of the tuned circuit being connected to the noninverting input of the operational amplifier and the output of the operational amplifier is fed back to the noninverting input of the operational amplifier. The oscillator circuit is designed to improve the dynamic behavior of the oscillator circuit by the second terminal of the tuned circuit —at least in terms of AC voltage —being directly connected to the inverting input of the operational amplifier.

Abstract: An electronic circuit device includes a negative resistance generating circuit, a second transistor and a path. The negative resistance generating circuit has a first transistor having a control terminal coupled to a resonator. The second transistor has a control terminal coupled to an output terminal of the first transistor and has an output terminal coupled to a DC bias terminal. The path is coupled to between the DC bias terminal and an output terminal of the first transistor through the second transistor and provides a bias to the first transistor.

Abstract: An adjustable inductor includes a first conductor line to receive an alternating current (AC) signal, a second conductor line configured in a loop arrangement, to generate an inducting current upon receiving the AC signal at the first conductor line, and a switch to adjust an inductance of the first conductor line by switching a loop connection of the second conductor line according to an external control signal.

Abstract: An injection-locked frequency divider (ILFD) can go beyond simple frequency division by an even number. In one embodiment, another differential pair of transistors is added to convert the injection signal into differential currents, which are mixed in the original transistor pair such as that of the conventional ILFD shown above. In another, a double-balanced ILFD structure includes multiple ILFD's which are independently tunable to allow phase differences other than quadrature.

Abstract: An injection-locked frequency divider is provided. The injection-locked frequency divider includes a variable reactance unit, a signal injection unit, a first switch, a second switch, a first transformer, and a second transformer. The variable reactance unit, the first switch, the second switch, the first transformer, and the second transformer form a transformer-based LC-tank oscillator. The signal injection unit receives an injection signal. When the injection-locked frequency divider is in a locked state, the transformer-based LC-tank oscillator outputs a frequency division signal. Employing the feedback action of the first transformer and the second transformer, the present invention not only has a wide locking range but also promotes the realization of the low operating voltage.

Abstract: A digitally controlled oscillator (DCO) includes a current generator which generates an electric current having a magnitude corresponding to an input signal, and a digitally controlled oscillating unit which generates an oscillating frequency based on an inductance which varies according to the magnitude of the electric current generated by the current generator.

Abstract: A voltage control oscillator (VCO) includes a VCO circuit and a back-gate coupling circuit, wherein the VCO circuit includes at least a first transistor, a second transistor and a resonant cavity formed by an inductor and a capacitor. The back-gate coupling circuit is formed by a plurality of capacitors and a plurality of resistors. In the embodiments of the present invention, the capacitors are coupled to the back-gate terminals of the first transistor and the second transistor, so as to reduce the power consumption and the phase noise of the VCO.

Abstract: A voltage-controlled oscillator includes an LC bank, a negative resistor circuit, a DC block, an AC block including a source resistor, and a first bias circuit controlled by a junction node of a first and second transistor, wherein the first bias circuit provides a first feedback voltage to a first control node, and maintains a voltage at the junction node of the first and second transistors, and a second bias circuit controlled by the junction node, wherein the second bias circuit provides a second feedback voltage to a second control node and maintains a voltage at the junction node.

Abstract: An oscillator circuit configuration comprising in an LC-parallel oscillatory circuit and a transistor as an amplifying element. A compensating winding is associated with the parallel oscillatory circuit whereby the collector voltage of the transistor is fed to said winding in order to compensate the effect of the parasitic collector capacity. Preferably, the collector current from the transistor is maintained constant be an amplifier.

Abstract: The design, fabrication, post-processing and characterization of a novel circular design SAW (Surface Acoustic Wave) based bio/chemical sensor in CMOS technology is introduced. The sensors are designed in AMI 1.5 ?m 2 metal, 2 poly process. A unique maskless post processing sequence is designed and completed. The three post-processing steps are fully compatible with any CMOS technology. This allows any signal control/processing circuitry to be easily integrated on the same chip. ZnO is used as the piezoelectric material for the SAW generation. A thorough characterization and patterning optimization of the sputtered ZnO was carried out. The major novelties that are introduced in the SAW delay line features are: The embedded heater elements for temperature control, compensation and acoustic absorbers that are designed to eliminate edge reflections and minimize triple transit interference. Both of these attributes are designed by using the CMOS layers without disturbing the SAW performance.

Abstract: A gyrator includes a gyrator core and at least one common mode feedback circuit. The gyrator core includes four inverters mutually connected in a loop configuration between a pair of input ends and a pair of output ends. The common mode feedback circuit is provided between the pair of input ends and/or the pair of output ends and includes a forward-reverse connection inverter set and a backward-reverse connection inverter set. The forward-reverse connection inverter set has a first inverter, a second inverter connected in reverse series with the first inverter, and a first feedback resistor connected in parallel with the second inverter. The backward-reverse connection inverter set has a third inverter, a fourth inverter connected in reverse series with the third inverter, and a second feedback resistor connected in parallel with the fourth inverter.

Abstract: An LC resonant circuit of an oscillator includes a parallel circuit of an inductor, a first fine adjustable capacitor and a first capacitor bank, and a series circuit of a second fine adjustable capacitor and a second capacitor bank. A frequency conversion gain of the oscillator is the sum of a frequency conversion gain of the oscillator based upon the first fine adjustable capacitor which decreases according to increase of a capacitance value of the capacitor bank and a frequency conversion gain based upon the second fine adjustable capacitor which increases according to increase of a capacitance value of the second capacitor bank. Accordingly, an LC resonant circuit for an oscillator with reduced fluctuation of a frequency conversion gain, and an oscillator and a data processing equipment using the same are provided.

Abstract: An LC resonator (117; 122) for a voltage controlled oscillator (13; 116) has an inductive transmission line 31; 51), and input and output ports (33a-b; 53a-b) connected to the transmission line, wherein the transmission line is grounded (G) in at least one end portion thereof. The inductive transmission line has a plurality of connection ports (P) that are capable of being connected to each other or to ground in order to tune the resonance frequency of the LC resonator from one frequency band to another. Further, a trimming capacitor (C) may be interconnected in the transmission line in order to further tune the resonance frequency of the LC resonator. Preferably, the LC resonator is formed as a microstrip or strip line structure in essentially a C or S shape on a laminate substrate (101-103).

Abstract: Apparatus and systems for synthesizing frequencies for use in a fast hopping wireless communications system. A frequency synthesizer comprises a plurality of oscillators with each oscillator having a first input coupled to a reference clock frequency signal, and a signal selector having a control signal input and a plurality of reference clock inputs with each reference clock input coupled to an output from an oscillator. Each oscillator produces a reference frequency that is a harmonic of a reference clock frequency of the reference clock frequency signal, and the signal selector couples a reference clock input to an output based on a control signal provided by the control signal input.

Abstract: An active inductor includes bipolar transistors T1, T2, T3 and TD (TD being arranged in diode), where T1's emitter is connected to an output port and to T2's collector. T2's base is connected to a first voltage line and between two connected capacitors. T2's emitter is connected to T3's collecter. An end of one capacitor is connected to T1's base and to a second voltage line. An end of the other capacitor is connected to T3's emitter and to a third voltage line. T1's collector is connected to a fourth voltage line and to TM's collecter, which is connected to TM's base. TM's emitter is electrically connected to T3's base. Preferably, the transistors T1-T3 and TD are Silicon based, and the active inductor is fabricated on a single substrate comprising Silicon. The active inductor is incorporated into adaptive oscillators and amplifiers and an improved transceiver.

Abstract: CMOS LC tank circuits and flux linkage between inductors can be used to distribute and propagate clock signals over the surface of a VLSI chip or processor. The tank circuit offers an adiabatic behavior that recycles the energy between the reactive elements and minimizes losses in a conventional sense. Flux linkage can be used to orchestrate a number of seemingly individual and distributed CMOS LC tank circuits to behave as one unit. In one example, the distribution of a 45° separated multi-phase balanced oscillations over the surface of die 1.6 cm×1.6 cm at 10 GHz is expected to dissipate under 10 W and offers a potential to significantly reduce the road map predictions of 100 W. Simulations of several CMOS tank circuits indicate that the power dissipation can be reduced an order of magnitude when compared to conventional techniques. A passive flux linkage, mechanical, and finite state machine technique of frequency adjustment of an oscillator are described.

Abstract: The present invention discloses an automatic page detector, to determine which page of a book is open. The automatic page detector uses a sensor plate and an inductor as a sensor. In the invention, there is a sensor plate at each page of the book and the locations of the sensor plates for different pages are different. There is an array of inductors just beneath the sensor plates when the book is closed. The inductors are connected to the feedback loop of a LC oscillator through analog switches. The proximity of a sensor plate to an inductor will change the frequency of the LC oscillator. Scanning the analog switches by a microprocessor and detecting the variation of frequency of the LC oscillator during each scanning time period, the status of each sensor plate will be detected and we can determine which page of a book is opened.

Abstract: A resistance having a high impedance is connected between anode terminals of two variable capacitance diodes sharing a cathode, and the components described above are sealed in one package. The resistance can be formed of a diffusion region between p-regions of the variable capacitance diodes or can be formed of polysilicon and disposed on a chip. Thus, the resistance can be mounted while a chip size of the variable capacitance diode is maintained. Accordingly, it is not required that a bias resistance having a high impedance is additionally provided, whereby achieving reduction in the substrate mounting area and reduction in costs of the set.